The effects of pastoral intensification on the feeding interactions of generalist predators in streams

Land use change can alter trophic interactions with wide-ranging functional consequences, yet the consequences for aquatic food webs have been little-studied. In part, this may reflect the challenges of resolving the diets of aquatic organisms using classical gut contents analysis, especially for soft-bodied prey. We used next generation sequencing to resolve prey use in nearly 400 individuals of two predatory invertebrates (the Caddisfly, Rhyacophila dorsalis, and the Stonefly Dinocras cephalotes) in streams draining land with increasingly intensive livestock farming. Rhyacophila dorsalis occurred in all streams, whereas D. cephalotes was restricted to low intensities, allowing us to test whether: i) apparent sensitivity to agriculture in the latter species reflects a more specialised diet and ii) diet in R. dorsalis varied between sites with and without D. cephalotes. DNA was extracted from dissected gut contents, amplified without blocking probes and sequenced using Ion Torrent techn...

土地利用变化可改变营养相互作用并产生广泛的功能后果，但针对水生食物网的此类影响却鲜有研究。究其原因，部分在于利用经典肠道内容物分析技术解析水生生物食谱存在诸多挑战，针对软体猎物的分析尤为困难。我们借助下一代测序（next generation sequencing）技术，对两条流经畜牧集约化程度逐步升高的流域的溪流中的两种捕食性无脊椎动物——纹石蛾（Rhyacophila dorsalis）与石蝇（Dinocras cephalotes）的近400个个体的猎物利用情况进行了解析。纹石蛾在所有采样溪流中均有分布，而该石蝇物种仅见于畜牧强度较低的样地，借此我们得以验证两项假设：其一，该石蝇物种对农业活动的表观敏感性是否与其更为特化的食谱相关；其二，纹石蛾的食谱在存在与不存在该石蝇物种的样地间是否存在差异。研究人员从解剖获取的肠道内容物中提取DNA，在不使用封闭探针的条件下进行扩增，并采用Ion Torrent测序技术（Ion Torrent）进行测序