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In the Front Line - Shoreline Protection and Other Ecosystem Services from Mangroves and Coral Reefs
UNEP Publication (2006)
In the front line
Shoreline protection and other ecosystem services
from mangroves and coral reefs
In the front line
Shoreline protection and other ecosystem services
from mangroves and coral reefs
In the front line
UNEP World Conservation Monitoring Centre ACKNOWLEDGEMENTS
219 Huntingdon Road, We gratefully acknowledge the many partners and
Cambridge CB3 0DL, institutions who contributed to this publication, in
United Kingdom particular the following individuals who provided
Tel: +44 (0) 1223 277314 information and comments on early drafts: John Agard,
Fax: +44 (0) 1223 277136 Tundi Agardy, Jackie Alder, Daniel Alongi, Andrew Baird,
Email: info@unep-wcmc.org Nicola Barnard, Juan Bezaury, Simon Blyth, Barbara
Website: www.unep-wcmc.org Brown, Marion Cheatle, Isabelle Côté, Salif Diop, Alasdair
Edwards, Norberto Fernandez, Harinda Fernando, Phil
THE UNITED NATIONS ENVIRONMENT PROGRAMME WORLD Fox, Alison Glass, Stefan Hain, Mark Huxham, Val Kapos,
CONSERVATION MONITORING CENTRE (UNEP-WCMC) is the Carmen Lacambra, Ian May, Nick Nuttal, Pascal Peduzzi,
biodiversity assessment and policy implementation arm of Pasi Rinne, Toby Roxburgh, Charles Sheppard, Jerker
the United Nations Environment Programme (UNEP), the Tamelander, Kristian Teleki, Ruben Torres, Collette
world’s foremost intergovernmental environmental Wabnitz, Alan White, Victoria Wood and Kaveh Zahedi.
organization. The Centre has been in operation for over 25
years, combining scientific research with practical policy
advice.
UNEP-WCMC provides objective, scientifically rigorous
products and services to help decision makers recognize
the value of biodiversity and apply this knowledge to all
that they do. Its core business is managing data about
ecosystems and biodiversity, interpreting and analysing
that data to provide assessments and policy analysis, and
making the results available to national and international
decision makers and businesses.
Lead Author: Sue Wells
Contributing authors: Corinna Ravilious and
Emily Corcoran
Front cover photos: Y Yusuf; UNEP/Topham;
E Clua/CRISP, 2005; S Wells; UNEP-WCMC World
Atlas of Coral Reefs.
Back cover photo: S Wells
Citation: UNEP-WCMC (2006) In the front line: shoreline
protection and other ecosystem services from mangroves
and coral reefs. UNEP-WCMC, Cambridge, UK 33 pp
©UNEP-WCMC/UNEP 2006
A Banson production
Printed in the UK by Cambridge Printers
The contents of this report do not necessarily reflect the views or policies of the United Nations Environment Programme, the UNEP World Conservation
Monitoring Centre, the International Coral Reef Action Network or IUCN–The World Conservation Union. The designations employed and the presentations
do not imply the expressions of any opinion whatsoever on the part of these organizations concerning the legal status of any country, territory, city or area
or its authority, or concerning the delimitation of its frontiers or boundaries.
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Contents
Introduction........................................................................................................................................................................... 4
Key messages....................................................................................................................................................................... 5
Global status of reefs and mangroves.................................................................................................................................. 7
Distribution...................................................................................................................................................... 7
Status............................................................................................................................................................... 7
Threats............................................................................................................................................................. 9
Value of ecosystem services................................................................................................................................................. 12
Regulating services – shoreline protection.......................................................................................................................... 14
Wind-generated waves and storms................................................................................................................ 15
Tsunamis......................................................................................................................................................... 16
Other ecosystem services..................................................................................................................................................... 18
Other regulating services................................................................................................................................ 18
Climate and global carbon cycle...................................................................................................... 18
Water quality..................................................................................................................................... 18
Cultural services.............................................................................................................................................. 18
Tourism............................................................................................................................................. 18
Provisioning services....................................................................................................................................... 19
Fisheries and other marine products.............................................................................................. 19
Mangrove forest products................................................................................................................ 20
Pharmaceuticals.............................................................................................................................. 20
Supporting services......................................................................................................................................... 20
What happens when ecosystem services are lost?.............................................................................................................. 21
Loss of regulating services............................................................................................................................. 21
Loss of provisioning services.......................................................................................................................... 22
Loss of cultural services................................................................................................................................. 22
Natural recovery – or rehabilitation and restoration?.......................................................................................................... 23
Coral reefs....................................................................................................................................................... 24
Mangroves........................................................................................................................................................ 25
Mangroves and coral reefs on tropical coastlines of the future.......................................................................................... 26
Maintaining regulating services...................................................................................................................... 26
Maintaining provisioning services................................................................................................................... 26
Maintaining cultural services.......................................................................................................................... 27
Essential management tools.......................................................................................................................... 27
Integrated coastal management..................................................................................................... 28
Marine protected areas.................................................................................................................... 28
Improved resilience and adaptive management............................................................................. 29
Financing the future........................................................................................................................................ 29
References............................................................................................................................................................................. 31
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Introduction
The Indian Ocean tsunami of 26 December 2004 and its hurricanes and typhoons, and other potential consequences
tragic and devastating consequences were a wake-up call of global warming. More than ever, it is essential to consider
for the global community, dramatically drawing attention to the full value of ‘ecosystem services’ (the benefits that
the vulnerability of tropical coastal ecosystems and the people obtain from ecosystems) when making decisions
dangers of undermining the services they provide to about coastal development.
humankind. This was further emphasized by the The aim of this publication is to help decision
catastrophic hurricane season in the Gulf of Mexico in makers and policy makers around the world understand the
2005 when Hurricanes Katrina, Rita and Wilma caused importance of coastal habitats to humans, using coral reefs
much publicized and extensive damage to coastal areas. and mangroves as an example. It looks at the role of these
The numerous other tropical storms that affected coastal ecosystems in protecting the coast, and takes into account
communities and ecosystems in other parts of the world new studies of this complex topic triggered by the tsunami
in the same year received much less attention, but were and tropical storms. The publication also addresses the
also notable. huge range of other benefits provided by these ecosystems
The lessons learnt in terms of loss of life, damage and the role that they can play in coastal development and
sustained, and approaches to reconstruction and mitigation in restoring and maintaining the livelihoods of those who
are critically relevant to future management of the coast in have suffered from extreme events, whether natural or
a context of increasing severe weather events such as induced by human activity.
NASA/Still Pictures
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Key messages
GLOBAL STATUS OF CORAL REEFS AND MANGROVES Ecosystems that can no longer provide their full ecological
Coral reefs and mangroves are two of the world’s rarest services have a social and economic ‘cost’ that can be felt
ecosystems, covering an area that is an order of magnitude locally and many miles away. Degradation of coral reefs and
less than that of tropical and subtropical forests. Both mangroves may, and in some cases already does, cause:
❏ Reduced fish catches and tourism revenue in
ecosystems are under serious threat.
❏ Some 30 per cent of reefs are already seriously coastal communities, and potentially even loss
damaged and 60 per cent could be lost by 2030. of food security and malnutrition due to lack
Threats include overfishing, use of destructive of protein.
❏ Loss of export earnings and decline of the
fishing methods, coral mining, pollution, sedi-
mentation, anchor damage and tourism, as well tourism industry.
❏ Increased coastal erosion and destruction from
as coral bleaching, disease and tropical storms.
This combination of impacts is causing a shift, on storms and catastrophic natural events, which
many reefs, from a coral-dominated ecosystem to affects coastal residents, tourism operations and
one dominated by algae. many other economic sectors.
❏ An estimated 35 per cent of the world’s original
mangrove cover has already gone, with some SHORELINE PROTECTION
countries having lost up to 80 per cent. Mangroves Reefs and mangroves naturally form barriers and thus
have been degraded by conversion to aquaculture, inevitably provide some shore protection, a fact long
timber extraction, use of wood for fuel and recognized by coastal communities, fishers and vessels
charcoal production, diseases and storms. which use the sheltered waterways behind these
ecosystems. Both reefs and mangroves can themselves be
ECOSYSTEM BENEFITS damaged by strong winds and waves, and so their buffering
Coral reefs and mangroves provide benefits under the four capacity is a balance between their resilience and their
categories of ecosystem services defined by the 2005 vulnerability. The current consensus is that:
❏ Reefs and mangroves play an important role in
Millenium Ecosystem Assessment:
❏ Regulating – e.g. protection of shores from storm shore protection under normal sea conditions
surges and waves; prevention of erosion. and during hurricanes and tropical storms. At
❏ Provisioning – e.g. fisheries, building materials. least 70-90 per cent of the energy of wind-
❏ Cultural – e.g. tourism, spiritual appreciation. generated waves is absorbed, depending on how
❏ Supporting – e.g. cycling of nutrients, fish nursery healthy these ecosystems are and their physical
habitats. and ecological characteristics.
❏ In a tsunami, the buffering capacity of reefs and
They are among the most valuable ecosystems in terms of mangroves is more variable and often reduced
their benefits to humankind: because of the different structure and form of
❏ Economic valuation of ecosystems needs to be the waves and their much greater force. Distance
treated with caution but annual values per km2 from the earthquake epicentre, the presence of
have been calculated at US$100 000-600 000 for inlets and headlands, the gradient of the
reefs and US$200 000-900 000 for mangroves. continental slope, shoreline elevation, the
❏ The small total area of coral reefs and mangroves presence of dunes and other vegetation, and
belies their importance in terms of fisheries, density of habitation and infrastructure seem to
other extractive uses, shoreline protection and, in explain most of the variation.
the case of reefs, tourism and recreation.
❏ Both ecosystems contribute significantly to PROS AND CONS OF REHABILITATION AND RESTORATION
national economies, particularly those of small Both reefs and mangroves will recover naturally once a
island developing states (SIDS), 90 per cent of stress has been removed, but this can be slow; for example,
which have coral reefs and over 75 per cent of the reefs most seriously damaged by the tsunami may take
which have mangroves. five to ten years to recover. New growth of coral colonies and
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❏ The devastation recently wrought by hurricanes
mangrove trees, and recruitment of coral larvae and
mangrove seedlings, is balanced by erosion and breakdown and tropical storms testifies to the priority that
from both human-induced and natural stresses. The must be accorded to the maintenance and
chronic human impacts faced by these ecosystems are enhancement of the resilience of natural coastal
tending to slow recovery, and the highest priority is to barriers such as reefs and mangroves.
❏ Post-tsunami and hurricane reconstruction
reduce and eliminate these stresses. It is tempting to try to
speed recovery of an ecosystem by active restoration, or efforts provide an opportunity to introduce and
repair. However, this is rarely totally successful because of expand good coastal management practices.
the difficulties involved in re-establishing full biodiversity These may indeed help to mitigate damage from
and ecological processes: future tsunamis but, since these are infrequent
❏ Mangrove restoration is relatively simple and events, the more important consequence is
large areas of new forest are being created using mitigation of the impacts of the more certain, but
volunteers and local labour. However, achieving a gradual, changes due to global warming.
❏ Short-term, small-scale rehabilitation progr-
mangrove forest with a full complement of
biodiversity is a more complex and long-term ammes should not take precedence over
process, and it is questionable whether any activities directed at the root causes of the
programmes have yet achieved this. decline in reef and mangrove health. Key tools
❏ Reefs, involving numerous species with very include integrated coastal management, marine
different life histories and poorly understood protected areas, and monitoring and assessment
growth and reproductive characteristics, are for adaptive management.
❏ Governments, civil society and the private sector
more difficult to restore. Many attempts have
been made using a variety of techniques. Most must recognize that, as with other benefits, there
methods are costly and require considerable is a price to pay for maintaining these eco-
skill, and there are few examples of successful systems. However, this is much lower than the
sustainable reef restoration over large areas. benefit received. For example, the estimated
average operational management cost of a
marine protected area is US$775 per km2, or less
CORAL REEF AND MANGROVE MANAGEMENT IN THE
FUTURE than 0.2 per cent of the estimated global value of
Investing in environmentally sustainable management a square kilometre of reef or mangrove.
❏ Many of the world's wealthiest nations have
and development of the coast will be more cost effective
than restoring human livelihoods and ecosystems after a jurisdiction over these ecosystems – more than
catastrophe. The relatively small amount of damage 30 per cent of reefs are in countries classified as
inflicted on coral reefs and mangroves by the highly developed. They also have strong links
2004 tsunami demonstrated the resilience of these with less developed countries struggling with
ecosystems to natural disturbance, but the worldwide their management. Political will and concerted
public concern generated also revealed our awareness of action are needed – coral reefs and mangroves
their vulnerability. are in the front line, and calling for attention.
D Sato/UNEP/Topham
S Wells
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Global status of reefs and
mangroves
Mangroves and tropical coral reefs
DISTRIBUTION
Of the 177 countries in the world, rather less than half (44 countries is very unequal. Australia and Indonesia each
have about 50 000 km2 of reef and account for nearly 35 per
per cent) have tropical coral reefs and about half have
mangroves. Our knowledge of the distribution of coral reefs cent of the world’s reefs, and Indonesia alone has 23-25 per
and mangroves is now relatively good, as a result of regional cent of the world’s mangroves. In general, other countries
have less than 10 000 km2 of reef and less than 1 000 km2 of
and global mapping programmes using navigational charts,
satellite imagery and aerial photography, as well as more mangroves (Spalding et al., 1997; 2001).
detailed field surveys.
Both ecosystems occur principally in the tropics, STATUS
with South-East Asia a major centre. Distribution between The coastal biome, which makes up only 4 per cent of the
Fig. 2: Distribution of tropical coral reefs and mangroves
Fig. 1: Area of coral reefs and mangroves
Coral reefs and mangroves are among the world’s rarest
ecosystems. Reefs cover an estimated 284 300 km2, or just 1.2 per
cent of the world’s continental shelf area (Spalding et al., 2001).
The total area of mangrove forest is less certain but is even
smaller, estimated at between 167 000 km2 (Valiela et al., 2001)
and 181 000 km2 (Spalding et al., 1997). As a comparison, tropical
and subtropical forests cover 23.3 million km2, an order of
magnitude larger (Millennium Ecosystem Assessment, 2005).
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planet’s total land area, is home to one-third of the world’s
P Dustan
population, and this population is predicted to double over
the next 15 years. In many countries, such as island nations
and those with inhospitable and arid interiors, humankind
lives almost entirely on the coast. With the exception of
some isolated atolls, all reefs and mangroves lie adjacent to
the coast; more than half these ecosystems occur within 25
km of urban centres inhabited by 100 000 or more people
(Millennium Ecosystem Assessment, 2005). Not
surprisingly, the health and extent of both reefs and
mangroves have declined dramatically over the last century.
Trends in reef health are well documented as
P Dustan
assessments are carried out at regular intervals, through
numerous monitoring programmes, the results of which
are published in the biennial Status of the World’s Reefs
Reports (Wilkinson, 2004), the regional World Resources
Institute’s Reefs at Risk reports (Burke and Maidens, 2004;
Burke et al., 2002) and many national reports.
Results from monitoring programmes indicate that
about 30 per cent of the world’s reefs are seriously
damaged, with possibly no pristine reefs at all remaining,
and it has been predicted that 60 per cent of reefs will be
lost by 2030 (Wilkinson, 2004). Using information on existing
and potential threats to reefs in 1998, the World Resources Carysfort Reef, the largest and most luxuriant reef in the Florida
Keys, United States, in 1975 (higher) and 2004 (lower) showing the
Institute suggested that 27 per cent of all reefs are
catastrophic decline of living coral cover.
potentially at high risk and a further 31 per cent are at
medium risk of damage (Bryant et al., 1998). More recent
regional predictions, using the same method, paint an even
Reefs at risk in the Caribbean
more disturbing picture. A 2000 analysis estimated that
human activities potentially threaten 88 per cent of the Nearly two-thirds of reefs in the Caribbean are potentially at risk
from human activities, according to a 2004 report, with over 40 per
reefs of South-East Asia, with 50 per cent at ‘high’ or ‘very
cent at ‘high’ or ‘very high’ risk, and about 28 per cent at low risk
high’ risk and only 12 per cent at low risk (Burke et al.,
(Burke and Maidens, 2004). In this region, elkhorn (Acropora
2002). palmata) and staghorn (A. cervicornis) corals have undergone
As yet there are no equivalent global mangrove massive die-offs (Gardner et al., 2003).
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Fig. 3: Area of mangrove lost to human activities
assessments, but several studies have shown this
(per cent)
ecosystem to be as much at risk as coral reefs. The
amount of mangrove lost varies widely among countries
but, where data are available, mangroves are on a
declining trend. An estimated 35 per cent of mangrove
forest has disappeared in the last two decades (Valiela et
al., 2001), and some countries have lost 80 per cent of
cover (Spalding et al., 1997). The average annual rate of
disappearance (or conversion to other forms of land use)
is estimated at 2.1 per cent, with the greatest rate of loss
in the Americas (3.6 per cent). The annual rate of loss of
mangroves thus exceeds the rate of disappearance of Source: Valiela et al., 2001
tropical rainforests (0.8 per cent) (Valiela et al., 2001).
little to the main structure of the reef (e.g. Agaricia) (Hughes
Estimates for some locations suggest that rates of
mangrove loss may be as high as 50 per cent a year et al., 2003; Knowlton, 2001).
(Alongi, 2002). Degradation of mangroves leads to long-term
Over the last few decades there have been major changes in the ecology of large areas of coastline. In
changes in the appearance and quality of reefs and particular, conversion of mangroves to shrimp farms, and
mangroves, the result of a combination of many ‘drivers’ or the subsequent aeration and use of fertilizers, alters the
threats. These have both direct and indirect impacts that composition and structure of the soil. Eventually ponds
often trigger an escalating series of problems. are abandoned, sometimes after only two to ten years, as
Many reefs, for example, are undergoing a shift from they are no longer suitable for production (Stevenson,
a coral-dominated to an algal-dominated state. Corals have 1997). There is little chance of mangrove regeneration in
been disappearing as a result of bleaching, disease, storm the remaining barren lands. Leading causes of mangrove
damage and a range of human activities, including forest loss and degradation are conversion for
overfishing, use of destructive fishing gear, anchor damage aquaculture, use of mangroves for timber for
and pollution. At the same time, algae have increased as construction and other functions, and for fuelwood and
herbivores and grazers, such as sea urchins and some fish charcoal, conversion to rice paddies, and freshwater
species, that keep them in control have declined through diversion and coastal development for tourism and other
disease and overfishing. Algae have further increased as a purposes (Valiela et al., 2001).
result of nutrient pollution. Where coral cover has started to
increase there are indications that the so-called THREATS
framework-building corals (e.g. Acropora, Montastrea) that
once dominated are being replaced by corals that contribute Overexploitation and destructive fishing
Many commercial fish species, such as rabbitfish
(Siganidae), feed on algae, and their removal can result in
The brown seaweed Chnoospora overgrowing branching corals.
excessive algal overgrowth of corals. Removal of
Y Latypov
‘keystone’ species (those that play a particular role in an
ecosystem) – such as triggerfish which prey on sea
urchins – may be the cause of urchin population out-
breaks which further degrade corals through bioerosion.
Dynamite, small-mesh nets and nets that are dragged
over the seabed, although illegal in many countries, are
still used and cause widespread physical damage as well
as removing or killing immature fish and other species of
no commercial value.
Habitat loss
Mangroves can be completely wiped out when forests are
cleared for salt production operations, for industrial,
residential and tourism development, or, particularly, for
aquaculture. In contrast, coral reefs generally suffer from
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UNEP
In Honduras, shrimp farms have progressively transformed the coast of the Gulf of Fonseca since the early 1970s. Although there were still large
areas of mangrove in 1987, by 1999 the only substantial forests were in protected areas such as Estero Real Nature Reserve (UNEP, 2005a).
a gradual decline in quality rather than a sudden Disease
disappearance. However, mining for corals for use as Coral diseases, rarely recorded until the 1970s, have had
building materials can eliminate, or reduce to rubble, a catastrophic effect on reefs, particularly in the
large areas of reef. Although coral mining is illegal or Caribbean, affecting 100 hard and soft coral species in 54
regulated in most countries, it is still having a major countries. The cause is still largely unknown, although
impact in India, the Maldives, Sri Lanka and Tanzania
Sediment plume in Monte Cristi National Park, Dominican Republic.
(Wilkinson, 2004).
Inland deforestation is causing sediment run-off on to nearby coral
reefs. As a result, coral cover tends to be low compared with other
Land-based sources of pollution less impacted areas.
More than 77 per cent of the pollutants entering the oceans
UNEP-WCMC
originate on land, and 44 per cent of these pollutants come
from improperly treated wastes and run-off (Cicin-Sain et
al., 2002). The nutrient content of the oceans has increased
dramatically in recent years as a result of fertilizer and other
agricultural run-off, sewage and aquaculture waste.
Nutrients such as nitrogen and phosphorus deplete oxygen
in the water and promote the growth of algae on reefs
(Hughes et al., 2003).
Many coastal development activities, such as
residential, tourist, industrial and port development, involve
land reclamation and dredging which invariably results in
sediment being stirred into the water column.
This reduces light penetration, may directly smother corals
and can damage mangroves. Construction activities inland,
agriculture and deforestation, and poor management also
contribute to increased sediment.
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A W Bruckner
Thomas Heeger
Coral attacked by black-band disease. Fishing with dynamite in the Philippines.
both fungi and bacteria have been identified as pathogens Furthermore, by 2100, rates of calcification (the
in two cases (Porter, 2001; UNEP-WCMC, 2003). There are process by which calcium is formed) on reefs may have
indications that abrasion of massive corals through tourist decreased by 17-35 per cent of pre-industrial levels as a
activities may make corals more susceptible to disease result of high levels of dissolved carbon dioxide in the
(Hawkins et al., 1999). oceans (these are now 380 parts per million (ppm),
compared with 280 ppm two centuries ago). This will cause
Climate change weakening of coral skeletons and slower growth rates,
There is now general consensus that extreme storm events making reefs even less effective as breakwaters (Feeley et
are becoming more frequent, and sea levels and al., 2004; Kleypas et al., 1999).
sea surface temperatures are rising as a result of global
warming. Reefs are already suffering from bleaching events Other threats
that have increased significantly since 1975. In the Individual tourists, tourist boats and anchors may have only
Caribbean bleaching events are predicted to become an a minor impact, but over time and in large numbers the
annual event as current sea surface temperatures are in the impact becomes significant (Hawkins et al., 1999; Zakai and
upper temperature threshold for coral survival (Gardner et Chadwick-Furman, 2002). Spills of oil and toxic chemicals,
al., 2005; Hughes et al., 2003). Tropical storms are forecast and dumping of other wastes, cause localized impacts to
to become even more frequent and/or more intense both reefs and mangroves. The introduction of alien species
(Trenberth, 2005), and this will compound the problem, is a threat to marine ecosystems that is growing rapidly with
causing more damage to both reefs and mangroves and increased shipping and susceptibility in systems degraded
resulting in shorter recovery times between events (Hughes by other stresses. Marine plants and animals can be
et al., 2003). transported immense distances on the hulls of vessels or in
The change on reefs from coral to algal dominance, ballast water. Non-indigenous sessile species have been
and from framework-building species to non-framework introduced to reefs in Guam via ships’ hulls, and other alien
species, may also compromise their ability to keep pace with species are spreading on the reefs of Hawaii, outcompeting
rising sea levels (Bellwood et al., 2004; Gardner et al., 2003). native species (Eldredge, 2003).
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Value of ecosystem services
The Millennium Ecosystem Assessment (Millennium
C Ravilious
Ecosystem Assessment, 2005) defines four categories of
ecosystem services:
❏ provisioning – e.g. food, medicines,
construction materials
❏ regulating – e.g. protection of shorelines,
water quality maintenance
❏ cultural – e.g. tourism, spiritual beliefs
❏ supporting – e.g. maintenance of basic life
support systems.
Coral reefs and mangroves provide benefits under all four
categories.
Ecosystem services Coral reefs Mangroves
REGULATING Protection of beaches and coastlines Protection of beaches and coastlines from
from storm surges and waves storm surges, waves and floods
Reduction of beach erosion Reduction of beach and soil erosion
Formation of beaches and islands Stabilization of land by trapping sediments
Water quality maintenance
Climate regulation
PROVISIONING Subsistence and commercial fisheries Subsistence and commercial fisheries
Fish and invertebrates for the Aquaculture
ornamental aquarium trade Honey
Pharmaceutical products Fuelwood
Building materials Building materials
Jewellery and other decoration Traditional medicines
CULTURAL Tourism and recreation Tourism and recreation
Spiritual and aesthetic appreciation Spiritual – sacred sites
SUPPORTING Cycling of nutrients Cycling of nutrients
Nursery habitats Nursery habitats
Techniques for valuing ecosystem services are still There is, however, no single agreed total value for all
relatively new and untested, and the results of such coral reefs or all mangroves, or even for the different
calculations must be interpreted with care. Putting services provided by these ecosystems. Values vary
a monetary value on an ecosystem, however, can help to according to:
❏ The location – e.g. reefs that are major tourist
demonstrate why its survival is important (IUCN/TNC/
World Bank, 2004; Turner et al., 2003). Economic values destinations will have a higher value in terms of
can be calculated from the cost of the products (e.g. fish) diving and other reef-related activities than
and services (e.g. tourism) derived from an ecosystem, or those where tourism has not been developed.
❏ The length of time being considered and
from the cost of replacing a service (e.g. building
seawalls where natural storm protection has been lost). whether a prediction for the future is involved
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(e.g. all reefs are potentially of value for diving Fig. 4: Economic value of the main ecosystem
services of coral reefs (billion US$)
tourism but some may have no value at present).
❏ The ‘beneficiaries’ of the service, since some
people will place a higher value on it than others.
❏ The method used and the assumptions made.
Furthermore, it is hard to calculate the economic value
of the aesthetic and ethical benefits of ecosystems, or of
the service some ecosystems provide through cycling
nutrients. Estimates of the ‘total’ economic value of an
ecosystem thus vary considerably and there is a risk
that using this approach underestimates the
ecosystem’s social benefits and overall importance. This
means that it is not always wise to use ecosystem Source: Cesar et al., 2003
valuations for policy making and investment decisions
(IUCN/TNC/World Bank, 2004). For example, the
to US$3.5 million per km2 have been calculated
apparent higher value assigned to mangroves than coral
reefs (see Fig. 4) should not be interpreted to mean that for mangroves (Sathirathai and Barbier, 2001).
they have a higher management priority. It is also true
that many of the activities that bring benefits, such as Some of the variation can be explained by the location of
fishing and tourism, also damage reefs and mangroves, the ecosystem. The value of reefs and mangroves for
and only careful management will allow the full values shore protection (often measured per linear kilometre)
to be materialized. depends on the activities under way or planned along a
However, if these limitations are taken into particular stretch of coast. In Indonesia, reefs have been
account, an economic valuation can help to demonstrate valued as follows (Cesar, 1996):
❏ Reefs adjacent to sparsely populated areas
the major role that reefs and mangroves play in the lives
of many people. Studies to date have shown that most where agriculture is the main activity: US$829
benefit comes from provisioning services (i.e. fisheries per km, based on the value of agricultural
and, for mangroves, timber and fuelwood), cultural production that would be lost if there were no
services (tourism) and regulating services (shore protection.
❏ Reefs adjacent to areas of high population
protection).
The total annual economic value of reefs has densities: US$50 000 per km, based on the cost
been estimated at between US$100 000 and US$600 000 of replacing housing and roads if coastal
per km2 (Cesar et al., 2003; Constanza et al., 1997) and protection were lost.
❏ Reefs in areas where tourism is the main use:
the value of mangroves even higher, at more
than US$900 000 per km2 (Constanza et al., 1997). US$1 million per km, based on the cost of
Figures are, however, very variable as some national maintaining sandy beaches.
estimates show:
❏ Sri Lanka’s coral reefs have been valued at Similar values have been obtained for the Caribbean,
between US$140 000 and US$7.5 million per varying from US$2 000 to US$1 million, with the highest
km2 over a period of 20 years (Berg et al., 1998). values in areas heavily developed for tourism (Burke and
❏ In American Samoa, mangroves, which cover less Maidens, 2004).
than 0.5 km2, have an estimated value There are also several methods for valuing
of US$104 000 per km2 (total value of about mangroves. The storm protection value of mangroves in
US$50 million a year) and reefs, which cover 222 Sri Lanka (before the tsunami) was put at US$7 700 per
km2, are estimated at US$14 300 per km2 (total km2 a year using a linear value (UNEP/GPA, 2003). A study
value of US$318 million a year) (Spurgeon and in Indonesia, in a different approach, calculated the
Roxburgh, 2005). erosion control value of mangroves as being equivalent to
❏ In Thailand, very high values of US$2.7 million US$600 per household per year (Ruitenbeek, 1992).
13
In the front line
Regulating services – shoreline
protection
S H Grady
Although reefs and mangroves form natural barriers Hotel built behind mangroves, Kenya.
along the coast and thus inevitably provide some
protection to the shore, there is surprisingly little Orissa, India, a powerful cyclone in 1999 and associated
scientific data to back this up. Most of the evidence is waves caused extensive damage and human mortality,
observational and anecdotal, and relates to normal wave but communities protected by mangrove belts were less
energy and storms. The calm lagoons inside reefs and affected (Mangrove Action Project, 2005). In Viet Nam,
behind mangroves are immediately evident on tropical mangroves have been observed to limit damage from
coastlines. Fishers use these sheltered waters as cyclone waves and tsunamis and are said to have led to
navigation routes and for fishing, particularly during large savings on the costs of maintaining sea dykes (Ha,
bad weather or the rough season monsoons. Holiday 2003; Tri et al., 1996).
makers and tourists benefit from the sheltered waters In southern India, the distinct differences
for numerous recreational activities. The breakwater between the Gulf of Mannar and Palk Bay, caused by the
role of reefs is emphasized by the importance accorded protection provided by reefs, have led to these seas being
to the channels through them. These allow safe passage equated with men and women by local villagers. The
to the lagoon and shore for fishing, navigation and former is considered ‘male' because waves hit the reef
recreational activities, particularly in bad weather, a and subside in force before they reach the shore. The
significance recognized by both coastal communities latter is considered ‘female’ because waters are
and port authorities. generally calmer, but, if disturbed by storms, cause
Coastal communities are often aware of the greater damage due to the lack of a reef. Fishing
particular protection afforded by mangroves. In India communities on Pamban, an area lying between the two
(Dahdouh-Guebas et al., 2005) and the Philippines seas, still remember the 1964 cyclone that washed away
(Walters, 2004), villagers tell of how they have been one village, while those behind reefs survived
protected from cyclones and typhoons in locations where (Whittingham et al., 2003). Further north, in Chidambaran
mangroves are intact, but suffer where mangroves have District the shore protection role of mangroves is
recognized by local people where a 113 km2 forest is used
been converted to shrimp farms or otherwise lost. In
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In the front line
as a sacred grove and is traditionally known in Tamil as reef flat between the reef edge and the shore, the more
Alaithi Kadukal, which means ‘the forest that controls the wave energy is lost. In Egypt, for example, the reef flat and
waves’ (WWF, 2005). reef crest of the fringing reef off the tourist resort of
Both reefs and mangroves also play a role in the Hurghada dissipate wave energy considerably, protecting
accretion of coastlines. Reefs produce sand that forms marinas and beaches (Frihy et al., 2004).
and replenishes sandy beaches and islands, the sediment
accumulating when corals and other calcified organisms
S Wells
break down after their death. Mangroves help to stabilize
coastal land, by trapping sediment washed down in rivers
or from more general run-off. Remains of rows of
mangroves planted to stabilize the coast by early
generations of Maoris can still be seen in New Zealand
(Vannucci, 1997).
The role of reefs as breakwaters is also
demonstrated by the many artificial structures that are
being installed for shoreline protection in locations with
no natural reefs. These often have a negative impact, in
terms of creating unwanted longshore drift, but they
nevertheless show how reef-type barriers influence wave
action, even being installed to improve surfing conditions
(Jackson et al., 2002).
Although the general buffering capacity of reefs
and mangroves thus seems obvious, the mechanical
processes involved are complex, and the extent to which
they provide shore protection compared with man-made
barriers and other natural features is not yet fully
The lagoon behind the fringing reef here in northern Zanzibar
understood. Furthermore, the reef and mangrove provides a shallow sheltered area where many activities can be
ecosystems are themselves damaged by events such as undertaken.
storms and tsunamis. Hurricanes, for example, can
reduce coral cover significantly (Gardner et al., 2005). The amount of energy reduction also depends on
Mangroves can be destroyed or seriously degraded by the extent of fragmentation of the reef, as a continuous
hurricanes, through defoliation and uprooting by the reef acts more as a breakwater than a reef that is broken
wind, erosion of the shoreline by waves and burial under by channels. The state of the tide and the depth of water
sediment. In 1999 Hurricane Mitch destroyed 97 per cent over the reef – at low tide a reef affords more protection –
of the mangroves of Guanaja, one of the Bay Islands in and whether it 'plunges' on to or 'spills' over the reef top
Honduras (Cahoon and Hensel, 2002). Thus the buffering also play a role (Gourlay, 1994; Kabdali and Turker, 2002).
capacity of both ecosystems is a balance between their Quantifying what the reduction in wave energy may mean
resilience and their vulnerability, with many factors in terms of shore protection is more difficult. In Sri Lanka,
involved. A healthy coral reef or mangrove, in the absence however, it has been estimated that with current rates of
of human impact, acts as a self-repairing breakwater, erosion and assuming that 1 kilometre of reef protects 5
kilometres of shoreline, 1 km2 of coral reef can prevent
with growth in equilibrium with the erosion caused by
2 000 m2 of erosion a year (Berg et al., 1998).
waves, storms and other processes.
Mangroves dissipate the energy and size of waves as
WIND-GENERATED WAVES AND STORMS a result of the drag forces exerted by their multiple roots and
The waves normally seen on the ocean are generated by stems. Wave energy may be reduced by 75
wind, and have most of their energy in the surface waters. per cent in the wave's passage through 200 metres
The reef flat (the zone of a reef extending seaward across of mangrove (Massel et al., 1999) but, as with coral
the lagoon) and the reef crest (the seaward edge of the reef reefs, other factors also have an influence, including coastal
flat) absorb most of a wave’s force, often up to or more than profile, water depth and bottom configuration. One study
90 per cent (Brander et al., 2004; Lugo-Fernandez et al., suggested that a 1.5-km belt of mangrove may be able to
1998; Roberts and Suhada, 1983). The greater the width of reduce entirely a wave one metre high (Mazda et al., 1997).
15
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2004 tsunami, and the damage they received,
A Baird
varied considerably.
Despite initial fears, both ecosystems were less
badly damaged than expected even on reefs in Aceh,
Indonesia, which were within 300 km of the epicentre
(Baird et al., 2005). In Thailand, of 175 reef sites surveyed
on the Andaman coast after the tsunami,
more than 60 per cent had little or no damage; 13 per
cent were seriously damaged, however. Shallow reefs on
wave-exposed islands and shorelines were most
vulnerable, as were the northernmost coast and offshore
islands (Phongsuwan and Brown, in press). At some sites,
differences were even more localized: at Patong Bay,
Phuket, reefs in the south were badly damaged but those
in the north were almost untouched, a pattern that was
Large boulder coral washed up on an Aceh beach following the
reflected in the destruction on land (Edwards, 2005).
tsunami of December 2004.
Post-tsunami surveys in Thailand and Aceh show
TSUNAMIS that most damage was in the form of overturning of
Compared with a wind-generated wave, a tsunami has a poorly attached boulder corals, breakage of branching
much longer wave length and the wave energy is corals, and smothering of the reef with sediment (Baird
distributed throughout the entire water column and is et al., 2005; Phongsuwan and Brown, in press).
on a much greater scale. As a tsunami approaches the Much greater damage was sustained by reefs directly
shore and water depth decreases, the wave height affected by the earthquake. Reef flats, with once diverse
increases dramatically as energy is converted to coral communities, have been permanently uplifted
surface layers, this effect being more pronounced on above the high water mark in many coastal areas of
gradually shallowing shores (Kowalik, 2004; Mojfeld Aceh and the Andaman and Nicobar islands (B. Brown,
et al., 2000). Tsunamis can cause substantial damage pers. comm.).
at locations protected from wind-generated waves, as An analysis by UNEP/GRID of more than 50 sites
they tend to accelerate through channels and up inlets, affected by the tsunami, using pre- and post-satellite
rapidly increasing in height. They can also be reflected imagery, indicated that there was greater coastal
off obstacles and travel in different directions (Yeh et flooding behind coral reefs (Chatenoux and Peduzzi,
al., 1994). It is thus perhaps not surprising that 2005), perhaps because channels through the reef
the roles of reefs and mangroves as buffers in the accelerated the flow. The same result was found in Aceh
UNEP-WCMC
June, 2002 January, 2005
Many parts of the coast of Tamil Nadu in India were severely hit by the tsunami. Three villages behind the mangroves in Pitchavaram
Sanctuary survived whereas the two in front were lost (Danielsen et al., 2005; Kathiresan and Narayanasamy, 2005). This could, however,
have been due to the reduced force of the wave, as the continental slope drops to deep waters much more sharply here, compared with areas
further south which suffered greater damage (Wood, 2005).
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UNEP-WCMC
The once extensive mangroves around Banda Aceh in Sumatra, Indonesia, an area which suffered devastating damage and loss of life in the
tsunami, had been largely replaced by shrimp farms, covering 360 km2 (UNEP, 2005b). Although loss of mangroves could have contributed to
the destruction, the area was also very close to the epicentre of the tsunami, and thus vulnerable to substantial impact.
dominated by genera such as Sonneratia or Rhizophora)
(Baird et al., 2005), and studies on the Queensland coast
of Australia have also shown that historically tsunamis were damaged (Dahdouh-Guebas et al., 2005). It therefore
have breached the Great Barrier Reef through passes in seems that the 'quality' of the mangrove forest contributes
the reef (Knott, 1997). in large measure to its buffering capacity, in addition to its
Some studies have suggested that, in certain size and the extent of regrowth if it had previously been
locations, reefs did provide protection. In Sri Lanka, at cleared. Tree density may certainly be important: one
Hikkaduwa where the reefs are in a better condition than study indicated that a 100 metre-wide belt of mangroves,
with trees at a density of 30 per 100 m2, would be sufficient
many in the country – and are protected in a marine park –
the tsunami caused damage to a distance of only 50 metres to reduce the flow pressure from a tsunami by as much as
inland and waves were only 2-3 metres high. At Peraliya, 90 per cent (Hiraishi and Harada, 2003).
just 3 km to the north but where the reefs have been Analyses of satellite images of a large number of
extensively affected by coral mining, waves were 10 metres tsunami-impacted sites do not show clear correlations
high, and damage and flooding occurred up to 1.5 km inland between the presence of mangroves and reduced
(Fernando et al., 2005, Liu et al., 2005). Detailed analysis of shoreline damage (Chatenoux and Peduzzi, 2005; Wood,
these areas is still needed, as other factors may also be 2005). In many cases the locations where mangroves have
involved. Dunes were particularly important in providing been reported to have helped protect the shoreline were
protection in Sri Lanka (Liu et al., 2005). out of the main path of the wave, or were adjacent to
Initially, there were many observations suggesting deeper water, and thus less susceptible to serious
that mangroves both dissipated the force of the tsunami damage. These findings demonstrate the importance, in
and caught the debris washed up by it, and thus helped to developing predictive models, of carefully analysing every
reduce damage (IUCN, 2005). In several cases, mangroves aspect of a site, both at the broad scale where satellite
were also instrumental in saving lives by preventing imagery can be useful and through detailed field surveys
people caught in the backwash of the wave from being and on-the-ground studies.
pulled out to sea. However, as with coral reefs, The general picture emerging since the tsunami
subsequent studies showed that the benefit of mangrove is that reefs and mangroves were not the main factor
protection was rather variable. In India, bathymetry and influencing the extent of damage on the coastline.
coastal profile were most important in determining the Nearshore bathymetry and coastline profile are probably
impact, but less erosion was observed in the Andamans the key factors determining the force of a wave at any
behind mangroves than where there were no mangroves particular coastal location. Shores adjacent to deep
(Department of Ocean Development, 2005). water tended to be less affected than those next to
A survey of 24 lagoons and estuaries along the shallow sloping shelves, regardless of the presence or
south-west, south and south-east coasts of Sri Lanka absence of reefs. The shape of the coastline is also
which suffered the greatest damage showed that where influential, with headlands often providing protection
good quality mangrove communities occurred there was while bays and inlets act as funnels, restricting and
little destruction to the coast, and the mangroves focusing the force of a wave. More research is required
themselves were not badly harmed. However, forests before it will be possible to predict where, and in what
dominated by less typical mangrove species (i.e. those way, a reef or mangrove will help to reduce the impact of
that had been degraded in the past and were no longer a tsunami.
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In the front line
Other ecosystem services
OTHER REGULATING SERVICES
Climate and global carbon cycle
Emissions of carbon dioxide from fossil-fuel combustion and
land-use changes are the leading cause of the build-up of
greenhouse gases. Forests, as well as crops, soil and other
organic matter, take up carbon (carbon sequestration) and
help to reduce the rate of global warming. Mangroves fix and
store significant amounts of carbon (Alongi, 2002) and they
play an important role in carbon sequestration, currently
absorbing an estimated 25.5 x 106 tonnes of carbon a year
(Ong, 1993).
Although reefs play an important role in the carbon
budget, contributing 7-15 per cent of global calcium
carbonate production, they do not help with carbon
sequestration. Sedimentary carbonates, including corals,
coralline algae and the shells of other marine organisms,
are the largest reservoir of carbon on Earth, and so
fluctuations in the global calcium carbonate budget
influence atmospheric carbon dioxide concentration.
However, the chemistry of the system is such that although
the oceans themselves are a ‘sink’ (i.e. they take up carbon
dioxide), reefs are ‘sources’ or net producers of carbon The number of dive operators along the Meso-American Barrier
Reef has increased dramatically in recent years, reflecting the
dioxide, albeit on a small scale in terms of the global carbon
growth of this leisure activity. In 2000, reef divers – numbering
budget, through the process of calcification (Suzuki and
about 3.6 million – made up 10 per cent of all tourists to the
Kawahata, 2004). Caribbean. Divers, however, contributed 17 per cent of tourism
revenue, spending about US$2 100 per trip, compared with
US$1 200 for tourists in general. It has been estimated that in 2000
Water quality
the net annual benefits from diver tourism in the Caribbean
Mangroves are capable of absorbing pollutants such as amounted to US$2.1 billion, with US$625 million being spent
heavy metals and other toxic substances (Lacerda and directly on diving on reefs (Burke and Maidens, 2004).
Abrao, 1984), as well as nutrients and suspended matter
(Ewel et al., 1998). This makes them natural wastewater tourism constitutes a large, and possibly the fastest
filters, preventing many pollutants from reaching deeper growing, sector. In Egypt, for example, the tourism sector as
water (Robertson and Phillips, 1995; Tann and Wong, 1999). a whole accounts for more than 11 per cent of gross
domestic product (GDP), and coral reefs have been central
CULTURAL SERVICES to the extremely rapid development of beach-based and
diving tourism in south Sinai since the 1990s; this area now
Tourism accounts for some 25 per cent of tourism’s contribution to
Coral reefs add significantly to the value of coastal tourism, national GDP (Jobbins, 2004).
supporting activities such as scuba diving, snorkelling and The 2004 tsunami brought home the economic
glass-bottom boat operations. They also contribute to the value of coastal and reef-based tourism, since this is vital to
formation of white sandy beaches. Tourism is the world’s the economies of the Maldives, Sri Lanka and Thailand. In
largest industry, with 694 million international tourist Sri Lanka, coastal tourism contributed about US$20 million
arrivals generating revenues of over US$500 billion in 2003. a year to the national economy in the mid-1990s (Berg et al.,
The tourism industry is a major employer and source of 1998). A study in 2003 of the reefs of the Phi Phi Islands in
foreign exchange and is growing rapidly; it is expected to Thailand, subsequently heavily damaged by the tsunami,
valued them at US$624 300/km2 a year for tourism and
reach 1.6 billion arrivals by 2020. Beach-based leisure
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valued species) in Belize, Honduras and Mexico is directly
S Wells
dependent on the health of the adjacent barrier reef, the
longest in the hemisphere. Sustainable annual catches of
fish from reefs vary from 0.2 to 30 tonnes/km2, with an
average of 5 tonnes/km2 (Jennings and Polunin,1995).
Depending on the value of the fish, reef fisheries are thus
potentially worth US$15 000-150 000/km2 a year, based on
catch values of US$1-10 per kg (Talbot and Wilkinson, 2001).
Reef fisheries in South-East Asia generate some US$2.4
billion a year (Burke et al., 2002), and in the Caribbean
US$310 million a year (Burke and Maidens, 2004).
There is now a global market for reef species.
Commercial reef fisheries are a major source of
employment and foreign exchange, supplying export
markets and retailers around the world, as well as the
restaurant and hotel industries. The live reef fish trade
supplies restaurants throughout South-East Asia with
A mangrove boardwalk for tourists on Wasini Island in southern
products from the Pacific and Indian Oceans (Hughes et al.,
Kenya, managed by a local women's group, generates several
2003). Tuna fisheries, such as those in the Maldives and
thousand dollars a year which are used for maintaining the
Lakshadweep, are often supported by reef-based bait
boardwalk and for community development activities (IUCN, 2004).
fisheries, and tuna themselves depend in part on reefs for
recreation, with a total value of US$205 million a year their food (Whittingham et al., 2003). Reef-based
(Seenprachawong, 2003). This provides a major incentive recreational fisheries generate over US$100 million
for careful management of the reefs post-tsunami, to annually (Cesar et al., 2003).
ensure that they recover rapidly and continue to provide A large proportion of fish and invertebrates in the
tourism benefit. aquarium trade comes from coral reefs, shipped to the 1.5-
Mangroves are not traditionally thought of as tourist 2 million people in Europe and North America who have
attractions or suitable sites for recreation, but this is aquaria. Sri Lanka, for example, earns about US$5.6 million
changing fast with the realization that this ecosystem a year exporting reef fish to about 52 countries, an activity
provides a fascinating educational experience and also that supports directly and indirectly around 50 000 people.
harbours a range of unusual species that can be easily Large quantities of corals, shells, starfish, pufferfish and
observed once boardwalks have been installed. Visits to other species are used in the curio trade. Reef-based
mangroves and birdwatching tours are now generating
significant revenue for local communities.
S Wells
PROVISIONING SERVICES
Fisheries and other marine products
Coral reefs and mangroves support numerous different
types of fishery: artisanal, commercial and recreational;
food, curios and souvenirs, bait, and items for decoration;
and fish, lobsters, crabs, molluscs, sea cucumbers and
many other species. However, much of the harvesting of
these species, as well as of species taken for non-food
purposes, is unsustainable, and current economic benefits
may thus be short term.
Of the estimated 30 million small-scale fishers in
the developing world, most are dependent to some extent
on coral reefs for food and livelihood. In the Philippines,
more than 1 million small-scale fishers depend directly on
Some estimates suggest that reefs contribute up to 25 per cent of
coral reefs for their livelihood. The productivity of the the annual total fish catch in developing countries, providing food
fisheries sector (shrimp, lobster, conch and other high- for 1 billion people (Cesar et al., 2003).
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In the front line
also used in large quantities locally for house, boat and
P Scott
jetty construction. Mangrove timber is particularly
valuable for construction as it is resistant to rot and to the
boring activities of many marine invertebrates. Wood
from several mangrove species has a high calorific value
and is thus of value both directly as fuelwood and as
charcoal. Mangrove wood was used as fuel in many of the
early train engines in India, and it is still widely used in
kilns to make lime (often using live corals from adjacent
reefs). The Matang mangroves in Malaysia provide
forestry products (timber and charcoal) with a value of
US$30 000/km2/year, and totalling US$10 million a year
(Talbot and Wilkinson, 2001).
Mangroves provide a variety of traditional products.
Tannins from mangroves were used to coat and preserve
wood, nets and other fishing gear, as well as being used as
a dye for cloth. In several countries, mangrove leaves
provide fodder for cattle and goats. Mangrove forests have
long been an important source of honey and beeswax.
The high-value, low-volume nature of the aquarium trade means
that it could provide a livelihood for many people if carefully Avicennia germinans in Florida in the United States is
managed: a kilo of aquarium fish was worth nearly US$500 in 2002,
particularly valued, as the bees that use this species make
compared with a kilo of food fish which sold for about US$6
high-quality honey, and large quantities were produced
(Wabnitz et al., 2003).
until the late 1800s when progressive loss of the best
curios provide significant export revenue, but the souvenir forests led to a decline in production. Honey has been
trade is largely unregulated and the benefits from it may be gathered from mangroves on a subsistence basis in
short term. numerous countries, and, with a renewed interest in this
Mangroves are important as breeding and nursery product, the activity is being developed on a small-scale
areas for fish and prawns that form the basis of major commercial basis in many places (Horst, 1998).
fisheries (Bann, 1997; Sasekumar et al., 1992). Annual
commercial fish harvests from mangroves have been Pharmaceuticals
valued at from US$6 200 per km2 in the United States to Marine organisms often contain pharmaceutically active
US$60 000 per km2 in Indonesia (Bann, 1997). An estimated compounds, many of the source species coming from reefs.
75 per cent of the commercially caught prawns and fish in Reef organisms have provided an HIV treatment and a
Queensland, Australia, depend on mangroves for part of painkiller, while a large part of current cancer drug
their lives and on nutrients exported from the mangroves to research focuses on coral reef species (Millennium
other ecosystems (Horst, 1998). The annual market value of Ecosystem Assessment, 2005). A study in Indonesia
seafood from mangroves has been put at US$7 500- estimated that mangroves provide a potential net benefit of
167 500/km2 (Millennium Ecosystem Assessment, 2005). US$1 500 per km2 (US$15/hectare) for medicinal plants
With fish catches averaging 1.3-8.8 kg an hour, a 400-km2 (Ruitenbeek, 1992).
managed mangrove forest in Matang, west Malaysia,
supports a fishery worth US$100 million a year SUPPORTING SERVICES
(US$250 000/km2/year). Many commercial shrimp fisheries The waters around mangroves are generally rich in
are dependent on mangrove-fringed coastlines and nutrients, as a result of the organic matter produced by the
estuaries including those in Central America and East trees and plants themselves, and also from the sediment
Africa. In the Gulf of Panama, the fisheries for shrimps and that is trapped around the roots. Mangroves produce about
1 kg litter/m2 annually, which forms the basis of a complex
fish generate an estimated US$95 000 per kilometre of
coastline (Talbot and Wilkinson, 2001). food chain and some of which is exported with the tide. As
a result mangroves support an abundant and productive
Mangrove forest products marine life, and often act as spawning areas, as well as
Several mangrove species provide high-quality nursery areas, sheltering juveniles of species that spend
commercial timber, used for building and for making their adult lives in other ecosystems such as coral reefs and
newsprint, matchsticks and matchboxes. Mangroves are seagrass beds (Mumby et al., 2004).
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What happens when ecosystem
services are lost?
SECA/CML
Just as it is hard to calculate accurately the economic value coral reef degradation continuing through to 2050 could
of different ecosystems, it is equally difficult to predict the reduce benefits from fisheries, dive tourism and shore
cost to society of losing their various services. It was thought protection by a predicted total of US$350 million to US$870
that the bleaching event of 1998 in the Indian Ocean would million over that period (Burke and Maidens, 2004).
have a major impact on tourism and fisheries. It was
estimated, for example, that Tanzania would potentially LOSS OF REGULATING SERVICES
suffer a direct loss of US$20 million from tourism revenue The impact of the loss of the protective functions of
(Westmacott et al., 2000a). However, neither sector coral reefs and mangroves is already being felt in
underwent the expected decline: tourism fluctuated but some countries. Parts of Sri Lanka, India, Indonesia
probably more as a result of worldwide political and and the Maldives, where coral mining and collection
economic changes; while fisheries are still in decline largely has almost eliminated some reefs, have already
because of overexploitation. seen serious erosion.
Both the 1997 bleaching and the 2004 tsunami were In Sri Lanka, erosion on the south and west coasts
single, if acute, events, and reefs and mangroves are now averages an estimated 40 cm a year, considered to be
expected to recover from damage incurred. A more typical partly due to damage to reefs. Some US$30 million has
scenario is of reefs and mangroves undergoing steady already been spent on breakwaters and other constructions
decline. Ecosystems that can no longer provide their full to curtail this, and it has been estimated that the cost of
ecological services have a social and economic ‘cost’ to replacing the coastal protection provided by these reefs
humanity, which can be felt in areas or situations many would be US$246 000-836 000 per km (Berg et al., 1998). A
miles away. Ultimately, therefore, degradation of coral reefs hotel in West Lombok, Indonesia, spent an average of
and mangroves will cause loss of fishing and tourism US$125 000 a year over a seven-year period restoring its
revenue and other forms of livelihood, loss of export 250-metre-long beach, which had been eroded largely
earnings, malnutrition due to lack of protein, increased because of offshore coral mining (Riopelle, 1995).
coastal erosion, and destruction from storms and Modelling and predictions of the impact of the loss
catastrophic natural events. of natural shore protection provide dire warnings. Modelling
It is predicted that, for example, over a 20-year of the changes in wave energy striking some island
period, blast fishing, overfishing and sedimentation in shorelines in the Seychelles (Sheppard et al., 2005)
Indonesia and the Philippines could lead to a net economic indicates that wave energy has recently doubled as a result
loss of US$2.6 billion and US$2.5 billion respectively for of sea level rise, loss of corals from reef flats due to
these two countries (Burke et al., 2002). In the Caribbean, bleaching, and changes in reef crest profiles and wave
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communities in the tropics, through loss of earnings and
S Westmacott
food security. Both overexploitation and habitat deterioration
(particularly of nursery areas which causes disruptions to
marine productivity) are leading to reduced catches in most
tropical regions. For the Caribbean, it is predicted that, in the
absence of reef degradation, fisheries production in 2015
could be 100 000 tonnes, with a revenue of US$310 million.
However, with the reef degradation that is projected to
occur, production may be 30-45 per cent less (60 000-70 000
tonnes), and revenue only US$140 million (Burke and
Maidens, 2004).
LOSS OF CULTURAL SERVICES
Scuba divers specifically look for coral reefs with rich live
coral, high fish and invertebrate diversity and clear water. In
the long term, degradation of reefs will reduce their value to
the tourist industry. Reefs will provide less interesting diving
and snorkelling, poorer sport fishing and, where erosion has
In the Maldives, a reef flat adjacent to the capital of Male was filled
using coral rubble and causing sedimentation of nearby reefs. taken hold, less attractive beaches. For the Caribbean, it is
Their degradation was partly responsible for reduced shore
predicted that, if reefs undergo no further deterioration, net
protection and extensive flooding in 1987, which resulted in 20-30
benefits from scuba diving could grow to US$5.7 billion by
per cent of the new infill being lost. Subsequently, artificial
2015. If reef health deteriorates further, however, dive
breakwaters of concrete tetrapods were installed at a cost of
US$10 000 per metre (or US$10 million per kilometre) (Brown, revenue could amount to only US$5.4-5.6 billion,
1997). Not only was this expensive, but it did not prevent serious
representing a future ‘loss’ of 2-5 per cent (Burke and
flooding during the tsunami.
Maidens, 2004). Already it is widely believed in Florida,
regime. The models predict that, over the next decade, it United States (although data are lacking) that the decline in
will double again as a result of further damage to coral reef quality is partly responsible for the shift from high-
reefs. The consequences of this will depend on the shore’s value, low-volume tourism to budget travellers; this reduces
composition, but there will almost certainly be increased revenue and potentially, if large numbers are involved,
erosion on sandy shores. further contributes to the degradation of the reefs (T.
In the Caribbean, more than 15 000 km of shoreline Agardy, pers. comm.).
could experience a 10-20 per cent reduction in protection
from waves and storms by 2050 as a result of coral reef
R A Patzner/University of Salzburg
degradation (Burke and Maidens, 2004). The economic
costs to Australia from a degraded Great Barrier Reef as a
result of the predicted impact of global warming have been
put at US$2.5 billion to US$6 billion over 19 years (Hoegh-
Guldberg and Hoegh-Guldberg, 2004).
Loss of mangroves causes saltwater intrusion and
deterioration of groundwater quality, as well as the
disappearance of the filtering mechanism provided by the
roots and the ecological characteristics of this ecosystem.
Mangroves play a sufficiently important role in the
global carbon cycle that it has been estimated that the loss
of 35 per cent of the world’s mangroves (Valiela, 2001) over
the last two decades has resulted in the release of large
quantities of stored carbon, thus further contributing to the The commercially important rainbow parrotfish Scarus guacamaia
greenhouse effect (Cebrian, 2002). in the Caribbean depends on mangroves as a juvenile but lives on
reefs as an adult. It is far less common on reefs with no adjacent
mangroves, and is one of probably many species that are declining
LOSS OF PROVISIONING SERVICES
from loss of habitat as well as overfishing (Mumby, et al., 2004).
The degradation of reefs and mangroves is already having a Local extinctions have been reported where mangroves have been
major impact on the livelihoods of thousands of coastal cleared, as at Glover’s Atoll in Belize (A. Edwards, pers. comm.).
22
In the front line
Natural recovery – or rehabilitation
and restoration
UNEP/Topham
Although our instinct is to repair or restore something Mangrove restoration.
that has been damaged, there is often an argument for
allowing natural recovery. There are, indeed, many There are two terms in common use: ‘restoration’, which
examples of reefs and mangroves recovering from a means that all the key ecological processes and functions
major impact such as a hurricane without human and all the former biodiversity are re-established; and
intervention. Although recovery may seem slow, natural ‘rehabilitation’ which means that most, but not all, are re-
regeneration increases the likelihood that the ecosystem established. Most experience so far with reefs and
will return to what it was before. mangroves is in terms of rehabilitation.
The many chronic, long-term impacts now Mangrove rehabilitation can be relatively simple
affecting these ecosystems often slow the rate of since comparatively few species are involved. However,
recovery. On reefs, for example, the shift from a coral- rehabilitation of reefs is more complex because coral
dominated to an algal-dominated ecosystem means that reproductive biology and growth rates are still poorly
new coral recruits are quickly outnumbered and those understood, many species are involved and the
that settle often have little chance of survival. The focus techniques are complex and expensive, requiring scuba-
now needs to be on removing the causes of this diving and other special equipment and materials. Reef
imbalance, and eliminating stresses in order to rehabilitation projects have so far been largely
encourage natural recovery of damaged ecosystems experimental and have involved only small areas (less
than 100 m2). A careful evaluation of the methods
(Edwards and Clark, 1998; Cahoon and Hensel, 2002).
However, there may be certain situations or available must be undertaken to determine feasibility and
conditions when active intervention is necessary or cost effectiveness before any attempt at rehabilitation is
beneficial, for example where an ecosystem has made. Research into coral reef restoration is currently
particularly high economic value or scientific interest. under way through the GEF/World Bank Coral Reef
23
In the front line
Targeted Research and Capacity Building for two years. Natural recovery of mined reefs in the
Management project (Edwards, 2004). Maldives has been particularly slow (Clark and
Reefs and mangroves comprise different comb- Edwards, 1994). Reefs in marine parks in eastern
inations of species and occur in a variety of physical Indonesia, which had previously suffered from long-
conditions and locations. These factors, combined with the term dynamite fishing, show little sign of recovery after
type and scale of damage suffered, will affect recovery seven years, despite good water quality and larval
processes and thus any decisions about rehabilitation. recruitment. The vast quantities of broken rubble act as
‘killing fields’ for juvenile corals, abrading or burying
CORAL REEFS the newly settled recruits (Fox et al., 2003). Reefs that
Reefs will generally recover provided there is an adequate suffered light damage from the 2004 tsunami in
supply of larvae of corals, fish and invertebrates, and as Thailand are predicted to take only three to five years to
long as chronic disturbances such as sediment, pollution recover; those that received greater damage may take
and overfishing are minimized. Recovery involves two five to ten years. However, the rates of recovery will
processes: the settlement of larvae which then develop depend on whether the reefs suffer other impacts in the
into new coral colonies; and growth of the remaining coral coming years, particularly bleaching which has
colonies and fragments. Both processes are affected by occurred several times in Thailand in the past
the prevailing environmental conditions and by the extent (Phongsuwan and Brown, in press).
of the damage. New coral growth and recolonization of The main approaches to rehabilitation of coral
fish populations will start to occur within one to two years reefs are (Westmacott et al., 2000b):
❏ Increasing the area of substrate for settlement
of a damaging event or the end of damaging activities.
Coral larvae require hard surfaces, preferably of coral larvae by installing artificial surfaces,
coral rock or coralline algae, for settlement, and so e.g. concrete blocks, wrecks or other purpose-
seaweeds, sediment and debris on the seabed will reduce designed structures. Stabilizing or removing
coral recruitment. However, coral spawning can take
place quite normally after a natural event such as a
www.reefball.org
hurricane. For example, in Guam, after a typhoon, coral
spawning took place at the normal time and even broken
coral fragments were seen to spawn.
Coral growth rates are highly variable,
depending on the species, the location of the colony on
the reef, the geographical location of the reef and
environmental conditions. Branching corals grow
relatively fast (10-20 cm a year) but are easily broken by
waves and storms. Massive corals grow very slowly (5-
25 mm a year) but may survive for hundreds of years;
colonies more than 1 000 years old have been found.
The reef as a whole grows more slowly than its
individual corals, as it is constantly being eroded, and
upward growth on reef flats is only about 4 mm a year,
while deeper reef thickets grow at about 10 mm a year.
The breakdown of coral skeletons results from either
mechanical damage or from ‘bio-eroders’, which
include sea urchins that graze on fine algae on the
surface of corals and abrade them in the process, and
sponges that bore into corals and weaken their
A major industry has developed in recent years to build artificial
structure.
reefs, such as this ‘Reefballs’ breakwater, to replace the original
The speed of a reef’s recovery from major natural reefs and create new amenity value. Although the costs of
damage thus depends on the balance between the such structures are decreasing, this approach is expensive, and
not feasible for large areas; most importantly, an artificial
growth of coral colonies and their erosion. Recovery
structure such as this will never replace all the ecosystem
time is generally a matter of decades (10-50 years) and
services of a natural reef. Before investing in potentially risky
is longer on reefs subject to other long-term stresses, 'engineering' solutions to reef restoration, it is essential to seek
although the process of recovery can start in as little as advice from scientists and other experts.
24
In the front line
MANGROVES
J Harris
Mangrove regeneration is affected by the patterns of
damage (e.g. broken branches, impact from debris,
sediment disturbance) and by the characteristics of the
area. After storms and impacts such as a tsunami,
sediment scouring leaves inorganic substrates that are
difficult for mangroves to colonize. Sediment turnover may
also expose and/or dump onto existing mangroves material
in which there has been long-term accumulation of heavy
metals, hydrocarbons and other contaminants that inhibit
seedling establishment and survival (Ellison and
Farnsworth, 1996; Cahoon and Hensel, 2002). As with reefs,
for effective recovery it is essential that the causes of the
damage are eliminated. Even when disturbance is reduced,
the altered soil conditions (e.g. increased acidity where
aquaculture was previously carried out) and limited natural
dispersal of many mangrove species mean that natural
recovery can be very slow.
Most mangrove species produce propagules that
are relatively easy to collect and plant and, in the right
conditions, growth is fast. Restoration projects usually
Reef restoration projects are under way in many areas, as here in
the Solomon Islands. The tsunami gave fresh impetus to such involve the direct planting of propagules (particularly for
projects but they will need careful assessment. Experience to date
Rhizophora spp.) in the recovery area, although
suggests they are appropriate only at the scale of tens to at most
seedlings and saplings can be grown up in advance in
hundreds of square metres, for example on reefs damaged by
nurseries. The exact technique to be used will depend on
shipping or used by tourists.
the species involved, whether the soil needs treatment
loose or soft substrate, such as coral fragments (for example to reduce acidity) or physical reworking (to
and seaweeds, can also help, but this procedure create a suitable grain size), the season, the
requires care and expert help. New surfaces developmental stage of the propagules and the
can be created by passing an electric current resources available. Replanting is generally most
through metal to cause deposition of calcium successful in relatively sheltered areas, but is also
carbonate (electrolysis). This requires carried out in more exposed areas where the main aim is
considerable financial and human investment, control of soil erosion (Stevenson, 1997).
and the long-term impact of the current in the Partly because of the ease with which propagules
water is not known. can be replanted, many mangrove restoration schemes
❏ Transplanting coral fragments or colonies from have been undertaken, often as a forestry production
healthy reefs to damaged reefs or to artificial initiative. Replanting schemes in Matang, Malaysia (Chan,
substrates. Many species survive transplantation 1996), Thailand (Fast and Menasveta, 2003) and East Africa
provided environmental factors are favourable, (Kairo et al., 2001) have been successful, although
but the process requires significant labour, and rehabilitated mangroves often lack their full biodiversity
transplanted fragments are easily dislodged by and ecological processes (Ellison, 2000). Many of the Asian
waves and human disturbance, or can easily be countries affected by the 2004 tsunami have embarked on
buried or smothered. In addition, there is a risk of ambitious replanting programmes which are nevertheless
damaging healthy reefs by removing corals from a first step. Indonesia, for example, has initiated a four-
them. Coral fragments can also be transplanted year operation to plant 150 000 hectares of mangroves
to a protected site and ‘grown out’ (or ‘farmed’) to along the coast of Aceh where 300 000 hectares of
a certain size before being used for rehabilitation mangroves were destroyed. Such programmes will require
(Epstein et al., 2003). careful monitoring and assessment if full restoration is to
❏ ‘Repairing’ the reef: Under some circumstances, be achieved. There is some evidence that greater success
it is possible to cement pieces of reef, or even in recovering the biodiversity is achieved when the
coral colonies, together, using glue, special replanting is carried out in association with integrated
cements, plastic or other binding agents. aquaculture systems (Ellison, 2000).
25
In the front line
Mangroves and coral reefs on
tropical coastlines of the future
Devastating as they were, the tsunami of December 2004 matter of urgency, and alternative livelihoods found for
and recent tropical storms have sent a clear message that those dependent on the activities that cause damage.
investing in environmentally sound development and Good coastal planning can considerably reduce
sustainable management of the coastal environment will, vulnerability to natural disasters, as well as help
in the long run, be more cost effective than restoring safeguard other regulatory services such as water quality
human lives and ecosystems after a catastrophe. Tsunamis maintenance. Full implementation of the UNEP Global
are relatively rare events compared with hurricanes and Programme of Action on Land-based Sources of Pollution
cyclones – fewer than 100 tsunamis were recorded over the will go a long way towards helping to maintain the
last 300 years in the Indian Ocean (Dahdouh-Guebas et al., regulating services of reefs and mangroves.
2005; Department of Ocean Development, 2005) compared
with three tropical cyclones a year (Dahdouh-Guebas et al, MAINTAINING PROVISIONING SERVICES
2005). Evidence for the shore protection benefits of coral The sustainable exploitation of reef and mangrove
reefs and mangroves is currently less for tsunamis than it fisheries and other resources is a recognized global
is for storms. This, however, does not lessen the urgency – priority. There are some success stories, such as the
the devastation recently wrought by hurricanes and harvesting of mangrove timber over a 20-30 year rotation
typhoons testifies to the priority that must be accorded to period in Bangladesh, Malaysia and Thailand. Much
shore protection measures, of which maintenance of greater attention must, however, be paid to fisheries
natural coastal barriers such as reefs and mangroves management. Techniques and approaches are well
must be among the first. developed but often poorly implemented. The FAO Code of
There are no simple management models for Conduct for Responsible Fisheries enshrines many of
mangroves or reefs. The variability of these ecosystems these, including elimination of destructive fishing gear,
means that a good understanding of local characteristics establishing no-take areas, and emphasizing the need for
is essential. In the case of mangroves, even though a management plans, developed with the full involvement
common feature is their regular inundation by the sea, the of fishers and users, that are fully enforced. In Sri Lanka,
extent of this inundation and the tidal regime vary greatly where 80-95 per cent of the fishing fleet was destroyed in
as do their species composition and the chemical and areas affected by ∆2the 2004 tsunami, there was an
microbial characteristics of the soils, all of which affect opportunity to introduce measures, such as reduction of
their resilience and ability to recover. overcapacity, to ensure sustainability. However, in the
rush to provide humanitarian aid, fishing gear and boats
MAINTAINING REGULATING SERVICES have been distributed in large numbers and without
Human activities that weaken reefs and make them less consideration of the long-term future. This demonstrates
effective breakwaters must be regulated or halted as a the need for a much greater understanding by the public
and decision makers of the management requirements of
Cancún Travel Online
nearshore tropical fisheries.
Thirty years ago, Cancún in Mexico, lying at the top of the great
Meso-American Reef System, was a small fishing village. Since
then, it has grown to a resort that receives more than 3.5 million
visitors annually, on top of its 650 000 residents, and has suffered
considerable environmental problems, particularly in the form of
numerous hurricanes, such as Ivan in 2004 (left) and Emily and
Wilma in 2005. In 2001, Guidelines for Low-Impact Tourism were
produced for the state of Quintana Roo (Molina et al., 2001). These
aim to ensure that further tourism development, particularly in the
Costa Maya to the south of Cancún, will avoid many of the existing
problems, and will contribute to the sustainable development of
this region without increasing its vulnerability.
26
In the front line
UNEP
The Sundarbans, lying at the southern end of the Ganges River and straddling the border between India and Bangladesh, is the largest
continuous area of mangrove in the world. The area provides a livelihood for more than 300 000 people, protects them from cyclones and tidal
waves and is an important source of revenue for both countries through commercial timber which is harvested on a 20-year felling cycle. The
total extent – some 6 050 km2 (Spalding et al., 1997) – has not changed significantly in the last 25 years, although there are concerns that
forest quality may be declining. The relative success of the Sundarbans is largely due to its management which has been aimed at taking
advantage of the mangroves’ provisioning and regulatory ecosystem services. It has been managed as a commercially exploited reserved
forest since 1875; wildlife sanctuaries and national parks protect key biodiversity areas, and the area is both a World Heritage and a Ramsar
site. Since the 1970s, the Sundarbans has also been managed as a protective belt against storm damage.
MAINTAINING CULTURAL SERVICES recognition of the role of communities in the stewardship of
The vulnerability of the tourism industry to natural events natural resources, and the numerous examples of how this
was made very clear by recent hurricanes as well as the can be successful, will help to ensure that the cultural
2004 tsunami. Maintaining the ecosystems on which the services of reefs and mangroves continue to be valued.
industry depends is thus of paramount importance to
both governments and the private sector. The ESSENTIAL MANAGEMENT TOOLS
International Ecotourism Society (Halfpenny, 2002), the There is no shortage of guidelines, codes of practice and
Convention on Biological Diversity (CBD, 2004), the information on how to manage reefs and mangroves but
Center for Environmental Leadership in Business there is there is still a notable lack of commitment to
(CELB/CORAL/ IHEI/TOI, 2004) and others have produced using and implementing them. The UNEP Regional Seas
guidelines to promote sustainable tourism. Political will Programme is among the organizations trying to reverse
and individual commitment are now needed to ensure this, by helping countries to work together to protect
their implementation. these ecosystems, recognizing that success involves
Although many coastal communities have transboundary action, regional co-operation and clear
traditionally valued the ecosystems on which they depend, demonstration of successful approaches (see for example
much of this understanding has been eroded. The growing UNEP 2004). Key management approaches that must be
27
In the front line
promoted include integrated coastal management (ICM), construction set-backs, green belts and other
marine protected areas (MPAs), and improved resilience no-build areas.
and adaptive management. Priority technical measures
2 Promote early resettlement with provision for
Integrated coastal management all basic livelihood needs.
Coastal development is often ad hoc and based on 3 Enhance the ability of natural ecosystems to
numerous unconnected small decisions, or, where plans provide protection by conserving, managing and
exist, may be illegal as a result of poor enforcement of restoring wetlands, mangroves, seagrass beds,
regulations (Kay and Alder, 2005). National and local ICM and coral reefs, and by seeking alternative
programmes can go a long way to improving coastal sustainable sources of building materials.
management. The links between impacts on the coast and 4 Promote design that is cost-effective and
watershed management need to be recognized. Plans consistent with best practices, favouring soft
should take into account soils, topography and the need to engineering solutions to coastal erosion control.
protect vulnerable ecosystems. Areas needing 5 Respect traditional access and uses of the
rehabilitation must be identified, as well as areas where shoreline.
construction should be restricted or banned. 6 Adopt ecosystem-based management measures;
In particular, the construction industry must promote sustainable fisheries management;
respect environmental principles (such as set-back encourage low-impact aquaculture.
regulations), and ensure that pollution and sedimentation 7 Promote sustainable tourism.
are minimized through measures such as the use of silt How to apply the principles
curtains, and building in the dry rather than the wet 8 Secure commitments from governments and
season. Incorporating knowledge of coastal processes international organizations to abide by the
and applying best management practices for beaches, principles.
lagoons, coastal vegetation, energy, sewage treatment, 9 Ensure public participation.
solid waste and wastewater into planning and 10 Make full use of tools such as strategic
infrastructure are essential. Construction behind reefs environmental assessment, spatial planning and
will need particular care, not only to prevent damage to environmental impact assessment.
these ecosystems, but to reduce future shoreline damage 11 Monitor the progress and impact of recon-
if channels through the reef do indeed increase struction.
vulnerability to flooding. Environmental impact assess- 12 Disseminate good practices and lessons learnt
ment legislation, now in place in most countries, must be as they emerge.
enforced as a matter of urgency.
The ICM approach is fully recognized in the 12 Marine protected areas
guiding principles that were drawn up at a meeting in There is growing evidence that reefs within MPAs recover
Cairo in February 2005 by the UNEP Asian Tsunami faster from catastrophes than those that are unprotected.
Disaster Task Force, in collaboration with the UNEP Co- The abundant fish populations in Hikkaduwa National
ordination Office of the Global Programme of Action for Park, Sri Lanka, showed little change as a result of the
the Protection of the Marine Environment from Land- 2004 tsunami, although unprotected reef sites appear to
have suffered losses (MPA News, 2005). Reefs in the
based Activities and other organizations (UK Department
for Environment, Food and Rural Affairs, the Food and Indian Ocean that were well managed or remote from
Agriculture Organization of the United Nations, the United human impact tended to recover more rapidly from the
Nations Educational, Scientific and Cultural Organization, 1998 bleaching; reefs under anthropogenic stress
IUCN, and WWF). Known as the Cairo Principles, these are recovered poorly, if at all (Wilkinson, 2004).
aimed at helping to ensure environmentally sound post- Many more MPAs are needed. Currently, some 685
tsunami reconstruction programmes, and are being protected areas contain mangroves, covering about 9 per
implemented through an Action Plan (UNEP/GPA, 2005). cent of the total area of mangrove (Spalding et al., 1997),
and 660 MPAs contain coral reefs. There is no global
THE CAIRO PRINCIPLES estimate of how much reef is protected (Spalding et al.,
Overarching principle 2001), but in the Caribbean an estimated 20 per cent of
1 Reduce the vulnerability of coastal comm- reefs lie within MPAs (Burke and Maidens, 2004). Many
unities to natural hazards by establishing a MPAs need to be larger and to be made part of carefully
regional early warning system and applying designed networks to ensure that connected ecosystems
28
In the front line
Improved resilience and adaptive management
Fig. 5: Management effectivenes of Caribbean
MPAs (per cent) Natural disasters have affected humans and the
environment since the beginning of time – but both have
the ability to regenerate and adapt to the impact of such
events and the new circumstances that may arise as a
result of them. This capacity to absorb recurrent
disturbances such as storms and floods is called
‘resilience’.
Already two-thirds of the coastal disasters
recorded each year are associated with extreme weather
events. The growing populations on, and rapid
development of, the coastal zone guarantee that we will
Most marine protected areas urgently need improved
see an increase in economic, social and environmental
management. Of 285 MPAs assessed in the Caribbean in 2004, only
damage in the future caused by the associated reduction
6 per cent were considered to be effectively managed (Burke and
in human and ecosystem resilience. The conventional
Maidens, 2004).
approach has been to try to reduce the damage and
eliminate change but a new thinking is developing. A far
T Heeger
better approach may be to promote the conditions that
improve resilience and also learn to adapt to the resulting
changes (Adger et al., 2005). Careful planning and
adaptive management can greatly reduce the impact of
large disturbances.
The rapid response of global, regional and
national monitoring programmes to the tsunami
demonstrated their value in providing essential
information for management. Guidelines for Rapid
Assessment and Monitoring of Tsunami Damage to Coral
Reefs were produced within ten days (ICRI/ISRS, 2005)
and disseminated by the UNEP Coral Reef Unit to the
various international and UN agencies conducting
environmental assessments in the region. Expert surveys
were also quickly initiated with assistance from the
Global Coral Reef Monitoring Network (GCRMN) and the
Mu Koh Surin National Park in Thailand, gazetted in 1981 and regional Coral Reef Degradation in the Indian Ocean
covering 135 km2, is an ICRAN demonstration site and has a good
(CORDIO) programme.
track record of effective management. The December 2004
tsunami largely destroyed tourism and the park’s infrastructure on
the islands, as well as sea gypsy villages, but there were no FINANCING THE FUTURE
fatalities. The coral reefs, which were especially healthy with high
Reefs and mangroves clearly provide significant benefits
biodiversity before the event (see above), were being surveyed at
and services to humankind, many of which have a high
the time of the tsunami, permitting first-hand accounts. Trees
economic value. Governments, civil society and the
were knocked onto the reefs, along with large amounts of
sediment. A survey was carried out two months later and private sector must recognize that, as with other benefits,
remarkably little damage had occurred: reefs had an average of 75
there is a price to be paid for maintaining these
per cent live coral cover, and some had 90 per cent, the sediment
ecosystems. The cost is, however, generally much lower
had gone, and there were already signs of some coral regeneration
than the benefit received.
in damaged areas (Comley et al., 2005).
Although costs are hugely variable depending on
are protected (not only representative sites), as well as the location, size and type of management, average
annual operational management costs of US$775 per km2
resilient ecosystems, such as reefs identified as resisting
or recovering quickly from bleaching (Grimsditch and have been estimated for MPAs (Balmford et al., 2004).
Salm, 2005). This is essential if species dependent on This is significantly less that the estimated global values
of ecosystems: US$100 000-600 000 per km2 per year in
different ecosystems at different stages of their life cycles
are to be protected, and the full range of ecosystem the case of reefs and possibly more for mangroves. Basic
services maintained. annual operating costs for MPAs can be as low as
29
In the front line
Fig. 6: Area of the world’s coral reefs and mangroves lying within the waters of countries in relation to those
countries’ position on the UN Human Development Index (left) and their GDP per capita (right) (per cent)
Many of the world’s wealthiest nations have jurisdiction over reefs and mangroves, either in their own coastal waters or in those of their
territories. Over 30 per cent of the world’s reefs lie in countries that are classified as highly developed, with a GDP per capita of more than
US$9 000. Australia, France, New Zealand, the United Kingdom and the United States directly influence about 25 per cent of reefs and a
significant proportion of mangroves. Furthermore, most of these countries are either sources of tourists to reef countries or have other
strong economic links with them and potentially could provide much greater financial and technical support. A higher proportion of
mangroves are found in the poorer countries, but nevertheless more than 10 per cent are found in highly developed countries.
US$200 000-600 000, as in the case of Belize and the have indicated, for example, that tourists are willing to
Seychelles (Lutchman, 2005). pay more than US$50 extra per holiday and divers US$25
There are vast untapped sources of funds and more per dive if these result in high-quality reefs
financing mechanisms, ranging from fishery and tourism (Westmacott et al., 2000a; Burke and Maidens, 2004). It
revenues and taxes, to royalties and fees from offshore seems a small price to pay for the future survival of these
mining and mineral exploitation, to voluntary donations small, priceless ecosystems.
and government aid (Spergel and Moye, 2004). Studies
A Cornish
30
In the front line
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33
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Shoreline protection and other
ecosystem services
from mangroves and coral reefs
The tragic and devastating consequences of the Asian tsunami, December 2004 ,
and the hurricanes and cyclones of 2005 were a wake up call for the global
community, dramatically drawing attention to the dangers of undermining the
services that coastal ecosystems provide to humankind.
This report has gathered lessons that have been learned since these events that
will be relevant to future management of the coasts in the context of severe
weather events and other potential consequences of global warming. More than
ever it is essential to consider the full value of ecosystem services – that is the
benefits that people derive from ecosystems – when making decisions about
coastal development.
The publication aims to help decision and policy makers around the world
understand the importance of coastal habitats to humans, focusing on the role of
coral reefs and mangroves. As well as coastal protection, it also addresses the
huge range of other benefits provided by these ecosystems and the role that they
can play in coastal development and in restoring livelihoods for those suffering
from the effects of extreme events.
www.unep.org
United Nations Environment Programme
P.O. Box 30552, Nairobi, Kenya
Tel: +254 (0) 20 621234
Fax: +254 (0) 20 623927
Email: cpiinfo@unep.org
Website: www.unep.org
UNEP World Conservation Monitoring Centre
219 Huntingdon Road, Cambridge CB3 0DL,
January 2006
DEW/0787/CA
United Kingdom UNEP-WCMC Biodiversity Series No 24
Tel: +44 (0) 1223 277314
Fax: +44 (0) 1223 277136 ISBN: 92-807-2681-1
Email: info@unep-wcmc.org
Website: www.unep-wcmc.org
Shoreline protection and other ecosystem services
from mangroves and coral reefs
In the front line
Shoreline protection and other ecosystem services
from mangroves and coral reefs
In the front line
UNEP World Conservation Monitoring Centre ACKNOWLEDGEMENTS
219 Huntingdon Road, We gratefully acknowledge the many partners and
Cambridge CB3 0DL, institutions who contributed to this publication, in
United Kingdom particular the following individuals who provided
Tel: +44 (0) 1223 277314 information and comments on early drafts: John Agard,
Fax: +44 (0) 1223 277136 Tundi Agardy, Jackie Alder, Daniel Alongi, Andrew Baird,
Email: info@unep-wcmc.org Nicola Barnard, Juan Bezaury, Simon Blyth, Barbara
Website: www.unep-wcmc.org Brown, Marion Cheatle, Isabelle Côté, Salif Diop, Alasdair
Edwards, Norberto Fernandez, Harinda Fernando, Phil
THE UNITED NATIONS ENVIRONMENT PROGRAMME WORLD Fox, Alison Glass, Stefan Hain, Mark Huxham, Val Kapos,
CONSERVATION MONITORING CENTRE (UNEP-WCMC) is the Carmen Lacambra, Ian May, Nick Nuttal, Pascal Peduzzi,
biodiversity assessment and policy implementation arm of Pasi Rinne, Toby Roxburgh, Charles Sheppard, Jerker
the United Nations Environment Programme (UNEP), the Tamelander, Kristian Teleki, Ruben Torres, Collette
world’s foremost intergovernmental environmental Wabnitz, Alan White, Victoria Wood and Kaveh Zahedi.
organization. The Centre has been in operation for over 25
years, combining scientific research with practical policy
advice.
UNEP-WCMC provides objective, scientifically rigorous
products and services to help decision makers recognize
the value of biodiversity and apply this knowledge to all
that they do. Its core business is managing data about
ecosystems and biodiversity, interpreting and analysing
that data to provide assessments and policy analysis, and
making the results available to national and international
decision makers and businesses.
Lead Author: Sue Wells
Contributing authors: Corinna Ravilious and
Emily Corcoran
Front cover photos: Y Yusuf; UNEP/Topham;
E Clua/CRISP, 2005; S Wells; UNEP-WCMC World
Atlas of Coral Reefs.
Back cover photo: S Wells
Citation: UNEP-WCMC (2006) In the front line: shoreline
protection and other ecosystem services from mangroves
and coral reefs. UNEP-WCMC, Cambridge, UK 33 pp
©UNEP-WCMC/UNEP 2006
A Banson production
Printed in the UK by Cambridge Printers
The contents of this report do not necessarily reflect the views or policies of the United Nations Environment Programme, the UNEP World Conservation
Monitoring Centre, the International Coral Reef Action Network or IUCN–The World Conservation Union. The designations employed and the presentations
do not imply the expressions of any opinion whatsoever on the part of these organizations concerning the legal status of any country, territory, city or area
or its authority, or concerning the delimitation of its frontiers or boundaries.
2
In the front line
Contents
Introduction........................................................................................................................................................................... 4
Key messages....................................................................................................................................................................... 5
Global status of reefs and mangroves.................................................................................................................................. 7
Distribution...................................................................................................................................................... 7
Status............................................................................................................................................................... 7
Threats............................................................................................................................................................. 9
Value of ecosystem services................................................................................................................................................. 12
Regulating services – shoreline protection.......................................................................................................................... 14
Wind-generated waves and storms................................................................................................................ 15
Tsunamis......................................................................................................................................................... 16
Other ecosystem services..................................................................................................................................................... 18
Other regulating services................................................................................................................................ 18
Climate and global carbon cycle...................................................................................................... 18
Water quality..................................................................................................................................... 18
Cultural services.............................................................................................................................................. 18
Tourism............................................................................................................................................. 18
Provisioning services....................................................................................................................................... 19
Fisheries and other marine products.............................................................................................. 19
Mangrove forest products................................................................................................................ 20
Pharmaceuticals.............................................................................................................................. 20
Supporting services......................................................................................................................................... 20
What happens when ecosystem services are lost?.............................................................................................................. 21
Loss of regulating services............................................................................................................................. 21
Loss of provisioning services.......................................................................................................................... 22
Loss of cultural services................................................................................................................................. 22
Natural recovery – or rehabilitation and restoration?.......................................................................................................... 23
Coral reefs....................................................................................................................................................... 24
Mangroves........................................................................................................................................................ 25
Mangroves and coral reefs on tropical coastlines of the future.......................................................................................... 26
Maintaining regulating services...................................................................................................................... 26
Maintaining provisioning services................................................................................................................... 26
Maintaining cultural services.......................................................................................................................... 27
Essential management tools.......................................................................................................................... 27
Integrated coastal management..................................................................................................... 28
Marine protected areas.................................................................................................................... 28
Improved resilience and adaptive management............................................................................. 29
Financing the future........................................................................................................................................ 29
References............................................................................................................................................................................. 31
3
In the front line
Introduction
The Indian Ocean tsunami of 26 December 2004 and its hurricanes and typhoons, and other potential consequences
tragic and devastating consequences were a wake-up call of global warming. More than ever, it is essential to consider
for the global community, dramatically drawing attention to the full value of ‘ecosystem services’ (the benefits that
the vulnerability of tropical coastal ecosystems and the people obtain from ecosystems) when making decisions
dangers of undermining the services they provide to about coastal development.
humankind. This was further emphasized by the The aim of this publication is to help decision
catastrophic hurricane season in the Gulf of Mexico in makers and policy makers around the world understand the
2005 when Hurricanes Katrina, Rita and Wilma caused importance of coastal habitats to humans, using coral reefs
much publicized and extensive damage to coastal areas. and mangroves as an example. It looks at the role of these
The numerous other tropical storms that affected coastal ecosystems in protecting the coast, and takes into account
communities and ecosystems in other parts of the world new studies of this complex topic triggered by the tsunami
in the same year received much less attention, but were and tropical storms. The publication also addresses the
also notable. huge range of other benefits provided by these ecosystems
The lessons learnt in terms of loss of life, damage and the role that they can play in coastal development and
sustained, and approaches to reconstruction and mitigation in restoring and maintaining the livelihoods of those who
are critically relevant to future management of the coast in have suffered from extreme events, whether natural or
a context of increasing severe weather events such as induced by human activity.
NASA/Still Pictures
4
In the front line
Key messages
GLOBAL STATUS OF CORAL REEFS AND MANGROVES Ecosystems that can no longer provide their full ecological
Coral reefs and mangroves are two of the world’s rarest services have a social and economic ‘cost’ that can be felt
ecosystems, covering an area that is an order of magnitude locally and many miles away. Degradation of coral reefs and
less than that of tropical and subtropical forests. Both mangroves may, and in some cases already does, cause:
❏ Reduced fish catches and tourism revenue in
ecosystems are under serious threat.
❏ Some 30 per cent of reefs are already seriously coastal communities, and potentially even loss
damaged and 60 per cent could be lost by 2030. of food security and malnutrition due to lack
Threats include overfishing, use of destructive of protein.
❏ Loss of export earnings and decline of the
fishing methods, coral mining, pollution, sedi-
mentation, anchor damage and tourism, as well tourism industry.
❏ Increased coastal erosion and destruction from
as coral bleaching, disease and tropical storms.
This combination of impacts is causing a shift, on storms and catastrophic natural events, which
many reefs, from a coral-dominated ecosystem to affects coastal residents, tourism operations and
one dominated by algae. many other economic sectors.
❏ An estimated 35 per cent of the world’s original
mangrove cover has already gone, with some SHORELINE PROTECTION
countries having lost up to 80 per cent. Mangroves Reefs and mangroves naturally form barriers and thus
have been degraded by conversion to aquaculture, inevitably provide some shore protection, a fact long
timber extraction, use of wood for fuel and recognized by coastal communities, fishers and vessels
charcoal production, diseases and storms. which use the sheltered waterways behind these
ecosystems. Both reefs and mangroves can themselves be
ECOSYSTEM BENEFITS damaged by strong winds and waves, and so their buffering
Coral reefs and mangroves provide benefits under the four capacity is a balance between their resilience and their
categories of ecosystem services defined by the 2005 vulnerability. The current consensus is that:
❏ Reefs and mangroves play an important role in
Millenium Ecosystem Assessment:
❏ Regulating – e.g. protection of shores from storm shore protection under normal sea conditions
surges and waves; prevention of erosion. and during hurricanes and tropical storms. At
❏ Provisioning – e.g. fisheries, building materials. least 70-90 per cent of the energy of wind-
❏ Cultural – e.g. tourism, spiritual appreciation. generated waves is absorbed, depending on how
❏ Supporting – e.g. cycling of nutrients, fish nursery healthy these ecosystems are and their physical
habitats. and ecological characteristics.
❏ In a tsunami, the buffering capacity of reefs and
They are among the most valuable ecosystems in terms of mangroves is more variable and often reduced
their benefits to humankind: because of the different structure and form of
❏ Economic valuation of ecosystems needs to be the waves and their much greater force. Distance
treated with caution but annual values per km2 from the earthquake epicentre, the presence of
have been calculated at US$100 000-600 000 for inlets and headlands, the gradient of the
reefs and US$200 000-900 000 for mangroves. continental slope, shoreline elevation, the
❏ The small total area of coral reefs and mangroves presence of dunes and other vegetation, and
belies their importance in terms of fisheries, density of habitation and infrastructure seem to
other extractive uses, shoreline protection and, in explain most of the variation.
the case of reefs, tourism and recreation.
❏ Both ecosystems contribute significantly to PROS AND CONS OF REHABILITATION AND RESTORATION
national economies, particularly those of small Both reefs and mangroves will recover naturally once a
island developing states (SIDS), 90 per cent of stress has been removed, but this can be slow; for example,
which have coral reefs and over 75 per cent of the reefs most seriously damaged by the tsunami may take
which have mangroves. five to ten years to recover. New growth of coral colonies and
5
In the front line
❏ The devastation recently wrought by hurricanes
mangrove trees, and recruitment of coral larvae and
mangrove seedlings, is balanced by erosion and breakdown and tropical storms testifies to the priority that
from both human-induced and natural stresses. The must be accorded to the maintenance and
chronic human impacts faced by these ecosystems are enhancement of the resilience of natural coastal
tending to slow recovery, and the highest priority is to barriers such as reefs and mangroves.
❏ Post-tsunami and hurricane reconstruction
reduce and eliminate these stresses. It is tempting to try to
speed recovery of an ecosystem by active restoration, or efforts provide an opportunity to introduce and
repair. However, this is rarely totally successful because of expand good coastal management practices.
the difficulties involved in re-establishing full biodiversity These may indeed help to mitigate damage from
and ecological processes: future tsunamis but, since these are infrequent
❏ Mangrove restoration is relatively simple and events, the more important consequence is
large areas of new forest are being created using mitigation of the impacts of the more certain, but
volunteers and local labour. However, achieving a gradual, changes due to global warming.
❏ Short-term, small-scale rehabilitation progr-
mangrove forest with a full complement of
biodiversity is a more complex and long-term ammes should not take precedence over
process, and it is questionable whether any activities directed at the root causes of the
programmes have yet achieved this. decline in reef and mangrove health. Key tools
❏ Reefs, involving numerous species with very include integrated coastal management, marine
different life histories and poorly understood protected areas, and monitoring and assessment
growth and reproductive characteristics, are for adaptive management.
❏ Governments, civil society and the private sector
more difficult to restore. Many attempts have
been made using a variety of techniques. Most must recognize that, as with other benefits, there
methods are costly and require considerable is a price to pay for maintaining these eco-
skill, and there are few examples of successful systems. However, this is much lower than the
sustainable reef restoration over large areas. benefit received. For example, the estimated
average operational management cost of a
marine protected area is US$775 per km2, or less
CORAL REEF AND MANGROVE MANAGEMENT IN THE
FUTURE than 0.2 per cent of the estimated global value of
Investing in environmentally sustainable management a square kilometre of reef or mangrove.
❏ Many of the world's wealthiest nations have
and development of the coast will be more cost effective
than restoring human livelihoods and ecosystems after a jurisdiction over these ecosystems – more than
catastrophe. The relatively small amount of damage 30 per cent of reefs are in countries classified as
inflicted on coral reefs and mangroves by the highly developed. They also have strong links
2004 tsunami demonstrated the resilience of these with less developed countries struggling with
ecosystems to natural disturbance, but the worldwide their management. Political will and concerted
public concern generated also revealed our awareness of action are needed – coral reefs and mangroves
their vulnerability. are in the front line, and calling for attention.
D Sato/UNEP/Topham
S Wells
6
In the front line
Global status of reefs and
mangroves
Mangroves and tropical coral reefs
DISTRIBUTION
Of the 177 countries in the world, rather less than half (44 countries is very unequal. Australia and Indonesia each
have about 50 000 km2 of reef and account for nearly 35 per
per cent) have tropical coral reefs and about half have
mangroves. Our knowledge of the distribution of coral reefs cent of the world’s reefs, and Indonesia alone has 23-25 per
and mangroves is now relatively good, as a result of regional cent of the world’s mangroves. In general, other countries
have less than 10 000 km2 of reef and less than 1 000 km2 of
and global mapping programmes using navigational charts,
satellite imagery and aerial photography, as well as more mangroves (Spalding et al., 1997; 2001).
detailed field surveys.
Both ecosystems occur principally in the tropics, STATUS
with South-East Asia a major centre. Distribution between The coastal biome, which makes up only 4 per cent of the
Fig. 2: Distribution of tropical coral reefs and mangroves
Fig. 1: Area of coral reefs and mangroves
Coral reefs and mangroves are among the world’s rarest
ecosystems. Reefs cover an estimated 284 300 km2, or just 1.2 per
cent of the world’s continental shelf area (Spalding et al., 2001).
The total area of mangrove forest is less certain but is even
smaller, estimated at between 167 000 km2 (Valiela et al., 2001)
and 181 000 km2 (Spalding et al., 1997). As a comparison, tropical
and subtropical forests cover 23.3 million km2, an order of
magnitude larger (Millennium Ecosystem Assessment, 2005).
7
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planet’s total land area, is home to one-third of the world’s
P Dustan
population, and this population is predicted to double over
the next 15 years. In many countries, such as island nations
and those with inhospitable and arid interiors, humankind
lives almost entirely on the coast. With the exception of
some isolated atolls, all reefs and mangroves lie adjacent to
the coast; more than half these ecosystems occur within 25
km of urban centres inhabited by 100 000 or more people
(Millennium Ecosystem Assessment, 2005). Not
surprisingly, the health and extent of both reefs and
mangroves have declined dramatically over the last century.
Trends in reef health are well documented as
P Dustan
assessments are carried out at regular intervals, through
numerous monitoring programmes, the results of which
are published in the biennial Status of the World’s Reefs
Reports (Wilkinson, 2004), the regional World Resources
Institute’s Reefs at Risk reports (Burke and Maidens, 2004;
Burke et al., 2002) and many national reports.
Results from monitoring programmes indicate that
about 30 per cent of the world’s reefs are seriously
damaged, with possibly no pristine reefs at all remaining,
and it has been predicted that 60 per cent of reefs will be
lost by 2030 (Wilkinson, 2004). Using information on existing
and potential threats to reefs in 1998, the World Resources Carysfort Reef, the largest and most luxuriant reef in the Florida
Keys, United States, in 1975 (higher) and 2004 (lower) showing the
Institute suggested that 27 per cent of all reefs are
catastrophic decline of living coral cover.
potentially at high risk and a further 31 per cent are at
medium risk of damage (Bryant et al., 1998). More recent
regional predictions, using the same method, paint an even
Reefs at risk in the Caribbean
more disturbing picture. A 2000 analysis estimated that
human activities potentially threaten 88 per cent of the Nearly two-thirds of reefs in the Caribbean are potentially at risk
from human activities, according to a 2004 report, with over 40 per
reefs of South-East Asia, with 50 per cent at ‘high’ or ‘very
cent at ‘high’ or ‘very high’ risk, and about 28 per cent at low risk
high’ risk and only 12 per cent at low risk (Burke et al.,
(Burke and Maidens, 2004). In this region, elkhorn (Acropora
2002). palmata) and staghorn (A. cervicornis) corals have undergone
As yet there are no equivalent global mangrove massive die-offs (Gardner et al., 2003).
8
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Fig. 3: Area of mangrove lost to human activities
assessments, but several studies have shown this
(per cent)
ecosystem to be as much at risk as coral reefs. The
amount of mangrove lost varies widely among countries
but, where data are available, mangroves are on a
declining trend. An estimated 35 per cent of mangrove
forest has disappeared in the last two decades (Valiela et
al., 2001), and some countries have lost 80 per cent of
cover (Spalding et al., 1997). The average annual rate of
disappearance (or conversion to other forms of land use)
is estimated at 2.1 per cent, with the greatest rate of loss
in the Americas (3.6 per cent). The annual rate of loss of
mangroves thus exceeds the rate of disappearance of Source: Valiela et al., 2001
tropical rainforests (0.8 per cent) (Valiela et al., 2001).
little to the main structure of the reef (e.g. Agaricia) (Hughes
Estimates for some locations suggest that rates of
mangrove loss may be as high as 50 per cent a year et al., 2003; Knowlton, 2001).
(Alongi, 2002). Degradation of mangroves leads to long-term
Over the last few decades there have been major changes in the ecology of large areas of coastline. In
changes in the appearance and quality of reefs and particular, conversion of mangroves to shrimp farms, and
mangroves, the result of a combination of many ‘drivers’ or the subsequent aeration and use of fertilizers, alters the
threats. These have both direct and indirect impacts that composition and structure of the soil. Eventually ponds
often trigger an escalating series of problems. are abandoned, sometimes after only two to ten years, as
Many reefs, for example, are undergoing a shift from they are no longer suitable for production (Stevenson,
a coral-dominated to an algal-dominated state. Corals have 1997). There is little chance of mangrove regeneration in
been disappearing as a result of bleaching, disease, storm the remaining barren lands. Leading causes of mangrove
damage and a range of human activities, including forest loss and degradation are conversion for
overfishing, use of destructive fishing gear, anchor damage aquaculture, use of mangroves for timber for
and pollution. At the same time, algae have increased as construction and other functions, and for fuelwood and
herbivores and grazers, such as sea urchins and some fish charcoal, conversion to rice paddies, and freshwater
species, that keep them in control have declined through diversion and coastal development for tourism and other
disease and overfishing. Algae have further increased as a purposes (Valiela et al., 2001).
result of nutrient pollution. Where coral cover has started to
increase there are indications that the so-called THREATS
framework-building corals (e.g. Acropora, Montastrea) that
once dominated are being replaced by corals that contribute Overexploitation and destructive fishing
Many commercial fish species, such as rabbitfish
(Siganidae), feed on algae, and their removal can result in
The brown seaweed Chnoospora overgrowing branching corals.
excessive algal overgrowth of corals. Removal of
Y Latypov
‘keystone’ species (those that play a particular role in an
ecosystem) – such as triggerfish which prey on sea
urchins – may be the cause of urchin population out-
breaks which further degrade corals through bioerosion.
Dynamite, small-mesh nets and nets that are dragged
over the seabed, although illegal in many countries, are
still used and cause widespread physical damage as well
as removing or killing immature fish and other species of
no commercial value.
Habitat loss
Mangroves can be completely wiped out when forests are
cleared for salt production operations, for industrial,
residential and tourism development, or, particularly, for
aquaculture. In contrast, coral reefs generally suffer from
9
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UNEP
In Honduras, shrimp farms have progressively transformed the coast of the Gulf of Fonseca since the early 1970s. Although there were still large
areas of mangrove in 1987, by 1999 the only substantial forests were in protected areas such as Estero Real Nature Reserve (UNEP, 2005a).
a gradual decline in quality rather than a sudden Disease
disappearance. However, mining for corals for use as Coral diseases, rarely recorded until the 1970s, have had
building materials can eliminate, or reduce to rubble, a catastrophic effect on reefs, particularly in the
large areas of reef. Although coral mining is illegal or Caribbean, affecting 100 hard and soft coral species in 54
regulated in most countries, it is still having a major countries. The cause is still largely unknown, although
impact in India, the Maldives, Sri Lanka and Tanzania
Sediment plume in Monte Cristi National Park, Dominican Republic.
(Wilkinson, 2004).
Inland deforestation is causing sediment run-off on to nearby coral
reefs. As a result, coral cover tends to be low compared with other
Land-based sources of pollution less impacted areas.
More than 77 per cent of the pollutants entering the oceans
UNEP-WCMC
originate on land, and 44 per cent of these pollutants come
from improperly treated wastes and run-off (Cicin-Sain et
al., 2002). The nutrient content of the oceans has increased
dramatically in recent years as a result of fertilizer and other
agricultural run-off, sewage and aquaculture waste.
Nutrients such as nitrogen and phosphorus deplete oxygen
in the water and promote the growth of algae on reefs
(Hughes et al., 2003).
Many coastal development activities, such as
residential, tourist, industrial and port development, involve
land reclamation and dredging which invariably results in
sediment being stirred into the water column.
This reduces light penetration, may directly smother corals
and can damage mangroves. Construction activities inland,
agriculture and deforestation, and poor management also
contribute to increased sediment.
10
In the front line
A W Bruckner
Thomas Heeger
Coral attacked by black-band disease. Fishing with dynamite in the Philippines.
both fungi and bacteria have been identified as pathogens Furthermore, by 2100, rates of calcification (the
in two cases (Porter, 2001; UNEP-WCMC, 2003). There are process by which calcium is formed) on reefs may have
indications that abrasion of massive corals through tourist decreased by 17-35 per cent of pre-industrial levels as a
activities may make corals more susceptible to disease result of high levels of dissolved carbon dioxide in the
(Hawkins et al., 1999). oceans (these are now 380 parts per million (ppm),
compared with 280 ppm two centuries ago). This will cause
Climate change weakening of coral skeletons and slower growth rates,
There is now general consensus that extreme storm events making reefs even less effective as breakwaters (Feeley et
are becoming more frequent, and sea levels and al., 2004; Kleypas et al., 1999).
sea surface temperatures are rising as a result of global
warming. Reefs are already suffering from bleaching events Other threats
that have increased significantly since 1975. In the Individual tourists, tourist boats and anchors may have only
Caribbean bleaching events are predicted to become an a minor impact, but over time and in large numbers the
annual event as current sea surface temperatures are in the impact becomes significant (Hawkins et al., 1999; Zakai and
upper temperature threshold for coral survival (Gardner et Chadwick-Furman, 2002). Spills of oil and toxic chemicals,
al., 2005; Hughes et al., 2003). Tropical storms are forecast and dumping of other wastes, cause localized impacts to
to become even more frequent and/or more intense both reefs and mangroves. The introduction of alien species
(Trenberth, 2005), and this will compound the problem, is a threat to marine ecosystems that is growing rapidly with
causing more damage to both reefs and mangroves and increased shipping and susceptibility in systems degraded
resulting in shorter recovery times between events (Hughes by other stresses. Marine plants and animals can be
et al., 2003). transported immense distances on the hulls of vessels or in
The change on reefs from coral to algal dominance, ballast water. Non-indigenous sessile species have been
and from framework-building species to non-framework introduced to reefs in Guam via ships’ hulls, and other alien
species, may also compromise their ability to keep pace with species are spreading on the reefs of Hawaii, outcompeting
rising sea levels (Bellwood et al., 2004; Gardner et al., 2003). native species (Eldredge, 2003).
11
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Value of ecosystem services
The Millennium Ecosystem Assessment (Millennium
C Ravilious
Ecosystem Assessment, 2005) defines four categories of
ecosystem services:
❏ provisioning – e.g. food, medicines,
construction materials
❏ regulating – e.g. protection of shorelines,
water quality maintenance
❏ cultural – e.g. tourism, spiritual beliefs
❏ supporting – e.g. maintenance of basic life
support systems.
Coral reefs and mangroves provide benefits under all four
categories.
Ecosystem services Coral reefs Mangroves
REGULATING Protection of beaches and coastlines Protection of beaches and coastlines from
from storm surges and waves storm surges, waves and floods
Reduction of beach erosion Reduction of beach and soil erosion
Formation of beaches and islands Stabilization of land by trapping sediments
Water quality maintenance
Climate regulation
PROVISIONING Subsistence and commercial fisheries Subsistence and commercial fisheries
Fish and invertebrates for the Aquaculture
ornamental aquarium trade Honey
Pharmaceutical products Fuelwood
Building materials Building materials
Jewellery and other decoration Traditional medicines
CULTURAL Tourism and recreation Tourism and recreation
Spiritual and aesthetic appreciation Spiritual – sacred sites
SUPPORTING Cycling of nutrients Cycling of nutrients
Nursery habitats Nursery habitats
Techniques for valuing ecosystem services are still There is, however, no single agreed total value for all
relatively new and untested, and the results of such coral reefs or all mangroves, or even for the different
calculations must be interpreted with care. Putting services provided by these ecosystems. Values vary
a monetary value on an ecosystem, however, can help to according to:
❏ The location – e.g. reefs that are major tourist
demonstrate why its survival is important (IUCN/TNC/
World Bank, 2004; Turner et al., 2003). Economic values destinations will have a higher value in terms of
can be calculated from the cost of the products (e.g. fish) diving and other reef-related activities than
and services (e.g. tourism) derived from an ecosystem, or those where tourism has not been developed.
❏ The length of time being considered and
from the cost of replacing a service (e.g. building
seawalls where natural storm protection has been lost). whether a prediction for the future is involved
12
In the front line
(e.g. all reefs are potentially of value for diving Fig. 4: Economic value of the main ecosystem
services of coral reefs (billion US$)
tourism but some may have no value at present).
❏ The ‘beneficiaries’ of the service, since some
people will place a higher value on it than others.
❏ The method used and the assumptions made.
Furthermore, it is hard to calculate the economic value
of the aesthetic and ethical benefits of ecosystems, or of
the service some ecosystems provide through cycling
nutrients. Estimates of the ‘total’ economic value of an
ecosystem thus vary considerably and there is a risk
that using this approach underestimates the
ecosystem’s social benefits and overall importance. This
means that it is not always wise to use ecosystem Source: Cesar et al., 2003
valuations for policy making and investment decisions
(IUCN/TNC/World Bank, 2004). For example, the
to US$3.5 million per km2 have been calculated
apparent higher value assigned to mangroves than coral
reefs (see Fig. 4) should not be interpreted to mean that for mangroves (Sathirathai and Barbier, 2001).
they have a higher management priority. It is also true
that many of the activities that bring benefits, such as Some of the variation can be explained by the location of
fishing and tourism, also damage reefs and mangroves, the ecosystem. The value of reefs and mangroves for
and only careful management will allow the full values shore protection (often measured per linear kilometre)
to be materialized. depends on the activities under way or planned along a
However, if these limitations are taken into particular stretch of coast. In Indonesia, reefs have been
account, an economic valuation can help to demonstrate valued as follows (Cesar, 1996):
❏ Reefs adjacent to sparsely populated areas
the major role that reefs and mangroves play in the lives
of many people. Studies to date have shown that most where agriculture is the main activity: US$829
benefit comes from provisioning services (i.e. fisheries per km, based on the value of agricultural
and, for mangroves, timber and fuelwood), cultural production that would be lost if there were no
services (tourism) and regulating services (shore protection.
❏ Reefs adjacent to areas of high population
protection).
The total annual economic value of reefs has densities: US$50 000 per km, based on the cost
been estimated at between US$100 000 and US$600 000 of replacing housing and roads if coastal
per km2 (Cesar et al., 2003; Constanza et al., 1997) and protection were lost.
❏ Reefs in areas where tourism is the main use:
the value of mangroves even higher, at more
than US$900 000 per km2 (Constanza et al., 1997). US$1 million per km, based on the cost of
Figures are, however, very variable as some national maintaining sandy beaches.
estimates show:
❏ Sri Lanka’s coral reefs have been valued at Similar values have been obtained for the Caribbean,
between US$140 000 and US$7.5 million per varying from US$2 000 to US$1 million, with the highest
km2 over a period of 20 years (Berg et al., 1998). values in areas heavily developed for tourism (Burke and
❏ In American Samoa, mangroves, which cover less Maidens, 2004).
than 0.5 km2, have an estimated value There are also several methods for valuing
of US$104 000 per km2 (total value of about mangroves. The storm protection value of mangroves in
US$50 million a year) and reefs, which cover 222 Sri Lanka (before the tsunami) was put at US$7 700 per
km2, are estimated at US$14 300 per km2 (total km2 a year using a linear value (UNEP/GPA, 2003). A study
value of US$318 million a year) (Spurgeon and in Indonesia, in a different approach, calculated the
Roxburgh, 2005). erosion control value of mangroves as being equivalent to
❏ In Thailand, very high values of US$2.7 million US$600 per household per year (Ruitenbeek, 1992).
13
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Regulating services – shoreline
protection
S H Grady
Although reefs and mangroves form natural barriers Hotel built behind mangroves, Kenya.
along the coast and thus inevitably provide some
protection to the shore, there is surprisingly little Orissa, India, a powerful cyclone in 1999 and associated
scientific data to back this up. Most of the evidence is waves caused extensive damage and human mortality,
observational and anecdotal, and relates to normal wave but communities protected by mangrove belts were less
energy and storms. The calm lagoons inside reefs and affected (Mangrove Action Project, 2005). In Viet Nam,
behind mangroves are immediately evident on tropical mangroves have been observed to limit damage from
coastlines. Fishers use these sheltered waters as cyclone waves and tsunamis and are said to have led to
navigation routes and for fishing, particularly during large savings on the costs of maintaining sea dykes (Ha,
bad weather or the rough season monsoons. Holiday 2003; Tri et al., 1996).
makers and tourists benefit from the sheltered waters In southern India, the distinct differences
for numerous recreational activities. The breakwater between the Gulf of Mannar and Palk Bay, caused by the
role of reefs is emphasized by the importance accorded protection provided by reefs, have led to these seas being
to the channels through them. These allow safe passage equated with men and women by local villagers. The
to the lagoon and shore for fishing, navigation and former is considered ‘male' because waves hit the reef
recreational activities, particularly in bad weather, a and subside in force before they reach the shore. The
significance recognized by both coastal communities latter is considered ‘female’ because waters are
and port authorities. generally calmer, but, if disturbed by storms, cause
Coastal communities are often aware of the greater damage due to the lack of a reef. Fishing
particular protection afforded by mangroves. In India communities on Pamban, an area lying between the two
(Dahdouh-Guebas et al., 2005) and the Philippines seas, still remember the 1964 cyclone that washed away
(Walters, 2004), villagers tell of how they have been one village, while those behind reefs survived
protected from cyclones and typhoons in locations where (Whittingham et al., 2003). Further north, in Chidambaran
mangroves are intact, but suffer where mangroves have District the shore protection role of mangroves is
recognized by local people where a 113 km2 forest is used
been converted to shrimp farms or otherwise lost. In
14
In the front line
as a sacred grove and is traditionally known in Tamil as reef flat between the reef edge and the shore, the more
Alaithi Kadukal, which means ‘the forest that controls the wave energy is lost. In Egypt, for example, the reef flat and
waves’ (WWF, 2005). reef crest of the fringing reef off the tourist resort of
Both reefs and mangroves also play a role in the Hurghada dissipate wave energy considerably, protecting
accretion of coastlines. Reefs produce sand that forms marinas and beaches (Frihy et al., 2004).
and replenishes sandy beaches and islands, the sediment
accumulating when corals and other calcified organisms
S Wells
break down after their death. Mangroves help to stabilize
coastal land, by trapping sediment washed down in rivers
or from more general run-off. Remains of rows of
mangroves planted to stabilize the coast by early
generations of Maoris can still be seen in New Zealand
(Vannucci, 1997).
The role of reefs as breakwaters is also
demonstrated by the many artificial structures that are
being installed for shoreline protection in locations with
no natural reefs. These often have a negative impact, in
terms of creating unwanted longshore drift, but they
nevertheless show how reef-type barriers influence wave
action, even being installed to improve surfing conditions
(Jackson et al., 2002).
Although the general buffering capacity of reefs
and mangroves thus seems obvious, the mechanical
processes involved are complex, and the extent to which
they provide shore protection compared with man-made
barriers and other natural features is not yet fully
The lagoon behind the fringing reef here in northern Zanzibar
understood. Furthermore, the reef and mangrove provides a shallow sheltered area where many activities can be
ecosystems are themselves damaged by events such as undertaken.
storms and tsunamis. Hurricanes, for example, can
reduce coral cover significantly (Gardner et al., 2005). The amount of energy reduction also depends on
Mangroves can be destroyed or seriously degraded by the extent of fragmentation of the reef, as a continuous
hurricanes, through defoliation and uprooting by the reef acts more as a breakwater than a reef that is broken
wind, erosion of the shoreline by waves and burial under by channels. The state of the tide and the depth of water
sediment. In 1999 Hurricane Mitch destroyed 97 per cent over the reef – at low tide a reef affords more protection –
of the mangroves of Guanaja, one of the Bay Islands in and whether it 'plunges' on to or 'spills' over the reef top
Honduras (Cahoon and Hensel, 2002). Thus the buffering also play a role (Gourlay, 1994; Kabdali and Turker, 2002).
capacity of both ecosystems is a balance between their Quantifying what the reduction in wave energy may mean
resilience and their vulnerability, with many factors in terms of shore protection is more difficult. In Sri Lanka,
involved. A healthy coral reef or mangrove, in the absence however, it has been estimated that with current rates of
of human impact, acts as a self-repairing breakwater, erosion and assuming that 1 kilometre of reef protects 5
kilometres of shoreline, 1 km2 of coral reef can prevent
with growth in equilibrium with the erosion caused by
2 000 m2 of erosion a year (Berg et al., 1998).
waves, storms and other processes.
Mangroves dissipate the energy and size of waves as
WIND-GENERATED WAVES AND STORMS a result of the drag forces exerted by their multiple roots and
The waves normally seen on the ocean are generated by stems. Wave energy may be reduced by 75
wind, and have most of their energy in the surface waters. per cent in the wave's passage through 200 metres
The reef flat (the zone of a reef extending seaward across of mangrove (Massel et al., 1999) but, as with coral
the lagoon) and the reef crest (the seaward edge of the reef reefs, other factors also have an influence, including coastal
flat) absorb most of a wave’s force, often up to or more than profile, water depth and bottom configuration. One study
90 per cent (Brander et al., 2004; Lugo-Fernandez et al., suggested that a 1.5-km belt of mangrove may be able to
1998; Roberts and Suhada, 1983). The greater the width of reduce entirely a wave one metre high (Mazda et al., 1997).
15
In the front line
2004 tsunami, and the damage they received,
A Baird
varied considerably.
Despite initial fears, both ecosystems were less
badly damaged than expected even on reefs in Aceh,
Indonesia, which were within 300 km of the epicentre
(Baird et al., 2005). In Thailand, of 175 reef sites surveyed
on the Andaman coast after the tsunami,
more than 60 per cent had little or no damage; 13 per
cent were seriously damaged, however. Shallow reefs on
wave-exposed islands and shorelines were most
vulnerable, as were the northernmost coast and offshore
islands (Phongsuwan and Brown, in press). At some sites,
differences were even more localized: at Patong Bay,
Phuket, reefs in the south were badly damaged but those
in the north were almost untouched, a pattern that was
Large boulder coral washed up on an Aceh beach following the
reflected in the destruction on land (Edwards, 2005).
tsunami of December 2004.
Post-tsunami surveys in Thailand and Aceh show
TSUNAMIS that most damage was in the form of overturning of
Compared with a wind-generated wave, a tsunami has a poorly attached boulder corals, breakage of branching
much longer wave length and the wave energy is corals, and smothering of the reef with sediment (Baird
distributed throughout the entire water column and is et al., 2005; Phongsuwan and Brown, in press).
on a much greater scale. As a tsunami approaches the Much greater damage was sustained by reefs directly
shore and water depth decreases, the wave height affected by the earthquake. Reef flats, with once diverse
increases dramatically as energy is converted to coral communities, have been permanently uplifted
surface layers, this effect being more pronounced on above the high water mark in many coastal areas of
gradually shallowing shores (Kowalik, 2004; Mojfeld Aceh and the Andaman and Nicobar islands (B. Brown,
et al., 2000). Tsunamis can cause substantial damage pers. comm.).
at locations protected from wind-generated waves, as An analysis by UNEP/GRID of more than 50 sites
they tend to accelerate through channels and up inlets, affected by the tsunami, using pre- and post-satellite
rapidly increasing in height. They can also be reflected imagery, indicated that there was greater coastal
off obstacles and travel in different directions (Yeh et flooding behind coral reefs (Chatenoux and Peduzzi,
al., 1994). It is thus perhaps not surprising that 2005), perhaps because channels through the reef
the roles of reefs and mangroves as buffers in the accelerated the flow. The same result was found in Aceh
UNEP-WCMC
June, 2002 January, 2005
Many parts of the coast of Tamil Nadu in India were severely hit by the tsunami. Three villages behind the mangroves in Pitchavaram
Sanctuary survived whereas the two in front were lost (Danielsen et al., 2005; Kathiresan and Narayanasamy, 2005). This could, however,
have been due to the reduced force of the wave, as the continental slope drops to deep waters much more sharply here, compared with areas
further south which suffered greater damage (Wood, 2005).
16
In the front line
UNEP-WCMC
The once extensive mangroves around Banda Aceh in Sumatra, Indonesia, an area which suffered devastating damage and loss of life in the
tsunami, had been largely replaced by shrimp farms, covering 360 km2 (UNEP, 2005b). Although loss of mangroves could have contributed to
the destruction, the area was also very close to the epicentre of the tsunami, and thus vulnerable to substantial impact.
dominated by genera such as Sonneratia or Rhizophora)
(Baird et al., 2005), and studies on the Queensland coast
of Australia have also shown that historically tsunamis were damaged (Dahdouh-Guebas et al., 2005). It therefore
have breached the Great Barrier Reef through passes in seems that the 'quality' of the mangrove forest contributes
the reef (Knott, 1997). in large measure to its buffering capacity, in addition to its
Some studies have suggested that, in certain size and the extent of regrowth if it had previously been
locations, reefs did provide protection. In Sri Lanka, at cleared. Tree density may certainly be important: one
Hikkaduwa where the reefs are in a better condition than study indicated that a 100 metre-wide belt of mangroves,
with trees at a density of 30 per 100 m2, would be sufficient
many in the country – and are protected in a marine park –
the tsunami caused damage to a distance of only 50 metres to reduce the flow pressure from a tsunami by as much as
inland and waves were only 2-3 metres high. At Peraliya, 90 per cent (Hiraishi and Harada, 2003).
just 3 km to the north but where the reefs have been Analyses of satellite images of a large number of
extensively affected by coral mining, waves were 10 metres tsunami-impacted sites do not show clear correlations
high, and damage and flooding occurred up to 1.5 km inland between the presence of mangroves and reduced
(Fernando et al., 2005, Liu et al., 2005). Detailed analysis of shoreline damage (Chatenoux and Peduzzi, 2005; Wood,
these areas is still needed, as other factors may also be 2005). In many cases the locations where mangroves have
involved. Dunes were particularly important in providing been reported to have helped protect the shoreline were
protection in Sri Lanka (Liu et al., 2005). out of the main path of the wave, or were adjacent to
Initially, there were many observations suggesting deeper water, and thus less susceptible to serious
that mangroves both dissipated the force of the tsunami damage. These findings demonstrate the importance, in
and caught the debris washed up by it, and thus helped to developing predictive models, of carefully analysing every
reduce damage (IUCN, 2005). In several cases, mangroves aspect of a site, both at the broad scale where satellite
were also instrumental in saving lives by preventing imagery can be useful and through detailed field surveys
people caught in the backwash of the wave from being and on-the-ground studies.
pulled out to sea. However, as with coral reefs, The general picture emerging since the tsunami
subsequent studies showed that the benefit of mangrove is that reefs and mangroves were not the main factor
protection was rather variable. In India, bathymetry and influencing the extent of damage on the coastline.
coastal profile were most important in determining the Nearshore bathymetry and coastline profile are probably
impact, but less erosion was observed in the Andamans the key factors determining the force of a wave at any
behind mangroves than where there were no mangroves particular coastal location. Shores adjacent to deep
(Department of Ocean Development, 2005). water tended to be less affected than those next to
A survey of 24 lagoons and estuaries along the shallow sloping shelves, regardless of the presence or
south-west, south and south-east coasts of Sri Lanka absence of reefs. The shape of the coastline is also
which suffered the greatest damage showed that where influential, with headlands often providing protection
good quality mangrove communities occurred there was while bays and inlets act as funnels, restricting and
little destruction to the coast, and the mangroves focusing the force of a wave. More research is required
themselves were not badly harmed. However, forests before it will be possible to predict where, and in what
dominated by less typical mangrove species (i.e. those way, a reef or mangrove will help to reduce the impact of
that had been degraded in the past and were no longer a tsunami.
17
In the front line
Other ecosystem services
OTHER REGULATING SERVICES
Climate and global carbon cycle
Emissions of carbon dioxide from fossil-fuel combustion and
land-use changes are the leading cause of the build-up of
greenhouse gases. Forests, as well as crops, soil and other
organic matter, take up carbon (carbon sequestration) and
help to reduce the rate of global warming. Mangroves fix and
store significant amounts of carbon (Alongi, 2002) and they
play an important role in carbon sequestration, currently
absorbing an estimated 25.5 x 106 tonnes of carbon a year
(Ong, 1993).
Although reefs play an important role in the carbon
budget, contributing 7-15 per cent of global calcium
carbonate production, they do not help with carbon
sequestration. Sedimentary carbonates, including corals,
coralline algae and the shells of other marine organisms,
are the largest reservoir of carbon on Earth, and so
fluctuations in the global calcium carbonate budget
influence atmospheric carbon dioxide concentration.
However, the chemistry of the system is such that although
the oceans themselves are a ‘sink’ (i.e. they take up carbon
dioxide), reefs are ‘sources’ or net producers of carbon The number of dive operators along the Meso-American Barrier
Reef has increased dramatically in recent years, reflecting the
dioxide, albeit on a small scale in terms of the global carbon
growth of this leisure activity. In 2000, reef divers – numbering
budget, through the process of calcification (Suzuki and
about 3.6 million – made up 10 per cent of all tourists to the
Kawahata, 2004). Caribbean. Divers, however, contributed 17 per cent of tourism
revenue, spending about US$2 100 per trip, compared with
US$1 200 for tourists in general. It has been estimated that in 2000
Water quality
the net annual benefits from diver tourism in the Caribbean
Mangroves are capable of absorbing pollutants such as amounted to US$2.1 billion, with US$625 million being spent
heavy metals and other toxic substances (Lacerda and directly on diving on reefs (Burke and Maidens, 2004).
Abrao, 1984), as well as nutrients and suspended matter
(Ewel et al., 1998). This makes them natural wastewater tourism constitutes a large, and possibly the fastest
filters, preventing many pollutants from reaching deeper growing, sector. In Egypt, for example, the tourism sector as
water (Robertson and Phillips, 1995; Tann and Wong, 1999). a whole accounts for more than 11 per cent of gross
domestic product (GDP), and coral reefs have been central
CULTURAL SERVICES to the extremely rapid development of beach-based and
diving tourism in south Sinai since the 1990s; this area now
Tourism accounts for some 25 per cent of tourism’s contribution to
Coral reefs add significantly to the value of coastal tourism, national GDP (Jobbins, 2004).
supporting activities such as scuba diving, snorkelling and The 2004 tsunami brought home the economic
glass-bottom boat operations. They also contribute to the value of coastal and reef-based tourism, since this is vital to
formation of white sandy beaches. Tourism is the world’s the economies of the Maldives, Sri Lanka and Thailand. In
largest industry, with 694 million international tourist Sri Lanka, coastal tourism contributed about US$20 million
arrivals generating revenues of over US$500 billion in 2003. a year to the national economy in the mid-1990s (Berg et al.,
The tourism industry is a major employer and source of 1998). A study in 2003 of the reefs of the Phi Phi Islands in
foreign exchange and is growing rapidly; it is expected to Thailand, subsequently heavily damaged by the tsunami,
valued them at US$624 300/km2 a year for tourism and
reach 1.6 billion arrivals by 2020. Beach-based leisure
18
In the front line
valued species) in Belize, Honduras and Mexico is directly
S Wells
dependent on the health of the adjacent barrier reef, the
longest in the hemisphere. Sustainable annual catches of
fish from reefs vary from 0.2 to 30 tonnes/km2, with an
average of 5 tonnes/km2 (Jennings and Polunin,1995).
Depending on the value of the fish, reef fisheries are thus
potentially worth US$15 000-150 000/km2 a year, based on
catch values of US$1-10 per kg (Talbot and Wilkinson, 2001).
Reef fisheries in South-East Asia generate some US$2.4
billion a year (Burke et al., 2002), and in the Caribbean
US$310 million a year (Burke and Maidens, 2004).
There is now a global market for reef species.
Commercial reef fisheries are a major source of
employment and foreign exchange, supplying export
markets and retailers around the world, as well as the
restaurant and hotel industries. The live reef fish trade
supplies restaurants throughout South-East Asia with
A mangrove boardwalk for tourists on Wasini Island in southern
products from the Pacific and Indian Oceans (Hughes et al.,
Kenya, managed by a local women's group, generates several
2003). Tuna fisheries, such as those in the Maldives and
thousand dollars a year which are used for maintaining the
Lakshadweep, are often supported by reef-based bait
boardwalk and for community development activities (IUCN, 2004).
fisheries, and tuna themselves depend in part on reefs for
recreation, with a total value of US$205 million a year their food (Whittingham et al., 2003). Reef-based
(Seenprachawong, 2003). This provides a major incentive recreational fisheries generate over US$100 million
for careful management of the reefs post-tsunami, to annually (Cesar et al., 2003).
ensure that they recover rapidly and continue to provide A large proportion of fish and invertebrates in the
tourism benefit. aquarium trade comes from coral reefs, shipped to the 1.5-
Mangroves are not traditionally thought of as tourist 2 million people in Europe and North America who have
attractions or suitable sites for recreation, but this is aquaria. Sri Lanka, for example, earns about US$5.6 million
changing fast with the realization that this ecosystem a year exporting reef fish to about 52 countries, an activity
provides a fascinating educational experience and also that supports directly and indirectly around 50 000 people.
harbours a range of unusual species that can be easily Large quantities of corals, shells, starfish, pufferfish and
observed once boardwalks have been installed. Visits to other species are used in the curio trade. Reef-based
mangroves and birdwatching tours are now generating
significant revenue for local communities.
S Wells
PROVISIONING SERVICES
Fisheries and other marine products
Coral reefs and mangroves support numerous different
types of fishery: artisanal, commercial and recreational;
food, curios and souvenirs, bait, and items for decoration;
and fish, lobsters, crabs, molluscs, sea cucumbers and
many other species. However, much of the harvesting of
these species, as well as of species taken for non-food
purposes, is unsustainable, and current economic benefits
may thus be short term.
Of the estimated 30 million small-scale fishers in
the developing world, most are dependent to some extent
on coral reefs for food and livelihood. In the Philippines,
more than 1 million small-scale fishers depend directly on
Some estimates suggest that reefs contribute up to 25 per cent of
coral reefs for their livelihood. The productivity of the the annual total fish catch in developing countries, providing food
fisheries sector (shrimp, lobster, conch and other high- for 1 billion people (Cesar et al., 2003).
19
In the front line
also used in large quantities locally for house, boat and
P Scott
jetty construction. Mangrove timber is particularly
valuable for construction as it is resistant to rot and to the
boring activities of many marine invertebrates. Wood
from several mangrove species has a high calorific value
and is thus of value both directly as fuelwood and as
charcoal. Mangrove wood was used as fuel in many of the
early train engines in India, and it is still widely used in
kilns to make lime (often using live corals from adjacent
reefs). The Matang mangroves in Malaysia provide
forestry products (timber and charcoal) with a value of
US$30 000/km2/year, and totalling US$10 million a year
(Talbot and Wilkinson, 2001).
Mangroves provide a variety of traditional products.
Tannins from mangroves were used to coat and preserve
wood, nets and other fishing gear, as well as being used as
a dye for cloth. In several countries, mangrove leaves
provide fodder for cattle and goats. Mangrove forests have
long been an important source of honey and beeswax.
The high-value, low-volume nature of the aquarium trade means
that it could provide a livelihood for many people if carefully Avicennia germinans in Florida in the United States is
managed: a kilo of aquarium fish was worth nearly US$500 in 2002,
particularly valued, as the bees that use this species make
compared with a kilo of food fish which sold for about US$6
high-quality honey, and large quantities were produced
(Wabnitz et al., 2003).
until the late 1800s when progressive loss of the best
curios provide significant export revenue, but the souvenir forests led to a decline in production. Honey has been
trade is largely unregulated and the benefits from it may be gathered from mangroves on a subsistence basis in
short term. numerous countries, and, with a renewed interest in this
Mangroves are important as breeding and nursery product, the activity is being developed on a small-scale
areas for fish and prawns that form the basis of major commercial basis in many places (Horst, 1998).
fisheries (Bann, 1997; Sasekumar et al., 1992). Annual
commercial fish harvests from mangroves have been Pharmaceuticals
valued at from US$6 200 per km2 in the United States to Marine organisms often contain pharmaceutically active
US$60 000 per km2 in Indonesia (Bann, 1997). An estimated compounds, many of the source species coming from reefs.
75 per cent of the commercially caught prawns and fish in Reef organisms have provided an HIV treatment and a
Queensland, Australia, depend on mangroves for part of painkiller, while a large part of current cancer drug
their lives and on nutrients exported from the mangroves to research focuses on coral reef species (Millennium
other ecosystems (Horst, 1998). The annual market value of Ecosystem Assessment, 2005). A study in Indonesia
seafood from mangroves has been put at US$7 500- estimated that mangroves provide a potential net benefit of
167 500/km2 (Millennium Ecosystem Assessment, 2005). US$1 500 per km2 (US$15/hectare) for medicinal plants
With fish catches averaging 1.3-8.8 kg an hour, a 400-km2 (Ruitenbeek, 1992).
managed mangrove forest in Matang, west Malaysia,
supports a fishery worth US$100 million a year SUPPORTING SERVICES
(US$250 000/km2/year). Many commercial shrimp fisheries The waters around mangroves are generally rich in
are dependent on mangrove-fringed coastlines and nutrients, as a result of the organic matter produced by the
estuaries including those in Central America and East trees and plants themselves, and also from the sediment
Africa. In the Gulf of Panama, the fisheries for shrimps and that is trapped around the roots. Mangroves produce about
1 kg litter/m2 annually, which forms the basis of a complex
fish generate an estimated US$95 000 per kilometre of
coastline (Talbot and Wilkinson, 2001). food chain and some of which is exported with the tide. As
a result mangroves support an abundant and productive
Mangrove forest products marine life, and often act as spawning areas, as well as
Several mangrove species provide high-quality nursery areas, sheltering juveniles of species that spend
commercial timber, used for building and for making their adult lives in other ecosystems such as coral reefs and
newsprint, matchsticks and matchboxes. Mangroves are seagrass beds (Mumby et al., 2004).
20
In the front line
What happens when ecosystem
services are lost?
SECA/CML
Just as it is hard to calculate accurately the economic value coral reef degradation continuing through to 2050 could
of different ecosystems, it is equally difficult to predict the reduce benefits from fisheries, dive tourism and shore
cost to society of losing their various services. It was thought protection by a predicted total of US$350 million to US$870
that the bleaching event of 1998 in the Indian Ocean would million over that period (Burke and Maidens, 2004).
have a major impact on tourism and fisheries. It was
estimated, for example, that Tanzania would potentially LOSS OF REGULATING SERVICES
suffer a direct loss of US$20 million from tourism revenue The impact of the loss of the protective functions of
(Westmacott et al., 2000a). However, neither sector coral reefs and mangroves is already being felt in
underwent the expected decline: tourism fluctuated but some countries. Parts of Sri Lanka, India, Indonesia
probably more as a result of worldwide political and and the Maldives, where coral mining and collection
economic changes; while fisheries are still in decline largely has almost eliminated some reefs, have already
because of overexploitation. seen serious erosion.
Both the 1997 bleaching and the 2004 tsunami were In Sri Lanka, erosion on the south and west coasts
single, if acute, events, and reefs and mangroves are now averages an estimated 40 cm a year, considered to be
expected to recover from damage incurred. A more typical partly due to damage to reefs. Some US$30 million has
scenario is of reefs and mangroves undergoing steady already been spent on breakwaters and other constructions
decline. Ecosystems that can no longer provide their full to curtail this, and it has been estimated that the cost of
ecological services have a social and economic ‘cost’ to replacing the coastal protection provided by these reefs
humanity, which can be felt in areas or situations many would be US$246 000-836 000 per km (Berg et al., 1998). A
miles away. Ultimately, therefore, degradation of coral reefs hotel in West Lombok, Indonesia, spent an average of
and mangroves will cause loss of fishing and tourism US$125 000 a year over a seven-year period restoring its
revenue and other forms of livelihood, loss of export 250-metre-long beach, which had been eroded largely
earnings, malnutrition due to lack of protein, increased because of offshore coral mining (Riopelle, 1995).
coastal erosion, and destruction from storms and Modelling and predictions of the impact of the loss
catastrophic natural events. of natural shore protection provide dire warnings. Modelling
It is predicted that, for example, over a 20-year of the changes in wave energy striking some island
period, blast fishing, overfishing and sedimentation in shorelines in the Seychelles (Sheppard et al., 2005)
Indonesia and the Philippines could lead to a net economic indicates that wave energy has recently doubled as a result
loss of US$2.6 billion and US$2.5 billion respectively for of sea level rise, loss of corals from reef flats due to
these two countries (Burke et al., 2002). In the Caribbean, bleaching, and changes in reef crest profiles and wave
21
In the front line
communities in the tropics, through loss of earnings and
S Westmacott
food security. Both overexploitation and habitat deterioration
(particularly of nursery areas which causes disruptions to
marine productivity) are leading to reduced catches in most
tropical regions. For the Caribbean, it is predicted that, in the
absence of reef degradation, fisheries production in 2015
could be 100 000 tonnes, with a revenue of US$310 million.
However, with the reef degradation that is projected to
occur, production may be 30-45 per cent less (60 000-70 000
tonnes), and revenue only US$140 million (Burke and
Maidens, 2004).
LOSS OF CULTURAL SERVICES
Scuba divers specifically look for coral reefs with rich live
coral, high fish and invertebrate diversity and clear water. In
the long term, degradation of reefs will reduce their value to
the tourist industry. Reefs will provide less interesting diving
and snorkelling, poorer sport fishing and, where erosion has
In the Maldives, a reef flat adjacent to the capital of Male was filled
using coral rubble and causing sedimentation of nearby reefs. taken hold, less attractive beaches. For the Caribbean, it is
Their degradation was partly responsible for reduced shore
predicted that, if reefs undergo no further deterioration, net
protection and extensive flooding in 1987, which resulted in 20-30
benefits from scuba diving could grow to US$5.7 billion by
per cent of the new infill being lost. Subsequently, artificial
2015. If reef health deteriorates further, however, dive
breakwaters of concrete tetrapods were installed at a cost of
US$10 000 per metre (or US$10 million per kilometre) (Brown, revenue could amount to only US$5.4-5.6 billion,
1997). Not only was this expensive, but it did not prevent serious
representing a future ‘loss’ of 2-5 per cent (Burke and
flooding during the tsunami.
Maidens, 2004). Already it is widely believed in Florida,
regime. The models predict that, over the next decade, it United States (although data are lacking) that the decline in
will double again as a result of further damage to coral reef quality is partly responsible for the shift from high-
reefs. The consequences of this will depend on the shore’s value, low-volume tourism to budget travellers; this reduces
composition, but there will almost certainly be increased revenue and potentially, if large numbers are involved,
erosion on sandy shores. further contributes to the degradation of the reefs (T.
In the Caribbean, more than 15 000 km of shoreline Agardy, pers. comm.).
could experience a 10-20 per cent reduction in protection
from waves and storms by 2050 as a result of coral reef
R A Patzner/University of Salzburg
degradation (Burke and Maidens, 2004). The economic
costs to Australia from a degraded Great Barrier Reef as a
result of the predicted impact of global warming have been
put at US$2.5 billion to US$6 billion over 19 years (Hoegh-
Guldberg and Hoegh-Guldberg, 2004).
Loss of mangroves causes saltwater intrusion and
deterioration of groundwater quality, as well as the
disappearance of the filtering mechanism provided by the
roots and the ecological characteristics of this ecosystem.
Mangroves play a sufficiently important role in the
global carbon cycle that it has been estimated that the loss
of 35 per cent of the world’s mangroves (Valiela, 2001) over
the last two decades has resulted in the release of large
quantities of stored carbon, thus further contributing to the The commercially important rainbow parrotfish Scarus guacamaia
greenhouse effect (Cebrian, 2002). in the Caribbean depends on mangroves as a juvenile but lives on
reefs as an adult. It is far less common on reefs with no adjacent
mangroves, and is one of probably many species that are declining
LOSS OF PROVISIONING SERVICES
from loss of habitat as well as overfishing (Mumby, et al., 2004).
The degradation of reefs and mangroves is already having a Local extinctions have been reported where mangroves have been
major impact on the livelihoods of thousands of coastal cleared, as at Glover’s Atoll in Belize (A. Edwards, pers. comm.).
22
In the front line
Natural recovery – or rehabilitation
and restoration
UNEP/Topham
Although our instinct is to repair or restore something Mangrove restoration.
that has been damaged, there is often an argument for
allowing natural recovery. There are, indeed, many There are two terms in common use: ‘restoration’, which
examples of reefs and mangroves recovering from a means that all the key ecological processes and functions
major impact such as a hurricane without human and all the former biodiversity are re-established; and
intervention. Although recovery may seem slow, natural ‘rehabilitation’ which means that most, but not all, are re-
regeneration increases the likelihood that the ecosystem established. Most experience so far with reefs and
will return to what it was before. mangroves is in terms of rehabilitation.
The many chronic, long-term impacts now Mangrove rehabilitation can be relatively simple
affecting these ecosystems often slow the rate of since comparatively few species are involved. However,
recovery. On reefs, for example, the shift from a coral- rehabilitation of reefs is more complex because coral
dominated to an algal-dominated ecosystem means that reproductive biology and growth rates are still poorly
new coral recruits are quickly outnumbered and those understood, many species are involved and the
that settle often have little chance of survival. The focus techniques are complex and expensive, requiring scuba-
now needs to be on removing the causes of this diving and other special equipment and materials. Reef
imbalance, and eliminating stresses in order to rehabilitation projects have so far been largely
encourage natural recovery of damaged ecosystems experimental and have involved only small areas (less
than 100 m2). A careful evaluation of the methods
(Edwards and Clark, 1998; Cahoon and Hensel, 2002).
However, there may be certain situations or available must be undertaken to determine feasibility and
conditions when active intervention is necessary or cost effectiveness before any attempt at rehabilitation is
beneficial, for example where an ecosystem has made. Research into coral reef restoration is currently
particularly high economic value or scientific interest. under way through the GEF/World Bank Coral Reef
23
In the front line
Targeted Research and Capacity Building for two years. Natural recovery of mined reefs in the
Management project (Edwards, 2004). Maldives has been particularly slow (Clark and
Reefs and mangroves comprise different comb- Edwards, 1994). Reefs in marine parks in eastern
inations of species and occur in a variety of physical Indonesia, which had previously suffered from long-
conditions and locations. These factors, combined with the term dynamite fishing, show little sign of recovery after
type and scale of damage suffered, will affect recovery seven years, despite good water quality and larval
processes and thus any decisions about rehabilitation. recruitment. The vast quantities of broken rubble act as
‘killing fields’ for juvenile corals, abrading or burying
CORAL REEFS the newly settled recruits (Fox et al., 2003). Reefs that
Reefs will generally recover provided there is an adequate suffered light damage from the 2004 tsunami in
supply of larvae of corals, fish and invertebrates, and as Thailand are predicted to take only three to five years to
long as chronic disturbances such as sediment, pollution recover; those that received greater damage may take
and overfishing are minimized. Recovery involves two five to ten years. However, the rates of recovery will
processes: the settlement of larvae which then develop depend on whether the reefs suffer other impacts in the
into new coral colonies; and growth of the remaining coral coming years, particularly bleaching which has
colonies and fragments. Both processes are affected by occurred several times in Thailand in the past
the prevailing environmental conditions and by the extent (Phongsuwan and Brown, in press).
of the damage. New coral growth and recolonization of The main approaches to rehabilitation of coral
fish populations will start to occur within one to two years reefs are (Westmacott et al., 2000b):
❏ Increasing the area of substrate for settlement
of a damaging event or the end of damaging activities.
Coral larvae require hard surfaces, preferably of coral larvae by installing artificial surfaces,
coral rock or coralline algae, for settlement, and so e.g. concrete blocks, wrecks or other purpose-
seaweeds, sediment and debris on the seabed will reduce designed structures. Stabilizing or removing
coral recruitment. However, coral spawning can take
place quite normally after a natural event such as a
www.reefball.org
hurricane. For example, in Guam, after a typhoon, coral
spawning took place at the normal time and even broken
coral fragments were seen to spawn.
Coral growth rates are highly variable,
depending on the species, the location of the colony on
the reef, the geographical location of the reef and
environmental conditions. Branching corals grow
relatively fast (10-20 cm a year) but are easily broken by
waves and storms. Massive corals grow very slowly (5-
25 mm a year) but may survive for hundreds of years;
colonies more than 1 000 years old have been found.
The reef as a whole grows more slowly than its
individual corals, as it is constantly being eroded, and
upward growth on reef flats is only about 4 mm a year,
while deeper reef thickets grow at about 10 mm a year.
The breakdown of coral skeletons results from either
mechanical damage or from ‘bio-eroders’, which
include sea urchins that graze on fine algae on the
surface of corals and abrade them in the process, and
sponges that bore into corals and weaken their
A major industry has developed in recent years to build artificial
structure.
reefs, such as this ‘Reefballs’ breakwater, to replace the original
The speed of a reef’s recovery from major natural reefs and create new amenity value. Although the costs of
damage thus depends on the balance between the such structures are decreasing, this approach is expensive, and
not feasible for large areas; most importantly, an artificial
growth of coral colonies and their erosion. Recovery
structure such as this will never replace all the ecosystem
time is generally a matter of decades (10-50 years) and
services of a natural reef. Before investing in potentially risky
is longer on reefs subject to other long-term stresses, 'engineering' solutions to reef restoration, it is essential to seek
although the process of recovery can start in as little as advice from scientists and other experts.
24
In the front line
MANGROVES
J Harris
Mangrove regeneration is affected by the patterns of
damage (e.g. broken branches, impact from debris,
sediment disturbance) and by the characteristics of the
area. After storms and impacts such as a tsunami,
sediment scouring leaves inorganic substrates that are
difficult for mangroves to colonize. Sediment turnover may
also expose and/or dump onto existing mangroves material
in which there has been long-term accumulation of heavy
metals, hydrocarbons and other contaminants that inhibit
seedling establishment and survival (Ellison and
Farnsworth, 1996; Cahoon and Hensel, 2002). As with reefs,
for effective recovery it is essential that the causes of the
damage are eliminated. Even when disturbance is reduced,
the altered soil conditions (e.g. increased acidity where
aquaculture was previously carried out) and limited natural
dispersal of many mangrove species mean that natural
recovery can be very slow.
Most mangrove species produce propagules that
are relatively easy to collect and plant and, in the right
conditions, growth is fast. Restoration projects usually
Reef restoration projects are under way in many areas, as here in
the Solomon Islands. The tsunami gave fresh impetus to such involve the direct planting of propagules (particularly for
projects but they will need careful assessment. Experience to date
Rhizophora spp.) in the recovery area, although
suggests they are appropriate only at the scale of tens to at most
seedlings and saplings can be grown up in advance in
hundreds of square metres, for example on reefs damaged by
nurseries. The exact technique to be used will depend on
shipping or used by tourists.
the species involved, whether the soil needs treatment
loose or soft substrate, such as coral fragments (for example to reduce acidity) or physical reworking (to
and seaweeds, can also help, but this procedure create a suitable grain size), the season, the
requires care and expert help. New surfaces developmental stage of the propagules and the
can be created by passing an electric current resources available. Replanting is generally most
through metal to cause deposition of calcium successful in relatively sheltered areas, but is also
carbonate (electrolysis). This requires carried out in more exposed areas where the main aim is
considerable financial and human investment, control of soil erosion (Stevenson, 1997).
and the long-term impact of the current in the Partly because of the ease with which propagules
water is not known. can be replanted, many mangrove restoration schemes
❏ Transplanting coral fragments or colonies from have been undertaken, often as a forestry production
healthy reefs to damaged reefs or to artificial initiative. Replanting schemes in Matang, Malaysia (Chan,
substrates. Many species survive transplantation 1996), Thailand (Fast and Menasveta, 2003) and East Africa
provided environmental factors are favourable, (Kairo et al., 2001) have been successful, although
but the process requires significant labour, and rehabilitated mangroves often lack their full biodiversity
transplanted fragments are easily dislodged by and ecological processes (Ellison, 2000). Many of the Asian
waves and human disturbance, or can easily be countries affected by the 2004 tsunami have embarked on
buried or smothered. In addition, there is a risk of ambitious replanting programmes which are nevertheless
damaging healthy reefs by removing corals from a first step. Indonesia, for example, has initiated a four-
them. Coral fragments can also be transplanted year operation to plant 150 000 hectares of mangroves
to a protected site and ‘grown out’ (or ‘farmed’) to along the coast of Aceh where 300 000 hectares of
a certain size before being used for rehabilitation mangroves were destroyed. Such programmes will require
(Epstein et al., 2003). careful monitoring and assessment if full restoration is to
❏ ‘Repairing’ the reef: Under some circumstances, be achieved. There is some evidence that greater success
it is possible to cement pieces of reef, or even in recovering the biodiversity is achieved when the
coral colonies, together, using glue, special replanting is carried out in association with integrated
cements, plastic or other binding agents. aquaculture systems (Ellison, 2000).
25
In the front line
Mangroves and coral reefs on
tropical coastlines of the future
Devastating as they were, the tsunami of December 2004 matter of urgency, and alternative livelihoods found for
and recent tropical storms have sent a clear message that those dependent on the activities that cause damage.
investing in environmentally sound development and Good coastal planning can considerably reduce
sustainable management of the coastal environment will, vulnerability to natural disasters, as well as help
in the long run, be more cost effective than restoring safeguard other regulatory services such as water quality
human lives and ecosystems after a catastrophe. Tsunamis maintenance. Full implementation of the UNEP Global
are relatively rare events compared with hurricanes and Programme of Action on Land-based Sources of Pollution
cyclones – fewer than 100 tsunamis were recorded over the will go a long way towards helping to maintain the
last 300 years in the Indian Ocean (Dahdouh-Guebas et al., regulating services of reefs and mangroves.
2005; Department of Ocean Development, 2005) compared
with three tropical cyclones a year (Dahdouh-Guebas et al, MAINTAINING PROVISIONING SERVICES
2005). Evidence for the shore protection benefits of coral The sustainable exploitation of reef and mangrove
reefs and mangroves is currently less for tsunamis than it fisheries and other resources is a recognized global
is for storms. This, however, does not lessen the urgency – priority. There are some success stories, such as the
the devastation recently wrought by hurricanes and harvesting of mangrove timber over a 20-30 year rotation
typhoons testifies to the priority that must be accorded to period in Bangladesh, Malaysia and Thailand. Much
shore protection measures, of which maintenance of greater attention must, however, be paid to fisheries
natural coastal barriers such as reefs and mangroves management. Techniques and approaches are well
must be among the first. developed but often poorly implemented. The FAO Code of
There are no simple management models for Conduct for Responsible Fisheries enshrines many of
mangroves or reefs. The variability of these ecosystems these, including elimination of destructive fishing gear,
means that a good understanding of local characteristics establishing no-take areas, and emphasizing the need for
is essential. In the case of mangroves, even though a management plans, developed with the full involvement
common feature is their regular inundation by the sea, the of fishers and users, that are fully enforced. In Sri Lanka,
extent of this inundation and the tidal regime vary greatly where 80-95 per cent of the fishing fleet was destroyed in
as do their species composition and the chemical and areas affected by ∆2the 2004 tsunami, there was an
microbial characteristics of the soils, all of which affect opportunity to introduce measures, such as reduction of
their resilience and ability to recover. overcapacity, to ensure sustainability. However, in the
rush to provide humanitarian aid, fishing gear and boats
MAINTAINING REGULATING SERVICES have been distributed in large numbers and without
Human activities that weaken reefs and make them less consideration of the long-term future. This demonstrates
effective breakwaters must be regulated or halted as a the need for a much greater understanding by the public
and decision makers of the management requirements of
Cancún Travel Online
nearshore tropical fisheries.
Thirty years ago, Cancún in Mexico, lying at the top of the great
Meso-American Reef System, was a small fishing village. Since
then, it has grown to a resort that receives more than 3.5 million
visitors annually, on top of its 650 000 residents, and has suffered
considerable environmental problems, particularly in the form of
numerous hurricanes, such as Ivan in 2004 (left) and Emily and
Wilma in 2005. In 2001, Guidelines for Low-Impact Tourism were
produced for the state of Quintana Roo (Molina et al., 2001). These
aim to ensure that further tourism development, particularly in the
Costa Maya to the south of Cancún, will avoid many of the existing
problems, and will contribute to the sustainable development of
this region without increasing its vulnerability.
26
In the front line
UNEP
The Sundarbans, lying at the southern end of the Ganges River and straddling the border between India and Bangladesh, is the largest
continuous area of mangrove in the world. The area provides a livelihood for more than 300 000 people, protects them from cyclones and tidal
waves and is an important source of revenue for both countries through commercial timber which is harvested on a 20-year felling cycle. The
total extent – some 6 050 km2 (Spalding et al., 1997) – has not changed significantly in the last 25 years, although there are concerns that
forest quality may be declining. The relative success of the Sundarbans is largely due to its management which has been aimed at taking
advantage of the mangroves’ provisioning and regulatory ecosystem services. It has been managed as a commercially exploited reserved
forest since 1875; wildlife sanctuaries and national parks protect key biodiversity areas, and the area is both a World Heritage and a Ramsar
site. Since the 1970s, the Sundarbans has also been managed as a protective belt against storm damage.
MAINTAINING CULTURAL SERVICES recognition of the role of communities in the stewardship of
The vulnerability of the tourism industry to natural events natural resources, and the numerous examples of how this
was made very clear by recent hurricanes as well as the can be successful, will help to ensure that the cultural
2004 tsunami. Maintaining the ecosystems on which the services of reefs and mangroves continue to be valued.
industry depends is thus of paramount importance to
both governments and the private sector. The ESSENTIAL MANAGEMENT TOOLS
International Ecotourism Society (Halfpenny, 2002), the There is no shortage of guidelines, codes of practice and
Convention on Biological Diversity (CBD, 2004), the information on how to manage reefs and mangroves but
Center for Environmental Leadership in Business there is there is still a notable lack of commitment to
(CELB/CORAL/ IHEI/TOI, 2004) and others have produced using and implementing them. The UNEP Regional Seas
guidelines to promote sustainable tourism. Political will Programme is among the organizations trying to reverse
and individual commitment are now needed to ensure this, by helping countries to work together to protect
their implementation. these ecosystems, recognizing that success involves
Although many coastal communities have transboundary action, regional co-operation and clear
traditionally valued the ecosystems on which they depend, demonstration of successful approaches (see for example
much of this understanding has been eroded. The growing UNEP 2004). Key management approaches that must be
27
In the front line
promoted include integrated coastal management (ICM), construction set-backs, green belts and other
marine protected areas (MPAs), and improved resilience no-build areas.
and adaptive management. Priority technical measures
2 Promote early resettlement with provision for
Integrated coastal management all basic livelihood needs.
Coastal development is often ad hoc and based on 3 Enhance the ability of natural ecosystems to
numerous unconnected small decisions, or, where plans provide protection by conserving, managing and
exist, may be illegal as a result of poor enforcement of restoring wetlands, mangroves, seagrass beds,
regulations (Kay and Alder, 2005). National and local ICM and coral reefs, and by seeking alternative
programmes can go a long way to improving coastal sustainable sources of building materials.
management. The links between impacts on the coast and 4 Promote design that is cost-effective and
watershed management need to be recognized. Plans consistent with best practices, favouring soft
should take into account soils, topography and the need to engineering solutions to coastal erosion control.
protect vulnerable ecosystems. Areas needing 5 Respect traditional access and uses of the
rehabilitation must be identified, as well as areas where shoreline.
construction should be restricted or banned. 6 Adopt ecosystem-based management measures;
In particular, the construction industry must promote sustainable fisheries management;
respect environmental principles (such as set-back encourage low-impact aquaculture.
regulations), and ensure that pollution and sedimentation 7 Promote sustainable tourism.
are minimized through measures such as the use of silt How to apply the principles
curtains, and building in the dry rather than the wet 8 Secure commitments from governments and
season. Incorporating knowledge of coastal processes international organizations to abide by the
and applying best management practices for beaches, principles.
lagoons, coastal vegetation, energy, sewage treatment, 9 Ensure public participation.
solid waste and wastewater into planning and 10 Make full use of tools such as strategic
infrastructure are essential. Construction behind reefs environmental assessment, spatial planning and
will need particular care, not only to prevent damage to environmental impact assessment.
these ecosystems, but to reduce future shoreline damage 11 Monitor the progress and impact of recon-
if channels through the reef do indeed increase struction.
vulnerability to flooding. Environmental impact assess- 12 Disseminate good practices and lessons learnt
ment legislation, now in place in most countries, must be as they emerge.
enforced as a matter of urgency.
The ICM approach is fully recognized in the 12 Marine protected areas
guiding principles that were drawn up at a meeting in There is growing evidence that reefs within MPAs recover
Cairo in February 2005 by the UNEP Asian Tsunami faster from catastrophes than those that are unprotected.
Disaster Task Force, in collaboration with the UNEP Co- The abundant fish populations in Hikkaduwa National
ordination Office of the Global Programme of Action for Park, Sri Lanka, showed little change as a result of the
the Protection of the Marine Environment from Land- 2004 tsunami, although unprotected reef sites appear to
have suffered losses (MPA News, 2005). Reefs in the
based Activities and other organizations (UK Department
for Environment, Food and Rural Affairs, the Food and Indian Ocean that were well managed or remote from
Agriculture Organization of the United Nations, the United human impact tended to recover more rapidly from the
Nations Educational, Scientific and Cultural Organization, 1998 bleaching; reefs under anthropogenic stress
IUCN, and WWF). Known as the Cairo Principles, these are recovered poorly, if at all (Wilkinson, 2004).
aimed at helping to ensure environmentally sound post- Many more MPAs are needed. Currently, some 685
tsunami reconstruction programmes, and are being protected areas contain mangroves, covering about 9 per
implemented through an Action Plan (UNEP/GPA, 2005). cent of the total area of mangrove (Spalding et al., 1997),
and 660 MPAs contain coral reefs. There is no global
THE CAIRO PRINCIPLES estimate of how much reef is protected (Spalding et al.,
Overarching principle 2001), but in the Caribbean an estimated 20 per cent of
1 Reduce the vulnerability of coastal comm- reefs lie within MPAs (Burke and Maidens, 2004). Many
unities to natural hazards by establishing a MPAs need to be larger and to be made part of carefully
regional early warning system and applying designed networks to ensure that connected ecosystems
28
In the front line
Improved resilience and adaptive management
Fig. 5: Management effectivenes of Caribbean
MPAs (per cent) Natural disasters have affected humans and the
environment since the beginning of time – but both have
the ability to regenerate and adapt to the impact of such
events and the new circumstances that may arise as a
result of them. This capacity to absorb recurrent
disturbances such as storms and floods is called
‘resilience’.
Already two-thirds of the coastal disasters
recorded each year are associated with extreme weather
events. The growing populations on, and rapid
development of, the coastal zone guarantee that we will
Most marine protected areas urgently need improved
see an increase in economic, social and environmental
management. Of 285 MPAs assessed in the Caribbean in 2004, only
damage in the future caused by the associated reduction
6 per cent were considered to be effectively managed (Burke and
in human and ecosystem resilience. The conventional
Maidens, 2004).
approach has been to try to reduce the damage and
eliminate change but a new thinking is developing. A far
T Heeger
better approach may be to promote the conditions that
improve resilience and also learn to adapt to the resulting
changes (Adger et al., 2005). Careful planning and
adaptive management can greatly reduce the impact of
large disturbances.
The rapid response of global, regional and
national monitoring programmes to the tsunami
demonstrated their value in providing essential
information for management. Guidelines for Rapid
Assessment and Monitoring of Tsunami Damage to Coral
Reefs were produced within ten days (ICRI/ISRS, 2005)
and disseminated by the UNEP Coral Reef Unit to the
various international and UN agencies conducting
environmental assessments in the region. Expert surveys
were also quickly initiated with assistance from the
Global Coral Reef Monitoring Network (GCRMN) and the
Mu Koh Surin National Park in Thailand, gazetted in 1981 and regional Coral Reef Degradation in the Indian Ocean
covering 135 km2, is an ICRAN demonstration site and has a good
(CORDIO) programme.
track record of effective management. The December 2004
tsunami largely destroyed tourism and the park’s infrastructure on
the islands, as well as sea gypsy villages, but there were no FINANCING THE FUTURE
fatalities. The coral reefs, which were especially healthy with high
Reefs and mangroves clearly provide significant benefits
biodiversity before the event (see above), were being surveyed at
and services to humankind, many of which have a high
the time of the tsunami, permitting first-hand accounts. Trees
economic value. Governments, civil society and the
were knocked onto the reefs, along with large amounts of
sediment. A survey was carried out two months later and private sector must recognize that, as with other benefits,
remarkably little damage had occurred: reefs had an average of 75
there is a price to be paid for maintaining these
per cent live coral cover, and some had 90 per cent, the sediment
ecosystems. The cost is, however, generally much lower
had gone, and there were already signs of some coral regeneration
than the benefit received.
in damaged areas (Comley et al., 2005).
Although costs are hugely variable depending on
are protected (not only representative sites), as well as the location, size and type of management, average
annual operational management costs of US$775 per km2
resilient ecosystems, such as reefs identified as resisting
or recovering quickly from bleaching (Grimsditch and have been estimated for MPAs (Balmford et al., 2004).
Salm, 2005). This is essential if species dependent on This is significantly less that the estimated global values
of ecosystems: US$100 000-600 000 per km2 per year in
different ecosystems at different stages of their life cycles
are to be protected, and the full range of ecosystem the case of reefs and possibly more for mangroves. Basic
services maintained. annual operating costs for MPAs can be as low as
29
In the front line
Fig. 6: Area of the world’s coral reefs and mangroves lying within the waters of countries in relation to those
countries’ position on the UN Human Development Index (left) and their GDP per capita (right) (per cent)
Many of the world’s wealthiest nations have jurisdiction over reefs and mangroves, either in their own coastal waters or in those of their
territories. Over 30 per cent of the world’s reefs lie in countries that are classified as highly developed, with a GDP per capita of more than
US$9 000. Australia, France, New Zealand, the United Kingdom and the United States directly influence about 25 per cent of reefs and a
significant proportion of mangroves. Furthermore, most of these countries are either sources of tourists to reef countries or have other
strong economic links with them and potentially could provide much greater financial and technical support. A higher proportion of
mangroves are found in the poorer countries, but nevertheless more than 10 per cent are found in highly developed countries.
US$200 000-600 000, as in the case of Belize and the have indicated, for example, that tourists are willing to
Seychelles (Lutchman, 2005). pay more than US$50 extra per holiday and divers US$25
There are vast untapped sources of funds and more per dive if these result in high-quality reefs
financing mechanisms, ranging from fishery and tourism (Westmacott et al., 2000a; Burke and Maidens, 2004). It
revenues and taxes, to royalties and fees from offshore seems a small price to pay for the future survival of these
mining and mineral exploitation, to voluntary donations small, priceless ecosystems.
and government aid (Spergel and Moye, 2004). Studies
A Cornish
30
In the front line
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33
In the front line
Shoreline protection and other
ecosystem services
from mangroves and coral reefs
The tragic and devastating consequences of the Asian tsunami, December 2004 ,
and the hurricanes and cyclones of 2005 were a wake up call for the global
community, dramatically drawing attention to the dangers of undermining the
services that coastal ecosystems provide to humankind.
This report has gathered lessons that have been learned since these events that
will be relevant to future management of the coasts in the context of severe
weather events and other potential consequences of global warming. More than
ever it is essential to consider the full value of ecosystem services – that is the
benefits that people derive from ecosystems – when making decisions about
coastal development.
The publication aims to help decision and policy makers around the world
understand the importance of coastal habitats to humans, focusing on the role of
coral reefs and mangroves. As well as coastal protection, it also addresses the
huge range of other benefits provided by these ecosystems and the role that they
can play in coastal development and in restoring livelihoods for those suffering
from the effects of extreme events.
www.unep.org
United Nations Environment Programme
P.O. Box 30552, Nairobi, Kenya
Tel: +254 (0) 20 621234
Fax: +254 (0) 20 623927
Email: cpiinfo@unep.org
Website: www.unep.org
UNEP World Conservation Monitoring Centre
219 Huntingdon Road, Cambridge CB3 0DL,
January 2006
DEW/0787/CA
United Kingdom UNEP-WCMC Biodiversity Series No 24
Tel: +44 (0) 1223 277314
Fax: +44 (0) 1223 277136 ISBN: 92-807-2681-1
Email: info@unep-wcmc.org
Website: www.unep-wcmc.org