Núria Bonada
Professor of Ecology at the University of Barcelona
The effects of climate change are significantly altering global hydrological patterns, causing changes in the availability and quality of water in rivers and lakes. Currently, around 60% of the world's river network experiences periods of drought at some point during the year, and projections indicate that this figure will increase, accompanied by a trend towards longer and more extreme droughts in many regions of the planet.
Numerous large rivers and lakes are experiencing rising temperatures and significant drops in water levels, and even episodes of partial or total drying up. The Amazon River basin, which has been poorly monitored until now, is a particularly worrying example due to its high biodiversity and the numerous ecological functions and ecosystem services it provides. The article published by Fleischmann and colleagues (2025) documents how an unprecedented heatwave and drought in 2023 transformed the lakes of the central Amazon into shallow and extremely hot basins, with water temperatures exceeding 40°C in some cases and levels falling to historic lows.
Declining water levels and rising temperatures in rivers and lakes cause habitat loss and mortality of aquatic species, leading in some cases to their extinction, which compromises the ecological integrity of these ecosystems. Given this scenario, it is urgent to implement conservation and adaptive management measures aimed at preserving biodiversity, ecological functions and ecosystem services in order to mitigate the impacts of prolonged droughts on these critical habitats.