| TROPICAL SHALLOW-WATER CORALS |
I.  Coral bleaching has become a major problem for coral reefs on a global basis. Coral bleaching is the process by which the endosymbiotic dinoflagellate alga called Symbiodinium (a zooxanthella) and/or photosynthetic pigments residing within the host and/or symbiont are reduced within the coral tissue, exposing the white skeleton beneath. The symptoms of bleaching (turning pale white in coloration), however, is not confined to corals and has been observed in many other benthic invertebrates including sea anemones, zoanthids, tridacnid (giant) clams, sponges, and foraminifera. It is a sign of stress, and, if severe, can result in death, sometimes on a massive scale. Studies indicate numerous causes of bleaching are involved including disease, elevated oxygen, increased and decreased salinity, and elevated temperature. Historically, elevated temperature appears to be the only factor that can be correlated with global bleaching of corals.
Current student projects include: (1) examining disease mechanisms that may induce bleaching in corals; (2) describing patterns of scleractinian, alcyonacean, and gorgonian corals bleaching in the Gulf of Mexico ; (3) characterizing near-shore coral patches as fishery habitat; and (4) assessing microbial assemblages commonly associated with shallow-water corals.
II. The health of coral reefs has been seriously declining since the 1970's. A decrease in coral abundance, by as much as 95% in some areas, has been associated with coral disease. One of the first diseases with a confirmed pathogen, white pox disease (WPD), was reported to affect corals off Key West , Florida , and is now considered a common threat to Caribbean corals, particularly the elkhorn coral, Acropora palmata. As many as 54 pathogens have been reported as 'agents' in the coral marine environments, with yellow band (YB) disease affecting the coral Montastrea annularis , dark spot syndrome (DSS) affecting Siderastrea siderea and Stephanocoenia michelinii , and white-band disease (WBD) causing Acropora mortality in Florida, the Bahamas, and the Caribbean, and their incidence appears to be increasing. It is believed that many benthic invertebrates respond to stress utilizing phagocytic-like cells called amoebocytes. In order to characterize how recognition occurs, it is necessary to describe the mechanisms of positively identifying "self" vs. "other" within corals.
Current projects are examining how coral cells identify and characterize normal vs. injured cells in scleractinian and gorgonian corals.
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