Extremely low tides in September 1970 Chronic oil spills ( ) Fish farms (since 1995) Diseases Bleaching in

Transcription

1 Lecture 13: Anthropogenic Impacts to Coral Reefs Bellwood et al Confronting the coral reef crisis Kristin McCully 24 Feb 2010 Anthropogenic Impacts to Coral Reefs Sediment Nutrients Pollutants Overfishing Disease Corallivore outbreaks Global changes Global warming Acidification Sea level change Curt Storlazzi s lecture several readings, Jimmy O Donnell Global Change lecture Case Study: Gulf of Eilat Extremely low tides in September 1970 Chronic oil spills ( ) Fish farms (since 1995) Diseases Bleaching in

2 3/7/2010 Mediterranean Sea Israel Sinai Peninsula Jordan Egypt Eilat Aqaba Saudi Arabia Red Sea Eilat 2000 Nature Reserve Japanese gardens 6 Percent abundanceof Percentcover cover and abundance of stony corals m. stony corals per per 10 m10 transect, 4m transect, 4 m. depth, Eilatdepth, Eilat Coral Nature Reserve Nature Japanese Reserve- Japanese Gardens gardens ( = 9 transects) - 21 transects) (n= n9 21 Extremely low tides in Sept % coral cover & no. of colonies % -76% % Coral cover No. of colonies

3 Runoff Triggered by rainfall (often a storm) Low salinity High turbidity (sediment) High nutrients High pollutants (sometimes) Landfill & Coastal Engineering Dubai Palm Island Malé(capital of the Maldives) Sediment Runoff Sources: Agriculture Overgrazing Deforestation Coastal development How: Turbidity reduced photosynthesis & filter-feeding Energy expenditure on mucus to remove sediment Loss of recruits & recruitment sites Burial & smothering Result: Less coral recruitment Less calcification Different species Nutrient Runoff: N, P Anthropogenic sources: Sewage Agricultural fertilizer Fish farms How? Algae can outcompete corals when high nutrients and/or low herbivory Phosphate can inhibit coral calcification Trigger COTS outbreak? Result: coral cover & fleshy algae cover PHASE SHIFT BUT high fleshy algae cover can be natural 3

4 Phase Shift/ Alternate Stable States Ecosystem State Macroalgae Corals H2 H1 Alternate States in Coral Reefs Bellwood et al Confronting the coral reef crisis low Nutrients high high Herbivory low From Wendy Cover s lecture 14 Eilat municipal sewage (3 million m 3 /year) flowing into the Gulf until 1994 Fish Farms 4

5 Faviafavus: Fish cages experiment, 19 m. depth, June 2002 Pollution Toxic metals Source: industry Bioaccumulate Organic pollutants Herbicides affect primary producers Pesticides bioaccumulate Antifouling paints Bioaccumulation ain_reaction/index.cfm Oil Pollution Source: oil spills Floats limited impacts Reduces light for a short time Sinks anoxic underneath State of tide Chemical content of oil Clean-up often multiply harmful effects Results: higher mortality reduced reproductive potential reduced recruitment Fisheries Small in terms of biomass or value But important Source of protein to island states & developing countries History & tradition Jobs tourism & recreation Structural complexity no heavy fishing gear Types: Commercial Subsistence Recreational Live fish (for restaurants or aquaria) Aquaculture 20 5

6 Fishing Methods Fished Species Impacts of Fishing Damage to target species Remove big reproductive fish Depletion of carnivorous species Damage to non-target species Bycatch Interactions Ghost fishing Damage to habitat Dynamite Trawling Marine debris Damage to economy & traditions Overfishing & Indirect Interactions + Humans + Predatory fish Urchins Herbivorous fish Algae - Nutrients (N,P) + -Coral 6

7 Managing Fisheries Minimum and maximum size limits Individual transferable quotas Limiting effort Gear restrictions Marine Protected Areas (MPAs) Seasonal or rotational closures Community control BEGIN 3/8/2010 Disease Disease = any impairment of an organism s vital organ, system, and body functions Main pathogens Bacteria Slime-molds Trematodes MICROBES Ciliates Cyanobacteria Viruses Hard to identify pathogens because marine organisms have lots of microbes! Are diseases increasing in the ocean? In some groups (turtles, mammals, mollusks, urchins) But not in others (seagrasses, crustaceans, sharks, fishes) Why? Warming Toxic pollution Eutrophication Introduction of new pathogens Aquaculture Change in population size Ward & Lafferty 2004, Lafferty et al Coral Disease Coral Disease Found in all areas of coral reef Only massive loss in the Caribbean Significant loss in coral cover, biodiversity, and habitat ~30 diseases now described Symptoms: White skeleton Unusual calcification patterns (enlarged corallites, tumors) Reduced growth rates Loss of zooxanthellae 7

8 Corals: Black Band Disease First scleractinian coral disease reported (in 1970s) Throughout Caribbean, but also Indo-Pacific and Red Sea Primarily massive corals Most active in shallow water in warm months Pathogen still not identified Usually low infection rate Faviafavusin Gulf of Eilat Yossi Loya Coral: White Band Disease NOAA s Coral Health and Monitoring Program First major disease 1970s Dramatically reduced cover of acroporidcorals Pathogen remains unknown Throughout Caribbean Coral: White Pox Disease After 1996 NOAA s Coral Health and Monitoring Program Caused by coliform bacteria associated with animal sewage Serratia marcescens Keeps elkhorncoral at low levels in Caribbean Seagrasses: Slime Molds Often beds of one species or even one genet very susceptible to disease Massive die-offs of turtle grass (Thalassia testudinum) in Florida Bay Eelgrass wasting disease in 1930s Within two years, 90% of all eelgrass populations in the North Atlantic disappeared Pathogen unknown, but hypothesized to be Labyrinthula slime mold Collapse of scallop fisheries Dramatic reductions in waterfowl population Only known extinction of marine gastropod 8

9 Coralline Algae Diseases Coralline Lethal Orange Disease Coralline White Band Syndrome Caribbean Coralline Lethal Orange Disease in Samoa Caribbean Diadema antillarum Mass Mortality Pathogen not clear First observed on Caribbean coast of Panama in Jan Adult populations reduced by % Ballantine et al Coral Reefs Williams & Sindermann 1992 Fish Lots of microbial & animal parasites Disease rarely observed Cleaner fishes & shrimps Rapid predation Occasionally mass mortalities that have not been attributed to a particular pathogen Neurofibromas on a bicolor damselfish (Pomacentrus partitus) similar to a human cancer, probably caused by a virus /models.jsp Turtles: Fibropapilloma External or internal tumors May interfere with swimming, seeing, feeding, breathing Caused by herpes-like virus Turtles may recover from external tumors Mostly in green turtles in tropical areas urtles.org/ 9

10 L07 Drupella spp. Dense aggregations in Southern Japan & Philippines, Western Australia, Hong Kong Prefers acroporids& pocilloporids(like COTS) Remove up to 95% live corals in patchy areas of high density Unclear if new or caused by humans COTS: Outbreaks 1 st recorded from Japan (1957) & GBR (1962) Now throughout Indo-Pacific Feed on any type of coral and other marine invertebrates Devastate whole reefs Drupellacf. rugosasnails feeding on Platygyra cf. sinensisat Sharp Island, Hong Kong 9/29-invert-coral.htm 37 COTS: Outbreaks 1 st recorded from Japan (1957) & GBR (1962) Now throughout Indo-Pacific Feed on any type of coral and other marine invertebrates Devastate whole reefs Appear & disappear suddenly Recovery Some in years Some in several decades May have different coral community COTS: Biology Normally found in low densities on reefs Why so destructive? High fecundity Rapid growth Rapid population growth Large size Multi-armed morphology can handle larger food Covered in poisonous spines few predators coralnotesfromthefield.blogspot.com 10

11 3/7/2010 Feeding COTS: 4 Cryptic Sibling Species How? Everts digestive system onto coral Excretes enzymes that consume the living tissue Geographical distribution of four COTS species based on mitochondrial cytochrome oxidase subunit I gene. Pie charts indicate relative frequency of each species per sampling location. Vogler et al. (2008) Preferentially predates on fast-growing corals Ex: Acropora, Pocillopora, Montipora Slow-growing corals (e.g., Porites) can survive & grow Change community composition COTS: Life History Long-lived pelagic larvae Very high fecundity Very few predators on adults Low egg & larval survival COTS: Predators Eggs & Larvae Any filter feeder Cryptic juveniles feed on coralline algae Predation on juveniles 11

12 COTS: Predators Juveniles & small adults Annelid worm Small crabs & shrimp Gastropods COTS: Predators Triton s trumpet Charonia tritonis Heavily collected for the ornamental shell trade Eat up to 3/month Fish COTS: Predators Triggerfish Pufferfish Maori wrasse Snappers, emperors, eat juveniles Cheilinusundulatus Hypothesized Causes of Outbreaks Natural phenomenon: Huge fecundity Very low larval survival Fluctuations in Temperature Salinity Food Caused by humans: Nutrient runoff more planktonic food for larvae Overfishing of predators of juveniles and/or adults 12

13 COTS: Control How? Manual removal Inject poison BUT Very costly Can only protect small areas Palau om/conservation.html Mainly at tourist sites Restoration Very high cost Uncertain success Much better to protect original habitat! How? Specify goals Involve local community Use knowledge of biology of species Remove stress Determine if natural recovery Choose suitable site carefully Plant large individuals of several species Protect against disturbance Monitor & assess success Coral Reef Restoration Mostly focused on repairing physical damage caused by man Design Elevate substrate above sand 3-D structure with refuges for organisms Correct spacing for organisms moving & recruiting between structures Coral Restoration Methods: Reef Balls 8 years after deployment of 3,000 reef balls in Indonesia 13

14 Coral Restoration Methods: Electric Reefs or Biorock Ecological Goods & Services of Coral Reefs Goods Services "Barnacle Reef" Ihuru in the Maldives Before: April 1997 After: November Ecological Goods & Services of Coral Reefs Moberg & Folke 1999 Ecological Economics Table 2: Goods and ecological services of coral reef ecosystems Reading Required: Sheppard p Crown-of-thorns starfish. Sheppard Chapter 8: Coral Reefs in the Modern World. Recommended: Sheppard Chapter 9: Consequences to Reefs of Changing Environmental Stress CRC Reef Research Centre, Australia. Crown-of-thorns starfish. Loya2004. Coral reefs of Eilat. Chapter 1 in Coral Health & Disease. ments/107_eilat-reef-background.pdf 14