How does rising atmospheric CO2 affect marine organisms?

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Live Long and Prosper ... With More CO2?
Melov, S., Ravenscroft, J., Malik, S., Gill, M.S., Walker, D.W., Clayton, P.E., Wallace, D.C., Malfroy, B., Doctrow, S.R. and Lithgow, G.J.  2000.  Extension of life-span with superoxide dismutase/catalase mimetics.  Science 289: 1567-1569.

What was done
The authors tested the theory that reactive oxygen species cause aging by examining the effects of two superoxide dismutase-/catalase-like mimetics (EUK-8 and EUK-134) on the life-span of normal and mutant Caenorhabditis elegans worms that ingested various concentrations of the mimetics.

What was learned
In every experiment, treatment of normal worms with the antioxidant mimetics significantly increased both mean and maximum life-span.  Treatment of normal worms with but 0.05 mM EUK-134, for example, increased their mean life-span by fully 54%.  And in mutant worms whose normal life-span was genetically shortened by 37%, treatment with 0.5 mM EUK-134 restored their life-span to normal by increasing their mutation-reduced life-span by 67%.  It was also determined that these effects were not due to a reduction in worm metabolism, which could have reduced the production of oxygen radicals, but "by augmenting natural antioxidant defenses without having any overt effects on other traits."

What it means
In the words of the authors, "these results suggest that endogenous oxidative stress is a major determinant of the rate of aging."  The significance of this statement resides in the fact that antioxidants tend to reduce such stresses in animals, including man, and in the observation that atmospheric CO2 enrichment has been shown to moderately enhance the concentrations of some of these plant constituents, such as vitamins A and C (see our Journal Review Why Are We Living Longer?), as well as several substances that have been proven effective in fighting a number of human cancers and viral infections (see our Journal Review CO2 Enhances Plant Production of Cancer-Fighting Substances).  These connections are very intriguing; and we continue to monitor advances in these potentially related fields as they continue to develop.

Reviewed 20 September 2000