Mercury concentrations in the prey of apex piscivores from a large subtropical estuary

Abstract

Estuaries are important ecosystems for mercury methylation and accumulation, yet few studies have quantified mercury levels in prey species that expose large estuarine piscivores to contamination. We measured mercury concentrations in key prey species from the Indian River Lagoon, Florida, USA, to characterize variability and assess the spatial distribution of mercury levels throughout the estuary. Mean mercury concentrations ranged from 0.015mg/kg in Mugil cephalus to 0.222mg/kg in Bairdiella chrysoura and varied considerably in some species. Spatial variation was observed within species, but a universal geographic pattern among species was not apparent, likely reflecting the broad habitat-use patterns associated with the estuarine-transient life histories of many of these common prey species. In contrast, estuarine-resident species, such as B. chrysoura, may be useful indicators of regional mercury methylation potential and bioaccumulation in biota. These results can advance future studies that relate dietary mercury uptake and mercury level variations in estuarine piscivores.