The effects of urbanization on the health of fish and benthic macroinvertebrate communities in the upper Cahaba River watershed (Alabama)

In order to evaluate the effects of urbanization on aquatic community health, three studies were conducted. In the first study, benthic macroinvertebrates were collected upstream and downstream of three wastewater treatment plants which discharge into Buck Creek, a tributary of the Cahaba River in Shelby County, Alabama. The downstream data for most collections showed little difference from that of the upstream collections. The only major findings to note were a healthier biological community below the Alabaster plant and poorer biological community below the Helena plant, both during the September, 2002 collection period.; The second study involved using a field-based approach to investigate the bioconcentration potential of the herbicide, atrazine, at environmental concentrations (<0.2 ppb). Tissue concentrations were measured in 9 Asiatic clam (Corbicula fluminea) samples and 8 riffle snail ( Elimia sp.) samples using enzyme linked immunosorbent assay in conjunction with acetone extraction. Two Corbicula samples had detectable levels of atrazine and bioconcentration factors of 52 and 57, while only one Elimia sample with detectable atrazine had a bioconcentration factor of 405. While this study did not yield enough data to accurately determine bioconcentration factors, it showed this extraction procedure to be an excellent screening tool for determining where further study of a particular site, or organism, is needed.; The third study examined fish and macroinvertebrate communities at fifteen sites on the upper Cahaba River over a 3-year period. Fishes were sampled by seining, with all individuals released after identification. Macroinvertebrates were sampled and analyzed using three different protocols: (1) single habitat approach in which only riffle/run areas were sampled; (2) multihabitat approach used by Region 4, United States Environmental Protection Agency; and (3) multihabitat approach used by the Alabama Department of Environmental Management. We found both the fish and macroinvertebrate communities to be generally in-balance, although heavy sediment loads have negatively impacted certain areas in the more urbanized reaches of the river.