The Water Framework Directive (WFD) aims to attain ‘good quality’ status for all European water bodies through the achievement of good ecological status. To this purpose, the WFD advocates the creation of cost-effective monitoring tools to deliver appropriate data that help to create links between chemical and ecological indicators, as those from ecotoxicological research. Here, it was evaluated whether the integration of ecotoxicological tools, as bioassays and biomarkers, did (or did not) strengthen the robustness of the assessment of the ecological status obtained through well stablished biotic indices in two Atlantic estuaries. For that, a battery of in-situ bioassays, including five macroinvertebrate species (the crab Carcinus maenas, the amphipod Echinogammarus marinus, the isopod Cyathura carinata, the snail Peringia ulvae and the polychaete Hediste diversicolor, each one providing complementary information regarding key ecological functions) and a set of biomarkers, was used. In addition, the concentrations of heavy metals in sediments, and in macroalgae (Fucus), were determined, along with sediment granulometric, water physicochemical and nutrients characterization. We show that by interpreting the values of all indicators together, along with environmental components, it is possible to perform a more holistic description of the quality status of a waterbody – and, to begin to allude to factors limiting that quality. Ecotoxicological tools (in situ bioassays and biomarkers) appear to provide an added value of useful information for monitoring programmes regarding the true state - within which, both known and unknown contaminants are potentially present at concentrations sufficient to cause biological effects. Our results support the use of in situ bioassays and biomarkers within protocols aimed at fulfilling the goals of the WFD. In doing so, more complete and informative assessments of the ecological quality status of water bodies can take place.

This paper is a result of the project QWATER (Bioassay integration under the European Water Framework Directive: A step towards an ecological approach) funded by the 7th Framework Programme (FP7 2007-2013) of the European Commission through a Marie Curie Intra-European Fellowship for Career Development (PIEF-GA-2011-299747), https://qwaterprojecteu.wordpress.com. JMN acknowledges the financial programme of the Fundação para a Ciência e Tecnologia, I. P (FCT) through the Individual support attributed in the scope of Decry-Law n° 57/2016, from 29th August. This study had the support of national funds through FCT and ERDF in the framework of the programme Portugal 2020, under the projects UIDB/04292/2020, UIDP/04292/2020, granted to MARE; LA/P/0069/2020, granted to the Associate Laboratory ARNET; UIDB/Multi/04423/2020 granted to CIIMAR; and LA/P/0101/2020 granted to CIMAR-LA.

Peer reviewed