How does rising atmospheric CO2 affect marine organisms?

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Growth Response to CO2 (Tubers) -- Summary
Nearly all of earth's plant life responds favorably to increases in the air's CO2 content by exhibiting enhanced rates of photosynthesis and biomass production.  In addition, plants grown in CO2-enriched air commonly exhibit preferential carbon allocation belowground to roots, especially when faced with adverse growing conditions.  Thus, one might logically expect plants that produce tubers to exhibit strong positive responses to atmospheric CO2 enrichment, particularly in these underground storage organs.

In reviewing the literature, it is clear that tubers do indeed respond strongly to elevated atmospheric CO2 concentrations.  In the study of Miglietta et al. (1998), for example, potatoes subjected to a 300-ppm increase in CO2 produced 40% more tuber biomass than potatoes grown at ambient CO2; and Ludewig et al. (1998) reported a doubling of tuber biomass in potato plants that were exposed to a 600-ppm increase in the air's CO2 concentration.

In an interesting study conducted by Idso et al. (2000), spider lily (Hymenocallis littoralis) plants were shown to increase their aboveground biomass by 48%, while their belowground (bulb) biomass was enhanced by 56%, in response to a 300-ppm increase in the air's CO2 content.  Furthermore, within the bulbs of this plant, the concentrations of five substances possessing anticancer and antiviral properties - which have been demonstrated to be effective in fighting a number of human maladies - were increased by an average of 12% in response to the elevated CO2 concentration.

These observations suggest that tubers will likely respond very positively to rising atmospheric CO2 levels, with increases in photosynthesis, growth, and the accumulation of various secondary carbon compounds that can be used for a variety of purposes.

Idso, S.B., Kimball, B.A., Pettit III, G.R., Garner, L.C., Pettit, G.R. and Backhaus, R.A.  2000.  Effects of atmospheric CO2 enrichment on the growth and development of Hymenocallis littoralis (Amaryllidaceae) and the concentrations of several antineoplastic and antiviral constituents of its bulbs.  American Journal of Botany 87: 769-773.

Ludewig, F., Sonnewald, U., Kauder, F., Heineke, D., Geiger, M., Stitt, M., Muller-Rober, B.T., Gillissen, B., Kuhn, C. and Frommer, W.B.  1998.  The role of transient starch in acclimation to elevated atmospheric CO2FEBS Letters 429: 147-151.

Miglietta, F., Magliulo, V., Bindi, M., Cerio, L., Vaccari, F.P., Loduca, V. and Peressotti, A.  1998.  Free Air CO2 Enrichment of potato (Solanum tuberosum L.): development, growth and yield.  Global Change Biology 4: 163-172.