Our current research evaluates the influence of habitat restoration, nutrient enrichment, and other anthropogenic disturbances on trophic interactions in coastal wetlands and subtidal seagrass beds. Current and planned projects include:

Current:

Nutrient enrichment alters seagrass and macroalgal composition, which may alter food quality or composition as well as increase the structural complexity of the plant canopy. Pilot studies indicate that nutrient enrichment in seagrass beds in Florida Bay is associated with increased epifaunal abundance and biomass and shifts in species composition. In collaboration with Dr. Jim Fourqurean at Florida International University, we are continuing studies of the spatial scale of faunal responses and the mechanisms driving shifts in faunal abundance, including changes in food resources (epiphyte and seagrass composition) or structural features (complexity of the seagrass-macroalgal infrastructure and its function as a refuge). Future plans include expansion of this project into Galveston Bay.

A recent Texas Sea Grant award will fund a new project to evaluate the ecological and economic values of tidal brackish and freshwater marshes as wastewater treatment wetlands. In collaboration with Dr. Jae-Young Ko (TAMUG) and Dr. Steven Pennings (University of Houston), we will conduct a field survey (beginning spring 2008) that investigates the role of vegetation in taking up nutrients from two point sources of anthropogenic nutrients into Armand Bayou (Houston, TX): a sewage treatment facility and a retention basin that filters drainage from a housing subdivision.

Pending:

The northern distribution limit of native red (Rhizophora mangle) and black (Avicennia germinans) mangroves in the Gulf of Mexico is determined by winter temperatures. Mild winters over the last 18 years have caused the expansion of both mangrove species northward along the Texas coast. As global warming brings milder winters, these mangrove populations are likely to continue to expand, replacing salt marshes and modifying coastal ecosystem processes. In particular, the conversion of marsh to mangrove habitat may alter food web interactions and decrease fishery values. Management of coastal wetlands in the context of climate change must consider potential competitive interactions with native mangroves that are invading marshes as freeze events become rarer.

Estimated sea level rise following near-term climate change (~18-50 cm within 100 years) threatens low-lying coastal wetlands with increased inundation and salinization. Upcoming studies will investigate the ecological and physiological responses of coastal marsh communities to simulated increases in flooding and salinity.

Many organisms modify their behaviors in the presence of a predator due to the threat of predation. For example, the presence of a predatory grouper on a coral patch reef can reduce the distance that herbivorous fish will forage off the reef into the surrounding seagrass beds. However, grouper populations in the Florida Keys are largely limited to no-take reserves, suggesting that their top-down impacts on reef and seagrass communities will be strongest inside the reserves. In collaboration with Dr. Mike Heithaus and Dr. Jim Fourqurean at Florida International University, we plan to explore the direct and indirect effects of top predators like grouper on herbivory patterns in seagrass beds around reefs. Maintaining healthy populations of both grouper and seagrass is a goal of many Marine Protected Areas in the Florida Keys, and defining links between top predators and primary producers will influence management policies in this area.