How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Volume 2 Number 15:  1 August 1999

What Consensus?: On 28 June 1999 some fifty-plus scientists converged on the U.S. Capitol "to urge lawmakers to heed their warnings about global warming," as reported in a news release from the Union of Concerned Scientists.  In their press conference, as reported by Wadman (1999), the scientists said that Congress "should not be distracted by the 'contrarian' views of a handful of scientists who dispute what they described as a mainstream scientific consensus on climate change."  We wonder just what "consensus" the fifty-plus scientists were talking about...

Journal Reviews
Acclimatization of Coral Reefs: A review of the literature suggests that both the coral host and its symbionts possess physiological mechanisms that can help them adapt or acclimatize to various environmental stresses.

Aquarium Corals: A review of corals growing in aquariums reveals that corals are not as delicate as is widely believed.

Photosynthesis and Calcification in Coral Reefs: A major review of the scientific literature reveals just how complex the process of coral reef growth is.  There are so many factors involved that it is almost impossible to make a prediction about the future in which we can place any confidence.  More studies of a host of crucial phenomena ought therefore to be commenced as soon as possible to enable us to develop rational policies relative to global environmental change and coral reef ecosystems.

Alkalinity Adjustments and Coral Calcification Rates: Increased CO2 concentrations may result in reduced rates of calcification in certain reef-building corals.  However, our understanding of this phenomenon is still somewhat limited and further investigation is warranted.

Historical Coral Growth at the Great Barrier Reef: A 500-year study of coral extension, density and calcification rates reveals a high degree of inter-annual variability in these three parameters.

Coral Reef Responses to Environmental Change: A review of reproduction and symbiotic relationships in coral reef communities reveals a number of ways by which reefs might successfully cope with major environmental changes.

Photosynthetic Acclimation of Sunflower to Elevated CO2: Elevated CO2 increased photosynthetic rates in upper canopy leaves of sunflower by about 50% relative to rates measured on leaves of plants grown at ambient CO2.  In addition, photosynthetic down-regulation was not apparent in the upper canopy, but was evident in older leaves located lower in the canopy, as evidenced by decreased rates of photosynthesis and leaf rubisco contents.

Photosynthetic Response of Longleaf Pine to Elevated CO2, Soil Nitrogen, and Water Supply: Longleaf pine seedlings grown for nearly two years in open-top chambers with 730 ppm atmospheric CO2 displayed rates of photosynthesis that were almost 50% greater than those of seedlings grown at 365 ppm CO2.  Although atmospheric CO2 enrichment reduced stomatal conductance and increased plant water-use efficiency, seedlings grown at high soil nitrogen exhibited greater whole-plant water-use, and subsequently greater water stress than seedlings grown at low soil nitrogen, which displayed less whole-plant water-use, and subsequently less water stress during periods of reduced water availability.

Response of an Orchid to Super-Elevated CO2: Epiphytic CAM orchids enriched with super-elevated CO2 concentrations of 10,000 ppm for three months attained total plant dry weights that were 2-fold greater than those of plantlets grown at ambient CO2.  Although CO2-enrichment led to starch tissue contents that were nearly 20-fold greater than those of ambiently-grown plants, no physical disruption or damage to chloroplasts from starch granules occurred.

Response of a C3 and C4 Forage Crop to Elevated CO2: A 75% increase in the CO2 content of the air led to 37 and 22% enhancements in the seasonal photosynthetic rates of a C3 (rhizoma peanut) and C4 (bahiagrass) perennial forage crop.  In addition, atmospheric CO2 enrichment increased whole-plot forage harvests of rhizoma peanut and bahiagrass by 21 and 17%, respectively.

Initial Response of a Forest Ecosystem to Elevated CO2: Loblolly pine ecosystems exposed to 560 ppm CO2 for one year in a FACE experiment located in North Carolina, USA, displayed growth rates that were 24% greater than those of control ecosystems.  In addition, elevated CO2 increased canopy biomass by 14% after just 12 months of atmospheric CO2 enrichment.