Archive for April, 2008

Effect of Ocean Acidification ‘turned on its head’

Ocean acidification doesn’t necessarily mean less calcification, or at least for coccolithophorids, according to a new study by Iglesias-Rodriguez et al. (Science, 17 April 2008).

As atmospheric concentrations of carbon dioxide rise due to human activities, the oceans will continue to become more acidic as they absorb the extra gas, but the effects on calcifying phytoplankton may not be simple to predict. In fact, over the industrial age, while CO2 emissions are steadily rising, coccolithophorids seemed to have increased their calcification.
Continue reading ‘Effect of Ocean Acidification ‘turned on its head’’

When our oceans turn sour

Climate change is a core issue on the Rudd Government’s agenda. But there’s another carbon problem that has been avoided and is largely independent of global warming.

In a speech to the Australian Strategic Policy Institute last week on Australia’s focus on the Pacific, parliamentary secretary for Pacific Island affairs Duncan Kerr pointed to the effect of marine acidity on coral reefs, the backbone of economic activity for many islander communities. Kerr noted that if land drowns and coral reefs die, the Pacific faces mass movements of people, presenting strategic and humanitarian challenges for Australia.
Continue reading ‘When our oceans turn sour’

Plankton hold surprise for climate research

Amid concerns about the damage that rising levels of CO2 will do to the oceans, including to corals and other species, there seems to be good news for at least one group of creatures.

Biological oceanographer M. Debora Iglesias-Rodriguez of the National Oceanography Center at the University of Southampton, U.K., found that one species of single-celled phytoplankton, Emiliania huxleyi, increases its calcification rate as CO2 levels rise in the water.
Continue reading ‘Plankton hold surprise for climate research’

Ocean acidification position available at the Australian Institute of Marine Science

Science Leader (Climate Change), Position 367

This position will lead one of four research teams and provide visionary leadership for AIMS response to the challenges of global climate change for tropical marine systems, especially the threat posed by ocean acidification. The successful applicant will have the ability to foster a collaborative research culture and effective working relationships among researchers from different disciplines and organisations. The applicant will also lead, present, and publish world-class research from a relevant area and is likely to have extensive experience in carbonate chemistry and/or the biology of calcification.
Continue reading ‘Ocean acidification position available at the Australian Institute of Marine Science’

Modeling the marine aragonite cycle: changes under rising carbon dioxide and its role in shallow water CaCO3 dissolution

The marine aragonite cycle has been included in the global biogeochemical model PISCES to study the role of aragonite in shallow water CaCO3 dissolution. Aragonite production is parameterized as a function of mesozooplankton biomass and aragonite saturation state of ambient waters. Observation-based estimates of marine carbonate production and dissolution are well reproduced by the model and about 60% of the combined CaCO3 water column dissolution from aragonite and calcite is simulated above 2000 m. In contrast, a calcite-only version yields a much smaller fraction. This suggests that the aragonite cycle should be included in models for a realistic representation of CaCO3 dissolution and alkalinity. For the SRES A2 CO2 scenario, production rates of aragonite are projected to notably decrease after 2050. By the end of this century, global aragonite production is reduced by almost one third and total CaCO3 production by 19% relative to pre-industrial. Geographically, the effect from increasing atmospheric CO2, and the subsequent reduction in saturation state, is largest in the subpolar and polar areas where the modeled aragonite production is projected to decrease by 65% until 2100.

Continue reading ‘Modeling the marine aragonite cycle: changes under rising carbon dioxide and its role in shallow water CaCO3 dissolution’

Increasing levels of atmospheric CO2 cause a rise in ocean plankton calcification

Increased carbon dioxide in the Earth’s atmosphere is causing microscopic ocean plants to produce greater amounts of calcium carbonate (chalk) – with potentially wide ranging implications for predicting the cycling of carbon in the oceans and climate modelling.

That is the conclusion of an international team of scientists led by investigators based at the UK’s National Oceanography Centre, Southampton and the University of Oxford, published in the journal, Science, on Friday, 18th April 2008.
Continue reading ‘Increasing levels of atmospheric CO2 cause a rise in ocean plankton calcification’

Does ocean acidification induce an upward flux of marine aggregates?

The adsorption of anthropogenic atmospheric carbon dioxide (CO2) by the ocean provokes its acidification. This acidification may alter several oceanic processes, including the export of biogenic carbon from the upper layer of the ocean, hence providing a feedback on rising atmospheric carbon concentrations. The effect of seawater acidification on transparent exopolymeric particles (TEP) driven aggregation and sedimentation processes were investigated by studying the interactions between latex beads and TEP precursors collected in the lagoon of New Caledonia. A suspension of TEP and beads was prepared and the formation of mixed aggregates was monitored as a function of pH under increasing turbulence intensities. The pH was controlled by addition of sulfuric acid. Aggregation and sedimentation processes driven by TEP were drastically reduced when the pH of seawater decreases within the expected limits imposed by increased anthropogenic CO2 emissions. In addition to the diminution of TEP sticking properties, the diminution of seawater pH led to a significant increase of the TEP pool, most likely due to swollen structures. A diminution of seawater pH by 0.2 units or more led to a stop or a reversal of the downward flux of particles. If applicable to oceanic conditions, the sedimentation of marine aggregates may slow down or even stop as the pH decreases, and the vertical flux of organic carbon may reverse. This would enhance both rising atmospheric carbon and ocean acidification.
Continue reading ‘Does ocean acidification induce an upward flux of marine aggregates?’

Scientists have discovered that some plankton can thrive in acidic oceans

Scientists have discovered that some plankton can thrive in acidic oceans, which are a result of increased levels of carbon dioxide.

According to a report in New Scientist, this was discovered by Debora Iglesias-Rodriguez from the National Oceanography Centre at the University of Southampton, UK, and her colleagues.
Continue reading ‘Scientists have discovered that some plankton can thrive in acidic oceans’

Acidic oceans may be water of life for plankton

Most life in the ocean will suffer as carbon dioxide levels increase and the water becomes more acidic. Some plankton will buck the trend, however, thriving and putting on weight as carbon dioxide levels rise – but it remains to be seen how this will affect the global carbon balance.

Débora Iglesias-Rodríguez, from the National Oceanography Centre at the University of Southampton, UK, and her colleagues, simulated the increase in dissolved carbon dioxide in surface ocean waters by bubbling carbon dioxide through cultures of coccolithophores, a type of single-celled photosynthesising plankton.

In previous experiments water acidity had been regulated by simply adding acid or base, but this method has been criticised for being too artificial. Iglesias-Rodríguez’s method found that higher carbon dioxide concentrations increased calcification, speeding up growth of the tiny calcite plates on the plankton cell.

Continue reading ‘Acidic oceans may be water of life for plankton’

Study sees an advantage for algae species in changing oceans

Contrary to expectations, a microscopic plant that lives in oceans around the world may thrive in the changing ocean conditions of the coming decades, a team of scientists reported Thursday.
Continue reading ‘Study sees an advantage for algae species in changing oceans’

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Ocean acidification in the IPCC AR5 WG II

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