Comparative ecotoxicity of interstitial waters in littoral ecosystems using Microtox(R) and the rotifer Brachionus plicatilis

The toxic effects of sediment interstitial waters collected from seven littoral sites in the Gulf of Cadiz were tested with the Microtox(R) assay and a 7-d Brachionus plicatilis (Rotifera) decline test. Dissolved organic carbon (DOG), nutrients (ammonia, phosphate, nitrate, nitrite, and silicate), the heavy metals (Fe, Mn, Zn, Cu, Pb, Cr, and Cd), and the linear alkylbenzensulfonate (LAS) concentrations in the interstitial water were measured. The results of assays were compared in a dose-response relationship between sites. This comparison has demonstrated a general agreement between toxicity values determined by Brachionus plicatilis and Photobacterium phosphoreum, except in the case of interstitial water toxicity from mixtures of heavy metals. Data derived from interstitial water chemistry and bioassays were assembled by multivariate statistical techniques (principal components analysis). Positive prevalence of these components in cases studied was used to establish those ranges in chemical concentrations associated with adverse effects. The interstitial water guidelines, in terms of concentrations at or below which biological effects have been shown to be minimal (mg/L), are: DOG, 12.8; phosphate, 0.28; LAS, 80.4; ammonia, 12.1; chromium, 0.0045.