University of California, San Diego, La Jolla, CA, 92093, USA.
Laboratory for Sensory Ecology, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, 43403, USA.
Bull Environ Contam Toxicol. 2019 Nov;103(5):663-669. doi: 10.1007/s00128-019-02707-w. Epub 2019 Aug 31.
Climate change is expected to alter hydrological cycles on global and regional scales, impacting groundwater and surface water inputs to stream habitats. In the midwestern United States, the volume and frequency of inputs are expected to become increasingly variable. This region has a high incidence of agriculture, creating enormous potential for transport of pesticides and herbicides into aquatic ecosystems. Metolachlor, an herbicide for corn and soybean crops, has been demonstrated to contaminate surface water and groundwater in the region. This study examines the impact of variable flow conditions on the toxicity of environmentally relevant concentrations of metolachlor in a macroinvertebrate found in midwestern streams, the rusty crayfish (Faxonius rusticus). Changes in crayfish foraging behavior were analyzed using a Mixed Model ANCOVA. Under toxicant exposure, crayfish significantly increased their consumption of macrophytes, but only under the variable flow regime. Thus, the increased variability in toxicant exposure impacted crayfish foraging behavior more than other flow regimes. This significant interaction between flow regime and metolachlor exposure suggests that the greater variability in toxicant inputs to streams may lead to more severe changes in behavior for exposed organisms.
预计气候变化将改变全球和区域尺度的水文循环，影响地下水和地表水对溪流生境的输入。在美国中西部，输入的水量和频率预计将变得更加不稳定。该地区农业发病率高，大量农药和除草剂有可能进入水生生态系统。甲草胺是一种用于玉米和大豆作物的除草剂，已被证明会污染该地区的地表水和地下水。本研究考察了可变流量条件对在中西部溪流中发现的一种大型无脊椎动物——铁锈螯虾（Faxonius rusticus）体内环境相关浓度的甲草胺毒性的影响。使用混合模型方差分析（ANCOVA）分析了螯虾觅食行为的变化。在有毒物质暴露下，螯虾显著增加了对大型植物的消耗，但仅在可变流量条件下。因此，有毒物质暴露的变化对螯虾觅食行为的影响大于其他流量条件。流量状况和甲草胺暴露之间的这种显著相互作用表明，溪流中有毒物质输入的更大变异性可能导致暴露生物的行为发生更严重的变化。
