Alternate Title

Preliminary Survey of Chemical Contaminants in Water, Sediment, and Aquatic Biota at Selected Sites in Northeastern Florida Bay and Canal C-111


Several actions are under way to alter water management capabilities and practices in south Florida in order to restore a more natural hydroperiod for the Everglades. Because relatively little research has been conducted on contaminants entering Florida Bay, we undertook a preliminary study in June 1995 to determine contaminant concentrations in surface water, sediment, and biota prior to major changes in water management. The areas studied were the C-111 canal (five sites) beginning just above water control structure S-197 and extending to Manatee Bay (part of the Biscayne Bay system), Shell Creek (three sites), the mouth of Taylor River, Trout Creek (two sites), and a site near the Key Largo Ranger Station. Hydrographic observations were made at each site, and samples of water and sediment were collected at each of the five areas except the Key Largo site. Bioresidues were determined for indigenous oysters collected from the C-111 canal and Shell Creek and for transplanted oysters exposed at the Key Largo site, the C-111 canal, Shell Creek, Taylor River, and Trout Creek for 5-29 days. Water samples were analyzed for selected organochlorine pesticides and metals; sediments were analyzed for the same compounds and for polycyclic aromatic hydrocarbons (PAHs). Fish filets and shucked oysters were analyzed for selected organochlorine pesticides, polychlorinated biphenyl (PCB) congeners, and metals. Other than low dissolved oxygen at some C-111 canal sites, water quality was generally good. Most contaminants were below water and sediment quality guidelines designed to protect aquatic life, and contaminant concentrations in oysters were low. Threshold effect levels were exceeded for some organochlorine pesticides and PAHs in some sediment samples, but all values measured were below probable effect levels. Low concentrations of organochlorine pesticides were detected in sediments from the C-111 canal, Shell Creek, Taylor River, and Trout Creek; except for Taylor River, low concentrations of PCB congeners and PAHs were detected from the same areas. The only organochlorine pesticide detected in filets from seven fish was 3.2 v-g DDE/kg (wet weight) in a sea catfish. Total mercury concentrations in filets of four species of fishes ranged from 0.53 to 1.3 μg/g, wet weight, which falls within a limited consumption advisory by the State of Florida.