Archive for November, 2013

Scientists, contribute to the OA-ICC data compilation on the biological response to ocean acidification!

Numerous papers report the effects of ocean acidification on marine organisms and communities, but it has been difficult to compare the results since the carbonate chemistry and ancillary data are often reported in different units and scales, and calculated using different sets of constants. 

In response to this problem, a data compilation on the biological response to ocean acidification initiated by the EU projects EUR-OCEANS and EPOCA is now resuming in the framework of the International Atomic Energy Agency (IAEA) project “Ocean Acidification International Coordination Centre (OA-ICC)”.

If you are a scientist publishing on the biological response to ocean acidification, you will likely be contacted in the future. The OA-ICC thanks you in advance for sharing your data, it is a great way to get more cited!

Continue reading ‘Scientists, contribute to the OA-ICC data compilation on the biological response to ocean acidification!’

UK waters grow cooler – and more acid

Dipping your toes in the waters around Britain has grown marginally less inviting: in the last few years the seas have grown slightly colder.

Against the background of a continued warming trend, this blip is explained by scientists as an example of the climate’s tendency sometimes to go “off trend”, and to show clear variations from the norm.

UK researchers say the average UK coastal sea surface temperature in the last decade was lower in 2008-2012 than in 2003-2007, an example of short-term variability which they say is at odds with temperature records which “continue to show an overall upward trend“.

The finding – perhaps not surprising, given the slower pace of atmospheric warming in recent years – is reported by the Marine Climate Change Impacts Partnership (MCCIP) and is published in its latest Report Card, which assesses how climate change is affecting UK waters.

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Marine Climate Change Impacts Report Card 2013

The Marine Climate Change Impacts Report Card 2013 includes information on ocean acidification. A full scientific report on ocean acidification is also available.

The 2013 MCCIP Report Card provides the very latest updates on our understanding of how climate change is affecting UK seas. Over 150 scientists from more than 50 leading science organisations contributed to this report card covering a wide range of topics ensuring that the information is timely, accurate and comprehensive.

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Ocean acidification

In my view, the most serious, debilitating circumstance affecting the ocean today is acidification, the changing pH or acid balance in the water column with devastating impacts on the marine food chain, species migration and reproduction, and sustainability of habitat. This is a global situation, mostly invisible, and demanding of immediate action. What follows is quoted from a fact sheet on Ocean Acidification: “20 Facts About Ocean Acidification” prepared by the U.S. OCB Sub-Committee on Ocean Acidification in partnership with other international research organizations. It is reported here in full because of the clarity of the presentation and the urgency for public awareness about this issue.

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Can coral reefs delay the damaging effects of ocean acidification?

According to a paper published in the November issue of the journal Nature Climate Change, coral reefs may respond to ocean acidification in ways that will partially offset expected changes in seawater acidity taking place as the oceans take up human-produced carbon dioxide.

Andreas Andersson, a chemical oceanographer at Scripps Institution of Oceanography at UC San Diego, and lead author of the paper, said that most predictions of seawater acidification on coral reefs are based on observations from the open ocean. But the effects of increasing CO2 on coral reefs are very different than the changes in the open ocean, because the reef itself modifies the chemistry through various biogeochemical processes.

Continue reading ‘Can coral reefs delay the damaging effects of ocean acidification?’

Le changement climatique menace la santé des océans (in French)

L’acidification des océans est un des aspects majeurs mais les plus oubliés du changement climatique : elle fragilise peu à peu les écosystèmes, blanchit les coraux et menace de nombreuses espèces. C’est ce que révèle un rapport scientifique publié les jours derniers.

L’acidification des océans est un phénomène en augmentation et un des marqueurs les plus visibles du réchauffement climatique. C’est la conclusion qui a été présentée le 18 novembre dans un rapport publié durant la Conférence sur les changements climatiques, qui s’est tenue à Varsovie du 11 au 22 novembre. Il est issu du troisième symposium sur l’acidification des océans qui s’est déroulé à Monterey (Californie). Ce résumé à l’intention des décideurs a été préparé par la Commission océanographique intergouvernementale (COI) de l’UNESCO, le Comité scientifique pour la recherche océanique (SCOR) et le Programme international de géosphère-biosphère (IGBP). Il résume les conclusions de 540 experts de 37 pays et dresse un bilan de la recherche sur le sujet. Résultat, l’eau de mer devient plus acide (son pH diminue) à une vitesse croissante et dans des proportions alarmantes.

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Job Vacancy – NERC PhD Studentship (subject to funding) – Winners and losers in a more acidified ocean: impact on physiology and life history of two pteropod species

Please quote ref no: DTP
Closing date for applications: 06 Jan 2014 at 11:59pm

Supervisors: Clara Manno (BAS), Dorothee Bakker (UEA), Victoria Peck (BAS), Geraint Tarling (BAS)

Ocean acidification, induced by increasing anthropogenic carbon dioxide emissions, is recognized by reductions in pH, carbonate ion concentration, and calcium carbonate saturation state in the upper ocean. These effects are especially severe at high-latitudes, where cold temperatures enhance the solubility of CO2. Pteropods, the main planktonic producers of aragonite in the worlds’ oceans, are particularly vulnerable to forecasted changes in sea water carbonate chemistry. Although polar species L. helicina and sub-polar species L. retroversa belong to the same genus, their life-history and physiology are different. Biogeographic shifts in species distributions resulting from a change in environmental conditions are widely reported, particularly during the present era of rapid regional climatic change. Since L. helicina is the dominant calcifying species in some parts of the Southern Ocean, its potential regional extinction through ocean acidification can have wide biogeochemical implications. Whether or not L. retroversa will replace L. helicina is an important question for polar foodwebs and carbon budget.

Continue reading ‘Job Vacancy – NERC PhD Studentship (subject to funding) – Winners and losers in a more acidified ocean: impact on physiology and life history of two pteropod species’

Ocean acidification in the Bay of Bengal

The present study dealt with acidification of the Bay of Bengal and its impact on marine environment. It revealed that the average pH value of water in the Bay of Bengal on an average was around 7.75. The study showed strong positive correlation between pH and bicarbonate (R2 is 0.930), between electric conductivity and salinity (R2 is 0.999) and between electric conductivity and dissolved oxygen (R2 is 0.999). The pH in the Bay of Bengal has fallen by 0.2 units between 2012 and 1994 (pH 7.95). The study infers an impact of reduction of pH on calcifying organisms such as sea shells, oyster and coral reefs that are playing essential roles in their respective ecosystems. Average calcium carbonate composition of the calcifying organisms was found to be 80% which was 17% lower than the standard composition. The lower pH (7.75) might have made the Mollusks vulnerable and fragile which was evidenced by the presence of lesser number of Mollusks compared to that of 5 to 6 years back.

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Iron limitation modulates ocean acidification effects on Southern Ocean phytoplankton communities

The potential interactive effects of iron (Fe) limitation and Ocean Acidification in the Southern Ocean (SO) are largely unknown. Here we present results of a long-term incubation experiment investigating the combined effects of CO2 and Fe availability on natural phytoplankton assemblages from the Weddell Sea, Antarctica. Active Chl a fluorescence measurements revealed that we successfully cultured phytoplankton under both Fe-depleted and Fe-enriched conditions. Fe treatments had significant effects on photosynthetic efficiency (Fv/Fm; 0.3 for Fe-depleted and 0.5 for Fe-enriched conditions), non-photochemical quenching (NPQ), and relative electron transport rates (rETR). pCO2 treatments significantly affected NPQ and rETR, but had no effect on Fv/Fm. Under Fe limitation, increased pCO2 had no influence on C fixation whereas under Fe enrichment, primary production increased with increasing pCO2 levels. These CO2-dependent changes in productivity under Fe-enriched conditions were accompanied by a pronounced taxonomic shift from weakly to heavily silicified diatoms (i.e. from Pseudo-nitzschia sp. to Fragilariopsis sp.). Under Fe-depleted conditions, this functional shift was absent and thinly silicified species dominated all pCO2 treatments (Pseudo-nitzschia sp. and Synedropsis sp. for low and high pCO2, respectively). Our results suggest that Ocean Acidification could increase primary productivity and the abundance of heavily silicified, fast sinking diatoms in Fe-enriched areas, both potentially leading to a stimulation of the biological pump. Over much of the SO, however, Fe limitation could restrict this possible CO2 fertilization effect.

Continue reading ‘Iron limitation modulates ocean acidification effects on Southern Ocean phytoplankton communities’

Ocean acidification reverses competition for space as habitats degrade

How marine communities are affected by CO2-induced climate change depends on the ability of species to tolerate or adapt to the new conditions, and how the altered characteristics of species influence the outcomes of key processes, such as competition and predation. Our study examines how near future CO2 levels may affect the interactions between two damselfish species known to compete for space, and the effects of declining habitat quality on these interactions. The two focal species differed in their tolerance to elevated CO2, with the species that is competitively dominant under present day conditions being most affected. Field experiments showed that elevated CO2 (945 μatm) reversed the competitive outcome between the two species with mortal consequences, and this reversal was accentuated in degraded habitats. Understanding these complex interactions will be crucial to predicting the likely composition of future communities under ocean acidification and climate change.

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Ocean acidification in the IPCC AR5 WG II

OUP book