Cyanobacteria (blue green algae)
Aphanizomenon is a scum forming cyanobacterium and it has the ability to produce several cyanotoxins. Aphanizomenon is a nitrogen-fixing cyanobacterium and you may see heterocysts in the colonies (circular cells without pigments). Aphanizomenon cells are rectangle-shaped and link end-to-end to form filaments, and filaments usually link side-by-side to form large colonies that look like grass clippings of a bushel of straw. Aphanizomenon colonies can be quite large and visible by the naked eye from a boat.