Assessing environmental and contaminant stressors in a benthic amphipod

Sammanfattning: Organisms in the aquatic environment encounter numerous stressors throughout their lifespan. Some of them are biotic such as food availability, predators and parasites. Others are abiotic and include shifting salinity and temperature change among others. Stressors with anthropogenic origin (for example pollution) add to these challenges and can interfere with the organisms´ ability to adapt, survive and successfully reproduce. This thesis focuses on the benthic amphipod Monoporeia affinis and how it responds to environmental (food availability and increased temperature) and contaminant (fenarimol, PFOS and TBT) stressors. M. affinis is a key species in the soft bottoms of the Baltic Sea and inland lakes in Scandinavia. It is considered particularly sensitive to contaminant exposure, especially during the reproduction. The animals were exposed to both single and combined stressors in soft-bottom microcosms during sexual maturation and mating.  Adverse effects on survival and reproduction as well as parasite infection, hormonal status and protein damage were analyzed and evaluated for potential population effects and any synergisms between stressors. Results from these studies give support to M. affinis being a sensitive crustacean in terms of contaminant stress. Female sexual maturation is reliant on sufficient food availability and sexual maturation in both sexes is vulnerable to increased water temperatures affecting reproduction fitness. Increased water temperature also acts synergistically with contaminant stress in decreasing the amount of viable eggs and embryos. Ecologically realistic concentrations of perfluorooctane sulfonate (PFOS) and tributyltin (TBT) severely increase the number of parasite infected animals. These results indicate that the M. affinis populations in the field could be adversely affected by pollutant exposure. Effects that could be enhanced by the predicted increase in water temperature due to global warming.