Abstract Water resources on the Canadian Prairies are at risk due to human settlement, agricultural intensification, and climatic change. The Red River Valley (RRV), Manitoba, Canada, represents a nexus of these cumulative stressors. Here land use change, combined with a recent increase in precipitation and runoff, imperils the protective function of tributaries draining to Lake Winnipeg. A concerted research effort over the past decade has greatly improved availability of data and knowledge about the RRV. However, a full synthesis of these data and information remain lacking. We undertook a review to identify and compare contemporary and historical land use, climatic, hydrologic, and water quality condition within the RRV. Then, using current knowledge of the ecological condition of streams in the RRV and elsewhere, we completed an ecological causal assessment of RRV tributaries to identify linkages and knowledge gaps between anthropogenic drivers and ecological endpoints. We found wastewater to be the candidate cause of ecological effects in RRV streams best supported by empirical evidence. A lack of complete lines of evidence linking agriculture, the greatest diffuse source of nutrient inputs, and ecological effects in RRV tributaries underscored a need for stressor-specific indicators and improved biomonitoring strategies to better detect likely impacts of land use. We also identified a need for research to connect well-known causal elements in the RRV, such as climatic variables and hydrological alteration, to ecological effects. Our findings provide direction for future research and can aid in development of an adaptive management strategy for tributaries of the RRV.

中文翻译：

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曼尼托巴省红河谷支流的生态因果评估

摘要 由于人类定居、农业集约化和气候变化，加拿大大草原的水资源处于危险之中。加拿大马尼托巴省的红河谷 (RRV) 代表了这些累积压力源的联系。这里土地利用的变化，加上最近降水和径流的增加，危及温尼伯湖支流的保护功能。过去十年的协同研究工作极大地提高了有关 RRV 的数据和知识的可用性。然而，仍然缺乏对这些数据和信息的全面综合。我们进行了审查，以确定和比较 RRV 内当代和历史的土地利用、气候、水文和水质状况。然后，利用当前对 RRV 和其他地方溪流生态条件的了解，我们完成了 RRV 支流的生态因果评估，以确定人为驱动因素和生态终点之间的联系和知识差距。我们发现废水是 RRV 流中生态影响的候选原因，得到了经验证据的最佳支持。缺乏完整的证据将农业、最大的营养投入分散来源和 RRV 支流的生态影响联系起来，这强调需要特定压力源的指标和改进的生物监测策略，以更好地检测土地利用的可能影响。我们还确定需要进行研究，以将 RRV 中众所周知的因果要素（例如气候变量和水文变化）与生态效应联系起来。