Usefulness of a freshwater macrophyte (Potamogeton pusillus) for an environmental risk assessment in a multi-source contaminated basin.

Abstract

Chemical analysis of pollutants in environmental matrices cannot always offer powerful evidence on their impact and toxicity on the aquatic biota. This paper reports the ability of Potamogeton pusillus to highlight in an aquatic ecosystem those sites with higher environmental degradation through an active biomonitoring. Organisms were exposed for 96 h in seven sites along a river where variation in pollutants mixtures and levels could be expected due to different pollution sources. Different anthropogenic activities favoured the presence of pharmaceutical compounds along the basin (atenolol and carbamazepine showed the highest levels in water) as well as metals in water (Pb, Al, As, B, Hg) and sediments (Hg) surpassing local and international environmental guidelines. Through several biomarkers responses, P. pusillus showed sensitivity when exposed to different environmental scenarios and succeeded indicating the most contaminated sites. An integrative biomarker response index (IBR) confirmed to be a useful tool to obtain a holistic interpretation of response expressed by organism despite being little used for macrophyte studies. The Principal Components Analysis (PCA) analysis showed consistently a positive association between the IBR and pollutants concentrations, being this linkage strongest when a higher compounds levels occurred in the basin (cold period). Moreover, multivariate analysis indicated that IBR values were boosted when the concentration of metal in water and in the bioavailable fraction of sediments, increased. Finally, the obtained results indicate that the use of P. pusillus in combination with chemical analysis could be considered a promising tool for environmental management of aquatic ecosystems contaminated by multi-source.