This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Tiny single-celled organisms help keep lakes clear, but some can also contaminate the water. An international research team has analyzed DNA data from 362 lakes to create the first global genome atlas of these organisms.
With the findings now published in Nature Communications, the new atlas lays the foundation for faster and more precise monitoring of lakes. A single drop of lake water teems with life too small to see: microscopic algae and single-celled organisms such as amoebae. These organisms convert sunlight into food, feed on bacteria and, in turn, provide food for the tiny animals eaten by fish.
When the ecological balance is disrupted, some can become deadly. In 2022, a bloom of a toxic microalga in the Oder River on the German–Polish border killed around 360 tonnes of fish. For decades, these organisms have been monitored in the same way: counted one by one under a microscope using a method developed in 1958.
The process is slow and relies on expertise that is becoming increasingly scarce. It also has a major blind spot. "Under the microscope, a harmless alga and its toxic relative can look identical," says Adrian-Stefan Andrei, head of the Microbial Evogenomics group at the Limnological Station of the University of Zurich (UZH).
"Their DNA likely holds the key to telling them apart." Until now, however, the genetic reference data needed to identify these organisms from their DNA have been largely missing. To expand the genetic reference library, principal investigator Andrei and his team analyzed 3,400 DNA data sets from 362 lakes and reservoirs in 28 countries across all continents. As part of an international collaboration, the researchers reconstructed nearly 20,000 mitochondrial genomes from around 3,660 species.
Mitochondria are the structures within cells that produce most of their energy. The result is the first global genomic atlas of these microscopic organisms found in lakes and reservoirs. It reveals a wealth of previously unknown biodiversity: For several groups of algae and related organisms, the researchers identified between six and more than 20 times as many species as are currently listed in the world's leading reference genomic database.
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