Archive for February, 2011

75% of World’s coral reefs currently under threat, new analysis finds

“Reefs at Risk Revisited” report presents comprehensive analysis of threats to coral reefs

A new comprehensive analysis finds that 75 percent of the world’s coral reefs are currently threatened by local and global pressures. For the first time, the analysis includes threats from climate change, including warming seas and rising ocean acidification. The report shows that local pressures— such as overfishing, coastal development, and pollution— pose the most immediate and direct risks, threatening more than 60 percent of coral reefs today.

Reefs at Risk Revisited,” the most detailed assessment of threats to coral reefs ever undertaken, is being released by the World Resources Institute, along with the Nature Conservancy, the WorldFish Center, the International Coral Reef Action Network, Global Coral Reef Monitoring Network, and the UNEP-World Conservation Monitoring Center, along with a network of more than 25 organizations. Launch activities are taking place in Washington, D.C., London, Malaysia, Indonesia, the Caribbean, Australia, and other locations around the world.
Continue reading ‘75% of World’s coral reefs currently under threat, new analysis finds’

Opportunity to attend ocb workshop on ocean acidification (22-24 March)


There are 6 spaces available for early career scientists and for scientists from underrepresented groups to attend the first meeting for US principal investigators working on ocean acidification research projects. This meeting will be held in Woods Hole, MA on March 22-24, 2011.

The meeting agenda and information can be found at
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Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers

Ocean acidification (decreases in carbonate ion concentration and pH) in response to rising atmospheric pCO2 is generally expected to reduce rates of calcification by reef calcifying organisms, with potentially severe implications for coral reef ecosystems. Large, algal symbiont-bearing benthic foraminifers, which are important primary and carbonate producers in coral reefs, produce high-Mg calcite shells, whose solubility can exceed that of aragonite produced by corals, making them the “first responder” in coral reefs to the decreasing carbonate saturation state of seawater. Here we report results of culture experiments performed to assess the effects of ongoing ocean acidification on the calcification of symbiont-bearing reef foraminifers using a high-precision pCO2 control system. Living clone individuals of three foraminiferal species (Baculogypsina sphaerulata, Calcarina gaudichaudii, and Amphisorus hemprichii) were subjected to seawater at five pCO2 levels from 260 to 970 μatm. Cultured individuals were maintained for about 12 weeks in an indoor flow-through system under constant water temperature, light intensity, and photoperiod. After the experiments, the shell diameter and weight of each cultured specimen were measured. Net calcification of Baculogypsina and Calcarina, which secrete a hyaline shell and host diatom symbionts, increased under intermediate levels of pCO2 (580 and/or 770 μatm) and decreased at a higher pCO2 level (970 μatm). Net calcification of Amphisorus, which secretes a porcelaneous shell and hosts dinoflagellate symbionts, tended to decrease at elevated pCO2. These different responses among the three species are possibly due to differences in calcification mechanisms (in particular, the specific carbonate species used for calcification) between hyaline and porcelaneous taxa, and to links between calcification by the foraminiferal hosts and photosynthesis by the algal endosymbionts. Our findings suggest that ongoing ocean acidification might favor symbiont-bearing reef foraminifers with hyaline shells at intermediate pCO2 levels (580 to 770 μatm) but be unfavorable to those with either hyaline or porcelaneous shells at higher pCO2 levels (near 1000 μatm).
Continue reading ‘Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers’

Ocean acidification impacts on the physiology and adhesive properties of the starfish Asterias rubens

The increase in atmospheric CO2 due to anthropogenic activity is an acidification of the ocean which could lead to pH as low as 7.7 and 7.4 by 2100 and 2300, respectively. The impact of this phenomenon will depend on the considered organisms and ecosystems. In particular little is currently known on the effects of acidification on temperate ecosystems. The intertidal rocky shores are of great interest in this context as intertidal organisms face tidal pH and temperature changes. They may harbor organisms pre-adapted to the changes predicted for the coming years and centuries. Furthermore, the intertidal environment will be more affected as shallow waters will face the highest decrease in seawater pH. Therefore, we studied the effects of ocean acidification on Asterias rubens, the common starfish of the Belgian coast which is known to structure some intertidal shores through its predator activity. Effects on the physiology but also on the adhesion capacities of the organism were investigated using organisms maintained at pH 8.1, 7.7 and 7.4 for periods of 15 and 31 days. Our results showed that Asterias rubens did not regulate its acid-base balance as no accumulation of HCO3 – was observed and no dissolution of the skeleton as a buffer was detected by measures of Mg2+ and Ca2+ in the coelomic fluid. However, the starfish showed no consequence from the decrease of the coelomic fluid pH as all activities measured (respirometry, adhesion capacities) were not significantly affected by seawater pH decrease. Equilibration of the coelomic pH with the seawater pH was fast (typically less than 24 hours). The former was always lower than the latter. This suggests an accumulation of respiratory CO2 inside the organism which creates a respiratory acidosis and so a decrease of the pH. In conclusion, it seems that Asterias rubens withstands the effects of ocean acidification, at least for short terms (one month). If this is confirmed, the balance between the predator and its prey (Mytilus edulis, the blue mussel) may shift with time as many studies have shown deleterious effects on the latter. The rocky intertidal shores may face changes in the coming centuries and move to a new equilibrium.
Continue reading ‘Ocean acidification impacts on the physiology and adhesive properties of the starfish Asterias rubens’

Ocean acidification (video)

This demonstration provides a clear, visual introduction to one of the important consequences of increasing atmospheric carbon dioxide concentrations on seawater, called ocean acidification.


  • Two (2) glasses or beakers
  • Tap water
  • Aquarium pH Indicator
    Ordinary aquarium pH indicator is readily available from pet stores. The photographs below show the results using this pH indicator (pH 6 = Yellow / pH7.6 = Blue). Alternatively, you can use phenolphthalein pH indicator for a more dramatic result. You will need to add a few drops of limewater (builder’s lime dissolved in water) to the water sample first to make a slightly basic solution. Blowing bubbles of exhaled air through this solution will cause it to change from bright pink to perfectly clear.
  • Baking soda
  • White vinegar
  • Citric acid
  • Straw
  • Safety goggles

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Ocean acidification commercial – GEICO style (video)

Continue reading ‘Ocean acidification commercial – GEICO style (video)’

Oldest species of a marine mollusc discovered

An international research team, with Spanish participation, has discovered a new species of mollusc, Polyconites hadriani, in various parts of the Iberian Peninsula. The researchers say this species, which is the oldest in its genus, adapted to the acidification of the oceans that took place while it was in existence. This process could now determine the evolution of modern marine systems.

The new species Polyconites hadriani, which was discovered in 2007, has been crowned the oldest in the Polyconites genus of the family Polyconitidae (rudists), a kind of extinct sea mollusc. To date, scientists had thought that the oldest mollusc in this genus was Polyconites verneuili.

‘P. hadriani is similar in shape to P. verneuili, but it is smaller (with a 30 mm smaller diameter), and with a thinner calcite layer to its shell (around 3 mm difference),’ Eulalia Gili, one of the authors of the study and a researcher at the Department of Geology of the Autonomous University of Barcelona (UAB), tells SINC.
Continue reading ‘Oldest species of a marine mollusc discovered’

Seafood producers tackle ocean acidification at annual Summit (video)

From 31 January to 2 February, more than 700 conferees from 30 countries convened at Seafood Summit 2011 in Vancouver, Bristish Colombia (BC). There they wrestled with how to improve the sustainability of commercial fishing and aquaculture.

Now in its ninth year, the event drew 40 per cent of its attendees from the seafood business. Industry personnel joined conservationists, researchers, and government officials in discussing a range of sustainability issues – marine spatial planning, traceability shortcomings, and next-generation aquaculture among them.

The toughest item on the agenda may well have been ocean acidification, which only recently has emerged as a major issue to those concerned with food security and the productivity of our seas.

Scientific and journalistic coverage of this problem has exploded; a search on Google Scholar shows more than 25,700 articles, most of them published since 2006.

Acidification results from CO2 in the atmosphere combining with sea water to form carbonic acid. The oceans absorb about a third of human society’s CO2 emissions every year.
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Efficiency of the CO2-concentrating mechanism of diatoms

Diatoms are responsible for a large fraction of CO2 export to deep seawater, a process responsible for low modern-day CO2 concentrations in surface seawater and the atmosphere. Like other photosynthetic organisms, diatoms have adapted to these low ambient concentrations by operating a CO2 concentrating mechanism (CCM) to elevate the concentration of CO2 at the site of fixation. We used mass spectrometric measurements of passive and active cellular carbon fluxes and model simulations of these fluxes to better understand the stoichiometric and energetic efficiency and the physiological architecture of the diatom CCM. The membranes of diatoms are highly permeable to CO2, resulting in a large diffusive exchange of CO2 between the cell and external milieu. An active transport of carbon from the cytoplasm into the chloroplast is the main driver of the diatom CCM. Only one-third of this carbon flux is fixed photosynthetically, and the rest is lost by CO2 diffusion back to the cytoplasm. Both the passive influx of CO2 from the external medium and the recycling of the CO2 leaking out of the chloroplast are achieved by the activity of a carbonic anhydrase enzyme combined with the maintenance of a low concentration of HCO3 in the cytoplasm. To achieve the CO2 concentration necessary to saturate carbon fixation, the CO2 is most likely concentrated within the pyrenoid, an organelle within the chloroplast where the CO2-fixating enzyme is located.
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Climate change and ocean acidification (video)

Researchers from SF State’s Romberg Tiburon Center for Environmental Studies examine a threat to the ocean’s ability to absorb greenhouse gasses.

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Ocean acidification in the IPCC AR5 WG II

OUP book