Coral Reef EcosystemsCoral Reef Ecosystems

Ecology and Environmental Ecology and Environmental ManagementManagement

Lecture contentLecture content

Coral reef ecologyCoral reef ecology– How they are How they are

formedformed– Physical Physical

EnvironmentEnvironment– Diversity patternsDiversity patterns– Threats to coral Threats to coral

reefsreefs– FisheriesFisheries

Coral reef Coral reef managementmanagement– Assessing damageAssessing damage– Management for Management for

ecology and ecology and economicseconomics

– DiversificationDiversification– TourismTourism

Introduction to coral reefsIntroduction to coral reefs

What is a “coral reef”What is a “coral reef” Biological (“coral community”)Biological (“coral community”)

– Organic, BiogenicOrganic, Biogenic– Coral and Algal communitiesCoral and Algal communities– Mostly “hermatypic” corals, algae, and other Mostly “hermatypic” corals, algae, and other

sessile animalssessile animals Geological features (“reef”)Geological features (“reef”)

– CarbonateCarbonate– In situIn situ buildup buildup– Topographic reliefTopographic relief– Wave resistantWave resistant– Cemented, consolidatedCemented, consolidated

CoralsCorals

Phylum Phylum AnthazoaAnthazoa

Class CnidariaClass Cnidaria Hermatypic Hermatypic

(hard) corals (hard) corals contain contain symbiotic symbiotic algaealgae

Up to 500 spp. Up to 500 spp. at some sitesat some sites

Rosen 1981

Threats to coral reef Threats to coral reef systemssystems

OverpopulatioOverpopulationn

Unsustainable Unsustainable fisheriesfisheries

Coastal Coastal developmentdevelopment

Global climate Global climate changechange

Non-selective and Non-selective and destructive fishing methodsdestructive fishing methods Subsistence fishing occurs Subsistence fishing occurs

regardless of effort requiredregardless of effort required Muro Ami, Dynamite (Blast), and Muro Ami, Dynamite (Blast), and

cyanide fishingcyanide fishing TrawlingTrawling Trapping and linesTrapping and lines

– Ghost fishingGhost fishing Total fishing mortality often not Total fishing mortality often not

knownknown

Malthusian overfishingMalthusian overfishing

““...occurs when poor fishermen, ...occurs when poor fishermen, faced with declining catches and faced with declining catches and lacking any alternative initiate lacking any alternative initiate wholesale resource destruction in wholesale resource destruction in order to maintain their incomes.order to maintain their incomes.

This may involve in order of This may involve in order of seriousness, and generally in seriousness, and generally in temporal sequence...temporal sequence...

1) Use of gears and mesh sizes not 1) Use of gears and mesh sizes not sanctioned by governmentsanctioned by government

2) Use of gears and mesh sizes not 2) Use of gears and mesh sizes not sanctioned within the fisherfolk sanctioned within the fisherfolk community…community…

3) Use of gears that destroy the resource 3) Use of gears that destroy the resource basebase

4) Use of gears such as dynamite or sodium 4) Use of gears such as dynamite or sodium cyanide that do all of the above and even cyanide that do all of the above and even endanger the fisherfolks themselves”endanger the fisherfolks themselves”

McManus 1997

Ecosystem effects of Ecosystem effects of fisheriesfisheries

Removal of predatorsRemoval of predators Removal of algal grazersRemoval of algal grazers Change in dominanceChange in dominance

– Californian Sea OttersCalifornian Sea Otters– UrchinsUrchins– Crown of Thorns starfish “COTS” Crown of Thorns starfish “COTS”

((Acanthaster planciAcanthaster planci)) Changes in size frequency of animalsChanges in size frequency of animals

Crown of Thorns StarfishCrown of Thorns Starfish

Crown of ThornsCrown of Thorns Eats coral by everting gutEats coral by everting gut Aggregations can remove 95% of coral Aggregations can remove 95% of coral

covercover May result in collapse of remaining May result in collapse of remaining

skeletonskeleton Pheromone controlled aggregated Pheromone controlled aggregated

spawningspawning Recovery takes at least 12 yearsRecovery takes at least 12 years Caused by loss of predators?Caused by loss of predators? Increased larval survival due to pollution? Increased larval survival due to pollution?

Climate changeClimate change Potential impacts on coral communitiesPotential impacts on coral communities

– Changes in water temperatureChanges in water temperature

– Increases in COIncreases in CO22 concentration concentration

– Changes in solar irradiation (if cloud cover Changes in solar irradiation (if cloud cover changes)changes)

– Sea level rises leading to drowning of reefsSea level rises leading to drowning of reefs– Changes in surface run-off (sedimentation)Changes in surface run-off (sedimentation)– Changes in land-use patterns leading to Changes in land-use patterns leading to

increased reef exploitationincreased reef exploitation

Kleypas et al 2001

Coral Coral bleachingbleaching

Loss of Loss of symbiotic symbiotic algaealgae

May cause May cause death of animaldeath of animal

A symptom of A symptom of climate climate change?change?

Coral BleachingCoral Bleaching First described in 1984First described in 1984 Multiple re-occurrences at same Multiple re-occurrences at same

sitessites New sites impacted during 1990sNew sites impacted during 1990s Many known triggersMany known triggers

– Temperature (especially increases)Temperature (especially increases)– Solar radiation (especially UV)Solar radiation (especially UV)– Combination of UV and temperatureCombination of UV and temperature– Reduced salinityReduced salinity– InfectionsInfections

Effects of bleachingEffects of bleaching Loss of symbiontic algae (Zooxanthellae) Loss of symbiontic algae (Zooxanthellae)

algae by:algae by:– Degradation Degradation In situIn situ– Loss of algae by exocytosisLoss of algae by exocytosis– Expulsion of intact endodermal cells containing Expulsion of intact endodermal cells containing

algaealgae Resulting impactsResulting impacts

– Vary between species, and even parts of the same Vary between species, and even parts of the same colonycolony

– Loss of sensitive species (especially Loss of sensitive species (especially AcroporaAcropora spp.) spp.)– Recovery slow and highly variable between sitesRecovery slow and highly variable between sites

The ProblemsThe Problems

A large (and growing) number of A large (and growing) number of people are dependent on coral reefspeople are dependent on coral reefs

Management of a multispecies Management of a multispecies fishery is extremely complex, and fishery is extremely complex, and often failsoften fails

Terrestrial development may destroy Terrestrial development may destroy coastal reef systemscoastal reef systems

Global climate change may exert Global climate change may exert new pressuresnew pressures

Coral reef managementCoral reef management

Monitoring the benthosMonitoring the benthos

Line intercept transectsLine intercept transects Visual transectsVisual transects QuadratsQuadrats Photography and videoPhotography and video

Marine protected areasMarine protected areas

Fisheries reservesFisheries reserves– ““No take zones” (NTZs)No take zones” (NTZs)– Controlled fishingControlled fishing

Effects on fish populationsEffects on fish populations– Coral reef fish often have small ranges Coral reef fish often have small ranges

Effects on fishing revenueEffects on fishing revenue Local management and ownershipLocal management and ownership

SourcesSources

The marine protected areas case studies are The marine protected areas case studies are based on the work of Russ and Alcala.based on the work of Russ and Alcala.

I think these are classic studies because they I think these are classic studies because they show both the conservation and economic show both the conservation and economic benefits of marine reserves AND how benefits of marine reserves AND how important co-operation with the local important co-operation with the local community can be.community can be.

These are not new references, work from These are not new references, work from Roberts’s paper for newer studies. See also Roberts’s paper for newer studies. See also Gell and Roberts 2003 – Trends in Ecology and Gell and Roberts 2003 – Trends in Ecology and Evolution, 18, 448 - 455Evolution, 18, 448 - 455

Biological effects of Biological effects of protectionprotection

Habitat protectionHabitat protection BiodiversityBiodiversity Protection of Protection of

vulnerable vulnerable speciesspecies

Allow fish to grow Allow fish to grow to maturityto maturity

Control Control (reference) sites(reference) sites

Economic effects of Economic effects of protectionprotection

Increased size and Increased size and abundance of stock abundance of stock speciesspecies

Emmigration into Emmigration into fishing grounds fishing grounds (Spillover)(Spillover)

Insurance against Insurance against management failuremanagement failure

Tourism “spin-offs”Tourism “spin-offs” Ease of enforcementEase of enforcement

Factors to considerFactors to consider Costs?Costs?

– Staff, setup, Staff, setup, monitoringmonitoring

– Initial loss of fishing Initial loss of fishing revenuerevenue

Size/shape of Size/shape of reserve?reserve?– Life history and Life history and

behaviour of fishbehaviour of fish– Fishing intensityFishing intensity– 20-40% of fishing 20-40% of fishing

groundground

Can you sell it?Can you sell it?– Any spin-off Any spin-off

benefits?benefits?– Employment of Employment of

local staff?local staff?– Compromise on Compromise on

size of reserve?size of reserve? What What

management management outside reserve?outside reserve?

Reducing diver impactReducing diver impact Mooring buoysMooring buoys Most damage Most damage

caused my minority caused my minority of diversof divers– EducationEducation– EnforcementEnforcement

Ban glovesBan gloves MonitoringMonitoring Zoning / Closure / Zoning / Closure /

RotationRotation

SummarySummary

Coral reefs contain diverse fish and Coral reefs contain diverse fish and invertebrate assemblagesinvertebrate assemblages– This makes them valuable, but This makes them valuable, but

difficult to managedifficult to manage Coral reefs are mainly found in the Coral reefs are mainly found in the

poorest areas of the worldpoorest areas of the world– This makes them prone to over-This makes them prone to over-

exploitationexploitation

SummarySummary

Reefs must be assessed and Reefs must be assessed and monitored to allow managementmonitored to allow management

Marine protected areas may protect Marine protected areas may protect biodiversity and maintain fish stocksbiodiversity and maintain fish stocks

Diversification of local economies Diversification of local economies may be effective in reducing may be effective in reducing pressurespressures

Tourism brings new pressures which Tourism brings new pressures which must also be managed.must also be managed.