Benthic Macroinvertebrates in Arroyo Seco River

(Taken from abstract online.) In the Arroyo Seco watershed, located east of Big Sur in Central California, a study was conducted to assess changes in the environment and their related changes in benthic macro-invertebrate diversities. By comparing differences in substrate to the corresponding diversity levels of insect communities, a relationship between substrate and biological metrics can be formed. To better understand this relationship, macro-invertebrate abundance levels, taxa richness, EPT taxa (number of taxa found in the orders: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddis flies)), EPT taxa composition and dominant taxa composition were analyzed given a cobble versus sand dominated substrate. EPT taxa, EPT composition, and taxa richness measures were higher in the upper site and decreased in the lower site. Dominant taxa composition was found to be higher in the sandy substrate than the cobble substrate. Overall, less diversity was found in the sandy substrate (lower site) than in cobble substrate (upper site).（摘自在线学术摘要）本研究针对位于加州中部大苏尔东侧的阿罗约塞科流域（Arroyo Seco Watershed）展开，旨在评估该区域的环境变化及其伴随的底栖大型无脊椎动物（benthic macro-invertebrate）多样性变化。通过对比底质差异与对应昆虫群落的多样性水平，可构建底质与生物指标间的关联关系。为进一步明晰该关联，本研究针对砾石主导与沙质主导两种底质场景，分析了大型无脊椎动物丰度、类群丰富度、EPT类群（EPT taxa，即蜉蝣目（Ephemeroptera，蜉蝣）、襀翅目（Plecoptera，石蝇）与毛翅目（Trichoptera，石蛾）下的类群数量）、EPT类群组成及优势类群组成。研究结果显示，上游样点的EPT类群数量、EPT类群组成及类群丰富度均更高，下游样点则呈下降趋势；优势类群组成在沙质底质中的占比高于砾石底质。总体而言，沙质底质样点（下游样点）的生物多样性低于砾石底质样点（上游样点）。