Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.
Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.
Biol Lett. 2022 Mar;18(3):20210598. doi: 10.1098/rsbl.2021.0598. Epub 2022 Mar 2.
Local and regional habitat conditions associated with agricultural activity can fundamentally alter aquatic ecosystems. Increased nutrient inputs, channelization and reduced riparian habitat both upstream and locally contribute to the degradation of stream ecosystems and their function. Here, we examine stream food webs in watersheds that feed into Lake Erie to determine the effects of agricultural land cover on major food web energy pathways and trophic structure. Given that higher agricultural intensity can increase nutrient runoff and reduce the riparian zone and litter in-fall into streams, we predicted that generalist fish would derive less energy from the terrestrial pathway and become more omnivorous. Consistent with these predictions, we show that both mean terrestrial energy use and trophic position of the resident top consumer, creek chub (), decrease with local agricultural intensity but not with watershed-level agriculture intensity. These findings suggest that local riparian buffers can maintain trophic structure even in the face of high whole-watershed agricultural intensity.
与农业活动相关的局部和区域生境条件可以从根本上改变水生生态系统。增加的养分输入、河道渠化和上游及局部减少的河岸栖息地都导致了溪流生态系统及其功能的退化。在这里，我们研究了流入伊利湖的流域中的溪流食物网，以确定农业土地覆被对主要食物网能量途径和营养结构的影响。鉴于较高的农业强度会增加养分径流并减少河岸带和进入溪流的凋落物，我们预测，广食性鱼类从陆地途径获得的能量将减少，并且变得更加杂食性。这些预测一致，我们表明，无论是居民顶级消费者（溪鱒）的平均陆地能量利用还是营养位，都随当地农业强度的增加而降低，但不受流域水平农业强度的影响。这些发现表明，即使在整个流域农业强度高的情况下，当地的河岸缓冲带也可以维持营养结构。
