Coral reef declines, particularly in coastal zones, have been linked to thermal stress and anthropogenic impacts on water quality. St. Lucie Reef near Stuart, Florida receives increased estuarine efflux as a result of watershed changes and management policies that have substantially altered historic, natural flows. This research used ambient and elevated temperatures (25°C and 30°C, respectively), and offshore versus St. Lucie Estuarine discharge water to investigate the individual and interactive effects of thermal and water quality stress on Montastraea cavernosa, a dominant scleractinian coral species at St. Lucie Reef. These goals were accomplished using ex-situ, factorial, experimental design that was supplemented with existing in-situ monitoring on St. Lucie Reef. Zooxanthellae density and chlorophyll content were evaluated to determine effects on the corals and their symbionts. Zooxanthellae populations were significantly affected by thermal stress. Significant interactions between temperature and water treatment were observed, suggesting that the impacts of discharge water may be supplanted when corals are exposed to thermal stress. In a supplement to the experiment, M. cavernosa colonies transplanted from Palm Beach to St. Lucie Reef demonstrated resilience despite exposure to more variable environmental conditions. Collaborative partnerships with multiple state agencies and local government offices facilitated data sharing to inform decision making for South Florida’s resource management strategies. Creating effective resource management is crucial for the conservation of coastal ecosystems impacted by land-based sources of pollution both locally and globally. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Coral reefs are in global decline, with seaweeds increasing as corals decrease. Though seaweeds have been shown to inhibit coral growth, recruitment, and survivorship, the mechanism of these interactions is poorly known. Here we use field experiments to show that contact with four common seaweeds induces bleaching on natural colonies of Porites rus. Controls in contact with inert, plastic mimics of seaweeds did not bleach, suggesting treatment effects resulted from allelopathy rather than shading, abrasion, or physical contact. Bioassay-guided fractionation of the hydrophobic extract from the red alga Phacelocarpus neurymenioides revealed a previously characterized antibacterial metabolite, Neurymenolide A, as the main allelopathic agent. For allelopathy of lipid soluble metabolites to be effective, the metabolites would need to be deployed on algal surfaces where they could transfer to corals on contact. We used desorption electrospray ionization mass spectrometry (DESI-MS) to visualize and quantify Neurymenolide A on the surface of P. neurymenioides and found the metabolite on all surfaces analyzed. The highest concentrations of Neurymenolide A were on basal portions of blades where the plant is most likely to contact other benthic competitors.