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Our studies seek to determine whether frogs can be used as bioindicators of environmental health in contaminated habitats. The Western Lake Pontchartrain Basin ecosystem has been influenced by a variety of stressors including logging, increased salinity and flooding from coastal erosion, human encroachment, and industrial contaminants. These studies seek to develop methods to identify immune system stressors that can help assess environmental health in contaminated areas and assist those carrying out cleanup, conservation and restoration efforts. 

Specifically, we are concerned with polycyclic aromatic hydrocarbon (PAH) exposure in bullfrogs. PAHs are one of the more widespread organic pollutants and can be point-source (i.e. oil spills) or non-point source (i.e. atmospheric deposition). Some are known or suspected carcinogens, and have been implicated in other health problems. We have developed methods for measuring lymphoid-specific mRNA levels in response to PAH exposure in bullfrog. Because development of the frog immune system is precisely controlled, the immunotoxic effects of xenobiotics such as PAHs are believed to be a possible factor in global amphibian population declines, and mass mortalities in frogs have been associated with fungal, bacterial, and viral infections.

Our studies, thus far, support the hypothesis that PAH, known to be present in sediments from Bayou Trepagnier, may negatively impact lymphocyte development in frog larvae.  Our hope is to extend our experiments to look at additional genes involved in lymphocyte development and activation.  These methods may then be applied not only to indicate environmental health in the region dictated by the presence of PAH, but also that dictated by other chemicals, such as pesticides and herbicides and their mixtures. Additionally, these methods may be used to look at environmental health in areas where environmental contamination is expected but uncharacterized.