Mass developments of cyanobacteria, so-called blue-green algae blooms, repeatedly threaten the quality of water bodies and drinking water resources worldwide. Cyanobacteria are considered to be heat-loving, and massive algal blooms are reported mainly in summer, when monitoring is particularly close.
Locations of cyanobacterial blooms occurring in water temperatures Limnology and Oceanography Letters (2023). DOI: 10.1002/lol2.10316 Now, an international research network involving the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) has shown that cyanobacterial blooms can also occur at colder temperatures—even under ice. If the algal blooms go unnoticed, they threaten drinking water production. The study was published in the journal Limnology and Oceanography Letters. Cyanobacteria—also known as blue-green algae—can produce toxins and deprive water of oxygen and aquatic plants of light for photosynthesis. Cyanobacterial blooms thus threaten aquatic ecosystems and their living organisms, as well as drinking water resources and bathing waters. These blooms have been the focus of attention, especially in the context of climate change, because warmer water temperatures above 25 degrees Celsius favor the growth of Cyanobacteria—that has been the scientific tenor so far. Now, a research team from the international Global Lake Ecosystem Observatory Network (GLEON) has shown that cyanobacterial blooms can also occur in lakes at relatively low water temperatures <15 degrees Celsius—even under a layer of ice. To do this, the researchers used existing scientific data, including that collected by citizen scientists via an app or with the help of microscope sets. Dr. Kaitlin Reinl, principal investigator of the study and research coordinator at the U.S. Lake Superior National Estuarine Research Reserve, says of the study's significance, "Cyanobacterial blooms are complex and challenging. The conventional wisdom about them is that they like it warm, and in many cases that's true. However, there is growing evidence that these blooms can also occur in cold…