Mercury in Florida Bay fish: spatial distribution of elevated concentrations and possible linkages to Everglades restoration

Evans, David W. and Crumley, Peter H. (2005) Mercury in Florida Bay fish: spatial distribution of elevated concentrations and possible linkages to Everglades restoration. Bulletin of Marine Science, 77(3), pp. 321-345.

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Abstract

Health advisories are now posted in northern Florida Bay, adjacent to the Everglades, warning of high mercury concentrations in some species of gamefish. Highest concentrations of mercury in both forage fish and gamefish have been measured in the northeastern corner of Florida Bay, adjacent to the dominant freshwater inflows from the Everglades. Thirty percent of spotted seatrout (Cynoscion nebulosus Cuvier, 1830) analyzed exceeded Florida’s no consumption level of 1.5 μg g−1 mercury in this area. We hypothesized that freshwater draining the Everglades served as the major source of methylmercury entering the food web supporting gamefish. A lack of correlation between mercury concentrations and salinity did not support this hypothesis, although enhanced bioavailability of methylmercury is possible as freshwater is diluted with estuarine water. Stable isotopes of carbon, nitrogen, and sulfur were measured in fish to elucidate the shared pathways of methylmercury and nutrient elements through the food web. These data support a benthic source of both methylmercury and nutrient elements to gamefish within the eastern bay, as opposed to a dominant watershed source. Ecological characteristics of the eastern bay, including active redox cycling in near-surface sediments without excessive sulfide production are hypothesized to promote methylmercury formation and bioaccumulation in the benthos. Methylmercury may then accumulate in gamefish through a food web supported by benthic microalgae, detritus, pink shrimp (Farfantepenaeus duorarum Burkenroad, 1939), and other epibenthic feeders. Uncertainty remains as to the relative importance of watershed imports of methylmercury from the Everglades and in situ production in the bay, an uncertainty that needs resolution if the effects of Everglades restoration on mercury levels in fish are to be modeled and managed.

Item Type: Article
Title: Mercury in Florida Bay fish: spatial distribution of elevated concentrations and possible linkages to Everglades restoration
Personal Creator/Author:
CreatorsEmail
Evans, David W.David.W.Evans@noaa.gov
Crumley, Peter H.
Journal or Publication Title: Bulletin of Marine Science
Volume: 77
Number: 3
Page Range: pp. 321-345
Date: 2005
Subjects: Ecology
Fisheries
Chemistry
Item ID: 2099
Depositing User: Patti M. Marraro
Date Deposited: 19 May 2009 16:32
Last Modified: 29 Sep 2011 19:41
URI: http://aquaticcommons.org/id/eprint/2099

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