Archive for May, 2007

Ocean acidification session ‘Geologische Vereinigung’ meeting, Bremen (Germany)

We would like to draw your attention to an upcoming scientific session on Ocean Acidification, part of this year’s annual ‘Geologische Vereinigung’ meeting, to be held in Bremen, Germany. The meeting runs from October 1 to 5 with sessions being held from October 3 to 5. The programme is posted in the second circular. The session is entitled: “Ocean acidification: back to the future”:

Due to the uptake of anthropogenic CO2, world oceans are getting less alkaline („ocean acidification“) with yet unpredictable consequences for the oceanic ecosystem. The global surface ocean pH has already dropped by 0.1 units since the beginning of the industralisation. In the history of our planet, this is not the first time that oceans experience acidification. Eventhough the causes for these events maybe of a different nature (bolide impact at the K/T boundary, methane clathrate release at the PETM and ELMO) and although the rate of change may be different, much may be learned from this. This session aims to provide a biogeoscientific view of past events and future consequences: Can we learn from the geological archives how the present day ecosystem could be affected? Can we learn from the present day ecosystem response to better interprete the archives?

We encourage colleagues from different fields, including geochemistry, marine geology, geobiology, (paleo)climatology, ……, to participate and help make this the interdisciplinary session we hope it will be. We encourage you to submit an abstract for this session. Abstracts deadline is June 15 (for details see web page).

Oral presentations and posters

Oral presentations: There will be several parallel sessions. Each presentation will be allocated 15 minutes (including time for discussion).

Poster presentations: Poster sessions will be scheduled in between parallel sessions. Posters should be closely related to the topics of the scientific sessions and should not exceed 120 cm (height) by 94 cm (width).

Please indicate your preference for your presentation (oral talk or poster) on the registration form; the final decision however, will be made by the organising committee based on advice from the convenors.

Abstract submission

Abstracts with a maximum of 450 words must be submitted by June 15, 2007. Please send digital abstracts as Word documents (*.doc) or in Rich Text Format (*.rtf ), attached to an email to GV-2007@marum.de or on CD-Rom to the conference address. Please, do not submit your abstract on paper and do not include figures. For additional submission instructions see the GV-2007 website. All abstracts will be published in Terra Nostra (ISSN coded). Your abstract will be processed on receipt of payment.

Outstanding student poster award

All first-author students presenting a poster are eligible to compete for this award. The successful student will be awarded financial support (up to € 1000) to attend a scientific meeting of his/her choice.

Registration

Please find the registration form on the GV-2007 conference website and return the filled form online (http://www.g-v.de/) or as an email attachment to GV-2007@marum.de

Please do not hesitate to contact us if you have any questions. We are looking forward to meeting you in Bremen.

Ulf Riebesell and Jelle Bijma

Disturbed, hungry and lost

Whales, dolphins and porpoises are facing increasing threats from climate change, according to a new report published by WDCS and WWF ahead of the 59th meeting of the International Whaling Commission.

The report Whales in hot water? highlights the growing impacts of climate change on cetaceans. They range from changes in sea temperature and the freshening of the seawater because of the melting of ice and increased rainfalls, to sea level rise, loss of icy polar habitats and the decline of krill populations, in key areas.

Krill – a shrimp-like marine animal that is dependent on sea ice, is the main source of food for many of the great whales.

Accelerating climate change adds significantly to disturbances from other human activities, such as chemical and noise pollution, collisions with ships and entanglement in fishing nets, which kills some 1,000 cetaceans every day.

Other projected impacts of climate change listed in the report include: reduction of available habitat for several cetacean species unable to move into colder waters (e.g. river dolphins); the acidification of the oceans as they absorb growing quantities of CO2; an increased susceptibility of cetaceans to diseases; and reduced reproductive success, body condition and survival rates.

Elliott, W. and Simmonds, M. 2007. Whales in Hot Water? The Impact of a Changing Climate on Whales, Dolphins and Porpoises: A call for action. WWF-International, Gland Switzerland / WDCS, Chippenham, UK. Full report.

Effects of increased temperature and CO2 on photosynthesis, growth, and elemental ratios in marine Synechococcus and Prochlorococcus (Cyanobacteria)

Little is known about the combined impacts of future CO2 and temperature increases on the growth and physiology of marine picocyanobacteria. We incubated Synechococcus and Prochlorococcus under present-day (380 ppm) or predicted year-2100 CO2 levels (750 ppm), and under normal versus elevated temperatures (+4°C) in semicontinuous cultures. Increased temperature stimulated the cell division rates of Synechococcus but not Prochlorococcus. Doubled CO2 combined with elevated temperature increased maximum chl a–normalized photosynthetic rates of Synechococcus four times relative to controls. Temperature also altered other photosynthetic parameters (α, Φmax, Ek, and ) in Synechococcus, but these changes were not observed for Prochlorococcus. Both increased CO2 and temperature raised the phycobilin and chl a content of Synechococcus, while only elevated temperature increased divinyl chl a in Prochlorococcus. Cellular carbon (C) and nitrogen (N) quotas, but not phosphorus (P) quotas, increased with elevated CO2 in Synechococcus, leading to ~20% higher C:P and N:P ratios. In contrast, Prochlorococcus elemental composition remained unaffected by CO2, but cell volume and elemental quotas doubled with increasing temperature while maintaining constant stoichiometry. Synechococcus showed a much greater response to CO2 and temperature increases for most parameters measured, compared with Prochlorococcus. Our results suggest that global change could influence the dominance of Synechococcus and Prochlorococcus ecotypes, with likely effects on oligotrophic food-web structure. However, individual picocyanobacteria strains may respond quite differently to future CO2 and temperature increases, and caution is needed when generalizing their responses to global change in the ocean.

Fei-Xue Fu, Mark E. Warner, Yaohong Zhang, Yuanyuan Feng, David A. Hutchins (2007). Effects of increased temperature and CO2 on photosynthesis, growth, and elemental ratios in marine Synechococcus and Prochlorococcus (Cyanobacteria). Journal of Phycology 43 (3), 485–496.. Article.

Acidic oceans affecting food fish

Carbon dioxide emissions could shake “the biological underpinnings of civilization” as increasingly acidic water undermines the oceanic food web, according to fresh research from the Pacific Ocean off Alaska.

The research shows that increasingly acidic Pacific water will affect king crabs and a snail that is a favorite food of Pacific salmon. How disruptions in the ocean food web could ultimately harm these and other popular food species is still uncertain.

The Senate Subcommittee on Oceans, Atmosphere, Fisheries, and Coast Guard will hear testimony today on the acidification of oceans from private, government and environmental group scientists.

Oceans had until recently been viewed as a great savior of the climate, because they have absorbed about one third of the carbon humans have emitted, buffering what would otherwise have been a greater warming of the atmosphere. But scientists have in recent years begun studying the consequences of oceanic carbon storage – a 25 percent increase in acidity since pre-industrial times.

Dan Shapley, The Daily Green. Article.

Are the reefs dying?

...
While warm sea temperature is clearly the causative agent for mass bleaching, marine researchers are also concerned about the increasing acidification of the sea. Explaining, Dr. Lough says this would also be a direct effect of increasing greenhouse gases in on ocean chemistry and its consequences for reefs. This alters the concentrate of carbonate and bicarbonate ions in sea water which corals use to calcify and build skeletons. Weakened skeletons will make corals more susceptible to storm damage and erosion.

The Hindu, 13 May 2007. Article.

Effect of aragonite saturation, temperature, and nutrients on the community calcification rate of a coral reef

In this study we investigated the relations between community calcification of an entire coral reef in the northern Red Sea and annual changes in temperature, aragonite saturation and nutrient loading over a two year period. Summer (April–October) and winter (November–March) average calcification rates varied between 60 ± 20 and 30 ± 20 mmol·m2·d1, respectively. In general, calcification increased with temperature and aragonite saturation state of reef water with an apparent effect of nutrients, which is in agreement with most laboratory studies and in situ measurements of single coral growth rates. The calcification rates we measured in the reef correlated remarkably well with precipitation rates of inorganic aragonite calculated for the same temperature and degree of saturation ranges using empirical equations from the literature. This is a very significant finding considering that only a minute portion of reef calcification is inorganic. Hence, these relations could be used to predict the response of coral reefs to ocean acidification and warming.

Silverman J., Lazar B. & Erez J., 2007. Effect of aragonite saturation, temperature, and nutrients on the community calcification rate of a coral reef. Journal of Geophysical Research 112, C05004, doi:10.1029/2006JC003770. Article.

A World Without Corals?

Until bleaching reared its head, many experts viewed rising sea levels as the chief peril of global warming for coral–and a relatively toothless one at that. “We thought reefs would respond by just growing higher,” says Strong. “Nobody was talking about changing sea chemistry.” Then researchers came to the creeping realization that rising ocean acidity is likely to throw a spanner in coral physiology.
The threat is glaringly simple. Currently, ocean pH hovers around 8.1. Carbon dioxide absorbed into the water column lowers the pH, and as it falls, fewer carbonate ions are available for shell-building critters to grab. Even in present conditions, corals are fighting an uphill battle: Erosion removes 80% of the calcium carbonate laid down. Acidification will accelerate that process as rising carbonic acid levels deplete carbonate. Eventually, corals, plankton, and other organisms will fail to form skeletons. And coral skeletons are to reefs what girders are to skyscrapers. “You have a potential world in which reefs and the limestone frameworks they have built are in net erosion,” says Hoegh-Guldberg.

IPCC scenarios of global emissions and ocean circulation indicate that by midcentury, atmospheric CO2 levels could reach more than 500 parts per million, and near the end of the century they could be above 800 ppm. The latter figure would decrease surface water pH by roughly 0.4 units, slashing carbonate ion concentration by half, paleocoral expert C. Mark Eakin, coordinator of NOAA’s Coral Reef Watch, testified last month at a hearing in the U.S. House of Representatives. Ocean pH would be “lower than it has been for more than 20 million years,” he said. And that does not factor in possible acidification from carbon-sequestration schemes now being considered.

Some coral species facing their acid test may become shape shifters to avoid extinction. New findings indicate that corals can survive acidic conditions in a sea anemone-like form and resume skeleton-building when returned to normal marine conditions (Science, 30 March, p. 1811). However, by pH 7.9, says Caldeira, “there would be a good chance reefs would be gone.”

The potential for an acid-induced coral cataclysm has cast a pall on the tight-knit community of reef specialists. “The reality of coral reefs is very dark, and it is very easy for people to judge coral reef scientists as pessimists,” says Mora. “We’re becoming alarmist,” adds Strong–for good reason, he insists. “How are reefs going to handle acidification? It’s not like sewage or runoff, where you may be able to just turn off the spigot.” Queensland’s Pandolfi, however, argues that it’s “too early to make really definitive doom-and-gloom statements.”

No one disputes that urgent action on greenhouse gas emissions is essential. “We could still have vibrant reefs in 50 years time,” Hughes says. But these will not be the reefs we know today. “They will be dominated by a different suite of species,” says Hughes, who notes that the shakedown is already under way.

Stone R., 2007. A world without coral? Science 316: 678-681. Article.

Eruptions linked to warmer period

A team of scientists announced Thursday confirmation of a link between massive volcanic eruptions along the east coast of Greenland and in the western British Isles about 55 million years ago and a period of global warming that raised sea-surface temperatures by 5 degrees (Celsius) in the tropics and more than 6 degrees in the Arctic.

The findings were reported in this week’s edition of Science.

The study is important, experts say, because it documents the Earth’s response to the release of large amounts of greenhouse gases — carbon dioxide and methane — into the atmosphere, and definitively links a major volcanic event with a period of global warming.

“There has been evidence in the marine record of this period of global warming, and evidence in the geologic record of the eruptions at roughly the same time, but until now there has been no direct link between the two,” said Robert A. Duncan, a professor in the College of Oceanic and Atmospheric Sciences at Oregon State University and one of the authors of the study.

Other authors are Michael Storey, from Roskilde University in Denmark, and Carl C. Swisher, from Rutgers University.

The Paleocene-Eocene thermal maximum, or PETM, was a period of intense warming that lasted roughly 220,000 years. In addition to the warming of sea-surface waters, this event — characterized by scientists as a “planetary emergency” — also greatly increased the acidification of the world’s oceans and led to the extinction of numerous deep-sea species.

Corvaliss Gazette-Times, 26 April 2007. Article.

Ancient global warming ‘triggered’ by volcanoes

Massive volcanic eruptions about 55 million years ago near Greenland and Europe triggered a period of global warming, scientists said today.

During this period, known as the Paleocene-Eocene thermal maximum (PETM), sea surface temperatures rose by five degrees C in the tropics and more than six degrees C in the Arctic.

PETM lasted for 220,000 years and the eruptions, which pushed Greenland and north-west Europe apart to create the north Atlantic ocean, also resulted in increased acidification of the world’s oceans and the extinction of numerous deep-sea species.

inthenews.co.uk, 27 April 2007. Article.


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