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Effects of local and landscape
heterogeneity on mercury loadings in palustrine amphibians from
Acadia National Park, Maine
We propose to
compare levels of mercury (Hg) contamination previously documented
in samples of soils, sediments, stream water, fish, and
salamanders collected in Acadia National Park (ANP) to those of
newly-collected samples of selected frog species inhabiting Park
wetlands, including those where amphibian die-offs have recently
been reported. The Hg loadings in amphibians at these sites are
unknown and have never been quantified or compared to sites where
amphibian die-offs have not occurred. Therefore, we propose to
compare the relative levels of Hg in amphibian larvae collected
from ANP sites with and without reported amphibian die-offs. We
predict that Hg concentrations in the larvae of the selected frog
species from ANP wetlands may be high in comparison to Hg levels
in local fish and lotic salamander larvae due to:
- life history
characteristics (i.e., length of larval period),
- diet,
- micro-habitat selection patterns, and
- the strong potential for
high rates of methyl Hg production in palustrine
environments.
Our approach examines Hg contamination in both the physical
environment and biota and across the landscape from headwaters to
the receiving surface waters. Hg levels in frog species
inhabiting lentic environments in watersheds with different biotic
communities, local geomorphology, fire disturbance histories, and
land cover types will be analyzed at multiple spatial scales to
determine important predictor variables of Hg levels in the
selected frog species. Since an extensive spatial database for Hg
concentrations in two-lined salamander larvae in ANP has been
developed, we have a unique opportunity to evaluate, in a cost
effective manner, the relationship between the observed salamander
larvae Hg levels from a given stream and the Hg levels in frogs
inhabiting the receiving surface waters at lower positions in the
watershed.
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