Multi-Marker Study of Dreissena polymorpha Populations from Hydropower Plant Reservoir and Natural Lake in Latvia

Hydropower plants (HPPs) are equipped with reservoirs that can accumulate the toxic effluents and disturb the water flow of rivers. The aim of this study was to evaluate the biochemical responses of zebra mussel Dreissena polymorpha inhabiting the reservoir of Riga HPP in comparison with the responses of the mussels from the natural lake Kanieris in Latvia. In the reservoir mussels, high Mn-SOD activity and low level of the lipid peroxidation (production of TBARS) in the soft tissues suggested an elevated antioxidant activity. Compared to the lake specimens, the reservoir mussels had low levels of RI GSH while their lactate/pyruvate ratio was 1.4 times higher. In the mussels from the reservoir, high level of protein carbonilation products, as well as lowered caspase-3 and extralysosomal cathepsin D activities (by 1.4 and 1.6 times respectively, compared to the lake specimens) indicated delayed apoptosis. Catalase and glutathione S-transferase activities and metallothionein concentration were similar in both groups. Vitellogenin-like proteins (detected as the alkali-labile phosphates) and cholinesterase levels were higher in the mussels from the reservoir. We chose the indexes of the redox capacity as the most suitable markers of the environmental impact on this organism.