CFAES Give Today

School of Environment and Natural Resources


Current estimates of Lake Erie algae toxicity may miss the mark

Aug. 14, 2023
A harmful algal bloom in the Western Basin of Lake Erie on Sept. 20, 2017. Photo: Zachary Haslick, Aerial Associates Photography, Inc.

This article was originally published by Ohio State News and written by Emily Caldwell.

Study suggests harmful algal bloom toxicity varies over the summer

There is more to a harmful algal bloom than the green stuff in water that meets the eye – specifically, a changing hazard level of toxins produced by the microbes that make up the scummy mess.

A new study analyzing toxins produced by Microcystis, the main type of cyanobacteria that compose the annual harmful algal bloom (HAB) in Lake Erie, suggests that the toxicity of the bloom may be overestimated in earlier warm months and underestimated later in the summer. 

The research is part of a large project, led by The Ohio State University, designed to develop a more accurate harmful algal bloom toxicity forecast for Lake Erie. 

The toxicity relates to the bloom’s concentration of the liver toxin microcystin, of which there are hundreds of varieties called congeners defined by very small molecular differences. The analysis showed that the toxicity level of the most common congeners found in Lake Erie relates strongly to nitrogen – when there is more nitrogen present in early warm months, dominant congeners tend to be of the less toxic variety. Later in the season, when nitrogen is nearly gone, the balance of dominant congeners changes to a more toxic type.

“The different levels of toxins will ultimately affect the toxicity and the human health impacts. We know that different populations are more sensitive to the toxins, especially those who have non-alcohol fatty liver disease,” said Justin Chaffin, senior researcher and research coordinator at Ohio State’s Stone Laboratory and lead author of the study. “Knowing which congeners are around can better inform beach management, better inform water treatment, and better inform those who need to avoid the water when they should avoid it.”

The research was published recently in the journal Harmful AlgaeRead more >>