The usefulness of ecotoxicological tools to improve the assessment of water bodies in a climate change reality

This study aimed to analyse the added value of using ecotoxicological tools to complement and improve the assessment of natural water bodies status, in situations of climate change, with a higher frequency of extreme events as floods or droughts. Four water bodies of streams in the Guadiana Basin (Álamos, Amieira, Lucefécit, Zebro) were studied in 2017 and 2018 and classified based on the Water Framework Directive (WFD) parameters: Biological Quality Element - Phytobenthos (diatoms), General chemical and physicochemical elements, Specific pollutants, and Priority Substances. Complementarily, bioassays (including lethal and sublethal parameters) were carried out with organisms of different trophic levels: (i) the bacteria Aliivibrio fischeri; (ii) the microalgae Pseudokirchneriella subcapitata; (iii) the crustaceans Daphnia magna, Thamnocephalus platyurus and Heterocypris incongruens. A classification system with 5 scores was developed, permitting to classify water bodies from non-toxic (EC50 > 100 %; growth and feeding rate > 80 %; blue) to highly toxic (EC50 < 10 %; growth and feeding rate < 10 %; red). The comparison between the classification based on the WFD parameters and on ecotoxicological endpoints showed similar results for 71 % of the samples, and significant positive Pearson correlations were detected between the diatom-based Specific Polluosensitivity Index (SPI) and EC50V.fisheri, the algae growth rate and Shannon diversity index. These results indicate that when the biological quality elements cannot be used (namely under drought or flooding conditions) the application of ecotoxicological bioassays may be a good alternative. Further, when ecotoxicological parameters were included, an increase of worse classifications (Bad and Poor) was observed, revealing an improvement in the sensitivity of the classification, mainly in presence of specific and priority substances. So, the ecotoxicological analysis appears to provide useful information regarding the potential presence of both known and unknown contaminants at concentrations that cause biological effects (even within the WFD limits), in agreement with several authors that have already suggested its use in biomonitoring.

[Changes in the electrophoretic proteinogram of calves with experimental helminthiasis]

Ten cross-bred calves (Holstein x Zebu) were infected with helmintics larvae. Three female calves had 4 to 5 months and 7 male calves, 4 to 7 months of age. Of the larvae given to them, 1720 were Cooperia sp., 1560 Oesophagostomum sp. and 720 were Haemonchus sp. This experiment was projected to study the changes in serum proteins, namely the total one and particulary its fractions: Albumin and the alpha 1, alpha 2, beta and gamma globulins. Before infection and after it 54 days, with 6 day intervals, the animals were bled for making the respective examination. The results were as follows low percentage of protein and albumin, alpha 1, alpha 2, beta e gamma globulins, as well as the ratio albumin/globulin were practically unchanged. The data were statistilly analysed.

[Peripherial ATP-ases in the different components of the central nervous system of Periplaneta americana L. (author's transl)]

A smaller ATP-ase activity in the abdominal nerve cord of the Periplaneta americana L. was observed when compared by peripheral area with ganglia activity of the central nervous system which have more complex physiological functions. There was no significant difference in the enzyme distribution in the pro, meso, metatoraxic, subesophageal ganglia and the sixth abdominal ganglion.