Agricultural land use leads to changes in physical and chemical characteristics of sediment that influence macroinvertebrate community diversity and abundance in streams. To the best of our knowledge the joint influence of sediment’s physical and chemical characteristics on stream macroinvertebrates has not been assessed. We measured sediment’s physical and chemical characteristics and sampled macroinvertebrates in eight agricultural headwater streams in Indiana, Michigan, and Ohio, United States, in 2017 and 2018 to determine the physical and chemical conditions of the sediment, to evaluate the relationships between physical and chemical characteristics of the sediment, and the relationship of macroinvertebrate communities with the sediment’s physical and chemical characteristics. Sediments within most sites were dominated by sand or silt. pH was suitable for macroinvertebrates and nitrate, herbicide, and trace metal concentrations were below concentration levels anticipated to affect macroinvertebrate survival. Linear mixed effect model analysis results indicated that a physical gradient of percent small gravel and percent silt was positively correlated (p < 0.05) with a chemical gradient of potassium concentrations, magnesium concentrations, and percent total nitrogen in the sediments. Our linear mixed effect model analysis results also indicated that Invertebrate Community Index scores were negatively correlated (p < 0.05) with a chemical gradient of simazine and calcium concentrations and were negatively correlated (p < 0.05) with physical gradient of grain size diversity and percent sand. Our results suggest that watershed management plans need to address physical and chemical degradation of sediment to improve macroinvertebrate biotic integrity within agricultural headwater streams in the Midwestern United States.

中文翻译：

---

沉积物理化特性​​对农业源流中大型无脊椎动物群落的影响

农业土地利用导致沉积物的物理和化学特性发生变化，从而影响河流中大型无脊椎动物群落的多样性和丰度。据我们所知，沉积物的物理和化学特性对河流大型无脊椎动物的共同影响尚未评估。我们于 2017 年和 2018 年在美国印第安纳州、密歇根州和俄亥俄州的 8 条农业源水流中测量了沉积物的物理和化学特征并采样了大型无脊椎动物，以确定沉积物的物理和化学条件，评估物理和化学特征之间的关系沉积物，大型无脊椎动物群落与沉积物物理和化学特征的关系。大多数地点内的沉积物以沙子或淤泥为主。pH 值适用于大型无脊椎动物，硝酸盐、除草剂和痕量金属浓度低于预期会影响大型无脊椎动物存活的浓度水平。线性混合效应模型分析结果表明，小砾石百分比和淤泥百分比的物理梯度与沉积物中钾浓度、镁浓度和总氮百分比的化学梯度呈正相关（p < 0.05）。我们的线性混合效应模型分析结果还表明，无脊椎动物群落指数得分与西玛津和钙浓度的化学梯度呈负相关（p < 0.05），与颗粒大小多样性和沙子百分比的物理梯度呈负相关（p < 0.05） .