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Very
little is currently known about the accumulation or effects of contaminants
on reptiles. To date, most studies examining reptile exposure to trace elements
report tissue burdens of field-captured animals, but seldom provide insight
into the dose, duration, or mode of exposure involved. For two years, we fed
juvenile banded water snakes (Nerodia fasciata) prey items collected
from a coal ash-contaminated site containing elevated levels of As, Cd, Cu,
Se, Sr, and V. With the exception of Cu, snakes accumulated significant concentrations
of elements, usually in a dose-dependent manner. Accumulation varied significantly
among liver, kidney, and gonads. Selenium accumulation was most notable, greatly
exceeding established toxicity thresholds for other vertebrates. Despite the
high concentrations of pollutants accumulated, snakes exposed to the contaminated
diet survived through the study and exhibited normal food consumption, growth,
over-winter survival and mass loss, metabolic rate, and gonadosomatic index.
However, accumulation of trace elements was accompanied by liver histological
abnormalities in 30% of snakes ingesting contaminated prey. The results of this
study confirm that diet can be a significant route of exposure to trace elements
in snakes and indicate that further studies on snakes are warranted to better
understand their responses to contaminants. |
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