Have you noticed thick, stringy algae floating on your lake? If so, you aren't alone; district staff noticed these mats during weekly water sampling. Luckily, the blooms are both temporary and non-toxic. The floating mats are caused by a group of several species known as filamentous green algae that usually live on the bottom of lakes. When the water is very clear, like in early spring, these algae can grow quickly forming a think layer. Eventually it gets too thick and the bottom layer dies. The mat then detaches and floats to the surface. Once at the surface, the mats will usually stay around for a few weeks before sinking. As other plants and algae begin to grow, the bottom-dwelling filamentous algae get less light, and grow more slowly. The two photos below are from Duck Lake and show a spring bloom of filamentous algae that had disappeared two weeks later.
One of the types of algae in these blooms is the genus Spirogyra. This group of related species gets its name from the spiral shape of its chloroplasts. These plant cell components capture energy from the sun and power the algae through photosynthesis.