A Comparison of Sediment Metal Concentrations as Potential Stressors to Resident Benthic Communities in an Agricultural Waterbody

Abstract

This study was designed to (1) determine the relationship between the sediment concentrations of eight total metals (As, Cd, Cr, Cu, Pb, Hg, Ni, and Zn) and five simultaneously extracted metals (SEM) (Ni, Cu, Zn, Cd, and Pb) with 11 benthic metrics based on a three-year data set including two seasons per year for an agricultural water body (Cache Slough, California), and (2) rank the importance of individual metals within a metal mixture as potential stressors to resident benthic communities. The total arsenic, lead, and cadmium showed the highest number of statistically significant and ecologically meaningful relationships with benthic metrics. The total copper, nickel, zinc, chromium, and mercury were not reported to show any statistically significant and ecologically meaningful relationships with any of the benthic metrics. There were also no statistically significant and ecologically meaningful relationships between the benthic metrics and the simultaneously extracted (bioavailable) metals. Both stress tolerant and stress sensitive benthic metrics were reported to have the best discriminatory power for detecting the adverse effects from metals. Mixed agreement results were reported when comparing statistically significant and ecologically meaningful benthic metric relationships with the threshold effect level (TEL) exceedances for the various metals.