Mundahl Neal D
Program in Ecology and Environmental Science and Large River Studies Center, Department of Biology, Winona State University, Winona, MN 55987, USA.
Insects. 2025 Jan 10;16(1):59. doi: 10.3390/insects16010059.
Prior to implementing watershed-wide projects to reduce the impacts of agriculture on regional streams and rivers, stream habitats and benthic aquatic macroinvertebrate communities were assessed at 15 sites on the South Branch Root River and its major tributaries in southeastern Minnesota, USA. Triplicate kick-net samples were collected from each site during three time periods (1998, 1999, 2006/2008) and stream habitats were inventoried within 150 m long sections at each site. In total, 26,760 invertebrates representing 84 taxa were collected and used to rate stream sites using a regional multi-metric benthic index of biotic integrity (BIBI). BIBI scores were significantly correlated with total invertebrate taxa richness. BIBI ratings improved from poor and very poor at headwater sites in channelized stream sections draining agricultural lands to fair to good to excellent in downstream sections flowing through natural channels in largely forested lands. Fifty percent of samples rated stream sites as poor or very poor. Over 85% of stream habitat assessments indicated the presence of fair to good habitats, although stream sites were relatively wide and shallow and dominated by fine sediments that also embedded coarser substrates. BIBI metrics and scores were strongly positively correlated with pool area, riffle spacing-to-stream width ratios, and silt-free substrate, and negatively correlated with width-to-depth ratios. Most stream sites had few Ephemeroptera, Plecoptera, Trichoptera, and Diptera taxa and too few intolerant taxa. It is expected that benthic invertebrate communities should improve as more riparian buffers are added along all streams. However, on-going channel maintenance activities in headwater stream sections, mandated to encourage drainage of adjacent agricultural fields, will continue to negatively impact headwater habitats and biotic communities.
在美国明尼苏达州东南部的南支根河及其主要支流上，在实施流域范围的项目以减少农业对区域溪流和河流的影响之前，对15个地点的溪流栖息地和底栖水生大型无脊椎动物群落进行了评估。在三个时间段（1998年、1999年、2006/2008年）从每个地点采集了三份踢网样本，并在每个地点150米长的河段内对溪流栖息地进行了清查。总共收集了代表84个分类单元的26760只无脊椎动物，并用于使用区域多指标底栖生物完整性指数（BIBI）对溪流地点进行评级。BIBI得分与无脊椎动物分类单元总丰富度显著相关。BIBI评级从流经农业用地的渠道化溪段源头地点的差和极差，改善为流经大片森林地区自然渠道的下游段的中等至良好至优秀。50%的样本将溪流地点评为差或极差。超过85%的溪流栖息地评估表明存在中等至良好的栖息地，尽管溪流地点相对较宽且浅，且以细沉积物为主，细沉积物还掩埋了较粗的基质。BIBI指标和得分与深潭面积、浅滩间距与溪流宽度之比以及无淤泥基质呈强烈正相关，与宽度与深度之比呈负相关。大多数溪流地点的蜉蝣目、襀翅目、毛翅目和双翅目分类单元很少，不耐受分类单元也很少。预计随着所有溪流沿线增加更多的河岸缓冲带，底栖无脊椎动物群落将会改善。然而，源头溪段正在进行的渠道维护活动，其目的是鼓励相邻农田排水，将继续对源头栖息地和生物群落产生负面影响。
