Stressors to Imperiled Fishes in the Etowah Basin Mechanisms, Sources and Management under the Etowah HCP

The Etowah River basin in Georgia, USA, supports nine imperiled fish species that are the object of protection under the proposed Etowah Habitat Conservation Plan (HCP). With urban land cover steadily increasing in the basin at the expense of forest and agricultural land cover, development-related activities and their consequences appear, as a group, to be the major threat to the species. However, urbanization is a complex phenomenon that involves numerous intermediate stressors. The purpose of this study is to review the scientific literature on urban stressors with the goal of identifying the major threats to the survival of fishes, so that management strategies may be implemented to avoid or minimize these threats as part of the Etowah HCP. We identify ten potential stressors: sedimentation, hydrologic alteration, extensive riparian buffer loss, contaminants (heavy metals, pesticides, etc.), movement barriers, channelization /piping of streams, invasive species, temperature alteration, loss of woody debris and eutrophication. For each we review the mechanisms by which the stressors may affect fish, the likely sources of the stressors within the Etowah, and the management strategies to be implemented under the Etowah HCP to address the stressors. We conclude that the first six stressors listed above are likely to be significant threats that must be managed by the Etowah HCP. We identify the most significant source of stressors as stormwater runoff from impervious surfaces, and the most critical policy as a stormwater management ordinance.