Are global influences of cascade dams affecting river water temperature and fish ecology?

Global warming is affecting animal populations worldwide, through chronic temperature increases and an increase in the frequency of extreme heatwave events. Reservoirs are essential for water security. All watersheds with reservoirs are impacted by their construction. These artificial ecosystems controlled by humans change considerably the natural terrestrial and aquatic ecosystem and systems and their biodiversity. The rapid increase in population growth, urbanization, and industrialization are accompanied by an increase in river discharges, which increases the total amount of pollutants. HMs contamination in aquatic environments, as well as the subsequent absorption of HMs into the food chain by aquatic creatures and people, endangers public health. Multiple uses of reservoirs promote benefits in terms of economic development, income, and employment. HMs in water can be ingested directly by aquatic species like fish and can also be ingested indirectly through the food chain; thus, it is much more important and required to conduct frequent monitoring of the aquatic environment. As a result, this review summarizes knowledge about the effects of cascade dams on river water temperature and increases on the stress physiology of fishes, and adaptation to climate change is also needed to produce more fish without global warming.

Automated summary

Global warming is negatively impacting animal populations with increasing temperatures and extreme heatwaves. Reservoirs play a crucial role in water security but their construction affects all watersheds, altering natural ecosystems and biodiversity. Population growth, urbanization, and industrialization contribute to river discharges and pollution. Contamination of aquatic environments by heavy metals (HMs) threatens public health through absorption into the food chain. While reservoirs have economic benefits, frequent monitoring of water bodies is necessary given the direct and indirect ingestion of HMs. This review highlights the effects of cascade dams on river water temperature and fish physiology, emphasizing the need for adaptation to climate change to sustain fish production without global warming.