Starfish Predator: The Crown Of Thorns

Starfish Predator: The Crown of Thorns

Corals     



Under the Phylum Coelentarata May consist of a single polyp or a colony Resemble sea anemones Colors due to algae living on them Most abundant in the tropics where there are high water temperatures Feed on planktons by night

Coral reefs 

Made up of coral skeleton and cementing coralline (encrusting) algae  Hard limestone structure



Importance:  Provide shelter to

fingerlings  Control sea water carbon dioxide  Protect shores from strong sea currents

Isn’t it beautiful?

Philippine Reef

Damaged Coral Reef

The Enemy: The Crown of Thorns  Species name: Acanthaster planci  Feeds on corals (mostly Acropora)  Commonly found in the Pacific and Indian oceans  Has long sharp venomous spines, 7-23 arms  Resilient against its predators (major: humphead wrasse and giant triton)  Vulnerable ventral/oral side

The Crown of Thorns

Biological Controls 

Planktonic phase – prey of filter feeding organism  Benthic form – prey of worms, crustaceans, gastropods, etc.  Adult – Triton shell and carnivorous fish

The Extent of their Damage 

Releases enzymes that digest the coral tissue and absorbs the released energy reserves  Individually can wipe out 5-6 sq. m. Of corals per year  In large numbers, can kill 90% of living corals

Impact 

Reduces abundance and surface cover of corals, species compositions, diversity, colony size distribution  Increase in algae and soft corals  decrease in topography complexity  Increased carrying capacity of herbivorous fish, decrease in other corallivore species

84% porotid coral

COT in dead coral

The Cause of Outbreaks (human) 

Increased nutrition in the sea Agricultural runoff and sewage

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Decrease in COT predators Major predators i.e. the humphead wrasse and the giant triton are overfished

The Giant Triton Snail feeding on a COT starfish

During an Outbreak

Densely piled on top of the corals

During an Outbreak

Solutions (Human Intervention)  Injecting

COT with poison

Copper sulfate Formaldehyde Sodium hypochlorite Ammonia Ammonium hydroxide Compressed air Acetic acid Diluted sodium bisulate

Solutions (Human Intervention)  Cutting

up the starfish  Harvesting the starfish

Philippine Setting “We are experiencing a return of the starfish in greater numbers,” said WWF-Philippines CEO Lory Tan. “The situation facing our reefs is far from normal.”(2007)

 From

25 000 sq. km  1% pristine, 50% unhealthy  COT outbreaks in: Apo Reef and Puerto Galera in Mindoro Mabini in Batangas Roxas in Palawan Bolinao in Lingayen Gulf Kiamba and Glan in Sarangani Bay

Philippine Setting 

Solutions: Harvesting the COTs/

Clean-up dives Fishing Ban ○ Working towards sustainable

coastal practices ○ Alternative livelihood for fishermen in the area Better sewage management Preventing agricultural runoff

Damaged Reef

This is how we want our reefs...