Idaho Department of Environmental Quality, Lewiston, Idaho, United States.
Cadmus Group, Waltham, MA, United States.
PeerJ. 2024 Oct 4;12:e18060. doi: 10.7717/peerj.18060. eCollection 2024.
Human activities can increase sediment delivery to streams, changing the composition, distribution, and abundance of stream aquatic life. Few U.S. states have numeric water quality standards for streambed sediment under the Clean Water Act, so managers often need to develop local application-specific benchmarks. This study developed stream surface fine sediment <2 mm (sand and fines, SF) and macroinvertebrate fine sediment biotic index (FSBI) benchmarks and an application framework to test for sediment-induced macroinvertebrate community composition changes in 1-4 order Idaho streams. FSBI reference benchmarks were calculated as the 25 percentile FSBI value among reference sites within three ecoregion-based site classes. Two approaches were used to develop SF benchmarks. Quantile regression was used to define reach-specific SF benchmarks representing an upper bound value expected under reference conditions. In addition, logistic regression was used to predict SF values with 50% and 75% probability that FSBI is worse than reference within each stream order and site class. The strength of association between SF benchmarks and macroinvertebrate community condition was evaluated by calculating relative risk using multiple datasets and examining responses of multiple macroinvertebrate indicators to SF benchmark status. SF reference benchmarks generally had stronger associations with poor macroinvertebrate condition than SF stressor-response benchmarks. Across datasets and macroinvertebrate indicators, poor macroinvertebrate condition was 1.8-3 times more likely when SF reference benchmarks were exceeded than when achieved. We propose rating the strength of evidence for a surface fine sediment-induced macroinvertebrate community composition change at the sample event scale as 'unlikely' if both SF and FSBI reference benchmarks are achieved, having 'mixed evidence' if only one reference benchmark is achieved, and 'likely' if both reference benchmarks are not achieved. We recommend combining ratings with other relevant data in a weight-of-evidence approach to assess if sediment impairs aquatic life.
人类活动会增加泥沙向溪流的输送，从而改变溪流中水生生物的组成、分布和丰度。在美国，根据《清洁水法》，很少有州对溪流底泥制定了水质标准，因此管理者通常需要制定特定于当地的应用基准。本研究制定了溪流表层细泥沙（<2 毫米，即砂和粉砂，SF）和大型底栖无脊椎动物细泥沙生物指数（FSBI）基准，并构建了一个应用框架，以检验 1-4 级爱达荷州溪流中泥沙引起的大型底栖无脊椎动物群落组成变化。FSBI 参考基准是通过在基于三个生态区的站点类别内，对参考站点的 FSBI 值进行 25%分位数计算得出的。两种方法用于制定 SF 基准。分位数回归用于定义特定于河段的 SF 基准，这些基准代表了在参考条件下预期的上限值。此外，逻辑回归用于预测在每个河流等级和站点类别中，FSBI 变差到参考值以下的概率为 50%和 75%的 SF 值。通过使用多个数据集计算相对风险，并检查多个大型底栖无脊椎动物指标对 SF 基准状态的响应，评估了 SF 基准与大型底栖无脊椎动物群落状况之间的关联强度。SF 参考基准与较差的大型底栖无脊椎动物状况的关联通常比 SF 胁迫-响应基准更强。在多个数据集和大型底栖无脊椎动物指标中，当 SF 参考基准超过时，大型底栖无脊椎动物状况较差的可能性是达到基准时的 1.8-3 倍。我们建议在样本事件尺度上，对表面细泥沙引起的大型底栖无脊椎动物群落组成变化的证据强度进行评级，如果 SF 和 FSBI 参考基准都达到了，则为“不太可能”；如果只有一个参考基准达到了，则为“有混合证据”；如果两个参考基准都未达到，则为“很可能”。我们建议将评级与其他相关数据结合起来，采用证据权重方法评估泥沙是否对水生生物造成损害。
