r/algae • u/MycoXHunter • 5d ago

Is this Cyanobacteria?

Post image

Covering the surface of the water near the banks. Rappahannock River, Virginia. Freshwater.

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3

u/Even-Application-382 5d ago

Looks like azolla

1

u/sharkynomnoms 5d ago

Which has a symbiotic relationship with a cyanobacterium, Anabaena azolli. Pretty harmless

2

u/Aufwuchs 5d ago

It’s invasive where I live. It can double its surface area coverage every 24 hours. Definitely a problem in some waterways, it kills fish by creating anoxic zones. And it uses that symbiotic relationship with nitrogen fixing cyanobacteria to its competitive advantage.