Toxic Algae Bloom in North American Lake Visible from Space

Lake Erie in North America has been overtaken by toxin-producing algae, as shown in photos taken from space. The lake has turned a bright green due to algae blooms spreading across its surface, and the public has been advised to avoid the water.

On August 13, the blue-green algae covered approximately 320 square miles of the lake, but by August 22, it had expanded to over 660 square miles, as seen in images captured by the OLI-2 (Operational Land Imager-2) on the Landsat 9 satellite.

According to NOAA, the algal bloom began on June 24, marking the earliest bloom in Lake Erie in over two decades. The algae can release toxins, and NOAA has warned that people and pets should stay away from areas where scum has formed, particularly during calm weather, when toxins tend to concentrate at the surface.

The dominant algae species in this bloom is *Microcystis aeruginosa*, a type of cyanobacteria or blue-green algae that is notorious for creating harmful algal blooms (HABs) in freshwater environments worldwide. *M. aeruginosa* produces microcystin, a toxin that mainly affects the liver and poses a risk to both humans and animals.

These algae form large mats or scums that float on the surface of water bodies, creating concentrated areas of toxins. NOAA’s Great Lakes Environmental Research Laboratory reported that toxin levels during the first week of the bloom exceeded recreational safety limits.

Exposure to microcystin through drinking contaminated water, consuming fish, or engaging in water activities can lead to symptoms such as nausea, vomiting, diarrhea, and skin irritation. In severe cases, it can cause liver damage, and animals can even die from poisoning.

Algal blooms also harm marine life by depleting oxygen levels in the water during decomposition, creating dead zones where aquatic organisms cannot survive.

The increase in nutrient pollution, particularly phosphorus and nitrogen from fertilizers, manure, wastewater, and stormwater runoff, has been closely linked to these blooms. Brice Grunert, a professor at Cleveland State University, explained that nutrient input from the Maumee River is the primary factor driving the variability of harmful algal blooms from year to year, according to a statement from NASA’s Earth Observatory.