Microalgae Growth Inhibition-Based Reservoirs Water Quality Assessment to Identify Ecotoxicological Risks

Sara Rodrigues,Sara C Antunes,Ivo Pinto,Nuno Formigo

doi:10.3390/w13192605

Abstract

This work intended to assess the adaptability of bioassay with Raphidocelis subcapitata to be used as a complement to the water quality assessment parameters of reservoirs imposed by the European Water Framework Directive (WFD). Thus, water samples of Portuguese reservoirs (Miranda, Pocinho, Aguieira, and Alqueva) were analyzed in three sampling periods (spring and autumn 2019, and spring 2020). A physical and chemical report of waters was also performed. R. subcapitata assay proved to be sensitive, indicating the presence of a potential perturbation that was not always associated with chemical analysis performed. In general, in the spring samplings, the water samples showed more disturbances to R. subcapitata, which in some situations may be associated with the higher content of nutrients and metals. Microalgae assay can be an effective complementary tool to indicate the ecotoxicological potential since they responded quickly to all sample components of water samples, in a wide-ranging variety of water conditions (different sites in several reservoirs). High similarities between the final ecotoxicological and the ecological potentials, according to the WFD parameters, were detected. The ecotoxicological approach based on our results allowed to confirm that bioassays with R. subcapitata are suitable and sensible to detect perturbations.

Highlights

General physical and chemical parameters determined at the sampling points in the three sampling periods are presented in Table 1, for the four reservoirs, as well as the environmental quality standards (EQS)
A GEP for all sampling sites of all reservoirs, in the three sampling periods was obtained, since the pH values recorded are within the range of EQS
Dissolved oxygen revealed values above within limits (EQS, Table 1), with exception of the Miranda and the Aguieira reservoirs (Ag1 and Ag2), in Autumn of 2019 (Aut19), since the oxygen values were slightly inferior to the quality limits (Table 1)

Summary

Introduction

The Water Framework Directive (WFD) 2000/60/EC [1] is an European directive that obliges all member states to attain the good quantitative and qualitative status of all water compartments [2]. In this directive, specific physical, chemical, biological, and hydromorphological elements aim to classify the ecological potential (EP) of heavily modified water bodies (e.g., reservoirs). For the physical and chemical parameters, only four parameters (pH, dissolved oxygen, nitrate, and total phosphorus) have established environmental quality standards (EQS) values

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Results

Conclusion