More than 100 shallow lakes stretching over 1,000 kilometers along the Atlantic coast of southern Brazil and Uruguay could become one of the world's most important natural laboratories for understanding how climate change and human activities reshape freshwater ecosystems. An international team of researchers reports that these largely overlooked subtropical lakes offer an unparalleled opportunity to monitor biodiversity, water quality, pollution, and ecosystem resilience in a rapidly changing world.
Published in One Ecosystem, the study is the first comprehensive assessment of the Southern American Coastal Shallow Subtropical Lakes, highlighting their global scientific importance and outlining a roadmap for long-term international monitoring.
Most of what we know about lakes comes from the Northern Hemisphere.
- says lead author Mariana Kluge of the Swedish University of Agricultural Sciences (SLU).
These subtropical lakes fill a major gap in global freshwater research. They allow us to test ecological theories under very different environmental conditions while providing crucial insights into how subtropical freshwater ecosystems respond to climate change and increasing human pressures.
- adds Prof. Renata Medina-Silva of Pontifical Catholic University of Rio Grande do Sul (PUCRS)
The lake network forms one of the largest continuous coastal shallow-lake systems on Earth. Despite its extraordinary size and diversity, it has received far less scientific attention than well-known freshwater systems elsewhere in the world. Yet the region is already experiencing many of the environmental challenges, expected to intensify in the coming decades - including a direct impact of the El Niño Southern Oscillation - alongside heavy urbanisation, which has driven eutrophication, agricultural and wastewater pollution, emerging contaminants such as pharmaceuticals and microplastics, and increasingly frequent extreme rainfall and flooding events.
Christian Wurzbacher of the Technical University of Munich argues that these lakes can serve as "sentinel ecosystems"- natural observatories that reveal early signs of environmental change. By combining microbial ecology, environmental DNA, remote sensing, water chemistry, and long-term ecological monitoring, scientists hope to develop new indicators capable of detecting ecosystem stress before irreversible damage occurs.
Our vision is to establish an internationally coordinated monitoring network that not only benefits South America, but also improves our understanding of freshwater ecosystems worldwide. The microbial communities living in these lakes can act as highly sensitive biological sensors, helping us identify pollution, ecosystem degradation, and even emerging public health risks.
- says Prof. Haig of the Federal University of Rio Grande do Sul (UFRGS).
The publication emerged from an international workshop held at two universities - PUCRS and UFRGS - in Porto Alegre, Southern Brazil, bringing together researchers from Brazil, Uruguay, Germany, and Sweden to define future research priorities. The team identified four representative large-scale lake regions that together capture the broad environmental gradients across the system and offer ideal sites for coordinated long-term observation.
As climate change accelerates and pressures on freshwater resources continue to grow, the researchers believe that protecting and studying these remarkable lake systems will generate knowledge extending far beyond South America - informing global strategies for safeguarding biodiversity, improving water management, and strengthening resilience to environmental change.
Original source:
Kluge M, Shubeita A, Uchaikina A, Alonso C, Herrman B, Menegotto-Silva C, Lopes C, Pagani D, Marques D, Moreira-Silva E, Kristiansson E, Quintana I, Cavalcanti J, Fleck J, Ribeiro K, Varghaei L, Oliveira L, Rodrigues LR, Ramilo L, Crossetti L, Stockenreiter M, Cabezudo M, Lima M, Gonçalves NP, Mazzeo N, Schneider R, Utz LP, Bertilsson S, Wurzbacher C, They NH, Medina-Silva R (2026) Coastal subtropical Southern American shallow lakes as unique ecosystems for monitoring anthropogenic induced ecosystem changes. One Ecosystem 11: e186107. https://doi.org/10.3897/oneeco.11.e186107