| Popis: |
Human activities and climate change have become the most consequential threats to freshwater ecosystems and their inhabitants, especially fish. The response of the fish population to their environment is not always straightforward because of joint effect of multiple parameters. Fish and fisheries in shallow lakes can be directly affected by changes in air temperature, and also changes can occur via other factors in lakes that are under the influence of climate change. Also, response of each fish species to those parameters can vary depending on their tolerance and adaptation. Therefore, examining complex relationships between fish and their environment plays important role at understanding the dynamic of fish population and fisheries. In this study, we aimed to determine general driving factors, including climate change impact, for fish and fishery in Estonian large lakes. Results show that although winter is one of the most affected seasons by climate change in this region, then the selected fish species and eel fishery in Estonian large lakes were more sensitive to other environmental parameters. However, since the changes in winter surface water temperature and ice formation can affect other parameters, the indirect effect should not be ignored. Nutrients, spring-summer temperature and alkalinity were the most important environmental parameters for the selected fish biomass. We found that the high blue-green algae biomass during restocking period is the strongest negative impact for the eel fishery in Lake Võrtsjärv. The impact of factors can occur subsequently in fish communities and may lead to irreversible consequences, whereas the effects of concurrent climate change and nutrient enrichment can mutually reinforce their symptoms. |
