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| Mid August algae bloom - photo by Dave Dvorak |
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Algae have no true roots, stems, or leaves and range in size from tiny, one-celled organisms to large, multi-celled plant-like organisms, such as chara or muckgrass. Plankton algae, which consist of free-floating microscopic plants, grow throughout the well-lit surface waters of an entire lake.
links and information above provided courtesy of the MN Dept of Natural Resources http://www.dnr.state.mn.us/aquatic_plants/algae/index.html
Harmful Algal Blooms
Most algae blooms are harmless, but some blue-green algal blooms can produce toxins that may sicken people and animals. Blue-green algae are found throughout Minnesota and thrive in warm, nutrient-rich lakes.
Harmful algal blooms (HAB) in Minnesota lakes were the focus of workshops in Sauk Centre on March 4, North Mankato on March 5, and St. Paul on March 6, 2008. Presentation downloads can be viewed via the links on the web at http://www.seagrant.umn.edu/water_quality/hab.php courtesy of Sea Grant Minnesota
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High Temperatures Can Bring Toxic Algal Blooms (excerpted from MPCA News release 6/30/08, full news release available at http://www.pca.state.mn.us/news/data/newsRelease.cfm?NR=279310&type=2)
When the summer sun beats down and temperatures climb, conditions are ripe for Minnesota lakes to produce dangerous algal blooms. Toxic blue-green algae can harm pets, livestock and even people, according to the Minnesota Pollution Control Agency (MPCA). Blue-greens are a form of aquatic algae that normally occur in many Minnesota waters, but under the right conditions, they can become toxic. "High rainfall, resulting in nutrient-rich runoff entering our lakes fuels the growth of algae," said MPCA lakes expert Steve Heiskary. "Earlier this summer, cloudy and cool conditions served to minimize algal blooms. However, as sunlight increases and temperatures warm, we can anticipate blooms of blue-green algae on many of our lakes."
Algae are microscopic plants that are a natural part of any aquatic ecosystem. There are hundreds of species. Under the right conditions, algae populations can "bloom," increasing so dramatically that they turn the water cloudy and green, a sight familiar to many summertime lake-goers. Most algal blooms are harmless. But blue-green algae, when present in high concentrations, can produce potent toxins that can harm people and animals. Blue-green algae are found throughout Minnesota, but thrive particularly in warm, shallow, nutrient-rich lakes.
As algal concentration can vary widely across a lake, so can algal toxins. Often occurring on downwind shorelines, high algal concentrations may produce harmful conditions. It is these near-shore blooms where humans and animals most often come in contact with blue-green algae and where the risk of algal toxins is greatest. Distinguishing blue-green algae from other types may be difficult for most people. However, toxic algal blooms generally look pretty nasty - like pea soup, spilled green paint or floating mats of scum. They often smell bad too. While such conditions would seem to keep most people away, it's surprising how many will swim or wade in such water or let their animals enter it.
For more information about toxic algae blooms call (651) 296-6300 or (800) 657-3864 or go to http://www.pca.state.mn.us/water/clmp-toxicalgae.html.
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