Presentation on theme: "Ecology and Environmental Management"— Presentation transcript:
1Ecology and Environmental Management Coral Reef EcosystemsEcology and Environmental Management
2Lecture content Coral reef ecology Coral reef management How they are formedPhysical EnvironmentDiversity patternsThreats to coral reefsFisheriesCoral reef managementAssessing damageManagement for ecology and economicsDiversificationTourism
4What is a “coral reef” Biological (“coral community”) Organic, BiogenicCoral and Algal communitiesMostly “hermatypic” corals, algae, and other sessile animalsGeological features (“reef”)CarbonateIn situ buildupTopographic reliefWave resistantCemented, consolidated
5Corals Phylum Anthazoa Class Cnidaria Hermatypic (hard) corals contain symbiotic algaeUp to 500 spp. at some sitesRosen 1981
6CaCo3 addition - CaCo3 loss = Accumulation Building the reefCaCo3 addition - CaCo3 loss = AccumulationBiological erosionMechanical erosionSediment export, dissolutionReef GrowthBiogenic productionSediment ImportCementationKleypas et al 2001
8Environmental requirements Physical environmentTemperature of 25-31oC (limited Northwards by the 18oC minimum isotherm)Salinity of pptLight levelPredominantly in top 30 m of waterBiological environmentOligotrophic, highly stratified water column
11MapsFor the lecture I used maps from a variety of locations, often more for clarity than scientific detail. I would recommend the maps from the World Conservation Monitoring Centre (www.wcmc.org.uk) which I would tend to value as reliable.The main point being that the high population densities in many coastal areas which contain high coral reef species richness represent a serious threat.
12Fish community Mainly Perciform teleosts 2 faunas, Diurnal and NocturnalOften territorial/site attachedIntraspecific interactions (pair bonding and harems) and interspecific mutualism (e.g. cleaning stations)Mostly planktonic larvaeEstimated 4500 spp, 25% of marine total~10% of world fishery landings
17Threats to coral reef systems OverpopulationUnsustainable fisheriesCoastal developmentGlobal climate change
18Coral reef fisheries Essential to survival of many Managed sustainably for generationsDiverse ecosystemMultispecies fisheriesInterspecies interactions may invalidate modelsCollection of sufficient data for all species may not be practicableReduction of fishing effort to sustain all fish species wastes the productivity of most stocks
19Non-selective and destructive fishing methods Subsistence fishing occurs regardless of effort requiredMuro Ami, Dynamite (Blast), and cyanide fishingTrawlingTrapping and linesGhost fishingTotal fishing mortality often not known
20Malthusian overfishing “...occurs when poor fishermen, faced with declining catches and lacking any alternative initiate wholesale resource destruction in order to maintain their incomes.This may involve in order of seriousness, and generally in temporal sequence...
211) Use of gears and mesh sizes not sanctioned by government 2) Use of gears and mesh sizes not sanctioned within the fisherfolk community…3) Use of gears that destroy the resource base4) Use of gears such as dynamite or sodium cyanide that do all of the above and even endanger the fisherfolks themselves”McManus 1997
22Ecosystem effects of fisheries Removal of predatorsRemoval of algal grazersChange in dominanceCalifornian Sea OttersUrchinsCrown of Thorns starfish “COTS” (Acanthaster planci)Changes in size frequency of animals
24Crown of Thorns Eats coral by everting gut Aggregations can remove 95% of coral coverMay result in collapse of remaining skeletonPheromone controlled aggregated spawningRecovery takes at least 12 yearsCaused by loss of predators?Increased larval survival due to pollution?
26Climate change Potential impacts on coral communities Changes in water temperatureIncreases in CO2 concentrationChanges in solar irradiation (if cloud cover changes)Sea level rises leading to drowning of reefsChanges in surface run-off (sedimentation)Changes in land-use patterns leading to increased reef exploitationKleypas et al 2001
27Coral bleaching Loss of symbiotic algae May cause death of animal A symptom of climate change?
28Coral Bleaching First described in 1984 Multiple re-occurrences at same sitesNew sites impacted during 1990sMany known triggersTemperature (especially increases)Solar radiation (especially UV)Combination of UV and temperatureReduced salinityInfections
29Effects of bleachingLoss of symbiontic algae (Zooxanthellae) algae by:Degradation In situLoss of algae by exocytosisExpulsion of intact endodermal cells containing algaeResulting impactsVary between species, and even parts of the same colonyLoss of sensitive species (especially Acropora spp.)Recovery slow and highly variable between sites
30The ProblemsA large (and growing) number of people are dependent on coral reefsManagement of a multispecies fishery is extremely complex, and often failsTerrestrial development may destroy coastal reef systemsGlobal climate change may exert new pressures
32Management Issues Biological What does the resource consist of? What state is it in?Is there overfishing?Is there habitat destruction?Socio-ecomomicLevels of resource exploitationMore sustainable ways of exploiting the resourceAlternatives to coral reef exploitation/damage
33Monitoring coral reefs What sites and parameters to monitor?FishMacroinvertebratesWater qualityBenthic habitat qualityCoral health
34SourcesAustralian Institute for Marine Science (AIMS) website contains all their standard techniques. From a comparability point of view it is extremely helpful to use common techniques.The AIMS site and their manual (English et al, 1997) even explains how to store the data in a database and manage it. Essential reading if you can get hold of it.The use of volunteers for some types of coral reef survey work is very common and slightly controversial. Common sense will be necessary in determining what techniques a volunteer can apply - in particular for qualitative judgements about reef “quality” and levels of impact.
35Large-scale studies Rapid Ecological Assessment “Manta tows”Estimates of % cover (live and dead coral)Abundance of highly visible speciesHuman impactsMapping and aerial photography
36Monitoring fish Visual census Fisheries monitoring Transects Point countsRandom searchingOften allow biomass estimatesFisheries monitoring
37Monitoring the benthos Line intercept transectsVisual transectsQuadratsPhotography and video
39Marine protected areas Fisheries reserves“No take zones” (NTZs)Controlled fishingEffects on fish populationsCoral reef fish often have small rangesEffects on fishing revenueLocal management and ownership
40SourcesThe marine protected areas case studies are based on the work of Russ and Alcala.I think these are classic studies because they show both the conservation and economic benefits of marine reserves AND how important co-operation with the local community can be.These are not new references, work from Roberts’s paper for newer studies. See also Gell and Roberts 2003 – Trends in Ecology and Evolution, 18,
41Biological effects of protection Habitat protectionBiodiversityProtection of vulnerable speciesAllow fish to grow to maturityControl (reference) sites
42Economic effects of protection Increased size and abundance of stock speciesEmmigration into fishing grounds (Spillover)Insurance against management failureTourism “spin-offs”Ease of enforcement
46Factors to consider Costs? Can you sell it? Size/shape of reserve? Staff, setup, monitoringInitial loss of fishing revenueSize/shape of reserve?Life history and behaviour of fishFishing intensity20-40% of fishing groundCan you sell it?Any spin-off benefits?Employment of local staff?Compromise on size of reserve?What management outside reserve?
47Impacts of tourism Terrestrial development Land reclamation and creation of beachesMangrove removalSand on reef flatBoatsAnchorsDiver/snorkeller impacts and fish feedingSewageHarbour dredging
50SourcesThis section is based on the works of David Medio and Julie Hawkins. A couple of their references are included at the end.Much other material is directly from the Egyptian Environmental Affarirs Agency (link at the end)
53Reducing diver impact Mooring buoys Most damage caused my minority of diversEducationEnforcementBan glovesMonitoringZoning / Closure / Rotation
54Managing terrestrial impacts Catchment managementAgricultureFertiliserSeafront corridorsControls on sewage systemsLimits on developmentDry beaches and walkways
55Who cares what happens to coral reefs anyway? FisheriesTourismCoastal protectionBioprospectingMoral reasonsMany coral reef functions are SubsistenceDo not show up as economic benefitsREPLACEMENT value may be extremely high
56Summary Coral reefs contain diverse fish and invertebrate assemblages This makes them valuable, but difficult to manageCoral reefs are mainly found in the poorest areas of the worldThis makes them prone to over-exploitation
57Summary Reefs must be assessed and monitored to allow management Marine protected areas may protect biodiversity and maintain fish stocksDiversification of local economies may be effective in reducing pressuresTourism brings new pressures which must also be managed.