Impacts of a Small Dam Removal on the Endangered Watercress Darter

Dam removals are typically well-planned events designed to restore sections of habitat to natural conditions within stream or river systems. In this paper, we document the deliberate but unplanned removal of a small dam that had created additional habitat for the federally-endangered watercress darter (Etheostoma nuchale) at Roebuck Spring in Birmingham, Alabama. On 19 September 2008, Birmingham city workers removed the dam without consulting U.S. Fish and Wildlife Service or the Alabama Department of Conservation and Natural Resources. This genetically-unique darter population was the largest of all native populations prior to dam removal. To determine the effects of the dam removal, we monitored basic water quality parameters and fish population characteristics for eight months following dam removal and compared these data to an ongoing study dating approximately 17 months prior to dam removal. Though no major changes in water quality were evident following this event, pre- and post-dam removal data were a valuable resource to ensure normal conditions were maintained during expedited restoration efforts. Destruction of the dam resulted in mortality of approximately 11,760 watercress darters, one of the largest documented losses of an endangered species. In addition, we observed a significant reduction in watercress darter abundance, increased mortality due to predation, and reduced reproduction potential the following spring, all of which could significantly impact this population's long-term viability. Our results show that long-term monitoring can play an important role in guiding restoration efforts following disastrous habitat alterations, but increased awareness and education of stakeholders and the local community should be essential components of any endangered species conservation plan.

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