Maternal Offloading and Tissue Distribution of Organochlorines in Three Species of Coastal Sharks: Physiological and Ecological Implications

Legacy organochlorine contaminants continue to persist in the environment and accumulate in animals long after use and production has ceased.  Since these contaminants also biomagnify with trophic level they can be used as a tool for examining ecological relationships within and among related species. Organochlorine contaminants were measured in different tissue types of three coastal shark species from the southeastern U.S. to determine physiological and ecological linkages to patterns of accumulation as well as maternal offloading.  Our results demonstrate differences in hepatic contaminant accumulation among gravid females sampled for this study with Blacknose Shark (Carcharhinus acronotus) females having the highest mean concentrations, followed by Atlantic Sharpnose Sharks (Rhizoprionodon terraenovae) and Bonnetheads (Sphyrna tiburo).  All species were found to transfer significant contaminant loads to their offspring; however, we did find discrepancies in distribution among tissue types.  For embryos of all species, we found the highest concentrations in liver, followed by brain and muscle.  Our preliminary results indicate that these species may not be as similar in their ecological roles as presumed by their previous management plans.  In addition, the accumulation of organochlorine contaminants in offspring throughout embryonic development warrants further investigation into the potential health impacts of this early-stage exposure.