Direct and indirect effects of metal pollutants on lotic food webs: comparative sensitivities of warmwater and coldwater forage fish

保护我们的水域取决于我们充分了解生态系统复杂性的能力，从而在污染物与暴露生物的反应之间的预测关系中获得一定程度的信心。由于水生生态系统的复杂性，我们对污染物(如金属和金属混合物)如何影响河流食物网的了解有限。我们的结果从温水到冷水鱼类的外推也非常有限。拟议研究的长期目标是更好地了解包括金属在内的污染物对鱼类食物网的直接和间接影响，以及鱼种之间的相对敏感性。我们将使用硒作为我们的模型污染物。硒是一种必需的微量营养素，在很小的浓度范围内既有益又有毒。采矿、农田灌溉、炼油和燃煤都会增加水生态系统中的硒含量。将利用简单的食物网(藻类、无脊椎动物、鱼类)研究Se对温水(黑头鳕鱼)和冷水(粘鱼)饲料鱼部分生命周期的直接(水中暴露)和间接(饮食暴露)影响，以及主要猎物(蚊虫)的生命周期。将开发一种部分生命周期的繁殖生物测定方法来检测粘液动物。将在不同的温度条件下，以及当这些鱼在同一自给自足的四级食物网(藻类、无脊椎动物、粘鱼、愚头鱼)中相互作用时，评估这些鱼对Se的敏感性。这项研究将使我们更好地理解Se对河流食物网的影响，以及冷水鱼和温水鱼对Se的不同敏感性。了解单一金属的生物反应将有助于我们理解对复杂混合物(例如，金属矿山废水)的反应。

Protection of our waters depends upon our ability to understand ecosystem complexity enough to attain a level of confidence in predictive relationships between a pollutant and the response of exposed organisms. Due to the complexities of aquatic ecosystems, our understanding of how pollutants (e.g., metals and metal mixtures) affect lotic (river) food webs is limited. Extrapolation of our results from warm water to coldwater fishes is also very limited. The long term objectives of the proposed research are to better understand direct and indirect effects of pollutants including metals on lotic food webs and comparative sensitivities among species of fish. We will use selenium as our model pollutant. Se is an essential micronutrient that is both beneficial and toxic within a narrow concentration range. Mining, irrigation of agricultural land, petroleum refining and coal combustion can increase Se in aquatic ecosystems. Direct (waterborne exposure) and indirect (dietary exposure) effects of Se on the partial lifecycles of warm water (fathead minnow) and cold water (slimy sculpin) forage fishes and the lifecycle of a dominant prey item (midge) will be investigated using simple food webs (algae, invertebrate, fish). A partial lifecycle reproductive bioassay will be developed for slimy sculpin. Sensitivities of fathead minnow and slimy sculpin to Se will be assessed under different temperature regimes and when these fish are interacting in the same self-sustaining four-level food web (algae, invertebrate, slimy sculpin, fathead minnow). This research will better our understanding of how river food webs are affected by Se and the different sensitivities of cold and warm water fishes. Understanding biological responses for single metals will assist our understanding of responses to complex mixtures (e.g., metal mine effluents).