Researchers ID organisms behind toxic algae bloom

Published: Monday, June 16, 2025 at 3:32 am

**Researchers Identify Culprit Behind Toxic Algae Blooms in Duluth-Superior Harbor**

Duluth, MN – Researchers have made a significant breakthrough in understanding the recurring blue-green algae blooms plaguing the Duluth-Superior Harbor. Through DNA sequencing, scientists have identified *Microcystis aeruginosa*, a cyanobacteria species, as the primary source of the toxins responsible for these harmful blooms. This discovery, supported by the Minnesota Sea Grant, marks a crucial step towards better understanding, detecting, and potentially mitigating the impact of these events.

The identified cyanobacteria species is known to produce toxins that pose a threat to both humans and animals. These toxins can cause serious health issues, including liver damage and respiratory problems. The blooms also have the potential to disrupt the ecosystem by choking out other species. The same species has been responsible for harmful algae blooms in other areas, including Lake Erie, where it led to water restrictions in 2014.

The research team, led by Cody Sheik and Chris Filstrup from the University of Minnesota Duluth, focused on blooms near Barkers Island, a known hotspot for these events. While current toxin levels in the harbor remain below drinking water standards, the blooms are becoming more prevalent and potentially more intense. The researchers emphasize the importance of monitoring the situation, particularly given the effects of climate change, which are contributing to warmer waters, less ice cover, and increased nutrient runoff – all factors that favor the growth of cyanobacteria.

The team hopes that identifying the specific species responsible will allow them to trace the algae back to its source within the St. Louis River Estuary. This knowledge could pave the way for remediation efforts, potentially preventing or reducing the impact of future blooms.

BNN's Perspective: This research highlights the complex challenges posed by climate change and its impact on our waterways. While the current situation in the Duluth-Superior Harbor appears manageable, the potential for increased intensity and frequency of these toxic blooms warrants continued vigilance and proactive measures. Investing in further research and implementing strategies to reduce nutrient runoff are crucial steps in protecting both public health and the environment.

Keywords: algae bloom, cyanobacteria, toxins, Microcystis aeruginosa, Duluth, Superior Harbor, water quality, climate change, St. Louis River Estuary, Lake Superior, harmful algae blooms, research, environment, public health, remediation

Full Story