Ann Arbor Times

In recent research from the University of Michigan, scientists have pinpointed the cyanobacteria accountable for dangerous toxins in Lake Erie. Known as Dolichospermum, this cyanobacteria has been confirmed as the producer of the toxin saxitoxin, which is considered one of the deadliest natural neurotoxins.

While harmful algal blooms (HABs) consist of various cyanobacteria, each producing different toxins, identifying the organisms responsible can aid scientists in addressing these blooms. Gregory Dick, a professor involved in the study, emphasized, "The main advantage of knowing which organism produces the toxin is that it helps us understand the conditions that cause toxin production—that is, what conditions make those organisms successful."

The researchers employed "shotgun" sequencing to analyze DNA from lake water samples, leading to the identification of several strains of Dolichospermum, not all of which produce saxitoxin. The research also suggested environmental factors like water temperature affect toxin production, as more toxin-related genes were found in warmer conditions. Paul Den Uyl from U-M’s Cooperative Institute for Great Lakes Research noted, "With the warming of the lakes, one of the big questions is, how is that going to change the biological communities, including harmful cyanobacterial blooms?"

Findings also indicate that saxitoxin production is potentially impacted by nitrogen concentration, as Dolichospermum can utilize atmospheric nitrogen, a rare trait. Dick explained, "You have the whole blueprint for what the organism can do, and we do see the capability of obtaining fixed nitrogen from the water. It’s just that getting it in the form of dinitrogen gas is kind of a superpower."

Despite having tracked the presence of saxitoxin in Lake Erie for nine years, researchers conclude that current data is insufficient to predict increased toxin production due to climate-induced lake warming. Dick stated, "But now that we know who’s producing it, I think we can keep a better watch on these organisms."

These results were published in Environmental Science & Technology.