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Brown watersnakes (Nerodia taxispilota) as bioindicators of mercury contamination in a riverine system

Journal Article · · Science of the Total Environment
 [1];  [2];  [3];  [4]
  1. Univ. of Georgia, Athens, GA (United States). Interdisciplinary Toxicology Program; Univ. of Georgia, Athens, GA (United States). Warnell School of Forestry and Natural Resources; Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Univ. of Georgia, Athens, GA (United States)
  2. Univ. of Georgia, Athens, GA (United States). Warnell School of Forestry and Natural Resources; Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)
  3. Univ. of Georgia, Athens, GA (United States). Interdisciplinary Toxicology Program; Univ. of Georgia, Athens, GA (United States). Warnell School of Forestry and Natural Resources
  4. Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)
Herein, mercury (Hg) is a contaminant that enters the environment through natural or anthropogenic means. Ecological risk assessments have examined Hg bioaccumulation and effects in many taxa, but little is known about Hg dynamics in reptiles, or their potential use as bioindicator species for monitoring Hg in aquatic systems. Numerous snake species, like North American watersnakes (Nerodia spp.), are piscivorous and are exposed to Hg through their diet. The purpose of this study was to identify factors associated with Hg accumulation in a common watersnake species and compare Hg concentrations of the snakes to those in fish occupying the same habitats. To this end, we sampled brown watersnakes (Nerodia taxispilota) from the Savannah River, a major river system in the southeastern U.S., and compared N. taxispilota Hg accumulation trends to those of bass (Micropterus salmoides), catfish (Ictalurus and Ameiurus spp.), and panfish (Lepomis and Pomoxis spp.) collected from the same reach. Total Hg (THg) in N. taxispilota tail tips ranged from 0.020 to 0.431 mg/kg (wet weight; mean: 0.104 ± 0.008). Snake tail THg was significantly correlated with blood THg, which ranged from 0.003 to 1.140 mg/kg (0.154 ± 0.019). Snake size and site of capture were significantly associated with tail THg. Snake tail THg increased at sites along and downstream of the area of historic Hg pollution, consistent with fish THg. Snake muscle THg was predicted based on tail THg and ranged from 0.095 to 1.160 (0.352 ± 0.022). To gauge Hg biomagnification in N. taxispilota, we compared predicted snake muscle THg concentrations to THg in fish of consumable size. Average biomagnification factors for THg in N. taxispilota were 3.1 (panfish) and 5.4 (catfish), demonstrating N. taxispilota likely biomagnify Hg through their diet. These results reveal N. taxispilota to be an effective bioindicator species for monitoring Hg in aquatic environments.
Research Organization:
Univ. of Georgia, Athens, GA (United States)
Sponsoring Organization:
USDOE Office of Environmental Management (EM)
Grant/Contract Number:
EM0004391
OSTI ID:
1848965
Alternate ID(s):
OSTI ID: 1776305
Journal Information:
Science of the Total Environment, Journal Name: Science of the Total Environment Journal Issue: P2 Vol. 755; ISSN 0048-9697
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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