Relyea Rick A
Department of Biological Sciences, University of Pittsburgh, 101 Clapp Hall, Pittsburgh, PA 15260, USA.
Oecologia. 2009 Mar;159(2):363-76. doi: 10.1007/s00442-008-1213-9. Epub 2008 Nov 11.
The ubiquity of anthropogenic chemicals in nature poses a challenge to understanding how ecological communities are impacted by them. While we are rapidly gaining an understanding of how individual contaminants affect communities, communities are exposed to suites of contaminants yet investigations of the effects of diverse contaminant mixtures in aquatic communities are rare. I examined how a single application of five insecticides (malathion, carbaryl, chlorpyrifos, diazinon, and endosulfan) and five herbicides (glyphosate, atrazine, acetochlor, metolachlor, and 2,4-D) at low concentrations (2-16 p.p.b.) affected aquatic communities composed of zooplankton, phytoplankton, periphyton, and larval amphibians (gray tree frogs, Hyla versicolor, and leopard frogs, Rana pipiens). Using outdoor mesocosms, I examined each pesticide alone, a mix of insecticides, a mix of herbicides, and a mix of all ten pesticides. Individual pesticides had a wide range of direct and indirect effects on all trophic groups. For some taxa (i.e., zooplankton and algae), the impact of pesticide mixtures could largely be predicted from the impacts of individual pesticides; for other taxa (i.e., amphibians) it could not. For amphibians, there was an apparent direct toxic effect of endosulfan that caused 84% mortality of leopard frogs and an indirect effect induced by diazinon that caused 24% mortality of leopard frogs. When pesticides were combined, the mix of herbicides had no negative effects on the survival and metamorphosis of amphibians, but the mix of insecticides and the mix of all ten pesticides eliminated 99% of leopard frogs. Interestingly, these mixtures did not cause mortality in the gray tree frogs and, as a result, the gray tree frogs grew nearly twice as large due to reduced competition with leopard frogs. In short, wetland communities can be dramatically impacted by low concentrations of pesticides (both separate and combined) and these results offer important insights for the conservation of wetland communities.
人为化学物质在自然界中无处不在，这给理解生态群落如何受到它们的影响带来了挑战。虽然我们正迅速了解单个污染物如何影响群落，但群落会接触到多种污染物，然而对水生群落中多种污染物混合物影响的研究却很少。我研究了低浓度（2 - 16 ppb）下单次施用五种杀虫剂（马拉硫磷、西维因、毒死蜱、二嗪农和硫丹）和五种除草剂（草甘膦、阿特拉津、乙草胺、异丙甲草胺和2,4 - D）如何影响由浮游动物、浮游植物、周丛生物和两栖类幼体（灰树蛙、变色树蛙和豹蛙）组成的水生群落。利用室外中型生态系统，我分别研究了每种杀虫剂、杀虫剂混合物、除草剂混合物以及所有十种农药的混合物。单个农药对所有营养级都有广泛的直接和间接影响。对于一些分类群（如浮游动物和藻类），农药混合物的影响在很大程度上可以从单个农药的影响中预测；对于其他分类群（如两栖动物）则不能。对于两栖动物，硫丹有明显的直接毒性作用，导致豹蛙84%的死亡率，二嗪农有间接作用，导致豹蛙24%的死亡率。当农药混合时，除草剂混合物对两栖动物的存活和变态没有负面影响，但杀虫剂混合物和所有十种农药的混合物使99%的豹蛙死亡。有趣的是，这些混合物并未导致灰树蛙死亡，结果，由于与豹蛙的竞争减少，灰树蛙的体型增长了近两倍。简而言之，湿地群落会受到低浓度农药（单独和混合使用）的显著影响，这些结果为湿地群落的保护提供了重要见解。
