John Wiley & Sons, Ltd.

Plasma cholinesterase activity as a biomarker for quantifying exposure of green sturgeon to carbaryl following applications to control burrowing shrimp in Washington State

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Willapa Bay (Washington State, USA) has been one of the rare intertidal locations where large‐scale pesticide applications occur. Until recently, carbaryl was applied to control burrowing shrimp that decrease commercial oyster productivity. The Bay is critical habitat for green sturgeon (Acipenser medirostris), an anadromous species listed as threatened under the Endangered Species Act. However, the hazard carbaryl posed is unknown. We exposed surrogate seawater‐acclimated white sturgeon (A. transmontanus) to 0, 30, 100, 300, 1,000 and 3,000 µg L−1 carbaryl for 6 h and measured brain acetylcholinesterase (AChE) and plasma butyrylcholinesterase (BChE) activities. Enzyme recovery was measured in an additional cohort exposed to 1,000 µg L−1 for 6 h. AChE activity was reduced (p ≤ 0.001) at concentrations > 100 µg L−1 with recovery in the 1,000 µg L−1 cohort by 72 h. Surprisingly, BChE activity was greater than controls at concentrations > 300 µg L−1 (p > 0.05); a finding confirmed in additional fish exposed to 3,000 µg L−1 for 6 h (+30%, p < 0.001) with apparent recovery by 48 h. Plasma samples were collected from free‐living green sturgeon before and 4‐5 d after application of carbaryl in Willapa Bay. BChE activity post‐application was reduced 28% (p < 0.001) indicating exposure to the pesticide. However, the lack of congruence between BChE and AChE activity in captive white sturgeon exposed to carbaryl indicates further studies are needed to better understand the risk carbaryl exposure poses to green sturgeon. This article is protected by copyright. All rights reserved

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