Figure 4: Respirometry Chamber

Figure 3: Minnow Trap

Sublethal effects of 137Cs and Hg on Florida Green Watersnakes (Nerodia floridana)Michaela Lambert1,2, Kyle Brown1,3, David Haskins1,4, Amelia Russell1,3, Melissa Pilgrim3, Tracey Tuberville1

1Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, 2University of Kentucky, Lexington, KY 40506, 3University of South Carolina Upstate, Spartanburg, SC 29303, 4D.B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602

Background• Contaminants of anthropogenic origin are a global issue• Many are readily accumulated by wildlife • Some persist in the environment for long periods of time • The Savannah River Site (SRS) offers a unique

opportunity to study the effects of persistent contaminants such as radiocesium (137Cs) and mercury (Hg)

• Sublethal effects to contaminants are seldom studied, especially in reptiles

Study System:Florida Green Watersnake (Nerodia floridana)• Florida Green Watersnakes (FGWs) occur throughout

Florida and southern Georgia with a disjunct population in South Carolina

• Common in vegetation choked, slow moving wetlands, such as the former nuclear reactor cooling reservoirs

• The largest piscivorous watersnake

Study Site• The Savannah River Site (SRS) is a large (800 km2)

Department Of Energy facility located near Aiken, South Carolina

• We sampled three former reactor cooling reservoirs: Pond B, PAR Pond, and Pond 2 (fig. 2)

• Savannah River water contaminated with Hg was pumped to reactors; all three reservoirs received Hg contaminated effluent from these reactors

• In addition, Pond B and Par Pond were contaminated by 137Cs releases during 1963-1964

ObjectivesThe objectives of our study were to determine: 1. Are there site-level differences in O2 consumption in

Florida Green Watersnakes?2. Does body size impact snake O2 consumption?3. Is O2 consumption correlated with 137Cs or Hg levels in

individual snakes?

Materials and MethodsSampling• 10-30 June 2016• 20 Funnel and 80 Minnow traps for each site (fig. 3)

Contaminants• 137Cs whole body burden determined• Tail clip total Hg determined

Respirometry• Snakes fasted for 7-10 days • Pre-respirometry mass taken• Ran through a SABLE system flow through respirometer that

measures O2 consumption and CO2 expiration (fig. 4)*75 minute acclimation period*30 minute recording time at 27°C

• Oxygen Consumption calculated using ExpeData software

Results• Average snake mass was significantly different among

sites (fig. 5)• After controlling for mass, there were significant

differences in average snake O2 consumption among sites (fig. 6)

• Mass and oxygen consumption showed a significant positive relationship (fig. 7)

• Sites with the highest O2 consumption were the same sites with the highest contaminant concentrations (Table 1)

• Preliminary multiple regression analysis showed Hg and 137Cs explained 26% of the variation in oxygen consumption

Conclusions• There were site level differences in O2 consumption• Radiocesium and Hg were associated with increases in O2

consumption• May indicate higher energetic costs associated with

contaminant body burdens

Future work• Develop more advanced models that incorporate additional

factors known to impact snake O2 consumption (e.g., sex, reproductive status, and age class)

• Evaluate relationship between blood parasite load and O2consumption

Watersnakes as Bioindicators• All are carnivorous• High site fidelity• Occur in a diversity of aquatic habitats• Known to bioaccumulate contaminants, including Hg and

137Cs

Figure 1: Florida Green Watersnake (Nerodia floridana)

Whicker et al.,1990

Pond B

PAR Pond

Pond 2

Figure 2: Pond B, PAR Pond, Pond 2

Figure 5: Mean mass (g) of snakes per site. ANOVA: F(2,75) = 16.31, P <0.0001.Letters designate significant differences based on Tukey’s HSD test (P < 0.01).

n=44

n=23

n=11

0

50

100

150

200

250

300

350

POND 2 POND B PAR POND

Mea

n m

ass

(g)

A

B

A

n=44

n=23

n=11

0

5

10

15

20

25

POND 2 POND B PAR POND

Mea

n O

2C

onsu

mpt

ion

(mL/

hr)

Figure 6: Mean oxygen consumption (mL/hr) for each site.ANCOVA: Oxygen consumption, F(2,73) = 4.908, P = 0.01; Mass (cov),F(1,73) = 63.551, P < 0.001

R² = 0.2617

R² = 0.8268

R² = 0.4079

0

10

20

30

40

50

60

0 100 200 300 400 500 600 700

O2

Con

sum

ptio

n (m

L/hr

)

Mass (g)

Pond 2

Pond B

Par Pond

Figure 7: The effect of mass on oxygen consumption. All P < 0.05

Pond B

PAR Pond

Pond 2

Pond B PAR Pond Pond 2

VO2 (mL/hr)16.68 19.69 8.04

Hg (ppm) 0.29 0.57 0.29

137Cs (bq/g)0.67 0.09 0.03

Table 1: Mean oxygen consumption (VO2), mercury (Hg) concentrations, and radiocesium (137Cs) concentrations in Florida Green Watersnakes on the Savannah River Site.

This material is based upon work supported by the Department of Energy under Award Number(DE-FC09-07SR22506)

Special thanks to Kimberly Price, Rad Con/Perry Bovan, Kirsten Work, Kurt Buhlmann, Larry Bryan and crew, and JD Willson.

ReferencesConant, R., & Collins, J. T. (1991). A field guide to amphibians and reptiles of eastern and central North America.

Jannik, G. T., Baker, R. A., Lee, P. L., Eddy, T. P., Blount, G. C., & Whitney, G. R. (2013, July). Long-Term Assessment of Critical Radionuclides and Associated Environmental Media at the Savannah River Site-13038. WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States).

Whicker, F. W., Pinder, J. E., Bowling, J. W., Alberts, J. J., & Brisbin, I. L. (1990). Distribution of Long-Lived Radionuclides in an Abandoned Reactor Cooling Reservoir. Ecological Monographs, 60(4), 471-496.