Coral and Coral Reefs, 1996).Four coral conditions have been identified as diseases: white band disease (WBD), and black band disease (BBD), bacterial infection and shut down reaction (Richmond, 1993). They are also susceptible to tumors and parasitic worms. These maladies are all stress related, and anthropogenic stresses can increase a corals susceptibility to these diseases.Diseases such as BBD and WBD actually kill coral tissue while advancing in a band around the coral and leaving the white coral skeleton behind. Edmonds (1991) stated that BBD, caused by cyanophyte, may have a role in maintaining coral diversity because it is most prevalent in coral species that form large colonies and provide a structural framework for the reef. When BBD kills part of these colonies, the skeleton is available to be colonized by other coral species recruits (Edmonds, 1991). James W. Hyde BIOL 1040WBD, which is believed to be caused by a bacteria pathogen yet unknown, has much of the same effect on corals, leaving behind a white, lifeless coral skeleton. Gladfelter (1982) does not see WBD as being beneficial to reefs. He feels that WBD destroys the reef structure because the dead coral skeleton brought about by the algae is colonized by algae, invertebrates, gastropods, and boring clionid sponges that work to weaken the coral skeletons making them more susceptible to breakage during storms.The exact method by which the diseases are transmitted are unknown. Even though healthy corals may get BBD through contact with an infected coral, diseased corals are aggregated naturally on the reef or can be separated by great distances (Edmonds, 1991).Human CausesThe use of cyanide to harvest live coral reef fishes is a se...
