Red algae

Olympusman · Post by **Olympusman** » Tue May 12, 2015 9:33 am

Some red algae. These aer small isolated colonies. I have found some pinkish springs where the red algae have taken over and I conclude that when they do so they are toxic and kill off all other life. From what I have read, these are the source of the infamous "red tides" that kill of fish in significant numbers.

vasselle · Post by **vasselle** » Thu May 14, 2015 9:12 am

Hello.
Very nice et jolie couleurs.
Cordialement seb

carlos.uruguay · Post by **carlos.uruguay** » Thu May 14, 2015 7:28 pm

Good!

Bruce Taylor · Post by **Bruce Taylor** » Fri May 15, 2015 4:52 am

Hi Michael, I don't think any freshwater red algae (rhodophyta) have been implicated in "red tides." That phenomenon is classically marine, and caused by certain dinoflagellates (e.g. Karenia, Alexandrium and Pfiesteria).

In freshwater, a wide variety of organisms can cause red blooms, including euglenoids (Euglena, Trachelomonas), cryptophytes (Plagioselmis), green algae (Haematococcus lacustris), and cyanobacteria (Oscillatoria rubescens, etc). Some such blooms are associated with eutrophication, which can kill fish.

Are you sure your organism is a red alga (rhodophyte) and not some kind of cyanobacterium? The red algae are mostly marine, but a small diversity is found in freshwater, too (more than half aren't red, though!

).

I know very little about algae, so can't be of much help with ID (if needed), but there's a good chapter on them in Wehr & Sheath's Freshwater Algae of North America.