How does rising atmospheric CO2 affect marine organisms?

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Volume 3 Number 6:  15 March 2000

A Matter of Faith: Everybody touts "science" as the source of their opinions with respect to CO2 and global change; yet everyone's opinion is deeply rooted in a "faith" that is forged in the course of their daily experience - a data-driven reason-based philosophy derived from their own or others' life-long observations of the real world.

Journal Reviews
Observed Trends and Model Forecasts of North American Storminess: No net change in the frequency of storms is found in North America over the period 1885-1996.  In addition, the inability of present-day GCMs to simulate changes in regional storminess is noted.

Decadal and Multidecadal Changes in Precipitation in Chesapeake Bay: A study of salinity oscillations in sediment cores from the Chesapeake Bay reveal a high degree of decadal and multidecadal variability in precipitation for the region over the past 1000 years, with extreme shifts sometimes occurring in as little time as a decade.

Will Global Warming Significantly Increase Malaria Transmission Rates?: Historical analysis of malaria epidemics reveals that the role of temperature in the spread of malaria is insignificant in comparison to other factors.

The Invasion of Honey Mesquite in the Southwestern U.S.: A woody species encroachment into an Arizona grassland area is found to increase both the total number and species richness of local bird populations.

Substance Not Registered for Use in Australia Threatens Corals There: A substance used in antifouling marine craft paints that can be toxic to the endosymbiotic microalgae of coral polyps has been found in the waters of the Great Barrier Reef Marine Park.  Its presence could weaken the ability of reef ecosystems to withstand any number of environmental stresses, such as global warming, leading to increased incidences of coral bleaching.

Effects of Elevated CO2 and Ozone on Aspen Clones: After one year of differential CO2 exposure in a FACE experiment, elevated O3 had caused significant visible damage to leaves of trembling aspen clones grown at ambient CO2.  When exposed to elevated CO2, however, this O3-induced foliar damage was significantly reduced.  In addition to ameliorating the negative effects of O3 on foliar tissue damage, elevated CO2 significantly increased light-saturated rates of net photosynthesis by 43%, lowered the light compensation point by 36%, and reduced dark respiration rates by 24%.

Effects of Elevated CO2 and Phosphorus on a Calcareous Grassland: Field and model studies of nutrient-poor calcareous grasslands suggest that biomass production in such communities is limited by low levels of soil nitrogen.  After two years of differential CO2 exposure and phosphorus fertilization, it was shown that community biomass from CO2-enriched microcosms containing legumes and adequate levels of soil phosphorus had greater nitrogen contents than those lacking leguminous species, phosphorus fertilization, and CO2 enrichment.  In addition, biomass was greatest in communities that contained legumes, phosphorus fertilization, and elevated levels of CO2.

Effects of Elevated CO2 on an Epiphytic Fern: Elevated CO2 tended to accelerate the germination process of spores from the epiphytic fern Pyrrosia piloselloides.  Atmospheric CO2 enrichment significantly increased photosynthetic rates in fern gametophytes within 40 days of germination.  Despite the onset of photosynthetic acclimation, gametophytes continued to exhibit CO2-induced enhancements of photosynthesis, which ultimately contributed to total gametophytic dry masses that were 43% greater at 515 ppm CO2 than they were at 350 ppm.  Thus, it is likely that rising CO2 concentrations will maintain, and possibly enhance, the abundance of ferns in earth's ecosystems.

Modifications of Leaf Surface Structures in Elevated CO2: Leaves of white oak trees growing near natural CO2-emitting springs in central Italy exhibited decreased stomatal frequencies as the air's CO2 concentration rose from 350 to 750 ppm.  In addition, raising the air's CO2 concentration from 750 to 2600 ppm, increased the amount of cuticular waxes on the leaves nearly three-fold.  Thus, it is likely that future increases in the air's CO2 content will enable white oak trees to better conserve water and maintain a good internal water status.

Short-Term Effect of Elevated CO2 on Respiration: Over a short several-hour experiment, enriching individual leaves of nine deciduous tree species with an extra 400 ppm CO2 had little to no effect on leaf dark respiration rates, with their median response being a 1.5% reduction in respiration.  Due to the extremely short duration of CO2 enrichment utilized in this experiment, however, we are at odds with the author's conclusion with respect to the implications of his data for future carbon sequestration in deciduous forests.