CYANOBACTERIA (“ BLUE-GREEN ALGAE ”)
Blue-green algae are not true algae but are a type of photosynthetic bacteria called cyanobacteria . Certain types of cyanobacteria may release toxins ( e . g ., microcystin ) that are potentially harmful to humans , animals , and aquatic life . However , not all algae blooms are blue-green , and not all blue-green blooms produce toxins .
Although most cyanobacteria blooms are not harmful , toxicity is hard to predict . A single species of cyanobacteria can have toxin-producing and non-toxin-producing strains , and a bloom that tests non-toxic one day can become toxic the next . There is no way to just look at an algae bloom and tell if it is producing toxins .
Cyanobacteria blooms may turn the water pea soup green , brownish , or even red . Many of us remember when the 2015-2016 winter Planktothrix ( cold-water cyanobacteria ) bloomed in Lake Anita Louise , turning the entire lake auburn-red for many weeks . Cyanobacteria blooms often begin as small rounded or fuzzy clumps of green in the water . As the bloom intensifies , the clumps come together , coating the water ' s surface . A cyanobacteria bloom may cause the water to look thick as pea soup . There may be a paint-like bright blue sheen in areas with very high densities or where the cyanobacteria have been blown to the shoreline . This is because when blue-green blooms start decomposing , they can turn bright blue or white . As a result , they are often reported as paint spills .
Blue-green algae can adapt to live anywhere in the water column . The development of blooms is affected by light , temperature , and nutrient concentrations . Blooms are more likely to occur in warm , shallow , stagnant water with significant nutrients ( e . g ., nitrogen and phosphorus ). Our lakes are known to have an abundance of nitrogen and significant phosphorus stores in accumulated bottom sediments , enough to fuel algae & cyanobacteria growth . Years of biological monitoring of our lakes have revealed a hospitable environment for resident populations of cyanobacteria to grow through the summer months and into fall before dying back before the cycle begins again the next year .
Since phosphorus fuels algae growth in Lake Linganore , the recent dredging of phosphorus-laden bottom sediments in the upper part of Lake Linganore may help reduce the frequency and severity of future cyanobacteria blooms and improve water quality overall .
BOTTOM LINE ON SEASONAL LAKE WATER SCUM
LLA advises residents to follow the Centers for Disease Control ( CDC ) recommendations when it comes to any algae , scum , or coating on the surfaces of our lakes :
• Avoiding swimming or boating in areas where the water is discolored or where you see foam , scum , or mats of algae on the water ; and
• on ' t let pets swim in or drink from areas where the water is discolored or where you see foam , scum , or mats of algae on the water . If pets ( especially dogs ) swim in scummy water , rinse them off immediately — do not let them lick the algae ( and toxins ) off their fur .
12 LakeTalk August 2022