Mixed metal and temperature stress in aquatic environments

Ondertitel:establishing functional links across different levels of organisation

Worldwide, aquatic ecosystems are under threat from metal pollution. Natural environments receive a wide variety of compounds and the prediction of mixture toxicity based on the toxicity of single compounds is difficult and shows a certain degree of uncertainty. Moreover, the effects of metal mixtures together with the effect of the temperature on toxicological processes remain very poorly documented. Considering that the temperature is one of the most important driving factors in organismal physiology and a crucial ecological factor, this is surprising. In this work, common carp (Cyprinus carpio) were exposed via water to copper (Cu (II), zinc (Zn (II)) and cadmium (Cd (II)) in single or mixture exposure scenarios. Differences in the accumulation of these metals were observed, with Cu and Cd accumulating to a greater extent compared to Zn in the analysed tissues. When present together, different metals can interact with each other influencing the uptake, bioaccumulation and toxicity. For instance in our experiments, we observed reduced Cd levels in the gills of common carp simultaneously exposed to Cu and Cd. Copper was the only metal found to cause an impairment in ion-homeostasis in the single exposure scenarios. In addition, when it is present in mixture scenarios (e.g Cu plus Cd) more marked effects on electrolyte levels (e.g. sodium) can be observed. In the final part of this work we focused on understanding to which extent different temperatures can affect metal mixture toxicity in common carp. In fish exposed to either a low (10 ºC) or high (20 ºC) temperature, both Cu and Cd accumulated in the gills, whereas Zn levels remained stable. However in fish kept at 10 ºC, Cu metal levels in the gills were higher compared to fish exposed at 20 ºC, in contrast to what was observed for Cd. Moreover at 20 ºC, after one week of exposure fish started to eliminate excess Cu. The obtained results suggest that at 20 ºC, fish had more efficient depuration processes for the essential elements Cu and Zn. Overall, the present thesis provides new insights into the effects of metal ion toxicity when present in mixture scenarios. Moreover, these findings highlight the importance of considering the effect of environmental parameters in designing standard toxicology tests to derive water quality guidelines that are protective for environmentally realistic conditions.

Jaar van publicatie:2021

Trefwoorden:Doctoral thesis

Toegankelijkheid:Open