Comparative sensitivity of Scenedesmus acutus and Chlorella pyrenoidosa as sentinel organisms for aquatic ecotoxicity assessment: Studies on a highly polluted urban river

Abstract

The effects of spatial and temporal differences on the water quality of the urban contaminated Reconquista River (Argentina) were evaluated by means of bioassays based on the growth of two algal populations (Chlorella pyrenoidosa and Scenedesmus acutus). The effects produced by the addition of cadmium and/or nutrient salts to the samples were also assayed. Noticeable differences in algal biomass were detected among samples from different sites, the highest values corresponding to the most polluted zones. The toxic effect of cadmium was more pronounced in S. acutus than in C. pyrenoidosa, particularly in the least polluted waters. The addition of nutrient salts to the culture medium attenuated heavy metal toxicity, mainly to C. pyrenoidosa, and also revealed nutrient limitation to algal growth in certain sites and dates. Site classifications based both on algal bioassays and on physical and chemical variables showed good agreement.