How does rising atmospheric CO2 affect marine organisms?

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Dandelion Reproduction in CO2-Enriched Air
McPeek, T.M. and Wang, X. 2007. Reproduction of dandelion (Taraxacum officinale) in a higher CO2 environment. Weed Science 55: 334-340.

What was done
The authors collected seeds from a single apomictic (capable of producing viable seeds) plant in Speedway, Indiana (USA), which they allowed to sprout and grow until reaching reproductive maturity, one to each of forty-two 8.4-L pots filled with pre-wetted and weekly-rewetted Premier Pro-Mix, half of which pots were placed within each of two controlled-environment chambers, one continually flushed with ambient air of 370 ppm CO2 and the other maintained at an elevated atmospheric CO2 concentration of 730 ppm. Then, after harvesting the plants and measuring numerous parameters related to their reproductive prowess, they conducted a second similar experiment where they measured various parameters related to the germination of the seeds produced in the two CO2 treatments, along with the physical characteristics of the second-generation plants 35 days after planting.

What was learned
McPeek and Wang report that the dandelion plants of their study "produced 83% more inflorescences and 32% more achenes, i.e., single-seed fruits, per plant at elevated than at ambient CO2," and that the "seeds from elevated CO2-grown plants were significantly heavier and had a higher germination percentage, leading to larger seedlings and earlier establishment in the subsequent generation." Furthermore, they say that "achenes from plants grown at elevated CO2 had characteristics, such as higher stalks at seed maturity, longer beaks, and larger pappi, which would increase the distance of seed dispersal by wind."

What it means
In the words of the two researchers, "dandelion can potentially become more widespread and noxious as atmospheric CO2 continues to rise because of human activities." And so it can; but so also can the desirable plants of the earth be benefited by the ongoing rise in the air's CO2 content; for like Deity, who sends forth life-supporting rain and causes the sun to shine upon the good and the evil alike, carbon dioxide bestows its life-enhancing blessings upon all of earth's plants as well, irrespective of whether we might deem them noxious or desirable. Truly, CO2 is an "equal-opportunity" benefactor of the biosphere.

Reviewed 9 January 2008