Biochemical parameters in Tubifex tubifex as an integral part of complex sediment toxicity assessment

Abstract

Background, aim, and scope Restoration of lakes and reservoirs with extensive cyanobacterial water bloom often requires evaluation of the sediment quality. Next to the chemical analysis of known pollutants, sediment bioassays should be employed to assess toxicity of the present contaminants and to make predictions of associated risk. Brno reservoir in the Czech Republic is a typical example of water bodies with long-term problems concerning cyanobacterial water blooms. Comprehensive assessment of reservoir sediment quality was conducted since successful reservoir restoration might require sediment removal. An important part of this survey focused on an examination of the utility of Tubifex tubifex and its sublethal biochemical markers for the assessment of direct sediment toxicity. Materials and methods This complex study included chemical analysis of contaminants (heavy metals, organic pollutants), ecotoxicity testing of sediment elutriates (tests with Daphnia magna, Pseudomonas putida, Sinapis alba, Scenedesmus subspicatus), and other parameters. We have tested in more detail the applicability of T. tubifex as a test organism for direct evaluation of contact sediment toxicity. Survival tests after 14 days of exposure were complemented by an assessment of parameters serving as biomarkers for sublethal effects [such as total glutathione content (GSH), activities of the enzymes glutathione transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR)]. The data matrix was subjected to multivariate analysis to interpret relationships between different parameters and possible differences among locations. Results The multivariate statistical techniques helped to clearly identify the more contaminated upstream sites and separate them from the less contaminated and reference samples. The data document closer relationships of the detected sediment contamination with results of direct sediment exposure in the T. tubifex test regarding mortality but namely regarding the sublethal endpoints rather than the results obtained with other test organisms exposed to sediment elutriates. Aside from the reduction in T. tubifex survival, the sediments with organic pollution caused an increase in glutathione content and increased activities of glutathione S-transferase and glutathione peroxidase in the exposed T. tubifex worms. Discussion Results of our study confirm the suitability of T. tubifex for toxicity testing of raw waters and sediments. This longer-lasting direct contact test has proven more sensitive and appropriate to reflect a lower level of pollution than do the elutriate tests. Sensitive biochemical changes in T. tubifex, including an elevation in GSH levels and GST activities, reflect a general stimulation of detoxification metabolisms in the presence of xenobiotics. The results also suggest an important role of glutathione and related enzymes in detoxification processes and possible involvement of oxidative stress in toxicity mechanisms in benthic sedimentdwelling worms such as T. tubifex. Conclusion...

Development and application of an innovative expert decision support system to manage sediments and to assess environmental risk in freshwater ecosystems

“…survival and reproduction rate) are tested on model organisms to assess possible effects at the organism and population levels. Finally, sediments with concentrations falling in the range between TEC and PEC, and with the overall toxic pressure (TPC TEC ) above a critical threshold level are classified as "mildly contaminated", rendering necessary a battery of sublethal biomarkers to define the potential effects induced on biota (Burton et al, 2000;Keddy et al, 1995;Norberg-King et al, 2006;Sforzini et al, 2008;Smutna et al, 2008).…”

Enantioselective Bioaccumulation and Dissipation of Soil‐Associated Metalaxyl Enantiomers in Tubifex

“…9 These burrowing worms come into contact with every phase of the benthic environment, both cutaneously and via the trophic pathway. 8,12 In conclusion, tubifex have proven suitable for the evaluation of acute, chronic toxicity and sediment toxicity, bioaccumulation studies, as well as benthic in situ indicators. 8,12 In conclusion, tubifex have proven suitable for the evaluation of acute, chronic toxicity and sediment toxicity, bioaccumulation studies, as well as benthic in situ indicators.…”

“…[6][7][8] These oligochaete worms play an important role in many aquatic systems because they are very widely distributed and frequently dominant in freshwater benthic communities, and they have a high level of resistance to unfavorable treatments. [6][7][8] These oligochaete worms play an important role in many aquatic systems because they are very widely distributed and frequently dominant in freshwater benthic communities, and they have a high level of resistance to unfavorable treatments.…”

“…10 Therefore, tubifex worms are particularly exposed to environmental pollutants, via sediment, pore water, and water column, 11 and they may accumulate these sediment-associated chemicals, and then pose a risk to higher trophic level organisms via food chain, at the same time help these compounds input into environment again through bioturbation. 8,10,[13][14][15][16][17] The objective of the present study was to study the differences in bioaccumulation behavior of metalaxyl enantiomers in tubifex. 8,10,[13][14][15][16][17] The objective of the present study was to study the differences in bioaccumulation behavior of metalaxyl enantiomers in tubifex.…”

“…Oligochaete species tubifex is one of the most abundant and ubiquitous groups in freshwater ecosystems and lives inside the sediment. [6][7][8] These oligochaete worms play an important role in many aquatic systems because they are very widely distributed and frequently dominant in freshwater benthic communities, and they have a high level of resistance to unfavorable treatments. 9 These burrowing worms come into contact with every phase of the benthic environment, both cutaneously and via the trophic pathway.…”