It’s Algae Season
Water clarity has been excellent so far this summer, but algae growth tends to increase this time of year. Sometimes growth indicates a larger water quality issue, but not always! Here are several ways to determine what kind of algae you see as we wade into the hottest time of year.
Cyanobacteria, also referred to as “blue-green algae,” are colonial, single-celled microorganisms that cause most lakewide algae blooms across Maine when conditions are favorable, i.e. high temperatures and the abundance of the limiting nutrient, phosphorus. The Maine DEP refers to lakewide blooms where water clarity drops below 1 meter (3.3 feet) as a “harmful algae bloom.” Thick scums of cyanobacteria can accumulate in coves in the absence of a lakewide bloom. We test scums for toxins each year and have never had a positive test.
Gloeotrichia echinulata (“Gloeo”) is a type of cyanobacteria we see annually on Great Pond, Long Pond, and sometimes Messalonskee Lake. Unlike other cyanobacteria, Gloeo appears in deep, clear lakes. It emerges from the sediment and rises to the surface where it can spread horizontally across the lake. Gloeo forms large (~2 mm) spherical colonies with a faint ring around their edge Gloeo can accumulate in coves and around docks, creating thick scums.
If you see stringy, green “cotton-candy” looking clumps, these are likely colonies of filamentous green algae. These are harmless, and often grow in shallow, vegetated areas of lakes but can break loose due to strong winds or large wakes. While they might pick up other detritus along the way and can sometimes look unsightly, they are not a concern, unlike a lake-wide algae bloom featuring cyanobacteria, or scum accumulations in a cove. If you are not sure what you are seeing, want to join our Gloeo monitoring project, or have questions, please contact lake scientist Matt Farragher or visit the 7 Lakes Alliance at 137 Main Street in Belgrade Lakes Village.
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