Contaminant Concentrations in Manatees in Florida

The status of the endangered manatee (Trichechus manatus) in relation to organochlorine pesticides, polychlorinated biphenyls, mercury, lead, cadmium, copper, iron, and selenium was investigated in Florida from 1977 to 1981. Concentrations of organochlorines in blubber, mercury in muscle and liver, lead in liver, and lead and cadmium in kidneys did not indicate high exposure to these contaminants. Only cadmium in kidneys showed a positive correlation with relative age. No significant relationship existed between iron and copper in liver; selenium concentrations in liver were low. Copper concentrations in livers of these aquatic herbivores were significantly elevated in areas of high herbicidal copper usage after adjustment for significant age-related effects; upper values of 1,200 ppm dry weight exceeded all previously reported concentrations in livers of any species of wild mammals from free-ranging populations. Liver copper concentrations comparable to those associated with toxic effects in some domestic species were found in manatees from areas of high copper herbicide use. The use of copper herbicides for control of aquatic plants should be carefully managed in areas used intensively by manatees.