In QWATER, a battery of five in situ bioassays was applied simultaneously in six different sampling sites within the estuaries of Mondego and Lima rivers. The battery was composed by ecological relevant species of the different trophic levels of estuaries: the crab Carcinus maenas (predator omnivorous), the snail P. ulvae (decomposer), the polychaete Nereis diversicolor (scavenging omnivourous), the isopod C. carinata (benthic omnivorous), and the amphipod E. marinus (macroalgae-associated omnivorous). Biomarkers (i.e., the enzymes Cholinesterase, Glutathione S-transferase, and Catalase, and lipid peroxidation) for a set of the individuals used in the battery were determined as another line of evidence in collaboration with Dr. Luis Vieira member of the ECOTOX Lab from University of Porto headed by Prof. Dra. Lúcia Guilhermino. Additionally, the chemical characterization of a set of metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) in samples of sediment and algae, and the proportion of the labile fraction of metals in sediments from each deployment site were studied. The chemical characterization was carried out in collaboration with Dr. Mark Taggart, from the University of the Highlands and Islands, UK, and Dra. Natalia Ospina-Alvarez from the University of Warsaw, Poland. Finally, the ecosystem status of the selected sites was addressed based on ecological indices (e.g., BAT, BENTIX, M-AMBI). Therefore, different sources of information, ecotoxicological (bioassays and biomarkers), chemical and ecological indices, were available for the integration.
Principal component analyses were performed independently for the indices of each source of information, in order to improve the interpretation of the resultant PCA-factors in biological terms. The values of the PCA-factors for each sampling site were extracted and comparatively assessed. Results shown some discrepancies in the water quality determined from each independent factor, i.e., the sampling sites were not equally ordered by all factors (see below). Therefore, only by interpreting the values of all PCA-factors together is possible to perform a complete assessment of water quality status. For instance, ecological indices highlighted one of the sampling sites in the Mondego as the best water quality. However, bioassays and biomarkers derived indices showed a high level of stress at that site, which was reinforced by high levels of pollutants from the chemical indices.
Thus, the QWATER working hypothesis about that the ecotoxicological indices are able to significantly contribute to the assessment and managing of water bodies in compliance with the WFD could be validated (manuscript in preparation).