Mercury and Radiocesium Accumulation and Associations With Sublethal Endpoints in the Florida Green Watersnake (Nerodia floridana)

Mercury (Hg) and radiocesium (137Cs) are well‐known environmental contaminants with the potential to impact the health of humans and wildlife. Snakes have several characteristics conducive to studying environmental contamination but have rarely been included in the monitoring of polluted sites. We i...

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Bibliographic Details
Published in:Environmental toxicology and chemistry 2022-03, Vol.41 (3), p.758-770
Main Authors: Brown, Marty Kyle, Haskins, David Lee, Russell, Amelia L., Lambert, Michaela L., Quick, Caleigh E., Pilgrim, Melissa A., Tuberville, Tracey D.
Format: Article
Language:English
Subjects:
Animals
Bioaccumulation
Bioindicators
Body size
Cesium 137
Cesium isotopes
Cesium radioisotopes
Contaminants
Contamination
Environmental Biomarkers
Environmental Monitoring
Florida
Heavy metal
Hepatozoon
Humans
Indicator species
Infections
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Mercury
Mercury (metal)
Mercury - analysis
Metabolic rate
Multiple regression models
Nerodia floridana
Parasitemia
Pollution
Pollution monitoring
Ponds
Radionuclide
Regression analysis
Reptile
Rivers
Snakes
Snakes - metabolism
Standard metabolic rate
Sublethal effects
Tails
Wildlife
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Summary:Mercury (Hg) and radiocesium (137Cs) are well‐known environmental contaminants with the potential to impact the health of humans and wildlife. Snakes have several characteristics conducive to studying environmental contamination but have rarely been included in the monitoring of polluted sites. We investigated the bioaccumulation of Hg and 137Cs and associations with sublethal effects (standard metabolic rate [SMR] and hemoparasite infections) in Florida green watersnakes (Nerodia floridana). We captured 78 snakes from three former nuclear cooling reservoirs on the US Department of Energy's Savannah River Site in South Carolina (USA). For captured snakes, we (1) determined whole‐body 137Cs, (2) quantified total Hg (THg) using snake tail clips, (3) conducted hemoparasite counts, and (4) measured the SMR. We used multiple regression models to determine associations among snake body size, capture location, sex, tail THg, whole‐body 137Cs, Hepatozoon spp. prevalence and parasitemia, and SMR. Average whole‐body 137Cs (0.23 ± 0.08 Becquerels [Bq]/g; range: 0.00–1.02 Bq/g) was correlated with snake body size and differed significantly by capture site (Pond B: 0.67 ± 0.05 Bq/g; Par Pond: 0.10 ± 0.02 Bq/g; Pond 2: 0.03 ± 0.02 Bq/g). Tail THg (0.33 ± 0.03 mg/kg dry wt; range: 0.16–2.10 mg/kg) was significantly correlated with snake body size but did not differ by capture site. We found no clear relationship between SMR and contaminant burdens. However, models indicated that the prevalence of Hepatozoon spp. in snakes was inversely related to increasing whole‐body 137Cs burdens. Our results indicate the bioaccumulation of Hg and 137Cs in N. floridana and further demonstrate the utility of aquatic snakes as bioindicators. Our results also suggest a decrease in Hepatozoon spp. prevalence related to increased burdens of 137Cs. Although the results are intriguing, further research is needed to understand the dynamics between 137Cs and Hepatozoon spp. infections in semiaquatic snakes. Environ Toxicol Chem 2022;41:758–770. © 2022 SETAC
ISSN:0730-7268
1552-8618
DOI:10.1002/etc.5281