Plankton Algae (Anabaena, Aphanizomenon, and many other varieties)

Plankton algae illustration

Common names: Blue-green algae, scum, waterbloom.

Location: Lakewide, generally free-floating, but concentrations occur along windward shores and backwater areas.

Description: Microscopic plants generally growing near the surface; may form multicellular colonies or filaments; abundant growth results in "blooms" that color the water green or turquoise blue.

Hints to identify: Look for a change in water color; severe blooms often resemble pea soup; blue-green algae form unsightly, jellylike masses or a blue, paint-like scum on beaches and shorelines.

Importance of plant: Provides food for certain small aquatic animals and young fish. Management strategy: See page 14 for DNR permit requirements. Abundant growth indicates that a lake has excessive nutrients, usually phosphorus.

Caution: When some species of blue-green algae are decaying, their cells release toxic materials, which can poison animals that drink the water. These toxic blooms are uncommon, but it is wise to keep your pets and livestock away from the water when any algal bloom is breaking up. Preventive measures such as limiting the flow of nutrients into the lake may reduce future blue-green algae blooms. You can get temporary control of existing algae blooms using an algicide.