An Assessment of Mercury Exposure for Multiple Trophic Levels in the Greater
Everglades Ecosystem
S. Haynes, T. Gross, K. Rice, F. Mazotti, T. Lange, J. Wiebe, S. Ruessler, C.
Wieser
USGS-Florida Integrated Science Center, Gainesville, FL USA
S. Haynes
Florida A&M University, Environmental Sciences Institute, Tallahassee, FL USA
The Everglades ecosystem comprised of peat soils and wetlands, is very sensitive
to the accumulation of environmental contaminants. Scientists and managers are
concerned that mercury is the most serious environmental threat to the health of
aquatic and terrestrial resources. Although, studies have identified mercury in top
predators of this ecosystem the extent of mercury distribution across trophic
levels and potential adverse effects on wildlife inhabiting this ecosystem is
unknown. The primary goals of the Everglades task force for restoration include
the delivery of adequate amounts of quality water to protect and sustain the
natural environment. However, restoration planning has not considered or
evaluated the resulting potential exposures to wildlife and the adverse effects of
restoration activities on contaminant distributions and subsequent wildlife
exposures. The objective of this study was to evaluate mercury exposures for
biota within the aquatic ecosystem of south Florida. For these analyses,
largemouth bass (n=5 per site) and alligators (n=10 per site) were captured from
23 areas critical to the South Florida Restoration and analyzed for total Hg. All
solid tissues were weighed and analyzed (i.e., without acid digestion) for Hg
using combustion atomic absorption spectrometry with gold amalgamation
(Milestone Inc., Monroe, CT). The mean Hg content in bass muscle contained
levels as high as 4024.5 μg/Kg wet wt. Hg concentrations in most alligator livers
contained levels above the 4700 μg/Kg calibration limit of this analytical method.
Documentation of Hg exposure for biota within the aquatic ecosystem of south
Florida will serve as a critical component for future assessment of risks, the goal
of which will be prevention of adverse effects on wildlife within the Greater
Everglades Ecosystem.
Sekeenia Haynes, USGS-Florida Integrated Science Center, 7920 NW 71st Street,
Gainesville, FL, 32653, phone: (352) 378-8181 Fax: (352) 378-4956,
shaynes@usgs.gov