Agricultural activity within coastal watersheds results in estuaries becoming the receiving environment for pesticide inputs. In estuaries, salinity can alter insecticide responses of exposed crustaceans. The acute toxicity of environmentally relevant doses of chlorpyrifos and imidacloprid were examined using the euryhaline amphipod Gammarus lawrencianus at 20 and 30 Practical Salinity Units (PSU). Responses were recorded every 24 h until an incipient (threshold) L(E)C₅₀ was reached. For chlorpyrifos, LC₅₀ ranged from 0.1 to 0.5 µg/L and was two-fold higher at 30 vs. 20 PSU at all time-points over the 96 h exposure. Imidacloprid immobility EC₅₀ ranged from 4 to 40 µg/L over the 144 h exposure. An effect of salinity was only observed at 48 h and the EC₅₀ values showed 1.4 times more potency at 20 PSU compared to 30 PSU. Measured concentrations of both compounds did not differ between salinities. Acetylcholinesterase activity in chlorpyrifos exposed amphipods showed no salinity effect at 96 h. We conclude that salinity level alters G. lawrencianus susceptibility to chlorpyrifos exposure, but not imidacloprid.

沿海流域内的农业活动导致河口成为农药输入的接收环境。在河口，盐度会改变暴露的甲壳类对杀虫剂的反应。使用20和30实用盐度单位（PSU）的盐卤两栖动物牙轮虫Gammarus lawrencianus检测了与环境有关剂量的毒死rif和吡虫啉的急性毒性。应答记录每24小时，直到（E）C的初始（阈值）L- ₅₀达到。对于毒死rif，在96小时暴露的所有时间点，LC _50的范围为0.1至0.5 µg / L，在所有时间点，其30倍于20 PSU的两倍。吡虫啉固定剂EC ₅₀在144小时的暴露时间内，浓度范围为4至40 µg / L。仅在48 h时才观察到盐度的影响，EC ₅₀值显示20 PSU时的效能是30 PSU的1.4倍。两种化合物的测量浓度在盐度之间没有差异。暴露于毒死rif的两足动物中的乙酰胆碱酯酶活性在96 h时未显示盐度效应。我们得出的结论是，盐度水平会改变罗氏沼虾对毒死rif的敏感性，但不会改变吡虫啉的敏感性。