Mariana Kluge noticed something strange. While scientists had studied thousands of lakes across North America and Europe for decades, hundreds of shallow lakes dotting the coast of southern Brazil and Uruguay had barely registered on the global research map. Kluge, a researcher at the Swedish University of Agricultural Sciences, wanted to change that.
Now she and an international team have made the case for why those overlooked lakes deserve worldwide attention. In a study published in the journal One Ecosystem, they describe a chain of more than 100 shallow lakes stretching over 1,000 kilometers along the Atlantic coast—a distance roughly equivalent to the length of France. This connected lake system, they argue, could become one of Earth's most valuable natural laboratories for understanding how climate change reshapes freshwater ecosystems.
"Most of what we know about lakes comes from the Northern Hemisphere," Kluge said. Her team's work aims to fill a major gap in global freshwater science. These subtropical lakes sit in environmental conditions very different from their well-studied northern counterparts, offering a rare chance to test ecological theories in new settings.
The region is already feeling the pressure. The lakes face El Niño weather patterns, rapid urbanization, farm runoff, and wastewater pollution. They also contain emerging threats like pharmaceutical residues and tiny plastic particles called microplastics. Flooding events are becoming more frequent. But the researchers see these challenges as a reason to act now—by monitoring the lakes closely, scientists could catch environmental damage before it becomes irreversible.
Christian Wurzbacher from the Technical University of Munich describes the lakes as "sentinel ecosystems," kind of like a canary in a coal mine for the environment. Tiny organisms living in the lake water could serve as early warning signals, alerting researchers to pollution or ecosystem stress before animals, plants, or people get sick.
The team held workshops at two universities in Porto Alegre, Brazil, bringing together scientists from Brazil, Uruguay, Germany, and Sweden. They identified four key regions across the lake system that best represent the diversity of conditions found there. Their vision is an internationally coordinated monitoring network that tracks these lakes year after year, generating knowledge that could help protect freshwater ecosystems everywhere—not just South America.
"The microbial communities living in these lakes can act as highly sensitive biological sensors," said Haig of the Federal University of Rio Grande do Sul. Such a network could help identify pollution, ecosystem degradation, and even emerging public health risks before they spiral out of control.
As climate change accelerates and human pressure on freshwater grows, the researchers believe these lakes hold lessons that could inform water management strategies worldwide.