A survey of potential stressor-induced physiological changes in carp (Cyprinus carpio) and barbel (Barbus bocagei) along the Tajo River.

The objective of this study was to evaluate fish response to acute stress induced by confinement after capture. Because of the previously reported presence of chemical compounds in the Tajo River basin where the study samplinig took place, an exposure biomarker to organic chemicals (retinol) was used. Cortisol and glucose were used as stress biomarkers. Plasma levels of cholesterol were used as lipidic metabolism indicators, and retinol level was used as a specific exposure biomarker. A reference site was established along 300 km of the Tajo River, and nine sampling sites were selected on the basis of whether various human activities and hydrographic characteristics were present. A total of 55 carp (Cyprinus carpio) and 52 barbel (Barbus bocagei) were examined. Cortisol and glucose levels were considered acceptable indicators of the response of the fish to induced stress. In the barbel, plasma retinol levels decreased at two of the sampling sites indicating possible exposure to organic compounds. The overall evaluation of these parameters enabled us to identify three sampling sites at which more studies should be carried out. The possible relationship between the health state of wild fish and the presence of organic compounds or sources of pollution was considered.

Identification of organic compounds and ecotoxicological assessment of sewage treatment plants (STP) effluents.

An integrated approach combining chemistry and biological methods was conducted to assess the toxicity of seven sewage treatment plant effluents. Solid phase concentration procedures were applied to facilitate the study of organic micro pollutants. A chemical analysis was performed by GC/MS. Organic fraction toxicity was determined by using bioassays such as Daphnia magna and Chlorella vulgaris tests and sub-lethal effects were also evaluated by using Salmonella typhimurium Test (mutagenicity), recombinant yeast screen (estrogenicity), and Oryzias latipes embryo-larval test. More than 49 compounds were detected in the organic fraction due to the various inputs of each effluents. The most frequently detected compounds in the effluents were bisphenol A (BPA), octylphenol (OP), 1,2-benzenedicarboxylic acid, bis(2-ethylhexyl) ester (DEHP) and 1,2-benzenedicarboxylic acid, bis(methylpropyl) ester (DBP). Biological assays showed toxicity effects on D. magna tests in all samples, whereas toxicity on C. vulgaris or S. typhimurium tests were not observed. Estrogenicity and teratogenicity were observed in several samples. The cause-effect relationship could not be established given the high chemical complexity of the effluents and the lack of information available on 70% of the detected compounds subsequent to reviewing various data bases. Nevertheless, due to the high chemical variability revealed by STP effluents, bioassay sets may provide a very useful amount of information for detecting potential toxicity risks.