A comparison of mercury in estuarine fish between Florida Bay and the Indian River Lagoon, Florida, USA

Concentrations of mercury (Hg) in fish were compared between two Florida es tuaries, the Indian River Lagoon and Florida Bay. The objective was to dete rmine if differences in Hg concentration exist and to attempt to relate tho se differences to sources of Hg. Five hundred and thirteen estuarine fish w ere collected and analyzed for Hg concentration. Fish species collected wer e black drum, bluefish, bonnethead shark, common snook, crevalle jack, gaff topsail catfish, gray snapper, Mayan cichlid, pompano, red drum, sheepshead , southern flounder, spadefish, and spotted seatrout. Analysis of variance of species-specific Hg data among the three defined regions of eastern and western Florida Bay and the Indian River Lagoon substantiated regional diff erences. Proximity to known anthropogenic sources of Hg appeared to be a si gnificant factor in the distribution of Hg concentration among the fish col lected. Sufficient numbers of crevalle jack, gray snapper, and spotted seat rout were collected to permit statistical analysis among regions. Hg concen trations in all three of these species from eastern Florida Bay were higher than those collected in the other two areas. A major fraction of the estua rine fish collected in eastern Florida Bay exceeded one or more State of Fl orida or U.S. Food and Drug Administration fish consumption health advisory criteria. In general, fish from western Florida Bay contained less Hg than those from the Indian River Lagoon, and fish from the Indian River contain ed less Hg than those from eastern Florida Bay. Crevalle jack from all area s and spotted seatrout from Florida Bay were placed on a consumption adviso ry in Florida. Detailed study of Florida Bay food web dynamics and Hg bioge ochemical cycling is recommended to better understand the processes underly ing the elevated Hg levels in fish from eastern Florida Bay. This informati on may be vital in the formulation of appropriate strategies in the ongoing South Florida restoration process.