Dolichospermum blooms in Lake Superior: DNA-based approach provides insight to the past, present and future of blooms

Cody S. Sheik, Kaela E. Natwora, Elizabeth E. Alexson, Jake D. Callaghan, Austin Sailer, Kathryn M. Schreiner, Byron A. Steinman, Matthew S. Finkenbinder, Christopher T. Filstrup, Andrew J. Bramburger

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Cyanobacterial blooms are increasing in frequency, duration, and severity globally in freshwater ecosystems. The Laurentian Great Lakes are prone to toxin-producing cyanobacterial blooms and have experienced annually recurring blooms. Because of its oligotrophic nature, Lake Superior has been relatively free of bloom occurrences. However, in recent years, Dolichospermum blooms have occurred with increasing frequency, especially in the western arm. During a Dolichospermum bloom in 2018, opportunistic samples were collected from the offshore bloom and investigated with shotgun metagenomics. We identified a near-complete Dolichospermum genome that is highly similar to genomes from cultures recovered in Lakes Erie and Ontario. The genomes from the Laurentian Great Lakes are typified by their putative ability to produce a suite of secondary metabolites like anabaenopeptin, but not toxins like microcystin. Additionally, we recovered a Dolichospermum lemmermannii 16S rRNA gene from the bloom and using datasets collected from the epilimnion and sediments in Lake Superior show this organism is ubiquitous and that several strains may exist. While there is much to learn about Lake Superior cyanobacterial bloom development and triggers, understanding this organism is endemic to the region, what its genome is capable of and that specific strains may have provenance within the lake provides a distinct ecological basis for understanding and working towards a predictive framework for future blooms.

Original languageEnglish (US)
Pages (from-to)1191-1205
Number of pages15
JournalJournal of Great Lakes Research
Issue number5
StatePublished - Oct 2022

Bibliographical note

Funding Information:
We thank the University of Minnesota Duluth Executive Vice Chancellor of Academic Affairs for providing funding for additional ship time to sample the blooms and the University of Minnesota Duluth Natural Resources Research Institute for providing funding for the molecular analysis. We also thank the captain and crew of the R/V Blue Heron for the tremendous support and assistance during the cruise. Authors have no conflicts of interest to report.

Publisher Copyright:
© 2022 The Author(s)


  • Cyanobacteria blooms
  • Dolichospermum
  • Lake Superior
  • Laurentian Great Lakes
  • Metagenomics
  • Pangenome


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