Channelized agricultural headwater streams are common throughout agricultural watersheds in the midwestern United States. Understanding fish-habitat relationships within these streams will provide information that can assist with developing conservation and restoration strategies for these degraded streams. From spring 2006 to fall 2010, we collected fishes and measured riparian habitat, instream habitat, and water chemistry variables from seven sites in Cedar Creek, Indiana, and 14 sites in Upper Big Walnut Creek, Ohio. We found that fish community structure was more strongly correlated with instream habitat than riparian habitat or water chemistry in both watersheds. We also observed interrelationships among instream habitat, watershed size, and fish communities within both watersheds that suggest that the hydrological changes that occur with increasing watershed size are the underlying factor for fish community changes that occur with increasing watershed size. Our results suggest that conservation and restoration efforts within channelized agricultural headwater streams in the midwestern United States, where nutrients and herbicide concentrations are low, need to address physical habitat degradation to positively influence fish community structure.

中文翻译：

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渠道化农业源头溪流中鱼类栖息地关系的保护意义

在美国中西部的整个农业流域中，渠道化的农业源头溪流很常见。了解这些河流中鱼类与栖息地的关系将提供有助于为这些退化河流制定保护和恢复策略的信息。从 2006 年春季到 2010 年秋季，我们从印第安纳州雪松溪的七个地点和俄亥俄州大核桃溪上游的 14 个地点收集了鱼类并测量了河岸栖息地、河流栖息地和水化学变量。我们发现，在两个流域中，鱼类群落结构与河内栖息地的相关性比河岸栖息地或水化学更强烈。我们还观察到了河流内栖息地、流域大小、和两个流域内的鱼类群落表明，随着流域大小的增加而发生的水文变化是随着流域大小的增加而发生的鱼类群落变化的潜在因素。我们的研究结果表明，在美国中西部，营养物质和除草剂浓度较低的渠道化农业源头河流中的保护和恢复工作需要解决物理栖息地退化问题，以积极影响鱼类群落结构。