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March 18, 2022

USGS and academic scientists examined cyanotoxins and cyanobacterial communities from recurring algae blooms in Kabetogama Lake in Voyageurs National Park, northern Minnesota. They documented the presence of 7 understudied toxins and identified correlations among toxins and cyanobacteria, revealing potential competitive relations among cyanobacteria.  

Cyanobacteria can produce cyanotoxins that may be a concern in recreational waters. Numerous cyanotoxins exist in lakes used for recreation and cyanobacteria capable of producing different toxins can be present at the same time. However, most research to date has focused on one toxin, microcystin. Less emphasis has been placed on various lesser studied toxins. Moreover, in a natural lake, environmental factors and species composition can be complex and associations among cyanobacterial species within the same algal bloom may be difficult to interpret. Therefore, USGS and academic scientists studied three recurring bloom sites in a remote temperate lake to characterize the phytoplankton and cyanobacterial communities and a suite of lesser studied cyanotoxins. 

This research study looked at phytoplankton and cyanobacterial communities, along with 19 toxins, including microcystin (11 variants), nodularins, microginins, cyanopeptides (3 variants), and anabaenopeptins (3 variants) at three sites with recurring algal blooms in Kabetogama Lake in 2019. The scientists found 7 of 19 toxins in various combinations. Anabaenopeptin A and B were detected in every sample. Microcystin-YR was detected more frequently than microcystin-LR, unlike other lakes in the region. Anabaenopeptins were correlated with six cyanobacteria, most of which lack available literature on anabaenopeptin production. The potential toxin producing cyanobacteria, Microcystis, was significantly correlated to microcystin-YR. Two cyanobacteria were strongly negatively related to several toxins, indicating potential competition  between organisms. Three cyanobacteria pairs were significantly correlated, which may reflect cooperation among taxa. This study highlights interactions among cyanobacteria and multiple cyanotoxins and the methods used may uncover additional patterns in cyanobacteria communities in other systems, leading to further understanding of how those interactions lead to toxin production. 

Photo of water flowing into Voyageurs National Park, forested landscape.
Water flowing into Voyageurs National Park, August 2019. (Photo by Victoria G. Christensen, USGS)  
Gloeotrichia, a type of cyanobacteria that can produce microcystin, in a water sample collected from Kabetogama Lake
Gloeotrichia, a type of cyanobacteria that can produce microcystin, in a water sample collected from Kabetogama Lake, Voyageurs National Park. (Photo by Viviana Mazzei, USGS)         

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