As long-lived fish-eating predators at the top of the food chain, bottlenose dolphins experience biomagnification of contaminants (i.e., as prey organisms are consumed, pollutants can accumulate in the predator, increasing in concentration with each step up the food chain). These mammals live year-round in Charleston waters and can act as ideal sentinels, reflecting spatial and temporal trends in the health of the marine environment.
Studies conducted by Dr. Patricia Fair and colleagues have indicated that total PCB, DDT and PBDE blubber concentrations and blood PFC levels in Charleston dolphins are among the highest reported values that have been measured in marine mammals! A total of 88% of the dolphins sampled from Charleston Harbor and the rivers and creeks of our watershed in one study exceeded the toxicity threshold for PCBs. When 82 dolphins from estuarine waters near Charleston were evaluated for health, 50% showed evidence of environmentally related symptoms and diseases. Dr. Fair and colleagues are now conducting a monitoring program measuring PFCs and other pollutants in the sediments at 42 sites in our watershed.
The high levels of organic contaminants detected in our local sentinel dolphins have raised concerns about the African-American Gullah people of the Sea Islands whose diet, like the dolphins, includes local fish. An ongoing study led by Dr. Diane Kamen at the Medical University of South Carolina is focusing on Gullah people at risk of developing the autoimmune disease lupus. Preliminary results indicate that PFCs may play a pathogenic role in triggering the disease. Learn more about the sentinel species.