An ecotoxicological approach can complement the assessment of natural waters from Portuguese reservoirs?

Within the scope of the European Water Framework Directive (WFD), the scientific community recognized clear opportunities to take advantage of the use of ecotoxicological tools in water quality assessments. In this perspective, bioassays and biomarkers were suggested to contribute to the integration of the chemical and biological conditions, and thus to provide an overall insight into the quality of a water body. This study aimed to assess whether current bioassays as feeding rate assays with Daphnia longispina and growth inhibition assays with Lemna minor are suitable to detect potential ecotoxicity, using waters from Portuguese reservoirs. Several sampling sites were defined in reservoirs (Miranda, Pocinho, and Alqueva). The samplings were conducted in autumn of 2018 and spring of 2019. Total chlorophyll, lipid peroxidation, and proline content were also evaluated in L. minor. Results demonstrated that D. longispina showed some sensitivity to water treatments; however, the results were difficult to interpret since no reason or trend can be accurate. All parameters of L. minor did not show sensitivity to detect potential ecotoxicological risks associated with natural water understudy, since no discrimination among the water treatments was recorded. However, biomarkers/bioassays proved to be concordant to each other. Under the conditions evaluated here (reservoirs and sampling periods), the biological responses observed were not consistent, clear, and coherent with the physical-chemical parameters and chemical analyses performed, suggesting that the ecotoxicological tools selected were not sensitive to assess water quality in this type of ecosystems. In this sense, species of different trophic levels are recommended for ecotoxicological analyses due to differences in species sensitivities.

Morphology, ultrastructure, genetics, and morphometrics of Diplostomum sp. (Digenea: Diplostomidae) metacercariae infecting the European flounder, Platichthys flesus (L.) (Teleostei: Pleuronectidae), off the northwest coast of Portugal.

The morphology, ultrastructure, genetics, and morphometrics of a species of Diplostomum von Nordmann 1832 (Digenea: Diplostomidae), isolated from the European flounder (Platichthys flesus (L.)) caught off the northwest coast of Portugal, are characterized. The metacercarial stage was found unencysted in the lens capsule of the eye. Light microscopical observations revealed the existence of some variability in specimen shape and size, with two morphotypes, referred to as "round" and "long", being apparent. Scanning electron microscopy revealed a smooth, unarmed tegument, with the lappet region being the most irregular and porose. Both the oral and ventral suckers were provided with a series of papillae, which presented very distinctive ultrastructural features and were particularly conspicuous in the case of the ventral sucker. The two morphotypes detected were found to have 100% genetic correspondence in the 18S + ITS1 + 5.8S region of the rDNA. Since the genetic data for this metacercaria differed from those of the species of Diplostomum available in GenBank, a description of a new genotype (accession number GQ370809) is provided. The molecular phylogenetic analyses, in conjunction with principal components and cluster analyses based on morphometric data, revealed the existence of consistent differences between the Diplostomum sp. metacercariae from flounder compared with Diplostomum spathaceum, Diplostomum mergi, Diplostomum pseudospathaceum, and Diplostomum paracaudum. The latter of these species was found to be the most similar to the present material. Our results do not support an evolutionary separation of the European and North American species of Diplostomum.