[Wonder Warthog]

"The limiting factor of phytoplankton growth is CO2 (presuming temp and sunlight are constant)."

I thought it had been shown that the limiting nutrient was trace iron??? And that adding just a small amount of iron caused massive blooms of phytoplankton??

[cogitator]

I thought it had been shown that the limiting nutrient was trace iron???

Depends on where you are. There's plenty of iron in coastal waters, so there nitrate and phosphate are the limiting nutrients. In the open ocean a long way from the continents, iron can be limiting.

[Blueflag]

As the other poster mentioned, it varies by local and depth and composition as to what THE specific limiting factor is. My point is that in the core reaction of photosynthesis, -- combining CO2 and H2O to make sugar, CO2 can be the limiting factor. This is true in hot house tomato farming and corn fields. I don't have the citation, but this was demonstrated IN DEPTH by the University of Southwestern Louisiana in the 1908s.