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Ecosystem Research and Harmful Algal Blooms

The recent increases in cyanobacterial Harmful Algal Blooms (HABs) in the Great Lakes has caused significant concern for human and ecosystem health due to the production of toxins by bloom species. In the Great Lakes, Microcystis dominates the cyanobacterial bloom community and produces the hepatotoxin microcystin (Brittain et al. 2000, Carmichael 1994, 1997, Vanderploeg et al. 2001). Preliminary studies have documented the presence of microcystins in the Great Lakes, at times exceeding the recommended limit of 1 µg L-1 of microcystin established by the World Health Organization for drinking water supplies (Brittain et al. 2000, Vanderploeg et al. 2001). The increase in large Microcystis blooms in recent years has caused considerable concern due to the dependence on these waters as a resource and the health risks attributable to microcystins. The ability to accurately measure the distribution and concentration of microcystin in the Great Lakes is therefore essential to protecting human and ecosystem health in this region.

We are investigating the impacts of microcystins on human health through a number of different routes. For multiple years, we have surveyed western Lake Erie and Saginaw Bay (Lake Huron), two regions in the Great Lakes that typically have significant cyanobacterial blooms, to determine the extent of Microcystis blooms. We have measured toxin concentrations and Microcystis cell counts and related these to environmental factors such as nutrients concentrations, light and wind speed. We are also working with collaborators who are using satellite imagery to detect surface blooms of Microcystis and inputting this data into the Great Lakes Forecast System for western Lake Erie to forecast how these blooms might move around the basin. This work is all leading to the capacity to forecast when cyanobacterial blooms might be in locations like a swimming beach or drinking water intake that would present a hazard to human health.

MERIS full resolution enhanced true color image from September 24, 2008. Microcystis concentrations are extremely high near the mouth of the Maumee River.

MERIS full resolution enhanced true color image from September 24, 2008. Microcystis concentrations are extremely high near the mouth of the Maumee River.

We are also looking more directly at the impacts of microcystins on human health. During the summer of 2009, we will conduct a study to measure microcystin concentrations at the intakes and finished drinking water of two of the inhabited islands in western Lake Erie. This study will tell us whether water treatment plants are effective in removing microcystins from the drinking water in these small communities and whether there is a risk of chronic exposure. We will also use the newly developed HAB Bulletin to identify when Microcystis blooms are likely to be present at the water intakes for these island communities and utilize the opportunity to further develop the Bulletin into a format that is useful to small water treatment operators, which are one of the target communities.

HAB bulletin put out by R. Stumpf, M. Tomlinson, T. Wynne – NOAA/NOS/CCMA

HAB bulletin put out by R. Stumpf, M. Tomlinson, T. Wynne – NOAA/NOS/CCMA

Dietary exposure may be another route of toxin exposure and has not been widely investigated. As a hepatotoxin, microcystin has been documented to accumulate in the livers of many animals, but the degree to which this toxin is present in the edible muscle tissue of popular Great Lakes recreational fish (e.g., yellow perch and bluegill) is not known. The main goal of this project is to address the potential for human exposure to cyanobacterial toxins through measurement of microcystins in wild-caught fish and the secondary goal is to conduct laboratory experiments to investigate the kinetics of toxin accumulation in fish tissue. Our data from wild-caught fish from Muskegon Lake and western Lake Erie suggest that while microcystin concentrations in livers could be a human health risk, even during periods of high microcystin concentration in the water column, microcystin concentrations in the muscle tissue of fish of edible size are not high enough to be an acute threat to human health.

Prediction of Potential Human Health Impacts through fish consumption following a Microcystin Bloom

(graphic by Ashley DeHudy)


Project Title Researcher(s)/Affiliation
Genetic and Environmental Factors Influencing Microcystis Bloom Toxicity Juli Dyble Bressie (NOAA/GLERL)
Gary Fahnenstiel (NOAA/GLERL)
Dr Wayne Litaker (NOAA, Beaufort NC)
Evaluation of the Hazard of Microcystis Blooms for Human Health through Fish Consumption Juli Dyble Bressie (NOAA/GLERL)
Peter Landrum (NOAA/GLERL)
Duane Gossiaux (NOAA/GLERL)
Steve Pothoven (NOAA/GLERL)
Oceans and Human Health: Microcystins in the Great Lakes Gary Fahnenstiel (NOAA/GLERL)
Juli Dyble Bressie (NOAA/GLERL)
Dave Millie () (Florida Institute of Oceanography)
Drinking Water as a Route of Human Exposure to Microcystins in Small Great Lakes Communities Juli Dyble Bressie (NOAA/GLERL)
Gary Fahnenstiel (NOAA/GLERL)
Duane Gossiaux (NOAA/GLERL)