A comparison of mercury burdens between St. Marks National Wildlife Refuge and St. Andrew Bay, Florida: Evaluation of fish body burdens and physiological responses in largemouth bass, spotted seatrout, striped mullet, and sunfish

Abstract

Musculature from the dorsal region of 130 largemouth bass (Micropterus salmoides), 140 sunfish (Lepomis sp.), 41 spotted seatrout (Cynoscion nebulosus) and 67 striped mullet (Mugil cephalus) were collected from five estuarine and five freshwater sites within the St. Marks National Wildlife Refuge and two estuarine and two freshwater sites from St. Andrew Bay, Florida, United States of America. Musculature was analyzed for total mercury content, sagittal otoliths were removed for age determination and physiological responses were measured. Largemouth bass and sunfish from the refuge had higher mercury concentrations in musculature than those from the bay. Male spotted seatrout, male striped mullet, male and female sunfish and female largemouth bass had mercury burdens positively correlated with length. The majority of all four species of fish from both study areas contained mercury levels below 1.5 part per million, the limit for safe consumption recommended the Florida Department of Health. In comparison, a significant percentage of largemouth bass and sunfish from several sampled sites, most notably Otter Lake and Lake Renfroe within St. Marks National Wildlife Refuge, had mercury levels consistent with the health department’s guidelines of “limited consumption” or “no consumption guidelines.” Introduction Although mercury is a universal contaminant in the biosphere, its distribution is not uniform (U.S. Environmental Protection Agency [USEPA], 2001b; Gulf States Marine Fisheries Commission, 2002). Mercury sources can be natural or anthropogenic. Natural mercury sources include volcanoes and geothermal activity, forest fires, degassing of sediment or rock containing mercury, and seawater evaporation. The majority of anthropogenic sources of mercury include combustion processes where mercury is emitted as a byproduct, mining practices, sewage discharge, and metal refining operations (U.S. Environmental Protection Agency, 2006). 1 D.H. Huge (dane_huge@usgs.gov; 352-264-3540) and C. M. Wieser, U.S. Geological Survey-Southeast Ecological Science Center, 7920 NW 71 st Street, Gainesville, Florida 32653. 2 R. H. Rauschenberger, U.S. Fish and Wildlife Service, 6620 Southpoint Drive South, Suite 310, Jacksonville, Florida 32216. 3 J. M. Hemming, U.S. Fish and Wildlife Service, 1601 Balboa Avenue, Panama City, Florida 32405.