The aim of this study was to test the effects of agricultural land use on benthic insect population body-mass and community biomass size spectrum. Agricultural land use effects were assessed by conducting a reciprocal transfer experiment between two stream reaches exposed to differing intensities of row crop and livestock agricultural activity representing best attainable and highly developed agricultural land use scenarios. We found that transferred insect communities showed no change in richness, abundance, distribution or biomass, indicating that exposure to increased agricultural intensity did not have selective lethal effects on transferred benthic insect communities. However, populations of Ephemerellidae and Hydropsyche demonstrated an increase and decrease, respectively, in body-mass following the transfer to the best attainable agriculture site. Furthermore, the community biomass size spectrum at the best attainable agriculture site contained large, predatory insects not found at the intensive agriculture site. Our findings suggest that taxon-specific body-mass and biomass size spectra have the potential to detect environmental effects prior to long-term community changes. Further research is needed to explore the mechanisms by which changes in the biomass size spectrum link agricultural intensity to shifts in benthic insect community structure.

中文翻译：

---

集约化农业改变了底栖昆虫的生物量大小谱和体重：来自互惠转移实验的证据

本研究的目的是测试农业土地利用对底栖昆虫种群体重和群落生物量大小谱的影响。通过在暴露于不同强度的中耕作物和畜牧业活动的两个河流河段之间进行互惠转移实验来评估农业土地利用效果，代表最佳可实现的和高度发达的农业土地利用情景。我们发现转移的昆虫群落在丰富度、丰度、分布或生物量方面没有变化，表明暴露于增加的农业强度对转移的底栖昆虫群落没有选择性致死影响。然而，Ephemerellidae 和 Hydropsyche 的种群分别表现出增加和减少，转移到最佳农业地点后的体重。此外，在可达到的最佳农业地点的群落生物量大小谱包含在集约化农业地点未发现的大型捕食性昆虫。我们的研究结果表明，特定于分类群的体重和生物量大小谱有可能在长期群落变化之前检测到环境影响。需要进一步研究以探索生物量大小谱变化将农业强度与底栖昆虫群落结构变化联系起来的机制。我们的研究结果表明，特定于分类群的体重和生物量大小谱有可能在长期群落变化之前检测到环境影响。需要进一步研究以探索生物量大小谱变化将农业强度与底栖昆虫群落结构变化联系起来的机制。我们的研究结果表明，特定于分类群的体重和生物量大小谱有可能在长期群落变化之前检测到环境影响。需要进一步研究以探索生物量大小谱变化将农业强度与底栖昆虫群落结构变化联系起来的机制。