Emerging Contaminants in Bottlenose Dolphins from Sarasota Bay
By Magali Houde, PhD student, University of Guelph

Thousands of anthropogenic (man-made) chemicals have been detected in air, soil and water worldwide. Emerging compounds, such as perfluorinated chemicals, which are used in paints, adhesives, polishes, and fire-fighting foams as well as stain repellent for clothes, furnitures and carpets have recently been detected in human blood and wildlife. Perfluorinated compounds are known to be toxic in laboratory mammals but their effects on marine mammals are still unknown.  The objectives of this project were to assess the concentrations of emerging contaminants in biological samples of dolphins. Capture, sampling and release of dolphins in the Sarasota Bay provides a unique opportunity for scientists to understand the distribution of these pollutants in the marine ecosystem. Since November 2002, blood samples from 50 dolphins have been collected for analysis of fluorinated compounds. Analysis of samples showed that high concentrations of ten perfluorinated compounds are detected in plasma of dolphins. Perfluorooctane sulfonate (PFOS) was the dominant compound in all animals with concentrations ranging from 0.2 to 1.8 ppm in plasma. Water, sediment, and fish have been collected during the past year in order to understand the possible entry of these contaminants into dolphins. In addition, parallel analyses of immune function parameters may help us understand if these contaminants adversely affect the health of these cetaceans.

Another group of contaminants of interest are hydroxylated polychlorinated biphenyls which are degradation products of PCBs. PCBs have been used extensively before being banned in the 1970s. Today, their concentrations in the environment are still high and were detected in elevated concentrations in blubber of Sarasota dolphins. It is believed that mammals have the capacity to biotransform PCBs into toxic by-products such as hydroxylated PCBs which are known to affect the endocrine system. Blood samples from dolphins were analyzed for these pollutants which were detected in all animals.

Age, gender and reproductive history data gathered during the long-term monitoring of this population will help us determine trends and patterns of accumulation of these pollutants in small marine mammals. The collection of samples over different seasons could enable the determination of temporal trends, increasing our knowledge on exposure and metabolism in free-ranging dolphins. In addition, analyses of stranded dolphin carcasses will enable the study of the body distribution of perfluorinated compounds which have already been detected in liver and kidney of Sarasota Bay dolphins. The monitoring of wild populations and their environment is essential in order to protect an ecosystem that has been, and still is, greatly disturbed by human activities.