Archive for December, 2012

Ocean acidification (video)

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Ocean acidification – free seminar

Join us to learn about ocean acidification and the strategies and actions to protect marine resources recommended by the state’s Blue Ribbon Panel on Ocean Acidification

Thursday 24 January 2012 6pm – 8pm, Everett Station, Weyerhaeuser Room, 3201 Smith Avenue, Everett, WA

Free and open to the public

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Preparing to manage coral reefs for ocean acidification: lessons from coral bleaching

Ocean acidification is a direct consequence of increasing atmospheric carbon dioxide concentrations and is predicted to compromise the structure and function of coral reefs within this century. Research into the effects of ocean acidification on coral reefs has focused primarily on measuring and predicting changes in seawater carbon (C) chemistry and the biological and geochemical responses of reef organisms to such changes. To date, few ocean acidification studies have been designed to address conservation planning and management priorities. Here, we discuss how existing marine protected area design principles developed to address coral bleaching may be modified to address ocean acidification. We also identify five research priorities needed to incorporate ocean acidification into conservation planning and management: (1) establishing an ocean C chemistry baseline, (2) establishing ecological baselines, (3) determining species/habitat/community sensitivity to ocean acidification, (4) projecting changes in seawater carbonate chemistry, and (5) identifying potentially synergistic effects of multiple stressors.

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Climate change and ocean acidification (video)

In this speech on the Senate floor, Sheldon talked about one of the most alarming effects of climate change: ocean acidification.

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Daily buffer usage may save some corals from ocean acidity

New research published this week indicates that some corals may in fact use alkalinity differently depending on the time of day.  While acidification impedes a corals ability to build calcium carbonate skeletons, some corals are able to switch to bicarbonate ions instead.

Published this week in the journal Proceedings of the Royal B, researchers are finding out more about how corals calcify both during the day and during the night and what alkalinity components are preferred.

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Could climate change boost toxic algal blooms in the oceans?

Preliminary research hints that ocean acidification may promote some types of algal blooms that make people and animals sick

In 1799 about a hundred Aleut hunters working for a Russian-American trading group died in Alaska’s Peril Strait only two hours after eating black mussels collected there. Those who survived did so because they threw up after desperately consuming gunpowder, tobacco and alcohol to purge toxin from their bodies. This was the first recorded incidence of paralytic shellfish poisoning on the west coast of North America.

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The free proton concentration scale for seawater pH

Due to the use of multiple pH scales in seawater, studies related to the pH of marine environments are unnecessarily complicated and prone to inaccuracy. It is desirable that a standard scale be adopted, and we suggest the free proton pH scale be used. To ensure the free proton scale is accurate and consistent with primary pH measurements in seawater, we use the Pitzer Ion-Interaction model to re-evaluate the free scale pH and stoichiometric dissociation constants ofHSO4andH2CO3. The Pitzer model is validated over a salinity range of 5 to 45 and temperatures of 0 to 45°C using the measured mean activity coefficient of HCl in artificial seawater. The resulting standard potential and stoichiometric dissociation constants are compared to previous estimates. The validated model results are used to evaluate more accurate values for the pH of equi-molal (m = 0.04 mol kg– 1) amine buffers on the free proton concentration scale, which can be used to calibrate free scale pH measurements in natural waters.

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Chemistry may save some coral from acidity

Ocean acidification may not affect some corals as badly as previously thought, suggests a new study.

Marine biologist Dr Steeve Comeau, of the California State University, and colleagues, report their findings today in the Proceedings of the Royal Society B.

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Coral reef calcifiers buffer their response to ocean acidification using both bicarbonate and carbonate

Central to evaluating the effects of ocean acidification (OA) on coral reefs is understanding how calcification is affected by the dissolution of CO2 in sea water, which causes declines in carbonate ion concentration [CO32−] and increases in bicarbonate ion concentration [HCO3]. To address this topic, we manipulated [CO32−] and [HCO3] to test the effects on calcification of the coral Porites rus and the alga Hydrolithon onkodes, measured from the start to the end of a 15-day incubation, as well as in the day and night. [CO32−] played a significant role in light and dark calcification of P. rus, whereas [HCO3] mainly affected calcification in the light. Both [CO32−] and [HCO3] had a significant effect on the calcification of H. onkodes, but the strongest relationship was found with [CO32−]. Our results show that the negative effect of declining [CO32−] on the calcification of corals and algae can be partly mitigated by the use of HCO3 for calcification and perhaps photosynthesis. These results add empirical support to two conceptual models that can form a template for further research to account for the calcification response of corals and crustose coralline algae to OA.

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Seasonality of CO2 in coastal oceans altered by increasing anthropogenic nutrient delivery from large rivers: evidence from the Changjiang-East China Sea system

Model studies suggested that human-induced increase in nutrient load may have stimulated primary production and thus has enhanced the CO2 uptake capacity in the coastal ocean. In this study, we investigated the seasonal variations of the surface water’s partial pressure of CO2 (pCO2sw) in the highly human-impacted Changjiang-East China Sea system between 2008 and 2011. The seasonality of pCO2sw has large spatial variations, with the largest extreme of 170 ± 75 μatm on the inner shelf near the Changjiang Estuary (from 271 ± 55 μatm in summer to 441 ± 51 μatm in autumn) and the weakest extreme of 53 ± 20 μatm on the outer shelf (from 328 ± 9 μatm in winter to 381 ± 18 μatm in summer). During the summer period, stronger stratification and biological production driven by the eutrophic Changjiang plume results in a very low CO2 in surface waters and a very high CO2 in bottom waters on the inner shelf, with the latter returning high CO2 to the surface water during the mixed period. Interestingly, a comparison with historical data shows that the average pCO2sw on the inner shelf near the Changjiang Estuary has decreased notably during summer, but it has increased during autumn and winter from the 1990s to the 2000s. We suggest that this decadal change is associated with recently increased eutrophication. This would increase both the photosynthetic removal of CO2 in surface waters and the respiratory release of CO2 in bottom waters during summertime, thereby returning more CO2 to the surface during the subsequent mixing seasons and/or episodic extreme weather events (e.g. typhoons). Our finding demonstrates that increasing anthropogenic nutrient delivery from a large river may enhance the sequestration capacity of CO2 in summer but may reduce it in autumn and winter. Consequently, the coastal ocean may not necessarily take up more atmospheric CO2 in response to increasing eutrophication, and the net effect largely depends on the relative time scale of air-sea gas exchange and offshore transport of the shelf water. Finally, the case we reported for the Changjiang system may have general ramifications for other eutrophic coastal oceans.

Continue reading ‘Seasonality of CO2 in coastal oceans altered by increasing anthropogenic nutrient delivery from large rivers: evidence from the Changjiang-East China Sea system’

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Ocean acidification in the IPCC AR5 WG II

OUP book