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TP12B Ecological Effects of Cholinesterase Inhibitors
() Differential swimming performance of two Natricine snakes exposed to a cholinesterase-inhibiting pesticide.
Hopkins, W1, Winne, C1, DuRant, S1, 1 Savannah River Ecology Laboratory, Aiken, SC, USA
ABSTRACT- Environmental contaminants have direct effects on organisms at the molecular, cellular, and tissue levels, but the net results of these sub-organismal effects are only consequential to exposed populations if they alter organism-level traits that ultimately influence fitness (e.g., growth, performance, reproduction, and survival). Here, we explore the possibility that a fitness-related trait, swimming performance, may be useful for assessing the effect of environmental contaminants on semi-aquatic reptiles. We assessed swimming performance in neonate black swamp snakes (Seminatrix pygaea) and diamondback water snakes (Nerodia rhombifer) following a 48 hour exposure to ecologically realistic concentrations of carbaryl (2.5 and 5.0 mg/L), a cholinesterase-inhibiting pesticide that disrupts nerve impulse transmission. Both species exposed to the highest concentration of carbaryl exhibited reduced swimming performance compared to controls, but N. rhombifer swam faster than S. pygaea even after the effects of body size were accounted for. Moreover, carbaryl caused greater reductions in swim velocity in S. pygaea than in N. rhombifer, particularly at the furthest swim distance measured. Most individuals recovered from the effects of carbaryl on swimming performance within 96 hours, but recovery was significantly slower in S. pygaea than in N. rhombifer. Our experiments suggest that S. pygaea is more sensitive than N. rhombifer to the effects of carbaryl on swim velocity. We hypothesize that the sensitivity of S. pygaea may arise from its highly permeable integument compared to other Natricines. Our findings also suggest that performance can serve as an ecologically relevant organism-level response to contaminant exposure in reptiles and warrants further study.
Key words: Snakes, Swimming, Reptiles, Cholinesterase inhibition
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