Montastraea cavernosa is an important scleractinian reef-building coral, found throughout South Florida and the Caribbean. Ultrastructural examination of numerous field-collected and experimental specimens with transmission electron microscopy (TEM) revealed the presence of coccoid bacteria in the epidermis of this species. Documentation of the presence of bacteria in coral tissue has been a topic of interest in our laboratory. In addition, we have found viruses in several ultrastructural studies of larval and adult coral. The degree to which viruses and bacteria may be associated with disease or reflect compromised immunity in corals is a topic of current interest. In our studies of bacteria in M. cavernosa, bacterial DNA was isolated from coenchyme tissue, and 16S rRNA sequence analysis identified the predominant bacteria as members of the Lactobacillus/Lactococcus bacterial groups, commonly associated with sewage. An objective of the proposed study is to identify and localize these bacteria using TEM, fluorescence in-situ hybridization (FISH) and molecular genetic analysis. We hypothesize that the incidence of these bacteria (and other enteric species) may be a function of distance from pollution sites (e.g Hollywood outfalls). In addition TEM documentation and identification of viruses present in the tissue will be examined so as to elucidate the degree to which viruses may play a role in reduced coral viability and disease. Two NSU Oceanographic Center graduate students will participate at the author level in all aspects of this study. Developing their skills in the complex methods utilized in these analyses is a goal of this proposal. This study examines potential causal relationships in coral pathology and advances the ultimate goal of effective protection of living coral reefs. The use of ultrastructural and biochemical interdisciplinary approaches in identification of potential sources of coral pathology facilitates establishment of a critical link between organismal, population, and community health.