Perspective Chapter: Daphnia magna as a Potential Indicator of Reservoir Water Quality – Current Status and Perspectives Focused in Ecotoxicological Classes Regarding the Risk Prediction

Abstract

Several types of stressors come into natural water bodies, degrading their quality, and having harmful effects on aquatic biota. As a result, many attempts have been made to develop complementary techniques to those imposed by the Water Framework Directive (WFD) to improve the water quality assessment strategy in a shorter time and be more faithful to the components and contaminants of the ecosystem. Daphnia magna has been extensively used as a model organism for ecotoxicity testing, and its ecotoxicological responses to several disturbance factors have been being well characterized. From this perspective, this work aimed to evaluate the applicability of the feeding bioassays with D. magna, as well as early distress tools (biochemical biomarkers), in the assessment of water quality of natural waters of reservoirs. Samplings were performed in several sites in three Portuguese reservoirs and were conducted in the spring of 2020. Bioassays and biomarkers results showed sensitivity to different reservoirs since the sites are minimally or moderately impacted. Biological responses can be related to several environmental factors, such as surrounding areas, seston composition, and chemical analysis (WFD), among others not quantified. This set of biological responses has presented good concordance with the ecological potential of the reservoirs.

Evidence for Links between Feeding Behavior of Daphnia magna and Water Framework Directive Elements: Case Study of Crestuma-Lever Reservoir

“…Moreover, the same authors propose the evaluation of filtered and unfiltered water treatments, with different meshes, to evaluate the seston quality. In the present study, the physical and chemical determinations performed in water samples at Portuguese reservoirs demonstrated that the heavily modified and artificial water bodies had a reasonable to good quality, as showed by previous studies [2,6,34].…”

“…Eutrophic water bodies promote the development of Cyanobacteria (e.g., Anabaena and Microcystis), which are unpalatable for D. magna, and may produce toxins that can interfere with the metabolism of these organisms [2]. Other studies conducted in Portuguese reservoirs detected that these heavily modified and artificial water bodies may contain organic pollutants [34], and/or pollutants such as zinc and mercury, which inhibit the feeding rate of D. magna [6]. Regarding the exception recorded in September, where a significant increase in FR was observed, the month was characterized by a GEP.…”

“…Green-Good Ecological Potential (GEP); Yellow-Moderate Ecological Potential (MEP). FR color evaluations were performed according to the classes of disturbances described in Rodrigues et al, [34].…”

“…Recent studies have demonstrated that food performance can be associated with the seston composition, potentially more associated with the quantity and quality of phytoplankton, which represent the main sources of stress for zooplankton in reservoir waters [2,6,34]. Moreover, the same authors propose the evaluation of filtered and unfiltered water treatments, with different meshes, to evaluate the seston quality.…”