Outdoors

What kind of algae is long and blown up like a balloon with thin, green, slippery skin?

filamentous algae Photo copyright Arthur Chapman/flickr CC BY-NC 2.0

What kind of algae is long and blown up like a balloon with thin, green, slippery skin? Do frogs indicate the health of the lake?

It’s probably filamentous algae. It’s also called blanket weed, elephant snot, and pond scum, but by any name you don’t have much to worry about. When it’s thriving, filamentous algae appears as a large, green blob of slender threads near the bottom of a lake. In late summer and fall, clumps die and float to the surface en masse. These clumps of decay can trap gases produced by decomposition and puff up. High temperatures can also cause more growth of this algae. Whether the summer is hot or not, filamentous algae can grow in areas with excellent water quality, but the good news is that it doesn’t produce toxins. Blue-green algae, on the other hand, does. For more on this, see “How you can stop your lake from turning blue-green” from the April/May 2006 issue of Cottage Life.

When it comes to assessing water quality, frogs and other amphibians such as toads, newts, and salamanders, are good indicators of the health of your lake. Frogs are constantly absorbing water through their skin and are particularly sensitive to harmful agents that cause poor water quality, so a declining population could mean your lake is in trouble.

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