Anthropogenic stressors such as urban development, agricultural runoff, and riparian zone degradation impair stream water quality and biodiversity. However, the intricate pathways that connect these stressors at watershed and riparian scales to stream ecosystems—and their interplay with climate and hydrology—remain understudied. In this study, we used Partial Least Squares (PLS) path modeling to examine these pathways and their collective impacts on stream water quality and fish community structures across 233 watersheds in the Great Lakes region. Our study suggests that moderate levels of watershed development enhance overall fish richness, potentially due to increased water temperature and nutrient availability, but reduces both the percentages and richness of cold water and intolerant taxa. Riparian quality exerts indirect effects on water quality with climate and stream order serving as key mediators. Complementing our SEM analysis, we also used Multiple Linear Regression (MLR) models and identified a significant positive relationship between the proportion of clay and agricultural land with TN concentrations. However, TP concentrations are influenced by a more complex set of interactions involving developed areas, soil, and slope. These findings emphasize the necessity of adopting integrated management strategies to preserve the health and integrity of freshwater ecosystems in the Great Lakes region. These strategies should integrate watershed and riparian protection measures while also taking into account the effects of climate change and specific local conditions.

中文翻译：

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将流域发展和河岸质量与溪流水质和鱼类群落联系起来的途径：来自大湖区 233 个子流域的见解


城市发展、农业径流和河岸带退化等人为压力因素会损害溪流水质和生物多样性。然而，将流域和河岸尺度的这些压力源与河流生态系统连接起来的复杂途径及其与气候和水文的相互作用仍然没有得到充分研究。在本研究中，我们使用偏最小二乘 (PLS) 路径模型来研究这些路径及其对五大湖地区 233 个流域的溪流水质和鱼类群落结构的集体影响。我们的研究表明，适度的流域发育可以提高鱼类的整体丰富度，这可能是由于水温和营养物质可用性的增加，但会降低冷水和不耐受类群的百分比和丰富度。河岸质量对水质产生间接影响，其中气候和河流秩序是关键调节因素。作为对 SEM 分析的补充，我们还使用了多元线性回归 (MLR) 模型，并确定了粘土和农业用地的比例与总氮浓度之间存在显着的正相关关系。然而，总磷浓度受到涉及发达地区、土壤和坡度的一系列更复杂的相互作用的影响。这些发现强调了采取综合管理战略来保护大湖区淡水生态系统的健康和完整性的必要性。这些战略应整合流域和河岸保护措施，同时考虑气候变化和当地具体条件的影响。