The potential impact of seawater acidification on the concentrations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP), and the activity of the enzyme DMSP-lyase was investigated during a pelagic ecosystem CO2 enrichment experiment (PeECE III) in spring 2005. Natural phytoplankton blooms were studied for 24 days under present, double and triple partial pressures of CO2 (pCO2; pH=8.3, 8.0, 7.8) in triplicate 25 m3 enclosures. The results indicate similar DMSP concentrations and DMSP-lyase activity (DLA) patterns for all treatments. Hence, DMSP and DLA do not seem to have been affected by the CO2 treatment. In contrast, DMS concentrations showed small but statistically significant differences in the temporal development of the low versus the high CO2 treatments. The low pCO2 enclosures had higher DMS concentrations during the first 10 days, after which the levels decreased earlier and more rapidly than in the other treatments. Integrated over the whole study period, DMS concentrations were not significantly different from those of the double and triple pCO2 treatments. Pigment and flow-cytometric data indicate that phytoplanktonic populations were generally similar between the treatments, suggesting a certain resilience of the marine ecosystem under study to the induced pH changes, which is reflected in DMSP and DLA. However, there were significant differences in bacterial community structure and the abundance of one group of viruses infecting nanoeukaryotic algae. The amount of DMS accumulated per total DMSP or chlorophyll-a differed significantly between the present and future scenarios, suggesting that the pathways for DMS production or bacterial DMS consumption were affected by seawater pH. A comparison with previous work (PeECE II) suggests that DMS concentrations do not respond consistently to pelagic ecosystem CO2 enrichment experiments.
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Dynamics of dimethylsulphoniopropionate and dimethylsulphide under different CO2 concentrations during a mesocosm experiment
Published 11 October 2007 Science ClosedTags: biogeochemistry, phytoplankton
Coccolithophores and calcite saturation state in the Baltic and Black Seas
Published 11 October 2007 Science ClosedTags: phytoplankton
Tyrrell et al.
The Baltic and Black Seas are both brackish, that is to say both have salinities intermediate between freshwater and seawater. The coccolithophore Emiliania huxleyi is abundant in one, the Black Sea, but absent from the other, the Baltic Sea. Here we present summertime coccolithophore measurements confirming this difference, as well as data on the calcium carbonate saturation state of the Baltic Sea. We find that the Baltic Sea becomes undersaturated (or nearly so) in winter, with respect to both the aragonite and calcite mineral forms of CaCO3. Data for the Black Sea are more limited, but it appears to remain strongly supersaturated year-round. The absence of E. huxleyi from the Baltic Sea could therefore potentially be explained by dissolution of their coccoliths in winter, suggesting that minimum annual (wintertime) saturation states could be most important in determining future ocean acidification impacts. In addition to this potential importance of winter saturation state, alternative explanations are also possible, either related to differences in salinity or else to differences in silicate concentrations.
Continue reading ‘Coccolithophores and calcite saturation state in the Baltic and Black Seas’
Impact of CO2-induced seawater acidification on the burrowing activity of Nereis virens and sediment nutrient flux
Published 5 October 2007 Science ClosedS. Widdicombe and H. R. Needham
A mesocosm experiment was conducted to quantify the effects of medium term (5 wk) exposure to acidified seawater on the structure of Nereis virens (Polychaeta) burrows and sediment nutrient fluxes. Worms were exposed to seawater acidified to a pH of 7.3, 6.5 or 5.6 using carbon dioxide (CO2) gas. These treatments mimicked the effects of either ocean acidification (pH 7.3) or leakage from a sub-seabed CO2 storage site (pH 6.5 and 5.6). Results from these treatments were compared to those from worms maintained in natural seawater with a pH ≈ 7.9. The experiment showed that the presence and structure of N. virens burrows significantly increased the sediment uptake of nitrate and the release of ammonium, nitrite and silicate. Phosphate flux was unaffected by the presence of burrows. Nutrient flux rates were also significantly affected by changes in seawater acidity. A reduction in seawater pH caused an increase in nitrate uptake and increase in ammonium release, a decrease in nitrite release and a decrease in phosphate uptake. The flux of silicate was unaffected by changes in seawater pH. As changes in acidity had no impact on the size and structure of worm burrows, it was concluded that the impact of seawater pH on nutrient flux was probably due to changes in the microbial communities responsible for nutrient transformations. Whilst this paper demonstrates that leakage from sub-seabed storage would have significant and immediate effects on nutrient cycling, impacts of ocean acidification through atmospheric absorption are less obvious. This paper concludes that ocean acidification could have a significant impact on sediment nutrient flux in coastal and shelf seas as a result of potential changes in the structure and function of bioturbating communities.
Continue reading ‘Impact of CO2-induced seawater acidification on the burrowing activity of Nereis virens and sediment nutrient flux’
ANCHORAGE, Alaska — A scientist from the National Oceanic and Atmospheric Administration says the acid level in oceans is increasing.
The culprit could be the same source that many attribute to global warming.
The North Pacific Ocean and Bering Sea are home to some of the richest fisheries in the world.
Dr. Richard Feely with the Pacific Marine Environmental Lab said those fisheries could be at risk from carbon dioxide emissions.
“Over the past 200 years or so, we have released about 500 billion metric tons of carbon dioxide in the atmosphere and the oceans have taken up about a third of that,” Feely said.
Feely said once carbon dioxide is taken in by the ocean, it turns to carbonic acid. Studies have measured a 30 percent rise in ocean acidification over the last 200 years.
Ancient corals may have been more adaptable to changing ocean chemistry than previously thought, a new study shows.
The findings may offer hope that modern corals can adapt as global warming causes seas to become more acidic.
These fossil corals in diverse reef communities adjusted to an acidic environment by altering the way they built their chalky skeletons.
Modern hard corals—known as scleractinians—form reefs of thousands of tiny skeletons made from a calcium carbonate called aragonite.
Aragonite is susceptible to the corrosive effects of acidic oceans, which today has become a byproduct of a build-up of carbon dioxide in the atmosphere.
“We now have many different arguments to prove that these corals were actually made originally out of calcite—and not just aragonite that was transformed after the coral died and become fossilized,” said study co-author Jaroslaw Stolarski, a paleontologist from the Institute of Paleobiology at the Polish Academy of Sciences.
Continue reading ‘Corals May Have Defense Against Global Warming’
Jaroslaw Stolarski, Anders Meibom, Radoslaw Przenioslo & Maciej Mazur
It has been generally thought that scleractinian corals form purely aragonitic skeletons. We show that a well-preserved fossil coral, Coelosmilia sp. from the Upper Cretaceous (about 70 million years ago), has preserved skeletal structural features identical to those observed in present-day scleractinians. However, the skeleton of Coelosmilia sp. is entirely calcitic. Its fine-scale structure and chemistry indicate that the calcite is primary and did not form from the diagenetic alteration of aragonite. This result implies that corals, like other groups of marine, calcium carbonate–producing organisms, can form skeletons of different carbonate polymorphs.
Continue reading ‘A Cretaceous scleractinian coral with a calcitic skeleton’
Climate change is the most important threat to the Earth. Even if we stabilize CO2 concentrations, the 2007 IPCC (Intergovernmental Panel on Climate Change) Assessment confirms that warming will continue for decades and sea level will continue to rise for centuries. Some direct effects of climate change in the marine environment are already visible, but others need to be defined by enhanced observations, analysis and modelling. We have a rudimentary understanding of the sensitivity and adaptability of natural and managed ecosystems to climate change. An assessment of the consequences of climate change on the World’s Oceans has a high scientific and social relevance and is urgently needed.
Continue reading ‘Effects of climate change on the World’s oceans’
Altered kelp (Laminariales) phlorotannins and growth under elevated carbon dioxide and ultraviolet-B treatments can influence associated intertidal food webs
Published 1 October 2007 Science ClosedSwanson K. & Fox C. H.
Due to the importance of brown algae, such as kelp (Laminariales, Phaeophyta), within most cool nearshore environments, any direct responses of kelp to multiple global changes could alter the integrity of future coastal marine systems. Fifty-five-day manipulation of carbon dioxide (CO2) and ultraviolet light (UVB) within outdoor sea-tanks, approximating past, present and two predicted future levels, examined the direct influences on Saccharina latissima (= Laminaria saccharina) and Nereocystis luetkeana development and biochemistry, as well as the indirect influences on a marine herbivore (Tegula funebralis; Gastropoda, Mollusca) and on naturally occurring intertidal detritivores. Kelp species displayed variable directional (negative and positive growth) and scale responses to CO2 and UVB manipulations, which was influenced by interactions. Kelp phlorotannin (phenolic) production in blade tissues was induced by elevated UVB levels, and especially enhanced (additively) by elevated CO2, further suggesting that some actively growing kelp species are carbon limited in typical nearshore environments. Negative indirect effects upon detritivore consumers fed CO2-manipulated kelp blade tissues were detected, however, no statistical relationships existed among UVB-treated tissues, and test herbivores did not distinguish between phlorotannin-altered CO2: UVB-treated kelp blade tissues. Results suggest that past and future conditions differentially benefit these kelp species, which implies a potential for shifts in species abundance and community composition. Higher CO2 conditions can indirectly impede marine decay processes delaying access to recycled trace nutrients, which may be disruptive to the seasonal regrowth of algae and/or higher trophic levels of nearshore ecosystems.
Continue reading ‘Altered kelp (Laminariales) phlorotannins and growth under elevated carbon dioxide and ultraviolet-B treatments can influence associated intertidal food webs’
Two of Britain’s leading environmental thinkers say it is time to develop a quick technical fix for climate change.
Writing in the journal Nature, Science Museum head Chris Rapley and Gaia theorist James Lovelock suggest looking at boosting ocean take-up of CO2.
Continue reading ‘Lovelock urges ocean climate fix’
James E. Lovelock & Chris G. Rapley
We propose a way to stimulate the Earth’s capacity to cure itself, as an emergency treatment for the pathology of global warming.
Measurements of the climate system show that the Earth is fast becoming a hotter planet than anything yet experienced by humans. Processes that would normally regulate climate are being driven to amplify warming. Such feedbacks, as well as the inertia of the Earth system — and that of our response — make it doubtful that any of the well-intentioned technical or social schemes for carbon dieting will restore the status quo. What is needed is a fundamental cure.
Continue reading ‘Ocean pipes could help the Earth to cure itself’
Hawaii’s tradewinds blow away much of the pollution caused by sulfur and nitrogen released into the atmosphere from human activities, says a University of Hawaii scientist.
That’s good news for Honolulu, but how about for the ocean?
The magnitude of nitrogen and sulfur-bearing acids falling into coastal waters is not really known, says Fred Mackenzie, professor emeritus of sedimentary and global geochemistry.
“We get a little smog downtown from combustion activities and see it at times, particularly when we get Kona winds, but most of the stuff really blows out to sea, past the coastal region,” he said.
Continue reading ‘Pollutants found to be making sea more acidic’
The US may violate its own standards on water quality by refusing to limit emissions of carbon dioxide, suggests a new study modelling ocean acidification.
“About one-third of the CO2 from fossil-fuel burning is absorbed by the world’s oceans,” explains Ken Caldeira at Stanford University in California, US, who led the study.
The CO2 lowers the pH of the ocean’s surface, a phenomenon known as ocean acidification. This is predicted to have dramatic consequences on marine life by dissolving the shells of tiny organisms and corals.
Continue reading ‘US set to violate its standards on CO2 emissions’
U.S. researchers say acid rain’s impact on the world’s oceans is greatest along the coastlines.
The report, published online in the Proceedings of the National Academy of Sciences, said ocean acidification hampers the ability of marine organisms to harness calcium carbonate for making hard outer shells or exoskeletons, which provide essential food and habitat to other organisms.
Ocean acidification occurs when chemical compounds such as carbon dioxide, sulfur or nitrogen mix with seawater, a process which lowers the pH and reduces the storage of carbon.
Continue reading ‘Acid Rain Hurting Marine Organisms’
A U.S. study shows that while acid rainfall plays a minor role in ocean acidity, the impact is much greater in the shallower waters of the coastal ocean.
Ocean acidification occurs when chemical compounds such as carbon dioxide, sulfur or nitrogen are produced by power plants and agricultural activities mix with seawater — a process that lowers water pH values and thereby reduces carbon storage.
“Acid rain isn’t just a problem of the land. It’s also affecting the ocean,” said Scott Doney, lead author of the study and a senior scientist at the Woods Hole Oceanographic Institution. “That effect is most pronounced near the coasts, which are already some of the most heavily affected and vulnerable parts of the ocean due to pollution, over-fishing and climate change.”
Continue reading ‘Study looks at acid rainfall in the ocean’
Acid Rain Has Disproportionate Impact on Near-shore Ocean Waters
Published 21 September 2007 Media coverage ClosedThe release of sulfur and nitrogen into the atmosphere by power plants and agricultural activities–commonly referred to as acid rain–plays a minor role in making the ocean more acidic on a global scale, but the impact is greatly amplified in the shallower waters of the coastal oceans, according to new research.
Continue reading ‘Acid Rain Has Disproportionate Impact on Near-shore Ocean Waters’
CO2 emissions could violate EPA ocean-quality standards within decades
Published 21 September 2007 Media coverage ClosedStanford, CA. In a commentary in the September 25, 2007, issue of the Geophysical Research Letters (GRL), a large team of scientists state that human-induced carbon dioxide (CO2) emissions will alter ocean chemistry to the point where it will violate U.S. Environmental Protection Agency Quality Criteria [1976] by mid-century if emissions are not dramatically curtailed now. This is the first recognition that atmospheric CO2 emissions will cause ocean waters to violate EPA water quality criteria.
Continue reading ‘CO2 emissions could violate EPA ocean-quality standards within decades’
Ocean Acidification: The Sleeper Environmental Issue of Our Time
Published 19 September 2007 Media coverage ClosedSome friends of mine are working on a new film about an alarming dimension of the global carbon-emission problem that’s received scant attention. Accomplished documentary filmmaker Barbara Ettinger (her previous works include Two Square Miles and Martha and Ethel) and her husband and partner Sven Huseby are traveling the globe speaking to leading scientists studying acidification of our oceans, which threatens to change life — both on land and sea as we know it.
Ocean acidification has been called the sleeper environmental issue of our time. We can smell — and often see — the havoc that emissions from smokestacks and car exhausts wreak on our air. But we fail to consider the huge amounts of carbon absorbed by our seas, even though they cover 70% of the planet. Carbon increases the water’s pH, leading to decreases in calcium carbonate, crucial for creating bones in fish, shells on crustaceans and coral reefs.
Continue reading ‘Ocean Acidification: The Sleeper Environmental Issue of Our Time’
Millions of juvenile clams are dying each year before they are large enough to be harvested by commercial diggers.
A marine science professor from Peaks Island believes he may have found a way to dramatically increase their likelihood of survival, and in the process, potentially increase the number of clams that can be harvested commercially here in Maine and around the world.
Mark Green, a marine science professor at Saint Joseph`s College in Standish, has demonstrated in field experiments that spreading crushed clamshells over marine sediment provides a buffer against acidic soil conditions, which he believes have been dissolving the shells of young clams.
Industry officials and clammers have long believed that it was predators, not acidic sediment levels, that were killing off massive amounts of baby clams. But Green`s research indicates that is likely not the case.
“Anything that can stop the (die-off) process could give clams an edge,“ said Don Card, a state marine biologist based in Bath who is familiar with Green`s research. “It has great potential.“
Last year, Green, who teaches at Saint Joseph`s College, received a $419,000 National Science Foundation grant to study why so many juvenile softshell and hardshell clams die before reaching maturity.
In laboratory experiments, Green had seen that clams dissolve in acidic mud. But Green and his assistant, Shannon Reilly, needed to test their theories in the field. Green chose West Bath.
Continue reading ‘Giving clams an edge’
News regarding climate change has largely fo cused on the increasing carbon dioxide content in the atmosphere and the effects of that increase on the land. Yet as the carbon dioxide in the atmosphere increases, the impact on the ocean environment is greater than it is on land. Carbon dioxide is absorbed by the ocean, where it reacts with other chemicals present in the water, thus mak ing the water more acidic. This process is known as ocean acidification.
