How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Genotypic Responses of a Perennial Grass to Elevated CO2 and Temperature
Norton, L.R., Firbank, L.G., Gray, A.J. and Watkinson, A.R. 1999. Responses to elevated temperature and CO2 in the perennial grass Agrostis curtisii in relation to population origin. Functional Ecology 13: 29-37.

What was done
Seeds were collected from ten populations of Agrostis curtisii spread across Europe and grown in solardomes subjected to ambient and elevated (700 ppm) combinations of atmospheric CO2 and ambient and elevated (ambient plus 3C) air temperatures to determine if any genotypic responses to elevated CO2 and temperature were related to the climate of population origin.

What was learned
After one year of growth in various treatment combinations, no significant effects of CO2 or temperature on plant biomass production were discovered, although biomass tended to be greater under the treatment combining elevated CO2 with elevated temperature. After two years of treatment exposure, biomass production was significantly enhanced by elevated temperature, but still was unaffected by elevated CO2. Interestingly, there were no significant effects of climate of origin on biomass production in the ten tested populations, indicating that growth responses to elevated CO2 and temperature need not be related to climate of origin.

What it means
The results of this paper suggest that as the CO2 content of the air increases, it will not become a selective agent that preferentially favors certain genotypes of Agrostis curtisii over other genotypes. In other words, the increasing atmospheric CO2 concentration should maintain the genetic diversity that exists within Agrostis curtisii populations spread across the European continent.

Reviewed 15 November 1999