World Atlas of Coral Reefs, Spalding and Al 2001

UNEP WCMC

World Atlas
Mark

The most

D. Spalding.

definitive

overview yet of a
living w/orld." --

BBC

Wildlife

Reefs

Corinna Ravilious. and Ednnund

and comprehensive

vital part of

of Coral

our

P.

Green


®iral reefs

are the most biologically

diverse marine habitats

the world, host to an

in

extraordinary variety of plants and animals. They are

also one of the world's

most

fragile

and endangered

ecosystems. The growth of tourism, combined with

the

boom

in

popularity of scuba diving, has brought

these spectacular ecosystems to public attention

around the planet.

Coral reefs provide essential fish habitat, support

endangered and threatened species, and harbor

protected marine

mammals and

turtles.

significant source of food, provide

They are a

income and employ-

countless other benefits to humans, including supply-

ing

compounds

Yet coral reefs

for

pharmaceutical development.

around the world are rapidly being

degraded by human

activities

such as overfishing.

coastal development, and the introduction of sewage.

fertilizer,

and sediment. And because corals are highly

sensitive to

changes

in

water temperature, they are

particularly vulnerable to climate change.

The World Atlas of Coral Reefs provides the

detailed

and

definitive

first

account of the state of our

planet's coral reefs. With

its

wealth of authoritative and

up-to-date information, the finest

maps

available,

and


nn^

Digitized by tine Internet Arciiive
in

2010 with funding from

UNEP-WCIVIC, Cambridge

Iittp://www.archive.org/details/worldatlasofcora01spal


World Atlas

of Coral

Reefs


The publisher gratefully acknowledges the

generous contribution to this book provided
by the Moore Family Foundation.

Published in association with

The contents of this volume do not necessarily reflect the views

UNEP-WCMC

or policies of

by The University

UNEP-WCMC, contributory organizations,

editors or

of California Press

publishers. The designations

University of California Press

not imply the expression of any opinion whatsoever on the part of

employed and the presentations do

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UNEP-WCMC

California

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University of California Press, Ltd.

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boundaries, or the designation of

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its

name

or allegiances.

Cloth edition ISBN:
^

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0-520-23255-0

Monitoring Centre

UNEP-WCMC

Cataloging-in-Publication data

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is

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+44 (0) 1223 277136

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Website: www.unep-wcmc.org
Tel:

on file with the Library of Congress

Citation: Spalding M.D., Ravilious C. and Green E.P. (2001). World

Fax:

Atlas of Coral Reefs. Prepared at the

UNEP World Conservation

Monitoring Centre. University of California Press, Berkeley, USA.

Printed in China
09
No part of this book may be reproduced by any means, or
transmitted or translated into

a

machine language without

the written permission of the publisher.

9

07

6

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of

in this publication

ANSI/NISO Z39. 48-1992

meets the minimum requirements

(R 1997) (Permanence of Paper).

@


^S

T

UNEP WCMC

ICLARM

THE WORLD FtSM CGNTER

World Atlas
Mark

D. Spalding,

Corinna Ravilious, and

UNIVERSITY OF CALIFORNIA PRESS
Berkeley

Los Angeles

London

of Coral

Reefs

Edmund

P.

Green


World Atlas
Prepared

The

of

Coral Reefs

at

UNEP

World Conservation

Monitoring Centre

219 Huntingdon Road

UNEP WCMC

Cambridge CB3 DDL. UK
Website; www.unep-wcmc.org
Director:

Mark

The UNEP World Conservation Monitoring

Collins

Centre provides objective, scientifically
rigorous

Authors

products and

services

that

D.

Spalding

include ecosystem assessments, support

Connna

Ravilious

for

Mark

Edmund

implementation

of

environmental

agreements, regional and global bio-

Green

P.

diversity information, research

on threats

Research assistants

and impacts, and development

Sarah Carpenter

scenarios for the living world.

The Centre became the biodiversity

Rachel Donnelly

arm

information and assessment

Space Shuttle photographic research
Julie A,

Robinson

United Nations Environment
in

June 2000.

lUCN and

Marco Noordeloos

in

Edmund R Green and Mark
unless otherwise stated

Cartography
Corinna Ravilious

Layout

John Dunne

Color separations

Swaingrove

China

A Banson Production
27 Devonshire Road

Cambridge, CBl 2BH.

UK

bansonlBou rplanet.com

D.

Spalding

organizations

years

is

was founded

lUCN,

financial support

Photographs

in

It

in

of the

Programme
in

1979 by

1988 was transformed

joint activity of

Printed

of future

WWF and

into a

UNEP. The

and guidance

of

these

the Centre's formative

gratefully acknowledged.


Supporting institutions

Supporting institutions
The United Nations Environnnent Programme
environment.

Its

role

is

to

is

the principal United Nations body

the field of the

in

be the leading global environmental authority that sets the global environmental

agenda, that promotes the coherent implementation

the environmental dimension

of

environment.

Its

objectives include analysis of the state of the global environment and

and regional environmental trends, provision
threats,

and

to catalyze

sustainable

of

development within the United Nations system and that serves as an authoritative advocate

for the global

assessment

of global

and early warning information on environmental

of policy advice

and promote international cooperation and

action,

based on the best

scientific

and

technical capabilities available. Website; w/ww.unep.org

ICLARM-The World

Fish Center

an international, non-profit research center working

is

and promote food security through the sustainable development and use
environmentally sound management. The focus of ICLARM's work
are one of the key resources systems studied.

Database on Coral Reefs. ReefBase aims

ICLARM

shallow tropical habitats,
activities

order

in

to

A major coral

of

to alleviate poverty

resources based on

developing countries and coral reefs

ICLARM

reef project led by

ReefBase: A Global

is

provide data and information on coral reefs and associated

to facilitate better

and the status and dynamics

is in

of aquatic

understanding

of the relationship

between human

these environments. Over 110 institutions and individuals have

contributed information and expert advice to ReefBase, Websites: www.iclarm.org and wiwwreefbase.org

Scientists

l^w

in

the Earth Sciences and Image Analysis Laboratory at the Johnson Space Center

with astronaut crews and
facilitate public

studies.

access

manage

in

is

located at

Strasbourg, France,

was formed

in

2000. The Aventis Foundation promotes

projects at the interface of culture, science, business and society. The Foundation

Aventisroundation

are international, interdisciplinary, and looking towards the future.

people

who

will

shape tomorrow and

activities in science, politics

and

PAOI (Professional Association

enable them

to

society.

Website:

to contribute to

One

of its

aims

to select projects that

prime aims

is to

identify the

sustainable development through their

www, aventis-foundation.org

of Diving Instructors) Project

and non-diving communities' environmental awareness,

humans and

closely

imagery, with an emphasis on using astronaut photographs for scientific

to the

The cataloged data and imagery

The Aventis Foundation, based

work

the Earth photography by astronauts on space missions. They also

to

AWARE

seeks

to

increase both the diving

encourage responsible interactions between

the aquatic environment and to emphasize the diver's role

in

preserving the aquatic realm.

Aquatic World Awareness, Responsibility and Education at www.projectaware.org

The non-profit fvlarme Aquarium Council
organizations, the

Marine

Aquarium
Council

and others

MAC

IS

to

aquarium

industry,

ensure quality and sustainability

an international network that brings together environment

in

(hobbyists), public

the collection, culture and

aquariums, government agencies

commerce

of

marine ornamentals.

doing this by developing an international system of certification and labeling that

will:

establish

standards for quality products and practices; document compliance with these standards and label the results;

and create consumer demand and confidence
Paul Holthus, Executive Director, 923
Fax:

(1

Nuuanu

for labeled

"products" from certified industry operators.

Ave, Honolulu, Hawaii 96817, USA. Tel:

(1

8081 550 8217;

808) 550 8317; E-mail: pauLholthusHaquanumcounciLorg; Website: wAvw.aquariumcouncil.org

The International Coral Reef

ICRI

is

aquarium keepers

Initiative

is

a voluntary partnership that allows representatives of over

80 countries with coral reefs to work with major donor countries and development banks, international

environmental and development agencies,

scientific associations, the private sector

and NGOs

to

decide on

LvrERjNATlUNAI-

CORALREtl

the best strategies to conserve the world's coral reef resources. ICRI

is

not a

permanent structure or

INITUTIVE

organization, but an informal network linked by a global Secretariat. Website: />
Dulverton Trust

The Dulverton Trust

was founded

is

a

UK grant-making

by Lord Dulverton

in

1949.

charitable trust, with an interest

in

the field of conservation.

It


WORLD ATLAS OF CORAL REEFS

Acknowledgments
would

authors

The

support

like

thank

to

have lent

organizations that

the

many

for the Earth Sciences

and Image Analysis Laboratory

other

Johnson Space Center

to contribute to this book.

or

financial

various stages in the preparation of this

at

These include the United Nations Environment

work.

Programme Division of Early Warning and Assessment,
Dulverton Trust,
the

ICLARM, NASA,

the

the Aventis Foundation,

Marine Aquarium Coimcil and PADI.

We

would also

our gratitude to the Moore Foundation for

like to express

providing support for the production costs of this book.

excellent support as research assistants during the prepara-

The information behind these maps has

been compiled over seven years and many thanks are due
all

those

who have

Jonathan

Blyth,

to

Map Room

UNEP we

the

to

for

all

of the

staff

help over

their

are also very grateful

Dan

to

Claasen. Salif Diop, Agneta Nilsson and Arthur Dahl for

Colin Watkins has been an incredible support on this
not only with fund-raising but also

with his

and optimism; thank you Colin. Thanks

persistence, vision

also to Heather Cross,
In

Mary Cordiner and

Rogowski

Will

Mania

evenings and weekends.

the

at

Spalding and Stephen Grady have shown great patience and
tolerance of the crazy hours

- many thanks indeed

We

to

we

put in to prepare this book

both of them.

part

of the

text

photographs, but also provided his newly prepared coral
distribution data

species

lists.

and thoroughly reviewed our resulting

Thanks

to Clive

Wilkinson, Bernard Salvat

and Lauretta Burke for supplying data and general
encouragement.

Thanks

International Coral

Jerry

Kemp, Doug

Reef

the

to

many

others

Initiative for their

some valuable

in

the

kind support.

Giotto Castelli

Perrine,

Fairhurst also provided

and Colin

A

images

Thanks must also go

that

appear

in the

book.

Lonely Planet/Pisces Books

to

number of copies of

a

In addition, considerable thanks are

their

Diving and

owed

to the

who have checked

reviewers, listed below,
text.

the high-

copies of film products that were the

digital

starting point for the

of the

Johnson

at

making

These have greatly improved the

final quality

which remain

the texts. However, any errors

responsibility of the authors.
Part

In

Chapter

Stephen Grady, Lucy Conway and Sarah

I:

and

1)

David Woodruff (primarily

1-3),

Paul

Holthus

(aquarium

Marco Noordeloos spent countless hours

sorting

showing coral

reefs. In addition to this,

of Kamlesh P LuUa

it

without the

many

would not have been possible

and

trade

certification).
In Part

II:

Jeremy Woodley (Chapters 4 and

Reyes BoniUa (Mexico), Juan Manuel Diaz
Hector

Guzman (Honduras,

Hector

5),

(Colombia),

Nicaragua, Costa Rica and

Panama), Sheila Marques Pauls (Venezuela) and Clive
Petrovic (British Virgin Islands).
Part

David Obura (East Africa), Nyawira

III:

Muthiga (Kenya), Chris

Horrill,

Richmond and Jason Reubens

Quod

Martin Guard, Matthew
Jean Pascal

(Tanzania),

(Eastern Africa), Arjan Rajasuriya (South Asia),

Charles Anderson (Maldives), Charles Sheppard (Chagos
Archipelago), Alain de Grissac (northern

DeVantier (Middle Eastern

reefs),

southern Arabia),

Ormond

Rupert

Hansa Chansang (Thailand),

Red

Jeremy

HM

Sea),

Kemp

(northern

Lyndon

(Red Sea,

Red

Part

IV:

JEN Veron

Guinea), Duncan Vaughan
Islands), Darrin

(Australia),

(Fiji),

Drumm (Cook

Sea),

Ibrahim (Malaysia),

Laura David (Philippines), Vo Si Tuan (Vietnam),

In

an earlier

of

are solely the

CF

(Melanesia and Polynesia), Aaron Jenkins (Papua

at

many

over large parts

Robinson has worked long and hard on the

through thousands of images to select those clearly

efforts

quality

to

(Taiwan) and Andre Jon Uychiaoco (Southeast Asia).

images from Space Shuttle and Mir, while,
stage,

Imaging Laboratory

Digital

to the

checking the

in

additions to the

photographs.
Julie

The

Space Center gave special attention

In

who not
and supplied some

are extremely grateful to Charlie Veron,

reviewed

only

and those who helped

staff

Carpenter (Chapters

their constant support.

UNEP-WCMC.

support

Snorkelling Guides.

in

to all the

photography of Earth. Particular thanks are due

who provided

Hagen. Also

and

orbit,

members of the Earth Sciences and Image Analysis
Laboratory who have over the years supported astronaut

Mary Edwards, Simon

University Library

project,

astronauts for their continuing efforts

"placement students"

the

Cambridge, many thanks are owed

In

NASA

to

helped, including

Joanna Hugues and Chantal

the years.

due

photograph coral reef areas from

Rhind and

Annabel Lee, Ivor Wheeldon, Alastair Grenfell, Susannah
Hirsh,

to

annotations.

Both Sarah Carpenter and Rachel Donnelly provided

tion of this work.

are

at

Thanks

Dai

Robin South

New

John Gourley (Mariana

Islands) and Flinn Curren

(American Samoa).

Thanks are also due

appraisal of the text.

to

James Nybakken

for his overall


Contents

Contents
PART

Introduction

II

The Atlantic and Eastern Pacific
Essential information

92

12

Chapter 4

Northern Caribbean

US

Gulf of Mexico

95

97

PARTI

Florida and the

Understanding Coral Reefs

Bermuda

101

Bahamas

103

Turks and Caicos Islands

106

Chapter

13

1

The World

of

Coral Reefs

U

Defining coral reefs

15

Chapter 5

Patterns

of diversity

19

Western Caribbean

110

Quantifying diversity

27

Mexico

113

Organisms

29

Belize

117

of the coral reef

Honduras. Nicaragua, Guatemala

and

Chapter 2
Signs of Change
The importance
Threats

of reefs

to reefs

Responses

El

121

Salvador

Panama

125

Ab

Costa Rica and

47

Colombia and Ecuador

130

56

Cuba

135

66

Jamaica

139

Cayman

U1

Islands

Chapter 3

Reef Mapping

78

Chapter 6

Reef mapping techniques

81

Eastern Caribbean and Atlantic

Global reef mapping

89

Haiti,

U7

the Dominican Republic and

1^'

Navassa Island
Puerto Rico and the Virgin Islands

The Lesser

Antilles,

Trinidad and Tobago

Venezuela and Aruba, Bonaire and Curacao
Brazil

and West Africa

153
1

58

168
1

73


WORLD ATLAS OF CORAL REEFS

PART

PART

III

The Indian Ocean and Southeast Asia

IV

178

The

Western Indian Ocean

180

Australia

302

Kenya and southern Somalia

183

West Australia

305

Tanzania

186

North Australia

309

191

Torres Strait and the Great Barrier Reef

310

194

The Coral Sea

319

197

High latitude reefs

320

Chapter 7

Ocean

300

Chapter 11

Mozambique and South

Africa

Madagascar
Mayotte,

Pacific

Comoros and

outlying islands

Seychelles

200

Mauritius and Reunion

205

Chapter 12

Melanesia

Central Indian Ocean
India.

Sri

325

Solomon Islands

330

215

New

334

219

Vanuatu

338

221

Fiji

342

212

Pakistan and Bangladesh

Lanka

Maldives
British Indian

Ocean Territory

323

Papua New Guinea

Chapter 8

Caledonia

226

Chapter 13
Chapter 9

Micronesia

Middle Eastern Seas

233

Northern Red Sea: Egypt,

Israel,

Jordan

235

Saudi Arabia

2/10

Central Red Sea: Sudan

2-13

Southern Red Sea: Eritrea and Yemen

lUk

Southern Arabian Region: Yemen,
northern Somalia and

Djibouti,

Oman

Northern Mariana

Guam

Micronesia

Marshall Islands

and Nauru

354
360
363

Chapter 14
251

Polynesia

369

Tuvalu and Wallls and Futuna

371

Tokelau,

Samoa and American Samoa

373

259

Tonga and Niue

377
381

Myanmar and Cambodia

261

Cook Islands

Malaysia, Singapore and Brunei Darussalam

266

French Polynesia, the Pitcairn Islands

Indonesia

272

Philippines

281

Thailand,

351

247

Chapter 10

Southeast Asia

Islands and

of thi5

Palau and the Federa ted States of

Kiribati

Arabian Gulf: United Arab Emirates,
Qatar, Bahrain, Kuwait, Iran

348

Commonwealth

and Cllppertor

385

Hawaii and the

392

Spratly Islands, Tung-Sha IDongsha

Qundaol Reefs and the Paracel Islands

287

Vietnam and China

289

Technical notes

401

Taiwan and Japan

293

Index

404


Introduction

Introduction

Coral reefs are one of the world's most spectacular

may

broad swathe around the globe. They are clearly

half and 2 million, perhaps more.

even from space, as patterns of dazzling colors

tracing the edges of coastlines and scattering

Up

into the oceans.

magic of coral

close, the

far

out

reefs

is

magnified. These ecosystems are packed with the highest
densities of animals to be found

Thronging with

anywhere on the

planet.

they rival even the tropical rainforests

life,

From

a

human

perspective coral reefs are not only a

source of wonder and fascination. They also represent a
resource for millions of people.

critical

For millennia

coastal peoples have relied on coral reefs as a source of

The wide

some ways

In

surprising.

Many

strips

of coral reefs lining their shores

of knowledge

lack

num-

be anything between

is

not

reefs are remote and, as they are far

from

this

regular shipping traffic, efforts to

map

these areas have

good charts other navigators

not been prioritized. Without

remain cautious about sailing

such areas. From an

in

ecological perspective our knowledge has been further

hampered by the

terms of diversity.

food.

coral reefs, but the total

ber inhabiting the world's reefs

visible,

in

named and described from

ecosystems. They straddle the tropics and cut a

humans

fact that

are terrestrial, air-

breathing creatures. Early scientists could only peer

down

with fascination through the intervening waters which
separated them from the reefs, or haul up dead or dying

samples for inspection. Only
diving

become

a popular

in

1950s did scuba-

the

and relatively safe

activity,

and

have also provided protection from the worst onslaughts

our scientific knowledge of the ecology of reefs has

of tropical storms. Over the centuries, these same reefs

almost entirely been amassed over the

last

50 years.

have actually provided the sand for the beaches and even

which make up the islands on which so many

the rocks

people

live. In

more recent times

coral reefs have

the treasured destination for millions

peace and

rest

some of

into

reef These same travelers are
for

most impoverished nations. Into the

This atlas presents a unique
It

provides a

of Coral Reefs
compendium of information.

summary of what we know about

graphic distribution and status of coral reefs
the

millennium. Unfortunately, even as

third

begun

to gather this

the geo-

at the start

information, the reefs themselves

have been changing. The atlas also provides information

most notably with

on the changes which have already occurred, and on the

development of new pharmaceuticals.

human impacts on
This

atlas

is

the coral reefs in every country.

primarily

an

information resource.

Putting such information together at the global level

How

we know

little

possible, even today, to pick

It is

more than

up the best navigational

charts for certain areas and find quite shocking gaps in

a

new

entirely

The

first

perspective.
three chapters provide a global review of the

coral reefs,

information about the location and dimensions of coral

perspective, then a

the

1

was gathered by Captain James Cook and others
8th century.

On some

of these "modern" charts there

remain dotted lines showing "possible" locations of
or

notes

describing

in

reefs

"position

as

reefs,

unconfirmed".

While sea monsters no longer populate our maps, many of
the gaps

where they once

sat still

This lack of knowledge

knowing where the

largely

restricted

As many

to

as

are

may have been

mapping

coral reefs.

The

then focussed towards a region-

is

The most important resource
themselves. The

work

100 000 species

perspective, and finally looking

by-region review of coral reefs.

Centre

wild extrapolations and educated

taking an ecological and geological

human

main bulk of the book

remain.

found on reefs remain

firstly

specifically at the task of

not simply confined to

reefs are. Efforts to quantify the total

numbers of species which

guesses.

is

more

is

summary, however, and provides us with an

our knowledge. For some parts of the world, the best

reefs

of

we have

have the capability to provide new resources

for the world's burgeoning populations,
the

sought

new source of income and employment

the world's

future, reefs

The World Atlas

become

on tropical shores, or adventure, diving

the world of the coral

providing a

who have

global

first

in

UNEP

in

any

atlas is the

maps

World Conservation Monitoring

commenced

its

global coral reef

mapping

1994 and has now developed the most detailed

maps of coral

reefs in existence.

These maps show

the distribution of the vast majority of the world's shallow
coral reefs. Equally important with the

maps

in this atlas

has been to place the location of coral reefs in a wider


WORLD ATLAS OF CORAL REEFS

The maps

context.

also significant

human

factors, including settlements, dive

centers and marine protected areas.

The

texts

provided on the maps, including information which cannot

shown on

and

tries
is

maps themselves. For

the

where there are

territories

all

coun-

reefs, basic information

provided describing the distribution of the reefs and

some

ecological features.

coral

reefs are

fiarther

Human

uses and impacts on

considered,

comparable information describing the countries,

and the human impacts on

their reefs,

of coral reefs around the world. Those traveling

regularly to coral reef areas, for leisure or for work, can use
the World Alias

before they

of Coral Reefs

visit, to

to learn about

new

areas

get a basic grounding in the ecology of

coral reefs, and to consider the issues and challenges facing

from particular locations,

reefs in particular areas. Experts

illustrate

the

has provided the very

critical

currently being threatened by

human

Indonesia,

Philippines,

countries

all

heritage

which

activities.

The most

diverse region of the world for coral reefs
the

is

centered on

is

New

Malaysia and Papua

Guinea, with between 500 and 600 species of coral

in

each

of these countries. Unfortunately these are also some of

most threatened coral

the

Reef tourism

reefs in the world.

now

is

a

major global industry. Visitors

Great Barrier Reef increased from

to the

1985 to over 10 million

in 1995.

numbers of scuba divers

million in

I.I

Scuba diving

most popular adventure sport

the

these.

Users of this book can learn about the location and
status

JEN Veron

information on coral biodiversity around the world.

and clearly

list

the protected areas with coral reefs, but also provide

directly

latest

including efforts to

control such impacts or protect coral reefs. Data tables
all

Corals of the World,

National statistics have been calculated for

and tables provide information which

enables a more detailed interpretation of the information

directly be

Using information from the new taxonomic work

book thus show major natural

in this

features (forests, rivers, topography and bathymetry), but

world and

in the

visit coral reefs

new database has been gathered which

probably

is

vast

every year.

A

gives the location

of dive centers around the world. This contains infor-

mation on over 2 000 dive centers, marked on the maps
throughout
tourism

and

is

this

now

work. They show, quite clearly, that diving
ubiquitous, and

is

located

in

91 countries

states.

or in particular subjects, can learn about other areas, and

Marine protected areas are becoming a

gain useful information about different parts of the world.

A

considerable amount of information held within the

pages of

this atlas

has never been published before.

widely used, not only for conservation, but also
fish catches,

The work includes
mated

a new, revised global estimate of the

of coral reefs worldwide. In Chapter

total area

1

it is

shallow coral reefs worldwide occupy

that

284 300 square kilometers, an area about half the
Madagascar. This

less than

is

1.2

critical tool for

They

the protection of coral reefs worldwide.

esti-

some

size of

percent of the world's

are being
to

enhance

by protecting small stocks of fish which are

now some 660

able to resupply adjacent areas. There are

marine protected areas worldwide which incorporate coral
reefs.

These include two of the world's

areas, Australia's Great Barrier

largest protected

Reef and the northwestern

Hawaiian Islands, covering entire large ecosystems.

continental shelf area, and only 0.09 percent of the total

area of the world's oceans. Coral reefs are a scarce, but

Unfortunately,

many

protected areas exist on paper

only - they are poorly managed and have

important resource.

critically

port or enforcement. Equally worrying

An

assessment of the area of coral reefs

countries

provides

in individual

an important perspective on the

ownership and responsibilities associated with
heritage. Indonesia

is

this critical

the largest coral reef country in the

world, followed by Australia and the Philippines. Also

high up the
area:

Papua

Islands,

are

list

New

Solomon

The same

many

Guinea,
Islands,

small nations in terms of land
Fiji,

the Maldives, the Marshall

Bahamas and Cuba.

statistics also point

to

or no sup-

that in

almost

every single case, protected areas are aimed solely
controlling the direct impacts of

Fishing and tourist activities

and sedimentation

humans on

may be

more remote sources of threats

at

coral reefs.

controlled, but the

to reefs, notably pollution

from the adjacent

land,

continue

unabated. Without a more concerted effort to control

all

of

impacts of humans on coral reefs even the best

the

managed marine

the important role

little

is

protected areas

There are other

stories,

may be managed

however,

in vain.

which provide

which a number of the world's very wealthy nations could

valuable examples of success. Fisheries reserves in a few

play

areas are

now

nomies of

local villages, while tourist

in

protecting

France, the

UK,

the

the

world's

USA

coral

and even

reefs.

New

Australia,

Zealand hold

jurisdiction or significant influence over coral reefs in
their

own

territories

waters and in the waters of their overseas

and associated

states.

one quarter of the world's coral

for the
It is

revitalizing the food supplies

income

and ecois

paying

wise management of a number of important areas.

vital that the

messages from these

Together these cover over

swiftly as possible to

reefs.

depend on coral

reefs.

all

sites are carried as

countries and communities

who


Introduction

Aside from such clear

statistics, the

pages of

this atlas

reveal a startling, recurring tale of degradation and loss.

urban development and intensive

deforestation,

reefs,

now producing

agriculture are

vast quantities of sediments

and pollutants which are pouring
Corals

extremely

are

sensitive

increases

to

known

temperature, exhibiting a stress response

in

considerably in recent years, and in 1998 a global mass

bleaching event occurred, with devastating mass mortalities

of corals

in

many

Recovery

areas.

now underway,

is

but there are very real concerns about the recurrence of

We

reefs

the

disease

damage from

Caribbean apparently natural

and hurricanes has been exacerbated by the

human

impacts of

and

activities,

cover and diversity

reefs have

lost

almost every country, even

in

in

is

who

and income. In many

we

are unable to

the existence of reefs before they are degraded.

much

has already gone.

further specter overshadowing the world of coral

of global climate change.

that

accepted that the global climate

human

erated rate as a result of

threats already mentioned,

it

an accelit

rising sea surface temperatures.

the

universally

at

to

many

among

now

most vulnerable ecosystems

would appear,

are

It is

changing

is

Coral reefs,

coral

apparently remote and protected locations.

shores.

millions of coastal peoples

for sustenance

have no idea how

A

many

activities affect not only the

areas these changes are so rapid that

document

such events with global climate change.

In

many

reefs, but also the

depend upon them

and rapidly

into the sea

proximity to

in close

The impacts of these

as coral

Records of such bleaching have increased

bleaching.

degrading coral reefs

activities.

Coming on

top of the other

seems highly probable

that the

predicted rises in sea surface temperatures over the next
In Southeast Asia burgeoning populations

coral reefs, and

and rising

placmg untenable pressures on the

living standards are

many

century

may

well cause the total demise of at least

some of

these critical, valuable and beautiful ecosystems.

are succumbing, no longer able to

provide the fish and other resources which have supported

Faint glimmers of hope
As our knowledge and our concern about coral

coastal populations for generations.

Even

the

In the past,

more remote
remote

testing nuclear

reefs

worldwide are not secure.

atolls in the Pacific

weapons and

today a number are

for

have been used for

dumping waste, and even

used for military target practice.

still

More widespread has been the impact of
many places traditional management and

fisheries.
restraint

In

has

enabled sustainable use of fish resources, but such
traditional

systems are breaking

down

in

some

areas,

so

increasing,

Overfishing

are

efforts

By

problem.

most dam-

setting aside small areas as "no-take" zones,

communities are finding

local

benefits. Fish stocks build

fi-om the

complete disappearance, even

is

of successful management efforts which can remedy the

some

remote locations.

its

reefs

problems.

the

now cropping up around the globe

Thankfully, examples are

into the surrounding area

target species towards

redress

on the fishing communities themselves.

is

while better transport and high prices are driving stocks of

in quite

to

worldwide problem, and

a

is

aging impact

the

wider area

is

up

that

in these

there

are

zones and

enormous
spill

over

such that the overall yield of fish

increased. Everyone benefits.

Tourism has caused considerable damage, through the
unplanned coastal development and pollution which are so
often linked to

The problems facing the world's reefs
Natural changes are a part of any ecosystem, and
at

still

the

early

dynamics of coral
the

are

However, the 20th century saw

reefs.

near exponential

we

of understanding the natural

stages

growth of human populations,

combined with even more rapid increases

it.

The sewage systems of many

directly into the waters

damage

to reefs

however,

major

is

hotels

empty

where the guests swim, and the

can be considerable. Increasing awareness,

leading to better controls on development and

efforts

to

improve sewage treatment. As such

measures develop, tourism can become

a force for good,

consumer

giving an added value to reefs in the eyes of the local

demands being placed on

the planet's limited resources,

communities, and often providing a direct income, through

and such trends are

to

century.

Humans

set

in

continue through the 21st

are thus bringing

new

pressures to bear

park fees, for the management of marine protected areas.

Most

importantly,

on the worlds coral reefs and driving more profound

the interactions

changes, more rapidly, than any natural impact has ever

terrestrial activities

done. Overfishing has

become

are few, if any, reefs in the world

This,

is

shifting the patterns

reef ecosystems.

of damaging activities

their

and between

reefs,

downstream impacts

coastal zone, are allowing for the development

which are not threatened.

planning.

We

solutions.

The challenge

as blast

and balances of

From onshore
is

and

so widespread that there

combined with such destructive practices

fishing,

many

our increasing understanding of

between humans and

a

much

life

in

greater suite

taking place. Often remote from

are aware of the problems,
is

to apply them.

in the

of integrated

and have the


WORLD ATLAS OF CORAL REEFS

Essential information
Key

to all

maps

in

Chapters A

to

U,

labeled a-j

Coral reef

National marine protected area

Mangrove

National marine protected area (boundary unknown!

Dive center

International protected area

Population center

International protected area [boundary

International boundary

River

Bathymetry

Water body

0-200 meters

Land

200-2 000 meters

Forest

>

2

000 meters

Space Shuttle photographs

^^^m^^^^^HQ
I

— ^ ^

I

7

km

Approximate scale

NASA

ISTS062-84-70. 19941

Throughout

Approximate North arrow

this publication the

relevant information

is

archive

number

use of na indicates that no

available.

For technical notes regarding the

text,

maps and

data tables, see page A01

.

unknown!


Unde rstanding Coral Reefs

Parti
Understanding Coral Reefs

13


WORLD ATLAS OF CORAL REEFS

Chapter

1

The World

reefs are

Coral
complex

of all

among

of

Coral Reefs

the most diverse and

ecosystems;

tfiey

are

among

changes that are now occurring on coral
responding

the most heavily utilized and economically

In

among

of their distribution,

most beautiful and fascinating.

It

Is

reefs are,

Important

how

to

lies

behind such acco-

appreciate exactly what coral

they are formed and where they are

found. Building on such a foundation

it

is

able to develop a basic understanding of

organisms that make up the complexity

also valu-

some

of the

and

for

This chapter offers a simple definition and description of coral reefs.

the

reefs,

such changes.

valuable to humankind; and they are also

order to understand what

lades

to

them

up.

It

goes on

and

of the

to

orovlde an overview

organisms that make

considers the elements determining these

It

distribution patterns, from factors of geological history
to

present day limiting processes and the very impor-

tant role of
briefly into

ocean currents. The chapter also looks

some

of the

patterns

of biodiversity

which

on coral

are observed at finer resolutions, patterns which are

reefs, and what role they play In maintaining these
ecosystems. Such knowledge provides the basis for
a wider understanding of the Interactions of humans

observed between neighboring reefs, and zonation

and

make up

reefs.

Above,

left:

It

Is

of

life

also critical for understanding the

Midway

Islands ISTS055-82-63.

Barrier Reef Below,

left:

19931.

Shallow waters of an

patterns across individual reefs. Finally, the chapter
provides an overview of the main organisms which
the patterns of

Above, right: The edge of the
atoll lagoon.

reef, with

life

on coral reefs.

spur and groove formations. Great

Below, right: The intricate branches of an Acropora coral.


The World

of

Coral Reefs

Defining coral reefs
who have seen

those

all

For

relatively simple to describe.

one, a coral reef

From

reefs are usually clearly visible,

air,

complex patterning of bright
turquoises and

colors.

marked by

a

These arrays of blues,

greens delimit a diverse and complex

physical structure

coming close

white of breaking surf and

dry land during the lowest
is still

more

ocean surface. The

to the

shallowest points are frequently

complexity

is

land or from the

shown by

the brilliant

may even briefly become
tides. From underwater the

clearly

shown -

reefs are typified

by the presence of large stony corals growing

profusion

in

corals are eroded by countless organisms.

a reef patterns or

or chemically dissolve the coral rock,

destroying

structure.

its

apparently destructive activities often
the reef while certain algae

fill

together with

more calcium carbonate

to

In this

the

way

a coral reef

is built.

growth of individual corals

Only

a tiny fraction

converted into upwards

a reef structure,

and so their formation

The most rapid

of reef "growth" have shown upwards accu-

mulation of reef structures reaching 9-15 meters
years in

of

is

periods

scientific definition

form a yet more

solid structure.

and water movements.
such descriptions incorporate

the interstices of

bind or overgrow such loose materials, cementing them

takes place over geological time scales.

more thorough

weakening and

and other corals may then

development of

simplistic,

some

areas, but

much

in

1

000

lower figures are probably

of a coral reef Coral reefs are shallow marine habitats,
defined both by a physical structure and by the organisms

found on them.
Corals themselves are very simple organisms. They are

found

in all the

worlds oceans,

described in more detail later

at all

depths. Although

in this chapter, typically

have a very small cylindrical body, topped with

which are used

tentacles

rounding waters.

A

large

to capture

number of

Among

these are

many

of

food from the sur-

corals have developed

the ability to live in colonies and to build
skeleton.

they

a ring

up a communal

species which lay

down

a

stony skeleton of calcium carbonate. These corals are

known

hermatypic or reef-building corals. They are

as

almost entirely confined to areas of warm, shallow water,

and

it

their skeletons,

is

which are

Even

critical to the

as large

essentially built of limestone,

formation of coral reefs.

in ideal conditions, these

slow growing.

Some massive

dome-shaped

corals,

structures,

which typically grow
build up a skeleton

at rates

of just a few millimeters per year. The faster

growing

tips

of branching corals

may extend

at rates

-

of

^:^

150 millimeters per year or more.

Over centuries or millennia

r-i

hermatypic corals are

may

"i

the active growth of these

corals (alongside other organisms such as coralline algae,

which also

lay

the building
is

down calcium carbonate

skeletons) leads to

up of vast carbonate structures. The process

not simple, and numerous additional factors

play.

come

into

Storms frequent many areas of tropical coastlines

and the waves they produce can, quite

literally,

pound

a

reef to rubble in a few hours. Over longer time scales,

V.

^^s^^l

Above: Individual polyps of the great star coral Montastrea cavernosa, clearly showing the cylindrical body, with a ring of
tentacles. Below: The

a

Sand and rubble from these

organisms, depending on factors such as depth, shelter

Although

is

great diversity of bio-eroding organisms that burrow into

zones become apparent, each dominated by different

the key elements of a

fish bite

algae on their surface. Unseen but equally important

and by an often bewildering array of species growing or

moving among them. Moving across

Some

chunks out of them, digesting the coral tissues and

large

growth of numerous corals builds up the massive physical structure of an Indian Ocean

reef.


WORLD ATLAS OF CORAL REEFS

more normal.

Types

In fact the majority of reef structures that

exist today are not the result

of continuous growth, but of

Corals can only grow

of reef

warm, well

in

lit

waters and require

pulses of growth interspersed with quiescent periods, or

a solid surface

even periods of erosion, when the reefs might be defined

initial

as fossil or non-living reefs. Sea levels in the oceans have

substrates

varied dramatically, particularly during the recent

skeletons provide a solid substrate for the appearance and

ages,

and many

reefs have intermittently

become dry

ice

land,

on which

to settle.

These factors

appearance of hermatypic corals

settlement

in

the

As

tropics.

corals

restrict the

shallow rocky

to

proliferate,

their

of more corals and other organisms. The

or have been flooded by waters too deep to allow corals to

upward growth of a physical reef structure can also allow

grow. Between these extremes, however, some of these

corals to continue to

fossil structures

become recolonized by

corals and reef

development recommences.

Over shorter time
actively

No

reef

is

grow

in

shallow well

Fringing reefs are perhaps the simplest structures to
understand. These develop from the simple upward growth

in a

constant state of growth.

of a calcium carbonate platform from a shelving coastline.

all

is,

reefs

in

undergo

Over years or decades,

the extent

Because growth

most rapid and prolific

is

a

shallow platform which

is

usually around the level of the

lowest tides. Further offshore growth

Recently observed events, including coral disease, coral

typical

bleaching, outbreaks of the coral-feeding crown-of-thorns

of important grazers such as the

long-spined sea urchin (see page 61), have

all

some

considerable losses of live coral cover to

Recovery from such events points

produced

structure of a mature

beyond which there

dropping down

Barrier reefs are usually older structures rising up

from

a

deeper base

at

some

distance from the shore, with

from only one particular moment

their origins as fringing reefs

Takmg such

points into consideration, a coral reef can

more rigorously defined

which has been

built

up,

as a physical structure

and continues

to

grow over

decadal time scales, as a result of the accumulation of

lagoon separating them from the coast.

Some have

on shelving coastlines, but

develop when the coastline on which they are growing
subsides or

is

flooded by rising sea levels. Under these

conditions the fringing reef continues to

grow upwards,

but deeper waters

fill

corals and

and the coastline.

In other cases barrier reefs

in

which such structures

simply developed

in

to the recognition

of a number of types of

calcium carbonate
other organisms.

develop has led

steeply shelving reef front

is a

a

time will be limited.

slower, but the

to the sea floor.

but also shows that any understanding of a "reef" measured
in

is

fringing reef includes a

shallow platform out to a sharply defined edge, the reef
crest,

reefs.

to a natural resilience,

laid

down by hermatypic

The manner

while there are also

many

shallow

in

water the corals quickly grow to the surface and produce

of actively growing coral cover also varies considerably.

thus be

waters, even

many

fossil reef

losses in coral cover and often considerable erosion of

starfish, or the die-off

lit

on which they are growing subsides or sea

between an

the division

During major tropical storm events,

their physical structure.

the basement

levels rise.

scales,

growing coral reef and a

areas, unclear

if

in a

lagoon between

this structure

offshore locations, but

may have

still

remain

separated from the coast by a lagoon.

other communities which,

Atolls are unique reef formations, broadly circular,

while not as obviously covered by these definitions, are

and enclosing a wide lagoon. They are typically found

reef,

clearly related

and equally important.

in

oceanic locations, away from the continental shelf

Figure 1.1: The main types of coral reef structure

Barrier

Bank or
platform

reel

reef


The World

Darwin was the

They

around isolated

reefs

usually volcanic, islands. Such islands then subside, but
the reefs continue to grow, first forming a barrier around

the sinking

but

island,

Coral Reefs

correctly understand their origin.

first to

form as fringing

initially

of

then,

as

island

the

disappears

Figure

1 .2:

The development

an

of

atoll,

based on

Darwin's original theory

A

volcanic island

is

colonized by corals and

surrounded by a fringing

becomes

reef.

beneath the surface, forming a single ring of coral. The
depths of coral limestone which

structures

may

accrue on these

considerable - drilling in the Marshall

are

Islands has revealed reef deposits up to 1.4 kilometers in

depth, dating back over 50 million years.

Bank

or platform reefs are simple physical structures

with a variety of origins. They are essentially reefs with

no obvious

link to a coastline, but without the clear struc-

ture of a barrier reef or atoll. In

similar origins to either of the

some

latter,

cases they

may have simply

or encircle a lagoon, in other cases they

grown up over
slightly

may have

but do not hold back

natural rises in the coastal shelf Larger or

submerged reef structures of

sometimes referred

The island

and

itself subsides, the corals

a barrier reef

is

continue

to

grow

formed.

this type are also

to as shoals.

Other types of reef and coral communities
These reef types can be clearly
However, the

illustrated (Figure

reality often reveals

which do not conform quite so

many

1.1).

other structures

easily to strict definitions.

Near-atolls are described in a few areas where there

remnant of the original high island

tiny

atoll ring.

There are also

platform reefs which

like

a considerable

may

is

a

center of an

in the

number of

atoll-

not have the true geological

The island

but coral maintains upward

is lost,

growth and a ring-shaped

formed.

atoll is

origin of an atoll (around a subsiding volcanic island), but

where the surface structure
atoll.

is

almost exactly that of an

There are also a number of structures which

lie

offshore in the location of a true barrier reef, but which

may

not quite

conform

to the definition or geological

Bank

origin of a barrier reef

barriers

are

commonly

described in parts of the Caribbean where small banks
at

some distance offshore and sometimes do not

Table

1.1:

lie

rise all

Estimates of global reef area calculated from the reef maps
Area (km^)

Region
Atlantic and Caribbean

Caribbean

% of world total

Figures are

rounded

7.6

20 000

7.0

600

0.6

261 200

91.9

llAOO

6.1

/,200

1.5

32 000

11.3

total of

91 700

32.3

this

115 900

40.8

1

Indo-Pacific

Red Sea and Gulf

of

Aden

nearest

the

100 square

place. National level statistics are provided in the

regional accounts later

Atlantic

to

kilometers, and percentage figures to one decimal

600

21

book.

in this

In

order to avoid

maps prepared
such calculations are made by

the problems associated with using
at

multiple scales,

first

simplifying the global coverage dov^^n to a

1

kilometer grid, each grid cell being simply marked as

Arabian Gulf and Arabian Sea
Indian

Ocean

Southeast Asia
Pacific

reef or non-reef. Reef area
1

method exaggerates the

actually

shown on the maps,

the grounds that the

Eastern Pacific
Total

1

600

ZBi 300

0.6

then calculated as the

is

square kilometer cells with

maps

this

only

reef.

total area

can be

show

Although

from that
justified

on

reef flat to reef

crest areas, while the true reefs extend beyond these

areas Isee also Chapter

31.


WORLD ATLAS OF CORAL REEFS

the

way

to the sea surface.

The long offshore reef tracts of

Cuba and elsewhere

Florida,

many

rival

true barrier reefs

regarded as true barrier

in length, but are frequently not

from the mainland

reefs because they are only separated

on the area of coral reefs

overall perspective

and

in

in the world,

allowing for regional comparisons. There are an

estimated

284 300 square kilometers of coral reefs

worldwide'. This figure represents only 0.089 percent of

by a very shallow lagoon, or because they are not located

the world's oceans

on the edge of the continental

shelf.

continental shelf area. Thus, at the global scale, coral reefs

structures, often lying within the

wider formation of

Small physical
a

barrier or atoll lagoon, are often referred to as patch reefs.

Perhaps more importantly, there are significant areas

and

less than 1.2 percent

are a rare habitat. Further analysis clearly

of the world's

shows

that the

great majority of coral reefs are found in the region
as the Indo-Pacific,

which stretches from

the

known

Red Sea

to

around the world where there are coral communities

the Central Pacific. Less than 8 percent of the world's

which perform the same ecological function as coral

reefs are

reefs,

formations where there

may be

a thin veneer of live coral,

or they

may

visible.

For clarity such structures are frequently referred to

be physical reefs, but not yet mature or clearly

as coral communities,

submerged

reefs, or sub-surface reefs.

found

Zooming

but lack a clear physical structure. These include recent

in the

Caribbean and Atlantic.

in to these

maps, new patterns emerge

at

finer resolutions. Reefs are often limited in their develop-

ment

nearshore waters of large continental land

in the

masses, although barrier structures are widespread
places.

They

in

such

are poorly developed close to large river

mouths. In contrast, they are particularly well developed

around islands and along the coastlines of drier con-

Global distribution
Charles Darwin was probably the

map of

a global

described

in

His and other efforts are

coral reefs.

Chapter

3.

Coral reefs are restricted to a

broad swathe, roughly confined

most of

far

the globe

from evenly

(Map

tinental areas.

person to prepare

first

I.I).

to the tropics,

Within

this

range they are

distributed, with large areas

remote island regions and offshore areas

and circling

far

confmed

to

order

In

distribution

make up

it

to
is

understand

these

necessary to look

the coral reef ecosystem.

patterns

at the

The

of reef

organisms which

factors impinging

on their evolution, dispersion, and survival are the same
factors

which have created the patterns

distribution that

we

in

coral

reef

see today.

from major

land masses. Further investigation shows that coral reefs
are largely absent

from the Central Atlantic and the shores

of West Africa, they are highly restricted along the western
(Pacific) shores of the Americas, and are also restricted

along the coastline of South Asia

from Pakistan

to

The reef area figures used tfiroughout this work are based on a new
and replace the early estimate provided by Spalding and Grenfell
It is likely, as mapping work continues,
that such figures will continue to be refined and improved. This may lead to
further upwards adjustment of the global total, although in some areas
1,

Bangladesh.

calculation,

Using the maps shown

in

this

publication

it

is

possible to estimate the total area of coral reefs in the

world.

Although there are clear limitations

to

such

estimates, these figures are clearly valuable for getting an

Map

1.1:

The coral reefs

of the

119971 of 255 000 square kilometers.

there

Thus

is
It

also likely to be

seems

some

unlikely that a

reduction of figures as
final" figure

maps

are improved.

would exceed 300 000 square

kilometers.

world

30

20

W:-^ ,."..-»?;;%

.

-^>^

r-l^i'

10

—
10

20

30

Distribution of scleractlnian corals


The World

Patterns
of

Observations

At the global

in the distribution

level,

Coral Reefs

of diversity

on coral reefs reveal

life

of striking patterns

of

Patterns at the global scale

number

a

of species.

few species are ubiquitous.

Corals are clearly the most important organisms
it

comes

understanding the

to

factors

that

when

drive

the

The majority of reef-building

Some may be widespread across one or even two ocean
basins, but many others are restricted to certain oceans or

distribution of coral reefs.

particular seas.

have been the subject of continuing studies by biologists

As a larger picture is built up through
many species, certain patterns emerge. Some

looking

at

regions are

highly distinctive with large numbers of endemic species,

found nowhere

else.

The

total diversity

of species

also

is

uneven, with centers of particularly high diversity, and
with clear gradients

mirroring environmental

in diversity

When

looking

resolutions,

finer

at

emerge. Certain species appear

to

new

patterns

predominate

in

near

continental reefs, while others are found on oceanic reefs.

and the position on the continental

still,

in

shelf, or

wind or currents, appears

that relative to the prevailing

hold sway

to

determining the species composition. At the

scale of tens or hundreds of meters, patterns of zonation
are observed across individual reefs, with species adapted
to different depths,

exposure, water circulation and so on.

of individual points or quadrats,

Finally, at the scale

the pattern of

disappear

in

a

which species are found where seems

random

noise.

factors driving the settlement

may be

far

Even

to

here, however, the

and survival of individuals

immediate sense and over the

life

and taxonomists for many years, and a considerable

amount
the

is

now known about

factors

their distribution

which influence

Some 794

it.

sclcractinian coral are considered to be reef builders, and

Map

1.2

shows

a plot

of their distribution, highlighting

the patterns of varying diversity.

A

number of

fairly rapidly

latitudes, with diversity

diminishing

along latitudinal clines.

There are two distinctive regions of coral distribution,

one centered around the Wider Caribbean (the Atlantic),
the other reaching

from East Africa and the Red Sea

to the

Central Pacific (the Indo-Pacific).
Diversity

is

far lower in the Atlantic than in the Indo-

Pacific.

Coral

diversity

is

at

its

highest

around

insular

Southeast Asia.
Coral diversity and reef development are very restricted
along the western shores of the Americas and West Africa.

Although only relating

Patterns of diversity

in

to

corals,

these

reef-building scleractinian corals

^^S:

* ""'^^^^^^^^^^^^^B
50

points can

Corals, like the reefs they build, are restricted to a

narrow band of low

-^-

<50

and about
species of

100

200

300

patterns

are

reflected in most other groups found in tropical coastal

history of the individual.

1.2:

They

from chaotic, but driven by highly complex

interactions, both in the

Map

as Scleractinia.

be observed:

gradients.

Closer

known

corals fall within the group

400

500

Number

of

species


WORLD ATLAS OF CORAL REEFS

waters, as

shown by

the statistics in Table 1.2.

These and

other patterns are derived from a complex interaction of
historical

and contemporary

some groups,

factors. For

parallel with coral diversity patterns

may

ecological associations between them.

number of

others,

it

may be

the

However, for a

same external

which have actually driven the change.

the

reflect direct

A

induced climate change,

events

may

be

at least a partial

limited reef development which

explanation for the highly
is

observed, for example,

along the western shores of the Americas.

factors

number of these

factors are briefly laid out below.

The

role of currents

While temperature influences can be broadly equated with
latitude,

The influence of temperature
To

has been suggested that

it

occasional high temperatures associated with El Niiio

a large extent, both scleractinian corals

In a

ocean currents can disrupt these simple patterns.

few areas of the world, major

warm

currents flow

all

and the reefs

year round from the tropics into higher latitudes. These

they build are restricted to a latitudinal band between

have allowed the development of reefs quite beyond their

30°N and 30°S. This general observation

normal

to

the decreasing temperatures

increasing latitude.

temperatures

Most reef

entirely related

which generally follow
corals cannot survive in

much below 16-18°C

In conditions

is

for

even

a

few weeks.

of extreme cold, corals can die within

limits. Notable are the Leeuwin Current in

Western Australia; the East Australian Current; the

Kuroshio Current

in Japan;

and the Gulf Stream warming

the isolated oceanic reefs of

Bermuda.

In a similar way,

a

cold waters prevent reef growth. Cold water upwellings

matter of hours or days, while under slightly less extreme

along the coastlines of northeastern Somalia and southern

conditions, their growth rates are reduced. There

is

some

Arabia are perhaps the clearest example,

while the

evidence that overgrowth by algae rather than the direct

extremely limited development of reefs and coral com-

m

munities along the western coastlines of the Americas

influence of cold water

some high

may

restrict coral

development

and West Africa may also be influenced by cold water

latitude areas.

High temperatures

are also inimical to coral growth.

upwellings.

Extreme high temperatures drive the phenomenon known
as "coral bleaching", during

which the corals expel

symbiotic algae (see Chapter

Left,

2).

Aside from human-

above: A smalt coral cay on the reef

Barrier Reef in

Fiji.

their

flat of

an

atoll,

Right: Fringing reefs, near Suva,

Fiji.

Another role of currents
to areas
is

Salomon

is in

the transport of larvae

of reef The establishment of corals

in

dependent on the transport of coral larvae

Atoll.

Chagos Archipelago.

Left,

new

areas

in

ocean

below. The Beqa


The World

of

Coral Reefs

Table 1.2: Regional patte rns of species diversity in coral reefs and related ecosystems:
the clear pattern of max mum diversity in the Indo Pacific reg on is shovim in all species groups

ndo-West

Taxonomic group

Alcyonarian corals

690+

Sponges (general

2U

Western Atlantic

Eastern Pacific

Pacific

34

719

Scleractinian corals'

Eastern Atlantic

62
6

117

Gastropods;

Cypraeidae

178

24

6

9

Conus

316

30

57

22

2 000

564

378

427

249

50

77

30

91

28

41*

Bivalves

Crustaceans:

Stomatopods
Caridean shrimps

Echinoderms

1

200

208

148

Fish

iOOO

650

1400

450

175

8

15

7

Seagrasses'

3A

7

9

2

Mangroves'

59

13

11

7

Butterflytish

•

and angelfish^

All Atlantic

Source; Paulay 119971 except:

l.Veron 120001.
2.

Allen el al 119991

3.

WCMC

^.

Spalding et all 19971.

database

- figures include

species with

currents. Unfavorable currents

zation of areas by

new

may

warm temperate

distribu ions.

prevent the coloni-

species, notably in the remote reef

regions of Brazil and the Eastern Pacific.

and the importance of

this

The mechanisms,
further con-

transport, are

only

the

Indo-Pacific.

may have prevented subsequent

disruption

Even

re-expansion

time since the end of these glaciations for any

little

The

further species radiation.

result today is clearly

shown

Changing patterns over geological time scales
Separate faunas - Atlantic and Indo-Pacific. Many of

in the far lower species diversity in the Atlantic reefs.

the global patterns in reef and coral development can be

the

explained by looking

of

at

the tectonic and climatic history

reefs. Scleractinian corals

evolved during the Triassic

(205-250 million years ago) and quickly developed a
circum-global distribution, only restricted by areas of
suitably shallow substrate.
shifted, the global

more

restricted.

As

the continents broke up

and

connection of tropical oceans became

With the closure of the Tethys Sea, the

waters of the Indian Ocean and Western Pacific were
separated
Pacific,

from those of the Atlantic and

and the coral reef communities

in

far

Eastern

each began to

Low

diversity in

the Atlantic. The closure of the

Panama divided

two. This entire region

the

For

scleractinian corals the Atlantic only holds about one tenth

number of species

as the Indo-Pacific, while similar

patterns hold for almost

between one

third

Atlantic reefs as

High

all

other species groups, with

and one tenth of the diversity on

compared

to Indo-Pacific reefs.

diversity in the Indo-Pacific.

of extinctions was not so extreme

now known

the area

as

in the

The same period
"eastern fauna",

the Indo-Pacific.

Right across

the region there are large areas of shallow coastal shelf

spanning considerable latitudinal ranges. Over these areas
there were

more

locations or refuges offering opportu-

nities for survival

of species during periods of environ-

mental adversity. Species diversity remains high across

develop distinctive characteristics.

isthmus of

as

and diversification of the coral reef fauna, and there has
been

sidered on page 23.

with

genera

seven

environmental conditions improved, continued eustatic

"western"

was then subjected

fauna into
to

massive

much of this
diversity

region, although there

moving

is

a clearer decline in

east across the Central Pacific.

The Southeast Asian center of diversity. Quite

apart

extinctions during the Pliocene/Pleistocene glaciations,

from the generally high diversity recorded across the Indo-

removing many of the species which were once commonly

Pacific, there

found on

all

coral reefs.

The Atlantic

corals

now

share

a triangle

is

an area of outstanding diversity centered on

encompassing the Philippines and central and