How does rising atmospheric CO2 affect marine organisms?

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That's One Tough Protist!
Bernhard, J.M., Mollo-Christensen, E., Eisenkolb, N. and Starczak, V.R. 2009. Tolerance of allogromiid Foraminifera to severely elevated carbon dioxide concentrations: Implications to future ecosystem functioning and paleoceanographic interpretations. Global and Planetary Change 65: 107-114.

What was done
The authors grew the marine foraminiferal protist Allogromia laticollaris -- which they describe as "a ubiquitous protistan constituent of marine microbial systems" and "an important link in the marine food web" -- in a mixture of 32%o seawater and Alga-Gro seawater medium in 20-ml glass culture tubes, while examining its response to a number of super-high atmospheric CO2 concentrations to which the tubes were exposed: 15,000, 30,000, 60,000, 90,000 and 200,000 ppm, which values are to be compared to the study's atmospheric control concentration of 375 ppm CO2.

What was learned
Bernhard et al. report that the protist they studied "is able to survive 10-14-day exposure to elevated CO2 as high as 200,000 ppm." In fact, they say that "both ATP [Adenosine Triphosphate, an indicator of cellular energy] data and microscopic examination indicate that considerable populations of A. laticollaris survived exposure to all experimental treatments of elevated CO2, even both replicates of the 200,000-ppm CO2 experiments [our italics]." And they found that "at least three specimens reproduced during exposure to either 90,000 ppm or 200,000 ppm CO2," while "such reproduction was observed only once in an atmospheric [375-ppm CO2] treatment."

What it means
The four researchers first note that "A. laticollaris is an appropriate species to predict the response of shallow-water thecate Foraminifera to predicted increases in atmospheric CO2, given its isolation [i.e., acquisition] from a shallow-water semi-tropical setting." Hence, they go on to say their results indicate that "at least some foraminiferal species will tolerate CO2 values that are one to two orders of magnitude [our italics] higher than those predicted for the next few centuries." And, last of all, they say that A. laticollaris will also tolerate CO2 values that are one to two orders of magnitude greater than those predicted to occur for the "extreme case" of burning all fossil fuels in the crust of the earth, which observation validates the title of our brief review: That's one tough protist!

Reviewed 8 July 2009