A SURVEY OF THE NORMAL AND PATHOLOGICAL HISTOLOGY OF SCLERACTINIAN CORALS WITH EMPHASIS ON THE EFFECTS OF SEDIMENTATION STRESS (ASTRANGIA DANAE, CARIBBEAN, HISTOPATHOLOGY)

The normal histological structure and composition of twenty-five species of Atlantic scleractinian corals revealed differences in cell types, cell distributions, and reproductive cycles between and within genera. These variations were consistent with known ecological requirements, modes of nutrition, and the ability of the species to remove sediment. The effects of increased sedimentation on tissue health and the incidence of disease were examined in the corals using histopathological techniques at the light microscope level. Pathological changes in the mucous secretory epidermis and accumulations of mucoid material in the calicoblast layers were found in colonies of Astrangia danae exposed to increasing applications of clean fine sand over a three-month period. Tissue damage correlated with reduced growth rates and was more evident in starved sediment-exposed symbiotic colonies than in similarly treated asymbiotic colonies. However, changes in metabolism due to the increased energy expenditures of sand removal were not reflected in measurements of photosynthesis and respiration, possibly because of large inter- and intra-colony variability in these parameters. Epidermal mucous secretory cells of several species of corals collected from a chronically sediment-stressed reef off Guayanilla Bay, Puerto Rico, exhibited increased or decreased activity compared to corals from more pristine reefs off Puerto Rico and St. Croix. Percent living coral cover and number of species were lowest at this site, compared to the latter sites. However, histopathological examination of corals from these other sites revealed a variety of lesions, Gram-negative colonial bacteria, and other microparasites, which were not always associated with signs of white band disease , black line disease or sediment-algal accumulations