A study in The ISME Journal shows that harmful algal blooms in western Lake Erie produce a far wider range of potentially toxic compounds than standard monitoring detects. Researchers sampled water monthly at four NOAA Great Lakes Environmental Research Laboratory stations in western Lake Erie from May through October, 2016–2022. They combined chemical detection with microbial DNA analysis, which let them link particular bacteria to the compounds those microbes produced.
In addition to well-known microcystin produced by the cyanobacterium Microcystis, the team detected several other bioactive cyanopeptides that had not been characterised in Lake Erie or tracked by routine monitoring. Gregory Dick, a senior author and professor at the University of Michigan, said microcystin "is the tip of the iceberg." The lead author, Lauren Hart, traced a seasonal sequence driven by spring runoff and rain that brings nitrogen into the lake.
- Phase 1: microcystin dominates.
- Phase 2: as nitrogen is depleted, other microbes produce anabaenopeptins and aeruginosins.
- Phase 3: later-season production includes aerucyclamides.
Hart also tested interactions between compounds and published those results in Environmental Toxicology. She exposed three human cell lines (lung, liver, kidney) to different combinations and dosages of microcystins and anabaenopeptins. The experiments showed anabaenopeptins can be as toxic as some microcystin congeners and that mixtures of the two amplified effects. Because cell-line responses do not directly predict effects in people or animals, the health implications remain unclear. The authors call for detailed characterisation of these compounds, toxicity testing, and studies of their interactions. The research involved UM’s Cooperative Institute for Great Lakes Research and Great Lakes Center for Freshwaters and Human Health, NOAA, and USGS, with support from NIH, the National Institute of Environmental Health Sciences, NSF, the Great Lakes Restoration Initiative, USGS, and NOAA.
Difficult words
- microcystin — a toxic peptide produced by freshwater cyanobacteriamicrocystins
- cyanopeptide — small chemical compounds produced by cyanobacteriacyanopeptides
- anabaenopeptin — a cyanopeptide produced by some cyanobacteriaanabaenopeptins
- aeruginosin — a type of cyanopeptide with biological activityaeruginosins
- cyanobacterium — photosynthetic bacteria that live in freshwater environments
- congener — a related chemical variant within the same classcongeners
- runoff — rain or melted water that flows into rivers
- deplete — use up a supply so little remainsdepleted
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What additional research do the authors recommend and why might that be important for public health?
- If routine monitoring began tracking the compounds found in this study, how could water-management decisions change?
- What are the limits of using human cell-line tests to predict health risks for people and animals, based on this article?
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