Native mangrove invasion into northern Gulf of Mexico salt marshes: the influence of climate change
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. Upcoming studies will survey current mangrove distributions in estuaries on the
coast, monitor mangrove growth and mortality dynamics, monitor changes in adjacent salt marsh communities, and determine herbivore and disturbance impacts on mangrove expansion. Texas
Influences of sea level rise on the ecology and economics of coastal freshwater treatment wetlands
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.
Cascading impacts of large predators on reef-seagrass communities
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.