How does rising atmospheric CO2 affect marine organisms?

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Differential Responses of Peat Moss to Elevated CO2 and Nitrogen Supply
Van der Heijden, E., Jauhiainen, J., Silvola, J., Vasander, H. and Kuiper, P.J.C.  2000.  Effects of elevated atmospheric CO2 concentration and increased nitrogen deposition on growth and chemical composition of ombrotrophic Sphagnum balticum and oligo-mesotrophic Sphagnum papillosumJournal of Bryology 22: 175-182.

What was done
The authors grew two peat moss species hydroponically within controlled environmental chambers receiving atmospheric CO2 concentrations of 360 and 720 ppm for four months.  In addition, these nonvascular plants were simultaneously subjected to low and high levels of nitrogen fertilization.  Thus, the authors studied the effects of atmospheric CO2 enrichment and nitrogen availability on the growth of these two differing moss species.

What was learned
Elevated CO2 increased total plant dry mass in Sphagnum papillosum by 70%, as did high nitrogen by 53%.  Together, these two variables stimulated total growth in this species by 68%.  However, neither elevated CO2 nor high nitrogen, alone or in combination, had any significant effects on the growth of Sphagnum balticum.

What it means
Simply stated, as the atmospheric CO2 concentration increases, it is likely that S. papillosum will respond by increasing its biomass, while S. balticum remains indifferent to the increase in CO2.  In swamps and bogs where both species coexist, or where only S. papillosum occurs, there should thus be an increase in carbon sequestration as the air's CO2 content continues to rise.