Aquatic ecotoxicology approaches in Western Mexico

A series of bioindicator organisms for aquatic ecosystems are being maintained under laboratory conditions in order to analyze effects of pollution on aquatic wildlife and potential effects on human health. Growth kinetics of algae Pseudokirchneriella subcapitata was used to evaluate effects of the surfactant nonilphenol (NP). Brachionus calyciflorus was used to set up a model of endocrine disruption using the fungicide vinclozolin (Vc). We exposed salamanders from the genus Ambystoma sp., to different concentrations of both the aneugen colchicine (COL) and the clastogen cyclophosphamide (CP) and we determined the frequency of micromicleated cells (MNC) in their shed skin. The presence of spontaneous micronuclei in peripheral blood erythrocytes from 10 fish species in Lake "La Alberca," Michoacan (Mexico), was evaluated as a possible biological indicator of genotoxic agents. Results confirm the sensivity of Pseudokirchnericlla subcapitata to growth kinetics: the range of concentration of NP (20, 200 and 2000 mu g L-1) shows an inverted U shape in its maximum growth rate; Dimethyl sulfoxide (DMSO) used as a positive control and to solvate NP induced an inverse stimulatory effect on growth rate in the range of concentrations analyzed (0.0023, 0.023 and 0.23% v v(-1)). In the use of the rotifer Brachionus calyciflorus, the range of Vc from 0. 185 mg L-1 to 3 mg L-1 clearly showed an inverted U shape characteristic of endocrine disruptions. We were able to use shed skin from Ambystoma sp., to measure MNC frequencies induced either by an aneugenic or a clastogenic compound. The MNC frequency was increased significantly by all doses of COL and CP, administered either as single or repeated exposures. The presence of MNC in the shed skin and the speed of sloughing lead us to propose that the sheds of Ambystoma sp., or other amphibians that slough their skin, as suitable alternative models for detecting genotoxic exposures relevant to aquatic environments. In the survey to determine potential biological fish indicators for genotoxic agents, the frequency of spontaneous micronucleated erythrocytes (MNE) found in the goodeid Xenotoca melanosoma (3.7 +/- 1.6 MNC) and the cichlid Oreochromis aureus (2.0 +/- 1.0 MNC) suggests that these species can be considered as potential biological indicators.