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Understanding coral disease dynamics within the heterogeneous populations in which they act is critical for predicting how the structure of reefs may change as a result of enzootic or epizootic levels of these important sources of mortality. This work focused on combining field studies and the development and testing of a spatially-explicit, individual-based epizootiological computer model with the aim of gaining a greater understanding of the dynamics and impact of white plague, a significant source of mortality on reef-building corals in the Caribbean region. Field studies focused on the incidence and distribution of all sources of coral mortality, including suspect white plague in situ, at two locations; the Florida Keys (United States of America) and Little Cayman Island (Cayman Islands, British West Indies). Results indicated that in both regions disease was the most significant source of mortality during the monitoring time periods, and that suspect white plague type II in Cayman is likely contributing to major structural changes. In Florida, observations made during a mass bleaching event indicated that a significant relationship exists between bleaching severity and disease incidence, and that mortality during the event was largely the result of disease and not bleaching. The simulation model was developed using a long-term data set from Little Cayman, and results of calibration indicated that suspect white plague type II on these reefs is transmissible between colonies within a limited field and require a yearly input from an outside source, and that host susceptibility to infection is low and likely not variable among species. Parameters describing the distribution and composition of the coral population were varied, and results indicated a significant effect of colony density, aggregation, and mean size on the impact of disease. Scenario testing of various disease management strategies indicated that should local prevention measures be developed in the future, it is they, and not treatment, that will likely be the most effective in limiting the impact of disease.

Patterns of settlement of larvae and population dynamics of juveniles are poorly known for coral reef fishes. During 1987 to 1989, I studied these phenomena in the domino damselfish (Dascyllus albisella), a species endemic to the Hawaiian Islands. Larvae settle onto branching coral heads as new recruits (10-15 mm in length), usually with conspecific groups, and remain on the coral heads through juvenile life until maturity (70 mm total length). By conducting experiments on natural patch reefs and on an artificially distributed grid of coral heads, I found that most larvae settle at night, and that they settle preferentially on corals supporting large conspecific groups compared to small groups or empty corals. Within a group, juveniles form a linear dominance hierarchy based on fish size; aggressive interactions are mainly directed by larger fish towards smaller fish. Tagging studies demonstrated that growth was retarded in larger groups and for fish of low social status, but that survival, especially of new recruits, was enhanced in larger groups. Therefore, I identified both a growth cost and a survival benefit to group living. I derived a measure of net benefit of group living by combining size-specific growth and survival data into an estimate of the probability of reaching mature size. This estimate increased with group size in 1988 but not in 1987. I developed a simulation model which used my field data on settlement rate, settlement preferences, and juvenile growth and survival to predict demography of juvenile groups. The model successfully predicted seasonal fluctuations in mean group size, and estimated the number of fish maturing in 1987 and 1988, as a function of settlement rate and preferences and of juvenile growth and survival. Numbers maturing were directly related to settlement rate in both years, except at high rates in 1987, suggesting that primary recruitment limitation of adult numbers could be occurring. Settlement preferences also influenced numbers maturing. At all settlement rates, numbers maturing differed between years, suggesting that secondary recruitment limitation of adult numbers may also occur. / Graduation date: 1991

Coral reefs are one of the world s most valuable ecosystems but are declining at an accelerating rate. Common stressors impacting coral health include elevated temperatures, changes in light intensity, sedimentation, and increased exposure to pollutants. Traditionally, physiological responses have been measured to assess coral health but usually do not identify the stressor or the underlying mechanisms causing a response. In addition, coral may be stressed beyond recovery by the time a physiological response is observed. Changes in gene expression are key elements of the stress response, usually occur before physiological damage is evident, and can be directly related to the causative agent of stress. My research focuses on detecting sublethal responses to stress in Scleractinian coral using genetic biomarkers and gene expression profiling. Through the application of molecular technology, I have developed a coral stress gene microarray to investigate the responses of coral to various stressors. Results from controlled laboratory exposures provide evidence for unique gene expression profiles associated with specific stressors. Results from field studies reveal the feasibility of using array technology to investigate changes in gene expression of natural coral populations across time and between sites. For example, the array has been used to detect stress in coral populations related to seasonal events, such as precipitation as well as point source stress, such as xenobiotics. The temporal and spatial regulation of specific genes within a genome determines the metabolic activity of an organism and can be used to identify changes in cellular responses to various stimuli. These cellular events precede population-level changes and could be useful biomarkers if linked to specific physiological or ecological events. This research is important because it identifies stress at a sub-lethal level and can aid resource managers in decision making by prioritizing the stressors impacting coral reefs.

In order to discover for bioactive compounds, we have studied the chemical constituents from the organic extracts of soft coral Klyxum molle. This study had led to the isolation of 16 eunicellin-type diterpenoids, including ten new compounds, klymollins A¡VJ (1¡V10), along with six know compounds 11¡V16. The structures of compounds 1¡V16 were established by spectroscopic methods and by comparison of the spectral data with those of the related known compounds. It is noteworthy to mention that compounds 1¡V10 represent the first example of eunicellins possessing a C-11/C-17 epoxide. The absolute configuration of 4 was determined using a modified Mosher¡¦s method. The cytotoxicity of compounds 1¡V8 and 11¡V16 against the A549 (human lung epithelial cells), HepG2 (human hepatocellular carcinoma), Hep3B (human hepatocellular carcinoma), MCF-7 (human breast adenocarcinoma)¡BMDA-MB231 (human breast adenocarcinoma) tumor cell lines were determined. Compound 11 showed cytotoxicity toward A549 tumor cells (IC50 value of 3.14 £gg/mL) and compounds 15 and 16 were found to exhibit cytotoxicity toward HepG2 tumor cell (IC50 values of 3.82 and 2.50 £gg/mL). Compounds 6 and 7 were found to show significant activity against the accumulation of the pro-inflammatory iNOS and COX-2 protein at 1 £gM.

Eighteen eunicellin-based diterpenoids were isolated from the organisms of the soft coral Cladiella krempfi. According to the results of 1D and 2D NMR spectroscopic experiments, the structures of these marine natural products were established. Among them, krempfielins A¡VJ (1¡V10) are new compounds, and sclerophytin B (11), sclerophytin F (12), litophynols A (13), (1R*, 2R*, 3R*, 6S*, 7S*, 9R*, 10R*, 14R*)-3-butanoyloxycladiell-11(17)-en-6,7-diol (14), litophynin I monoacetate (15), (1R*, 2R*, 3R*, 6S*, 9R*, 10R*, 14R*)-3- acetoxycladiell-7(16)-11(17)-dien-6-ol (16), 6-acetoxy litophynin E (17) and litophynin F (18) are the previously isolated compounds. The anti-inflammation activity of these compounds at 10 £gM was studied. The results showed that 9, 14 and 17 effectively inhibited more than 80% expression of iNOS protein in LPS stimulated RAW 264.7 macrophage cells, and 5, 6, 10, 13 and 18 inhibited more than 60% expression of iNOS protein. Also, 9, 12, 16 and 18 were found to inhibit the expression of COX-2 protein in LPS stimulated RAW 264.7 macrophage cells to 52.5, 79.2, 82.2 and 48.2%. Cytotoxicity of these compounds were tested by the MTT assay using five human cancer cell lines (A549, BT483, H1299, Hep3B and SAS) and one normal cell line, BEAS2B. Compounds 9, 10, 11, 14, 17 and 18 were shown to exhibit cytotoxic activity.

In order to discover bioactive secondary metabolites, we have studied the chemical constituents from the organic extracts of soft coral Sinularia flexibilis. This study had led to the isolation of eighteen natural compounds 1¡V18, including seven new cembrane-type diterpenoids, flexibilisolides C¡VG (1, 2, 3, 6, 7), flexiblilisin C (5), 11,12-secoflexibillin (4) along with eleven know compounds. The structure of compounds 1¡V18 were established by detailed spectral data analysis (IR, MS, 1D, 2D NMR) and by comparison of the spectral data with those of the related known compounds. The cytotoxicity of compounds 1¡V6, 8¡V14, 16¡V18 against the Hela (human cervical epitheloid carcinoma), SK-Hep1 (human liver carcinoma), and B16 (human melanin carcinoma) tumor cell lines were screened. Compounds 1, 9, 12, and 13 showed moderate activity toward the Hela and SK-Hep1 tumor cells. Compound 12 also showed moderate activity toward the B16 cells, and compound 14 showed activity toward the Hela cells. On the other hand, compounds 1, 9, 13, and 17 were found to show significant activity against the accumulation of the pro-inflammatory iNOS and COX-2 protein at 10 £gM. Compounds 2¡V4, 7, 8, 10, 14, 16 were found to show activity against the accumulation of the pro-inflammatory iNOS protein at 10 £gM.

In order to search for bioactive compounds, we have studied the chemical constituents from the organic extracts of soft coral Klyxum molle. In this study, fifteen eunicellin-type diterpenoids, including eleven new compounds, klymollins K¡VU (1¡V11), along with four known compounds 12¡V15 were isolated. Compounds 16 and 17 were prepared by chemical synthesis. The structures of all compounds were established by spectroscopic methods and comparing the spectral data with known compounds. Compound 5 represents the first eunicellin-type compound with phenylacetyl group. The cytotoxicity of compounds 1¡V17 against K562 (human erythro myeloblastoid leukemia), Molt-4 (human acute lymphoblastic leukemia), and T47D (human breast earcinoma) were determined. Compounds 1, 2, and 3 exhibited weak cytotoxicity against Molt-4 (with ED50 11.52 ¡Ó 2.75, 20.41 ¡Ó 2.92, and 13.11 ¡Ó 3.87 £gg/mL). Compound 5 was found to exhibt significant cytotoxicity toward K562, Molt-4, and T47D (with ED50 4.32 ¡Ó 1.38, 2.36 ¡Ó 0.34, and 4.65 ¡Ó 0.93 £gg/mL). Compound 5 also displayed significant inhibitory effects on superoxide anion generation and elastase release by human neutrophils at 10 £gg/mL (with Inh % 81.56 ¡Ó 3.23, and 89.16 ¡Ó 5.77).

Chromotographic separations of Formosan soft coral Sarcophyton crassocaule (GN-55) led to the isolations of four diterpenes, sarcophine (1), sarcophytoxide (2), (7R*, 8S*)-dihydroxysarcophytonin A (3), sarcophtonin A (4), one steroid, 17