Algae – the good, the bad and the ugly

For most of us around the lakes, the word algae conjures up visions of huge jelly-like green blobs invading our swimming areas, or worse, fears about possibly toxic blue-green algae.

Few of us realize that algae are a natural part of fresh water lake systems and that algae are the basis of the entire aquatic food chain. Algae take energy from the sun and convert it through photosynthesis into food for invertebrates and small fish, which are then fed on by larger fish and predators. Algae also produce much of the oxygen that we rely on.

Andrew Neil Olscher

Algae are also the “canaries” of the lakes, signaling important changes in the aquatic environment – usually not for the better. In general, overly green water is the sign of an algal bloom, and it may be accompanied by an unpleasant smell. In addition to being a nuisance and a worry, blooms can affect the healthy functioning of the lake ecosystem, resulting in low oxygen at lower levels and occasional fish kills.

While most people would agree that excessive algae blooms are a problem, they are not the problem, but a symptom of a greater problem – poorer water quality, due to excessive nutrients in the water itself and in lake sediments.

Algae not only need sun and moisture to thrive, they need nutrients, such as nitrogen and phosphorus, and small amounts of many other minerals. When all the required nutrients are available in abundance at the same time, algae grow very rapidly. Long hours of sunlight and warm water temperatures also spur growth.

What can we do about excessive algae?

There is no quick fix. The only way to achieve or maintain healthy levels of algae in our lakes is to avoid putting phosphorus and nitrogen into the water. This means properly maintaining your septic system and cleaning up pet and goose poo from shoreline areas. Use only phosphate-free, biodegradable cleaning products and personal care products, and never use tri-sodium phosphate (TSP) a common degreaser.

Avoid having a lawn near the shore. Instead, naturalize your shoreline with ground covers, shrubs and trees (preferably native species). Planting along your shoreline helps prevent soil erosion – another source of nutrients for algae – and traps sediments and dissolved nutrients from runoff water. Taller vegetation will also deter geese.

Blue-green algae

Worries about possible blue-green algae blooms on our lakes have increased in the last few years, especially since they were reported upstream in Sturgeon Lake and Pigeon Lake in the late summer of 2011. In early and late summer of 2013, blue-green algae blooms were reported at the south end of Clear Lake and in localized spots around central Stony Lake.

Blue-green algae are actually a type of bacteria called cyanobacteria. They grow rapidly in warm still water and give it the look of blue-green paint or pea soup. Some types release toxins into the water and can pose a health risk for humans, pets and wildlife. Health effects depend on the type of toxin, its concentration and the degree of exposure. Symptoms can range from skin irritation, headaches, fever, and digestive distress to more serious and chronic symptoms such as damage to the liver and nervous system. The greatest risk is from drinking water contaminated with toxins.

If you suspect a blue-green algae bloom is present, avoid using the water – don’t drink it, cook with it, shower in it or swim in it, and keep pets away from it. Don’t boil water in an attempt to make it safe. Boiling will not destroy cyanobacterial toxins and may release more toxin into the water being boiled.

For more information about blue-green algae and health, go to Peterborough Public Health, blue-green-algae

To report a suspected blue-green algae bloom, contact the Ministry of the Environment’s Spills Action Centre at 1-800-268-6060. If it is the first report of a bloom in the area, Ministry staff will collect a sample of the algae and determine if it is hazardous. The local Health Unit will then issue an official water-use warning.

The Kawartha Lake Stewards Association has published a brochure on algae. To learn more about blue-green algae and other forms of algae, and how to prevent their excessive growth, go to KLSA Algae Book.  

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