Archive for February, 2007

The fate of pelagic CaCO3 production in a high CO2 ocean: A model study

This model study addresses the change in pelagic calcium carbonate production (CaCO3, as calcite in the model) and dissolution in response to rising atmospheric CO2. The parameterization of CaCO3 production includes a dependency on the saturation state of seawater with respect to calcite. It was derived from laboratory and mesocosm studies on particulate organic and inorganic carbon production in Emiliania huxleyi as a function of pCO2. The model predicts values of CaCO3 production and dissolution in line with recent estimates. The effect of rising pCO2 on CaCO3 production and dissolution was quantified by means of model simulations forced with atmospheric CO2 increasing at a rate of 1% per year from 286 ppm to 1144 ppm. The simulation predicts a decrease of CaCO3 production by 27%. The combined change in production and dissolution of CaCO3 yields an excess uptake of CO2 from the atmosphere by the ocean of 5.9 GtC.

M. Gehlen, R. Gangstø, B. Schneider, L. Bopp, O. Aumont, C. Ethe, 2007. The fate of pelagic CaCO3 production in a high CO2 ocean: A model study. Biogeosciences Discussions 4:533-560. Article.

Paleophysiology and end-permian mass extinction

Knoll A. H., Bambach R. K., Payne J. L., Pruss S. & Fischer W. W., 2007. Paleophysiology and end-Permian mass extinction. Earth and Planetary Science Letters 256:295-313.

Physiological research aimed at understanding current global change provides a basis for evaluating selective survivorship associated with Permo-Triassic mass extinction. …

Continue reading ‘Paleophysiology and end-permian mass extinction’

Influence of elevated CO2 concentrations on thermal tolerance of the edible crab Cancer pagurus

Metzger R., Sartoris F. J., Langenbuch M. & Pörtner H. O., 2007. Influence of elevated CO2 concentrations on thermal tolerance of the edible crab Cancer pagurus. Journal of Thermal Biology 32:144-151.

Current trends of global climate change affect marine ectothermal animals not only through the increase in ambient temperature…
Continue reading ‘Influence of elevated CO2 concentrations on thermal tolerance of the edible crab Cancer pagurus’

Physiological changes in marine picocyanobacterial Synechococcus strains exposed to elevated CO2 partial pressure

Unicellular marine cyanobacteria are abundant in both coastal and oligotrophic environments, where they contribute substantially to primary production. The physiological effect of future increases in atmospheric CO2 concentrations on the marine picocyanobacteria is still poorly known. We studied the physiological changes in marine phycocyanin (PC)-rich and phycoerythrin (PE)-rich Synechococcus strains under different CO2 partial pressures (350, 600 and 800 ppm). The PE strain showed no significant change in growth rate over the experimental CO2 range. A significant increase (25.4%) in carbohydrate was observed at 800 ppm CO2, but no significant change in protein and RNA/DNA ratio was observed in any CO2 treatment. The PC strain showed a significant increase (36.7%) in growth rate at 800 ppm CO2, but no significant change in carbohydrate or protein content was observed over the entire CO2 range. The RNA/DNA ratio increased with increasing CO2 concentration and was positively correlated with growth rate. Cellular red fluorescence and orange fluorescence of the PE strain tended to decline in all CO2 treatments. However, no such decline was observed at higher CO2 treatments in the PC strain. Our results suggest that the PC strain would probably benefit more than the PE strain from future increases in atmospheric CO2 concentrations.

Lu, Z., Jiao N., Zhang H., 2006. Physiological changes in marine picocyanobacterial Synechococcus strains exposed to elevated CO2 partial pressure. Marine Biology Research 2(6):424-430. Article.

Elevated CO2 enhances nitrogen fixation and growth in the marine cyanobacterium Trichodesmium

The increases in atmospheric pCO2 over the last century are accompanied by higher concentrations of CO2(aq) in the surface oceans. This acidification of the surface ocean is expected to influence aquatic primary productivity and may also affect cyanobacterial nitrogen (N)-fixers (diazotrophs). No data is currently available showing the response of diazotrophs to enhanced oceanic CO2(aq). We examined the influence of pCO2 [preindustrial~250 ppmv (low), ambient~400, future~900 ppmv (high)] on the photosynthesis, N fixation, and growth of Trichodesmium IMS101. Trichodesmium spp. is a bloom-forming cyanobacterium contributing substantial inputs of ‘new N’ to the oligotrophic subtropical and tropical oceans. High pCO2 enhanced N fixation, C : N ratios, filament length, and biomass of Trichodesmium in comparison with both ambient and low pCO2 cultures. Photosynthesis and respiration did not change significantly between the treatments. We suggest that enhanced N fixation and growth in the high pCO2 cultures occurs due to reallocation of energy and resources from carbon concentrating mechanisms (CCM) required under low and ambient pCO2. Thus, in oceanic regions, where light and nutrients such as P and Fe are not limiting, we expect the projected concentrations of CO2 to increase N fixation and growth of Trichodesmium. Other diazotrophs may be similarly affected, thereby enhancing inputs of new N and increasing primary productivity in the oceans.

Levitan et al., 2007. Elevated CO2 enhances nitrogen fixation and growth in the marine cyanobacterium Trichodesmium. Global Change Biology 2007 13:2 531. Article.

IPCC report “Climate Change 2007: The Physical Science Basis”

The Summary for Policymakers of “Climate Change 2007: The Physical Science Basis” is available today on the IPCC web site.

Coral bleaching ‘could occur yearly’

… Dr Reichelt said the reef would face new problems in the future, such as the spread of coral disease, possible negative impacts caused by the overfishing of sharks and “acidification”.

Acidification occurs when atmospheric carbon dioxide (CO2) is absorbed into oceans at great levels.

Conservative estimates predict that CO2 concentrations in the atmosphere could double or triple by the end of the century, increasing the acidity of oceans significantly.

“When that happens the animals and plants that live in the ocean and make skeletons made out of calcium carbonate … won’t be able to make their skeletons anymore,” Dr Reichelt said.

“It will be hopefully some centuries away but it will happen if CO2 levels keep going up.”

The Age, 2 February 2007. Article.

Workshop on the Significance of Changes in Surface CO2 and Ocean pH in Shelf Sea Ecosystems

The ocean is becoming more acidic as increasing atmospheric carbon dioxide (CO2) is absorbed at the surface. It is thought that the pH of the global ocean has fallen by about 0.1 units over the past 200 years and that it could drop by a further 0.5 units by the year 2100 if CO2 emissions are not regulated (Royal Soc, 2005). A recent study of potential change in the North Sea suggests that pH change this century may exceed its natural variability in most of the North Sea. Impacts of acidity change are likely but their exact nature remains largely unknown and may occur across the range of ecosystem processes.  This aspect of climate change is potentially a precursor to the longer-term thermal effects.This workshop will concentrate on shelf sea environments as most previous  work has concentrated on open ocean systems.

Web site.

Richard Feely elected AGU fellow

Richard (Dick) Feely elected AGU fellow: NOAA/PMEL senior scientist Dick Feely has been elected as a new AGU fellow. As only 0.1% of AGU members are elected as fellows each year, it is quite an honour. The new fellows will be recognised in Acapulco, Mexico during the Joint Assembly in May. Dick was nominated for “His groundbreaking research and scientific leadership to quantify oceanic uptake of anthropogenic CO2 and the effect of ocean acidification”.

Source: International Ocean Carbon Coordination Project

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Ocean acidification in the IPCC AR5 WG II

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