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21 February 2008 Effects of Suspended Sediment on Whole-Body Cortisol Stress Response of Two Southern Appalachian Minnows, Erimonax Monachus and Cyprinella Galactura
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Abstract

Total immunoreactive corticosteroid (IRC) levels (adjusted for fish mass; ng/g) were measured in whole-body homogenates of 2- and 8-months old Whitetail Shiners (Cyprinella galactura) and 4-months old federally threatened Spotfin Chubs (Erimonax monachus) exposed for 48 hours to varying suspended sediment concentrations (SSC; 0, 25, 50, 100, and 500 mg/L). Hydrophobic fractions were extracted from individual frozen fish after sonication and centrifugation of tissues. Extracts were resuspended in a buffer compatible with a commercially available enzyme-linked immunosorbent assay (ELISA) kit. Serially diluted concentrations of cortisol and extracts collected from unstressed fish were used to standardize the assay. Two-months old C. galactura had the highest resting level of whole-body IRC at 0 mg/L SSC. They also elicited the greatest response (three- to four-fold increase) when exposed to SSCs greater than 25 mg/L. Resting whole-body IRC levels were lowest in 8-months old C. galactura. For these fish IRC levels at 25, 50, and 100 mg/L SSC were similar to controls. Four-months old E. monachus showed a non-linear response with a possible threshold effect between 50 and 100 mg/L. At SSC greater than 100 mg/L E. monachus demonstrated a three-fold increase in whole-body IRC levels over control fish. Exposure to SSC levels greater than 100 mg/L caused a significant increase in IRC levels above baseline in both species and in all three life stages. This investigation shows that whole-body levels of IRC in young minnows increase dramatically upon exposure to SSCs greater than 25 mg/L. These data suggest that even moderate levels of suspended sediment (i.e., 100 mg/L) can severely stress young-of-year E. monachus. The imperilment of E. monachus may in part be due to stress imposed on young fish by elevated suspended sediment.

2008 by the American Society of Ichthyologists and Herpetologists
Andrew B. Sutherland, Joanne Maki, and Vicki Vaughan "Effects of Suspended Sediment on Whole-Body Cortisol Stress Response of Two Southern Appalachian Minnows, Erimonax Monachus and Cyprinella Galactura," Copeia 2008(1), 234-244, (21 February 2008). https://doi.org/10.1643/CP-07-092
Received: 11 April 2007; Accepted: 1 August 2007; Published: 21 February 2008
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