Assessment of the toxicity of inorganic and organic pollutants using the benthic alga Closterium ehrenbergii
von Andreas Weber-Theen geb. Theen
Datum der mündl. Prüfung:2024-02-27
Erschienen:2024-03-20
Betreuer:Prof. Dr. László Dören
Gutachter:Prof. Dr. László Dören
Gutachter:Prof. Dr. Thomas Friedl
Dateien
Name:Dissertation Andreas Weber-Theen.pdf
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Format:PDF
Zusammenfassung
Englisch
In this thesis, Closterium ehrenbergii was selected as test species for the assessment of the toxicity of environmentally relevant pollutants towards a representative of benthic algae. Therefore, a miniaturized bioassay for toxicity tests on C. ehrenbergii was developed. Metals and pharmaceuticals were investigated to address both inorganic and organic pollutants of high concern. Established test procedures were questioned in order to identify potential drawbacks of existing standards. Finally, the knowledge gained from the tests with C. ehrenbergii was compared to existing data from standard species to highlight the benefits of non-standard species testing. Chapter 1 outlines the dimensions of anthropogenic pollution, summarizes the key aspects of ecotoxicology, and highlights the essential role of algae in natural cycles. Chapter 2 presents a miniaturized method for toxicity tests on C. ehrenbergii applied to metals. The necessity of culture medium modification is demonstrated in order to avoid metal complexation and underestimation of metal toxicity. Chapter 3 deals with the toxicity of pharmaceuticals and highlights the relevance of extended test durations in order to avoid an underestimation of delayed adverse effects. Maximum photosynthetic quantum yield is shown to be a feasible additional endpoint for identifying adverse effects on photosynthetic efficiency. Chapters 2 and 3 both address the different modes of action of the test substances and analyze effects on quantitative and qualitative endpoints. Effect concentrations are based on cell growth and maximum photosynthetic quantum yield. Toxic effects are visualized based on the alteration of cell morphology and chlorophyll fluorescence. Chapter 4 synthesizes the findings of chapters 2 and 3 and discusses the knowledge gained from this thesis. Future research is required to investigate whether the outcomes of this study also apply to standard species and procedures. In particular, the observed occurrence of delayed effects of pharmaceuticals highlights the need for further studies with standard species and extended test durations in order to question whether the current standard of short-term exposure sufficiently assesses the hazards of pharmaceuticals towards algae. In conclusion, this thesis has assessed the toxicity of thirteen inorganic and organic pollutants towards an important representative of benthic algae, demonstrated the benefits of investigations beyond recognized standards, and contributed to the understanding of the effects of anthropogenic pollutants on algae.
Keywords: Ecotoxicology; PAM; Pharmaceuticals; Heavy metals; Algae