Archive for April, 2010

So long, shellfish: Oysters falling victim to ocean acidification

Increasing ocean acidification has taken a big toll on Northwest oyster farms, and that could translate to a shellfish shortage.

Could seafood fans be saying goodbye to shellfish sometime soon? Millions of oyster larvae have been dying in Northwest farms due to increasingly acidic ocean waters, which robs them of their ability to grow their shells, according to ABC News. The world’s oceans are absorbing more carbon dioxide than ever as greenhouse gas emissions increase on land.

“The chemistry is very simple. It is 101. Carbon dioxide makes the water more acidic, that is irrefutable,” said Oregon State University professor of oceanography Burke Hales.

Oyster farmers Mark Wiegardt and Sue Cudd of Tilamook, Oregon’s Whiskey Creek Shellfish Hatchery called in Hales and his team when their larvae suddently started dying. The hatchery’s 8,000 gallon tanks were pumping in water from the Pacific Ocean, which turned out to be increasingly acidic.
Continue reading ‘So long, shellfish: Oysters falling victim to ocean acidification’

The influence of engineered Fe2O3 nanoparticles and soluble (FeCl3) iron on the developmental toxicity caused by CO2-induced seawater acidification

An embryo development assay using a common test organism, the edible mussel (Mytilus galloprovincialis), exposed to both Fe2O3 nanoparticles and soluble FeCl3 at 3 acidic pHs, has provided evidence for the following: (1) CO2 enriched seawater adjusted to pH projections for carbon capture leakage scenarios (CCS) significantly impaired embryo development; (2) under natural pH conditions, no significant effect was detected following exposure of embryos to Fe, no matter if in nano- or soluble form; (3) at pH of natural seawater nano-Fe particles aggregate into large, polydisperse and porous particles, with no biological impact detected; (4) at pH 6 and 7, such aggregates may moderate the damage associated with CO2 enrichment as indicated by an increased prevalence of normal D-shell larvae when nano-Fe was present in the seawater at pH 7, while soluble iron benefited embryo development at pH 6, and (5) the observed effects of iron on pH-induced development toxicity were concentration dependent.Developmental toxicity of hypercapnia mediated by exposure to engineered Fe2O3.
Continue reading ‘The influence of engineered Fe2O3 nanoparticles and soluble (FeCl3) iron on the developmental toxicity caused by CO2-induced seawater acidification’

Ocean acidification and the Santa Barbara County Vintner’s Festival (audio)

This week on Poodle Radio, Colin Marshall host three live guests in the KCSB studio. First up is Indy reporter Ethan Stewart, here to discuss his cover story on ocean acidification. What is happening to the oceans, anyway? How much of it is likely to happen? What sort of research did he have to do before grasping the scientific and technological issues at hand, much less being able to explain them and express their possible consequences to the general reader?
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Stanford scientists link ocean acidification to prehistoric mass extinction

Earth experienced its biggest mass extinction 250 million years ago. New evidence from Stanford, which looks at calcium isotopes, suggests massive volcanic eruptions were to blame for ocean acidification that wiped out 90 percent of marine biodiversity. The result may parallel today’s climate change and ocean acidification.

New evidence gleaned by analyzing calcium embedded in Chinese limestone suggests that volcanoes, which spewed massive amounts of carbon dioxide into the atmosphere for a million years, caused the biggest mass extinction on Earth.

In a paper published April 26 in the Proceedings of the National Academy of Sciences, a team of researchers led by a Stanford geologist said that as carbon dioxide gas dissolved in the oceans, it raised the acidity of seawater.

The research team said it was a deadly combination – carbon dioxide in the atmosphere and higher acidity in the oceans – that eventually wiped out 90 percent of marine species and about three-quarters of land species, in a cataclysmic event 250 million years ago known as the “end-Permian extinction.”
Continue reading ‘Stanford scientists link ocean acidification to prehistoric mass extinction’

Calcium isotope constraints on the end-Permian mass extinction

The end-Permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope (δ13C) composition of carbonate minerals. Several extinction scenarios consistent with these observations have been put forward. Secular variation in the calcium isotope (δ44/40Ca) composition of marine sediments provides a tool for distinguishing among these possibilities and thereby constraining the causes of mass extinction. Here we report δ44/40Ca across the Permian-Triassic boundary from marine limestone in south China. The δ44/40Ca exhibits a transient negative excursion of ∼0.3‰ over a few hundred thousand years or less, which we interpret to reflect a change in the global δ44/40Ca composition of seawater. CO2-driven ocean acidification best explains the coincidence of the δ44/40Ca excursion with negative excursions in the δ13C of carbonates and organic matter and the preferential extinction of heavily calcified marine animals. Calcium isotope constraints on carbon cycle calculations suggest that the average δ13C of CO2 released was heavier than -28‰ and more likely near -15‰; these values indicate a source containing substantial amounts of mantle- or carbonate-derived carbon. Collectively, the results point toward Siberian Trap volcanism as the trigger of mass extinction.
Continue reading ‘Calcium isotope constraints on the end-Permian mass extinction’

Sigourney Weaver: ‘The oceans are not prospering’ (video)

At the screening of a new documentary on ocean acidification, actress Sigourney Weaver said people “cannot prosper” unless the oceans prosper, too — and that is not happening, she said.

Weaver, known for her roles in the popular films “Ghostbusters” and “Avatar,” narrated “Acid Test,” which examines ocean acidification.

“We also forget this very important fact that we all depend on the ocean for our survival, regardless of where we live or what we eat. Ocean organisms generate most of our oxygen. Oceans regulate our climate, and they provide much of our population with sustenance,” Weaver said at the screening on Capitol Hill.
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Report: Acidic oceans are an impending disaster

Ocean acidification – dubbed global warning’s “evil twin” – is a potentially disastrous consequence of rising levels of carbon dioxide in the Earth’s atmosphere, according to a recent report from the National Research Council.

The report says that ocean chemistry is changing faster than it has in hundreds of thousands of years because of the CO2 being absorbed from the atmosphere. The resulting increased acidity of the oceans poses a serious threat to shellfish and other marine life.

The increased acidity corrodes seashells, and thousands of species build shells around them to live. “It removes the building block for producing shells,” Steve Palumbi of Stanford University said last year. “A lot of organisms may not be able to survive.”
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Symposium on the Ocean in a High-CO2 World III

SCOR, IOC, and IGBP are co-sponsors of the Third Symposium, to be held in 2012. A planning committee of 14 members has been approved by the co-sponsors. Ulf Riebesell (Germany) is chairing the committee; other members are Claire Armstrong (Norway), Peter Brewer (USA), Ken Denman (Canada), Richard Feely (USA), Kunshan Gao (China-Beijing), Jean-Pierre Gattuso (France), Dan Laffoley (UK), Yukihiro Nojiri (Japan), James Orr (France), Hans-Otto Poertner (Germany), Carlos Eduardo Rezende (Brazil), Daniela Schmidt (UK), and Anya Waite (Australia). The committee will meet in December 2010 to begin planning the symposium.
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Ocean acidification: how bad can it get?

In a special issue of Oceanography published in December of 2009, Feely et al. review what we supposedly know about the current pH status of the world’s oceans, as well as what they say we can likely expect by the end of the current century.
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Side effects and accounting aspects of hypothetical large-scale Southern Ocean iron fertilization

Recent suggestions to slow down the increase in atmospheric carbon dioxide have included ocean fertilization by addition of the micronutrient iron to Southern Ocean surface waters, where a number of natural and artificial iron fertilization experiments have shown that low ambient iron concentrations limit phytoplankton growth. Using a coupled carbon-climate model with the marine biology’s response to iron addition calibrated against data from natural iron fertilization experiments, we examine biogeochemical side effects of a hypothetical large-scale Southern Ocean Iron Fertilization (OIF) that need to be considered when attempting to account for possible OIF-induced carbon offsets. In agreement with earlier studies our model simulates an OIF-induced increase in local air-sea CO2 fluxes by about 60 GtC over a 100-year period, which amounts to about 40% of the OIF-induced increase in organic carbon export. Offsetting CO2 return fluxes outside the region and after stopping the fertilization at 1, 7, 10, 50, and 100 years are quantified for a typical accounting period of 100 years. For continuous Southern Ocean iron fertilization, the return flux outside the fertilized area cancels about 8% of the fertilization-induced CO2 air-sea flux within the fertilized area on a 100-yr timescale. This “leakage” effect has a similar radiative impact as the simulated enhancement of marine N2O emissions. Other side effects not yet discussed in terms of accounting schemes include a decrease in Southern Ocean oxygen levels and a simultaneous shrinking of tropical suboxic areas, and accelerated ocean acidification in the entire water column in the Southern Ocean on the expense of reduced globally averaged surface water acidification. A prudent approach to account for the OIF-induced carbon sequestration would account for global air-sea CO2 fluxes rather than for local fluxes into the fertilized area only. However, according to our model, this would underestimate the potential for offsetting CO2 emissions by about 20% on a 100 year accounting timescale. We suggest that a fair accounting scheme applicable to both terrestrial and marine carbon sequestration has to be based on emission offsets rather than on changes in individual carbon pools.
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Ocean acidification in the IPCC AR5 WG II

OUP book