Sedimentation

Removal of natural buffers between land and sea, such as mangroves, allows the products of terrestrial erosion to wash straight into marine habitats. The coral animal is able to tolerate acute episodes of sedimentation by secreting mucus as a defense mechanism, helping to keep their surfaces clean. Nonetheless, destructive activity on land allows the continual input of sedimentation. This form of pollution, in particular the fine silt fraction of the sediment, directly smothers coral reefs blocking out the sunlight required for photosynthesis (Loya 1976). The short-term effect can interfere with corals by lowering growth rates, metabolism and fecundity (Rogers 1990). Prolonged smothering and burial eventually causes the coral to die. In addition, the silt covers the hard substrate that was available for settlement of juvenile corals making recruitment of the propagules impossible and reducing their reproductive success (Gilmour 1999).

Credits
Cinematography: Dr. Forest Rohwer
Edited by: Neilan Kuntz
Written by: Dr. Olga Pantos
Location: Palmyra Island, Line Islands, Central Pacific (2005)

Gilmour J (1999) Experimental investigation into the effects of suspended sediment on fertilization, larval survival and settlement in a scleractinian coral. Marine Biology 135: 451-462.

Loya Y (1976) Effects of water turbidity and sedmentation on the community structure of Puerto Rican corals. Bulletin Marine Science 26: 450-466.

Rogers CS (1990) Responses to coral reefs and reef organisms to sedimentation. Marine Ecological Progress Series 62: 185-202.

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Science & Technology

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