Introduction: Several studies have found high mercury levels in wild dolphins, though it is uncertain at what dose health is negatively impacted. Mercury levels in other dolphin populations have been found to vary based on sex, diet, length, and age, with the most determinant factor being age (Pompe-Gotal et al, 2009). Mercury enters the ocean primarily from atmospheric deposition and runoff. In the ocean, it is methylated, and readily enters the food chain, accumulating in the tissues of marine predators (Selin 2009). Methods : Tissues were subsampled from 76 bottlenose dolphins which had stranded between June 2009 and October 2014 and were collected by the Virginia Aquarium Stranding Response Program. Fifty-eight of these were part of an Unusual Mortality Event, stranding between July 2013 and October The tissue types sampled were liver, kidney, cerebrum, cerebellum, muscle and skin. The samples were freeze dried and then analyzed for total mercury (Cristol et al. 2011). Mercury concentration data was log transformed prior to linear regression analysis. References Cristol, D., Smith, F., Varian-Ramos, C., Watts, B., Mercury levels of Nelson’s and saltmarsh sparrows at wintering grounds in Virginia, USA. Ecotoxicology 20, Durden, W., Stolen, M., Douglas, A., Stolen, E Mercury and selenium concentrations in stranded bottlenose dolphins from the Indian River Lagoon System, Florida. Bulletin of Marine Science 81(1) Holsbeek, L., Siebert, U., Joiris, C Heavy metals in dolphins stranded on the French Atlantic coast. The Science of the Total Environment Pompe-Gotal, J., Srebocan, E., Gomercic, H., Prevendar Crnic, A Mercury concentration in the tissues of bottlenose dolphins (Tursiops truncatus) and striped dolphins (Stenella coeruloalba) stranded on the Croatian Adriatic coast. Veterinarni Medicina Rawson, A., Patton. G., Hofmann, S., Pietra, G., Johns, L Liver abnormalities associated with chronic mercury accumulation in stranded Atlantic bottlenose dolphins. Ecotoxicology and Environmental Safety =47. Roditi-Elasar, M., Kerem, D., Hornung, H., Kress, N., Shoham-Frider, E., Goffmna, O., Spanier, E Heavy metal levels in bottlenose and striped dolphins off the Mediterranean coast of Israel. Marine Pollution Bulletin Selin, N Global Biogeochemical Cycling of Mercury: A Review. Annual Review of Environment and Resources Acknowledgments Kristen Phillips, Margaret Lynott, Mark Swingle, Maury Howard, Margaret Reese, Dan Cristol, John Swaddle. VWC Undergraduate Research Fund, Virginia Aquarium Stranding Response Program, National Fish and Wildlife Service. "This presentation was developed under GRO Fellowship Assistance Agreement no. MA awarded by the U.S. Environmental Protection Agency (EPA). It has not been formally reviewed by EPA. The views expressed in this presentation are solely those of Erin Michelle Smith, and EPA does not endorse any products or commercial services mentioned in this presentation.” Conclusions:  Mercury concentrations in tissues of Bottlenose dolphins showed a large variation, and were correlated to length  Mercury concentrations were highest in the liver tissues  Approximately 20% of mercury liver concentrations were above the observed effect level for which liver damage has been seen in a previous study  Observed concentration distributions are similar to that from previous studies of bottlenose dolphins from the Atlantic coasts of Florida, the Mediterranean coast of Israel, and the French Atlantic Coast Abstract: Mercury is a highly toxic metal that enters the ocean through runoff and atmospheric deposition. In water and sediments, it can be converted by bacteria to methylmercury, which may then bioaccumulate through aquatic food webs. In an original study designed to assess mercury levels in dolphins stranded in Virginia, tissues were obtained from 76 dolphins (Tursiops truncatus) that had been recovered and necropsied by the Virginia Aquarium Stranding Response Program from Preliminary results indicate that tissue of longer length dolphins had higher mercury levels. There were no notable concentration differences between male and female dolphins of similar length. Thirteen individuals had liver concentrations greater than the observed effect level for liver abnormalities seen by Rawson et al. (1993), which suggests that mercury may have impacted liver function in these animals. Mercury levels in this population are similar to levels published for bottlenose dolphins from Florida, Israel and France. Results & Discussion: Mercury concentrations were the highest in liver tissues, followed by kidney tissues. Brain, skin and muscle exhibited lower concentrations of mercury, a trend which agrees with previous studies (Roditi-Elasar et al., 2003). A correlation was seen between liver and kidney tissues(r 2 =0.87, p=1E-12, n=25, Fig 3). Mercury concentration was correlated to dolphin length for both the liver and kidney (liver: r 2 =0.86, kidney r 2 =0.87). This is likely due to the correlation between age and length, though age data was not available for these dolphins. The thirteen highest liver concentrations were above above the observed effect level of 61  g/g for liver abnormalities seen by Rawson et al. (1993). This suggests that mercury may have impacted liver function in as many as 20% of the animals studied. Rawson’s observed effect level however is based on a small sample size (n=18) and should be confirmed by future studies. The distribution of mercury concentrations versus dolphin length for this study was similar to that found for bottlenose dolphins from the Atlantic coast of Florida (Durden et al., 2007), the Mediterranean coast of Israel (Roditi-Elasar et al., 2003) and the French Atlantic coast (Holsbeek et al., 1998) suggesting similar exposure levels (Fig 4). Some individual dolphins from Israel and Florida had higher mercury relative to length. One explanation could be higher levels of mercury in the prey of the these dolphins, but with such a small sample size it is difficult to draw any conclusions. Mercury in Bottlenose Dolphins (Tursiops truncatus) from the Coast of Virginia Hannah Rice 1, Matt Cooke 1, Erin M. Smith 1, Sherie Coleman 1,3, Elizabeth G. Malcolm 1, Rachel M. Ellick 2 1 Virginia Wesleyan College, 2 College of William and Mary, 3 Virginia Aquarium Figure 2. Stranded dolphin before necropsy and muscle tissue before subsampling. Figure 1. Mercury exposure in marine food webs. Figure 3. Mercury concentration in liver versus kidney. Concentrations are dry weight and log- transformed. Figure 4. Mercury in A) liver and B) kidney versus dolphin length for this study and three others. General increase in concentration with length is evident, with variation in individual dolphins possibly resulting from difference in exposure levels due to differences in prey and habitat. Concentrations are on a wet weight basis.