Not trying to be a dick, but I figured Algae is still a carbon based life form... So I googled and it said: Uptake of CO2 by algae is approximately twice of the weight of algae.

But I assume other stuff is doing most of the heavy lifting... I think I remember something about coral forests, just trying to ask people who know more - what's taking up all that carbon? Is algae a threat to it?

P.S looked it up, apparently seagrasses and mangroves absorbed the most carbon in the ocean, and Algae van risk sea grass by shading it too much... I still suspect they're not totally at odds, because it didn't say anything about being a direct threat, just making too much shade.... Anyways. I'm sure others will comment.

EDIT: oh, maybe it's that sea grass is more stable in its effects/consumption of carbon. Where as Algae patches probably float and fluctuate, or die off... But that probably fertilizes other stuff... I guess this is all why "sustainable" solutions are the focus...