Evaluation of heavy metal sediment toxicity in littoral ecosystems using juveniles of the fish Sparus aurata

Abstract

The toxicity of sediments from two littoral ecosystems of the Gulf of Cadiz was tested using juveniles of the fish Sparus aurata (seabream). Concentrations of total carbon and nitrogen, organic carbon, 14 heavy metals (Fe, Mn, Cu, Zn, Pb, Cd, Ag, Hg, As, Sn, V, Ni, Co, Cr), and the surfactant linear alkyl benzenesulfonate (LAS) in the sediments were measured. Chemical analysis was performed in the stations to determine the degree and nature of contamination. Four different endpoints were selected in the toxicity test: survival, superficial alteration, hematocrit analysis, and histological damage. After 14 days, survival, superficial alteration, and hematocrit analysis did not reveal effects of the different sediments tested. The histological and cellular damage revealed a more sensitive response to measured chemicals in sediments and they were found to be a powerful tool to evaluate sediment toxicity effects. Semiquantitative evaluation of the histological damage demonstrated correlation with sediment concentrations of some of the heavy metals (Cr, Cd, Pb, Ag, Cu) and the surfactant (LAS). Data derived from chemical concentrations and toxicity tests were assembled by multivariate statistical techniques (principal components analysis) to identify the ranges of chemical concentrations associated with an adverse effect. The results obtained, as suggested by site-specific sediment quality values, were the following: Cr>/=90.2; Cd>/=1.24; Pb>/=52.5; Ag>/=0.68; Cu>/=71.2; LAS>/=8.7 mg kg-1 of dry sediment. These results are mainly in concordance with studies performed in other areas of the world and therefore support wide application of the method.