Lake Erie's algae crisis threatens wildlife and public health
Lake Erie, the fourth largest in the complex of five Great Lakes of North America, is struggling with extensive blue-green algae blooms. There are so many that the lake appears green in satellite photos.
NASA's Landsat-9 satellite captured photos of Lake Erie in August this year. The satellite photographed visible changes in the western part of the basin, which covers about 830 square kilometres.
Lake Erie changed colour
The unusual green-blue hue of the water results from excessive blue-green algae activity, microscopic organisms that bloomed due to high temperatures and large amounts of nutrients such as nitrogen and phosphorus, mainly from agriculture.
The phenomenon that brought about these effects began in June, but observations indicate it reached its largest size on August 22. That day, blue-green algae covered about 1,700 square kilometres of Lake Erie's surface.
This phenomenon is not new to Lake Erie, as its waters regularly experience algae blooms, mainly due to the influx of nutrients from the Maumee River. Despite its spectacular appearance in satellite photos, blue-green algae blooms severely threaten wildlife and people. The dominant blue-green algae in Lake Erie's bloom, of the genus Microcystis, produce a toxin (microcystin) that can accumulate on the water surface and even become airborne. Contact with toxins produced by these blue-green algae can lead to allergic reactions such as skin rashes, eye irritation, or respiratory symptoms.
Scientists monitor the level of dangerous toxin
Monitoring stations belonging to the Great Lakes Environmental Research Laboratory (GLERL), located in the western part of Lake Erie, are tracking the levels of this dangerous toxin. Although the peak concentration of microcystin was at the turn of July and August, it is also maintained in early September.
GLERL data, along with satellite images, play a key role in understanding algae blooms and predicting their occurrence. They also help develop guidelines for why such phenomena are starting to appear in other Great Lakes, including Lake Superior. One of the main suspects for researchers is climate change.
