Other than calcium what does coralline require for nutrients?

[Reefmack]

I just used a razor scraper to remove over a year's worth of heavy coralline growth from the back and sides of my tank. Someone questioned whether the coralline being gone will lead to green algae reappearing, as there's less coralline to consume what green algae would normally consume - nitrates.

I don't think that coralline algae controls green algae by outcompeting it for nitrates? Then again, other than calcium, magnesium, maybe other trace elements, and light energy, does coralline consume any nitrates at all? What are all of the other requirements to keep coralline alive - surely it must need some organic compounds of some type to support it?

 

[Sk8r]

Probably mostly light: it seems to bloom if you have excess mag, above what supports your alk and calcium levels.

I'm not sure how relevant it is, but i read an interesting bit on cyano that says it lays down that white calcite stuff in stromatolites (those sea-knobby-things) by depleting the water of---is it carbon?---which causes a tiny microzone in the water near the cyano where calcite deposits: hence the slow growth of these mostly calcite knobs in the shallows. I have wondered if maybe something similar wasn't going on with coralline algae: it yanks something from the water and starts the encrustation that is partly calcite.

Interesting question: I'm sure Greenbean or one of our other resident experts has the straight scoop on this.

 

[Reefmack]

Thanks Sk8r. I agree that light has to have a major part to play in keeping coralline alive, but surely there must be more involved than light plus inorganic compounds like calcium & magnesium. Although the stuff seems for all purposes like a non-living rock form, there must be some type of carbon based organics involved in the equation to keep it alive. My ages old biology background makes me think this way. It's an interesting question that I can't fully answer.

By the way, I recently read somewhere that cyano has given us the oldest known fossils - those stromatolites that you mentioned - one of the oldest known life forms on earth. Pretty interesting.

 

[Sk8r]

I've gotten interested in the---is it eukaryotes?---the really primitive life forms. I think it's bailing the Titanic with a thimble to think we can avoid scattering cyano in our tanks: the stuff is amazing. I started wiki-ing and googling cyano and diatoms and coralline and its just really interesting reading.
http://www.paleoweb.net/algae/
http://en.wikipedia.org/wiki/Red_alga
http://en.wikipedia.org/wiki/Coralline_algae

 

[Reefmack]

Interesting articles. I never realized there were branching forms of coralline - weird looking stuff!

Branched coralline