The effect of chromium on the hemoglobin concentration of Limnodrilus hoffmeisteri (Oligochaeta: tubificidae)

The purpose of this study was to determine the toxic effects of polluted sediments, mainly chromium, the El Niagara reservoir (Aguascalientes, Mexico) on a benthic oligochaete species. Acute toxicity tests with hexavalent chromium in an artificial sediment-water system resulted in 24-, 48-, and 96-h LC50 values of 49.53, 22.81, and 5.11 mg available chromium/kg dry sediment, respectivley, in Limnodrilus hoffmeisteri. The uptake of chromium by tubificids from artificial and polluted reservoir sediments was found to increase with metal concentration in sediments and exposure time. The increase was higher in experiments with artificial sediment. Cr concentration in worms was related to hemoglobin content, which decreased significantly when Cr concentrations were above 1.0 mug/g dry weight. Bioavailable chromium in the El Niagara reservoir sediments may be an important factor limiting the benthic species in this ecosystem. (C) 2001 Elsevier Science.