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Filamentous algae (Spirogyra, Cladophora, and many other varieties)

Filamentous algae photograph

Common names: Pond scum, water net, frog spittle, moss.

Location: Ponds, shorelines, and backwaters.

Description: Mass of long, stringy, hairlike strands; usually green in color but may become yellow grayish or brown; individual filaments are a series of cells joined end to end, which give them a thread-like appearance.

Hints to identify: Forms greenish mats on the water surface; begins growth along the water's edges or bottom and rises to the surface as a bubble-filled mass when mature; slimy or cotton-like in appearance; may form hair-like growth on logs, rocks, and other vegetation at lake bottom and on the shoreline. Spirogyra gives water a "grassy" taste and odor.

Importance of plant: Provides cover for small animals such as aquatic insects, snails, and scuds, which are valuable fish food.

Management strategy: See DNR regulations. Nuisance growth of filamentous algae may indicate that a lake has excessive nutrients (usually phosphorus). Adopting preventative measures such as limiting the flow of nutrients into the lake may help reduce the severity of nuisance conditions. For existing nuisances, you may achieve better control if you break up large surface mats before applying an algicide.