Assessment of Metal Contamination in Seabirds of South Florida

Metal concentrations will be determined in the kidney, liver, breast muscle, and feathers of brown pelicans (Pelecanus occidentalis), royal terns (Thalasseus maximus), laughing gulls (Leucophaeus atricilla), herring gulls (Larus argentatus), northern gannets (Morus bassanus), and double-crested cormorants (Phalacrocorax auritus) collected from four wildlife rehabilitation centers in South Florida. Currently, results for total mercury concentrations in all tissue samples with the exception of feathers have been determined for 44 birds. The mean total mercury concentrations in muscle, kidney and liver ranged from 0.559 to 9.57 μg/g (dry wt.), 2.06 μg/g to 12.16 μg/g (dry wt.), and 2.18 to 42.67 μg/g (dry wt.), respectively. Ongoing research will provide metal concentrations by March 2016 for nickel, copper, lead, zinc, cadmium, vanadium and manganese. In the liver and kidney, values of methylmercury between 20 and 30 μg/g (dry wt.) are reported to cause morbidity and mortality effects in birds. According to the values so far, royal terns and cormorants on average have values of total mercury exceeding or within the reported range. Further assessment will help to confirm whether the seabirds of South Florida face a significant threat from metal pollution.