Wednesday, November 28, 2007

Recent thoughts & new research ideas

Research questions and ideas are always evolving. Here are some of my latest new project ideas:

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 Texas coast, monitor mangrove growth and mortality dynamics, monitor changes in adjacent salt marsh communities, and determine herbivore and disturbance impacts on mangrove expansion.

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.

Wednesday, October 10, 2007

Graduate Student Position Available: Nutrient Impacts on Seagrass Communities

UPDATE 01.23.08: Position is no longer available!

My colleague, Dr. Jim Fourqurean, and I are seeking an M.S. or Ph.D. applicant through Florida International University Department of Biological Sciences and Southeast Environmental Research Center beginning in the summer of fall of 2008. The graduate student will be involved in a long-term project that explores the relationships between increased freshwater and nutrient supply and seagrass community composition in Florida Bay. The project will also include short-term in situ experiments to evaluate the mechanisms driving nutrient-induced shifts in seagrass epifaunal abundance (e.g., changes in food resources or seagrass refuge value). This is a two-year National Park Service-funded collaborative effort between researchers at Florida International University (Dr. Jim Fourqurean) and Texas A&M University at Galveston (Dr. Anna Armitage).

Applicants should be self-motivated, have completed undergraduate coursework in ecology or marine science, be comfortable with the principles of marine chemistry, and be willing to learn analytical techniques. Preferred qualifications include previous fieldwork experience and scuba diving and small-boating certifications.

Interested individuals should send a brief cover letter describing your background, research interests and career goals, a CV, unofficial transcripts, and if available, GRE scores to Dr. Jim Fourqurean ( Review of applications will begin on November 15, 2007, and will continue until the position is filled. Upon reviewing the applicant pool, we will ask select applicant(s) to apply to the graduate program to be considered for admission.

Graduate Student Position Available: Ecological and Economic Values of Tidal Freshwater Marshes as Treatment Wetlands

UPDATE 4.16.08: Allison Parnell will work on this project for her thesis.

My colleague, Dr. Jae-Young Ko, and I were recently awarded a Texas Sea Grant to evaluate the ecological and economic values of tidal brackish and freshwater marshes as wastewater treatment wetlands.
Beginning in spring 2008, we will conduct a field survey that investigates the role of vegetation in taking up nutrients from two point sources of anthropogenic nutrients into Armand Bayou: a sewage treatment facility and a retention basin that filters drainage from a housing subdivision.

We are looking for a graduate student (M.S.) or part-time technician to assist with a
field survey to measure percent vegetation cover, species composition and diversity, gross morphometric characteristics, and biomass of the dominant plant species. The student/technician will also measure carbon, nitrogen, and phosphorus content and stable isotopic values of plant tissue, sediments, and water samples. These data will be used to create an ecological nutrient budget in each study area and estimate nutrient removal rates by marsh vegetation within Armand Bayou.

Preferred qualifications include: B.S. or senior status in a biology-related field, experience with biological field work, a positive attitude, and a willingness to get wet and dirty. Project dates are from March 2008-February 2010. Interested parties should send a letter of interest, CV, unofficial transcripts and GRE scores, and the names and contact information for two references to Dr. Anna Armitage.

UPDATE: Additional funding for this project has been supplied by the Environmental Institute of Houston in collaboration with Dr. Steven Pennings at the University of Houston. We plan to begin field work in March 2008.