Area 1. Biological and geochemical transformations of chemicals in aquatic ecosystems.

Nutrients, allelopathic or toxic chemicals, and metabolic by-products can affect organisms in a variety of ways, from inhibiting or stimulating growth (Targett & Arnold 2001), to inducing aggregations or mediating habitat choice (McClintock & Baker 2001). The production and fate of these chemicals is often influenced by geochemical and biological processes in water columns, in sediments or in the guts of animals. Many of these transformations are mediated by microbes. This area includes determining the mechanisms, rates, and impacts of these processes, as well as developing methods to study these transformations (e.g., in situ analysis of microbial populations, analytical chemical methods, metagenomic analyses, etc). Prior student projects include:

  1. Light intensity affects the timing and magnitude of N2 fixation by Trichodesmium (cyanobacteria)
  2. 18S rRNA-based methods for detection of dechlorinating bacteria in environmental samples and community analysis of dechlorinating consortia
  3. Amino acid profiling in biological mixtures by reactive desorption electrospray ionization tandem mass spectrometry
  4. Biodegradation of the allelopathic compound m-tyrosine and the pollutant 4-nitroaniline
  5. Effects of low concentrations of arsenic on nitrate reduction by Shewanella putrefaciens
  6. Metal reduction as a mechanism for ammonium oxidation in marine sediments

Area 2. Sensory biology and ecology of aquatic chemical communication.

Chemical signals are used by animals to find prey, escape predators, locate/choose mates, and determine suitable habitats (Hay 2009). The ability of animals to successfully use chemical signals determines their fate and the rates of critical ecological interactions. This area includes determining how chemical cues are transmitted in aquatic habitats and analyzing behavioral and sensory mechanisms by which animals detect and respond to these signals. This area also includes examining the role and identity of defensive compounds and signal molecules in population regulation and community structure. Prior student projects include:

  1. Sexual dimorphism and egg-carrying vulnerability in Eurytemora herdmani and Temora longicornis (copepods)
  2. Behavior responses of crab larvae in the presence of well-controlled upwelling and downwelling flow mimics
  3. Identifying the mating pheromone of the copepod Temora longicornis through a metabolomic approach
  4. Chemical signals as non-consumptive effects: the influence of blue crab (Callinectes sapidus) urine on mud crabs (Panopeus herbstii)
  5. Behavioral response of whale sharks to odor plumes: implications for foraging ecology

Area 3. Ecological roles and consequences of chemicals in aquatic environments.

Chemical cues influence the behavior of individuals and their ecological interactions with predators, prey, competitors, hosts, and mates. Thus, chemical cues have significant impacts on population and community structure when their effects are extrapolated over a large number of individual interactions (Hay & Kubanek 2002). This area includes the direct and cascading effects of chemical cues on competitive, predatory, and other interactions (e.g. chemically-mediated allelopathic interactions, trophic cascades). Example student projects include:

  1. Inducing hormesis in Brachionus manjavacas using hypoxia
  2. Induction of chemical defenses in the freshwater macrophytes, Cabomba caroliniana and Egeria densa
  3. Identification of freshwater fungi that inhibit growth of competing microorganisms
  4. The effects of species richness and assembly history on community invisibility
  5. Microbial warfare on chitin surfaces: The Type VI secretion system of Vibrio cholerae

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