Fish that live in hot and arid regions are accustomed to facing adverse conditions. In the hottest months of the year, the rivers and streams where they reside may stop flowing or even dry up completely, but several species know how to cope with this.
However, a study published in the publication Ecology and Evolution warns that even these fish highly adapted to dry and hot climates may not be able to adapt quickly enough to survive on a planet that is becoming increasingly warmer and drier due to the effects of climate change caused by human actions.
The study analyzed data from about 1,500 watercourses in arid regions of the United States of America (USA) and Australia, between 1980 and 2022. The researchers found a reduction in the number of fish species living there, coinciding with rising temperatures and with decreases in precipitation and river and stream flows.
The most affected species were smaller fish that feed on plants and algae, and also those with very limited distribution areas, as they have few chances to find refuges with suitable conditions when the rivers or streams where they live begin to have less water than usual.
Although they acknowledge that the data collected do not allow for a doubt-free assertion that the decline in species is directly related to the reduction in water availability, the scientists argue that, even so, what they have found should serve as a warning, since it is expected that the number of ecosystems with water limitations will become larger.
The team also suggests that other factors, besides the effects of climate change on rainfall patterns and the reduction of water in rivers and streams, may be influencing species loss, such as competition with invasive species and habitat destruction due to the expansion of human infrastructure.
“If highly adapted fish cannot survive in hot and dry climates, it is not a good sign for fish that are used to much milder climates,” said in a press release a researcher from the University of Buffalo (USA) and the study’s first author.
“Fish that live in dry climates are ‘a canary in the coal mine’ when it comes to climate change, so it is crucial to have a full understanding of what is causing this decline in their species diversity,” they emphasize.
