Effects of St. Lucie Estuarine Discharge Water and Thermal Stress on the Coral Montastraea cavernosa

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.