Archive for August, 2007

Effect of varying calcium concentrations and light intensities on calcification and photosynthesis in Emiliania huxleyi

Various protective and metabolic functions for coccolithophore calcification have been proposed such as providing a means to supply CO2 for photosynthesis. It has also been speculated that calcification helps to dissipate excess energy under high irradiance, thereby circumventing photoinhibition. To address these questions, cells of a calcifying strain of Emiliania huxleyi were grown at three irradiances (30, 300, and 800 µmol photons m-2 s-1) in combination with four calcium (Ca) concentrations (0.1, 1, 2.5, and 10 mmol L-1) leading to different degrees of calcification in the same strain. Growth rates (µ), particulate organic carbon (POC), and inorganic carbon (PIC) production as well as carbon isotope fractionation (ep) were determined. Photosynthetic O2 evolution and CO2 and HCO3- uptake rates were measured by membrane inlet mass spectrometry (MIMS).
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The contribution of acid deposition to ocean acidification in the subtropical North Atlantic Ocean

Bates N. R. & Peters A. J.

The absorption of anthropogenic CO2 and atmospheric deposition of acidity can both contribute to the acidification of the global ocean. Rainfall pH measurements and chemical compositions monitored on the island of Bermuda since 1980, and a long-term seawater CO2 time-series (1983-2005) in the subtropical North Atlantic Ocean near Bermuda were used to evaluate the influence of acidic deposition on the acidification of oligotrophic waters of the North Atlantic Ocean and coastal waters of the coral reef ecosystem of Bermuda.

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Effects of acidification and primary production on coccolith weight: Implications for carbonate transfer from the surface to the deep ocean

The coccolithophores are not only an important group of oceanic primary producers; they are also one of the main carbonate producers in the ocean. Because the calcium carbonate plates (coccoliths) secreted by these unicellular algae are so small and light (a few picograms each), they cannot be directly weighed, with the result that very little is known about the effect of primary production and dissolution on the coccoliths. Using a new method that allows a rapid estimate of the weight of discrete coccoliths, we analyzed the effect of dissolution.
Continue reading ‘Effects of acidification and primary production on coccolith weight: Implications for carbonate transfer from the surface to the deep ocean’

Ocean acidification and scleractinian corals

In their Brevia “Scleractinian coral species survive and recover from decalcification” (30 March, p. 1811), M. Fine and D. Tchernov present an exciting experimental approach documenting how coral skeletons dissolve as a physiological response to increased atmospheric CO2, a subject currently at the height of public concern (1, 2). The fact that these authors demonstrated that five species of living scleractinian corals could lose their aragonitic skeletons, in response to elevated CO2, and then continue to exist perfectly well as soft-bodied polyps is a confirmation of the ephemeral or “naked coral” hypothesis (3, 4). This physiological response assists our understanding of the survival potential of corals after mass extinctions such as after the devastating one at the end-Permian (5). In addition, it explains the previously unexplained, geologically “sudden” appearance of order Scleractinia in Middle Triassic time, when geochemically perturbed oceans returned to normal. Before this time, corals and reefs disappeared from the fossil record for millions of years but may have continued to exist as “naked corals,” thus remaining paleontologically “hidden” from our view.

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Ocean acidification and scleractinian corals (response)

Stanley highlights the dual significance of our findings: a confirmation of his naked coral hypothesis (1) and a plausible explanation for the enigma of discontinuity in the geological record of coral reefs (2).

Stanley uses our findings to suggest that scleractinians and noncalcifying species that are typically classified as a different order (such as corallimorpharians) are probably one clade. This is supported also by phylogenetic studies using molecular tools (3), demonstrating that a clade of scleractinians is more closely related to noncalcifying corallimorpharia than to another clade of scleractinians.
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Global warming threatens sea life, wildlife expert says

By SAMMY FRETWELL – sfretwell@thestate.com

Dan Kipnis has fished off Florida for most of his life. He has organized tournaments for anglers and taken vacationers into the ocean to cast their lines.

But to go fishing, you need fish — and Kipnis, a long-time charter boat captain from Miami Beach, says rising global temperatures threaten sea life across the globe. In fact, climate change could have a more devastating effect on the ocean than many people realize, Kipnis said during a presentation Wednesday in Columbia.

“It’s easy to see an ozone haze over Columbia. But when people go to the ocean, they see something flat with a few ripples on it. And they don’t see what is in it.”

Off the South Atlantic Coast, certain species of grouper and snapper are among the types of fish in decline.

Kipnis spoke at the request of state environmental groups trying to raise awareness about global warming.

Kipnis, who has worked with former Vice President Al Gore on global warming, is paid $1,000 a month by the National Wildlife Federation to get the word out. He spoke earlier this week in Georgetown, McClellanville, Beaufort and Hilton Head Island. He’ll be in Charleston today.

Two major threats of global warming to fish, he said, are from increasing acid levels in the ocean and rising sea temperatures.

Higher acid, the byproduct of increasing carbon dioxide emissions, “eats the shells” of crabs, certain types of plankton and krill that young fish rely on for survival, he said.

“You take bait out of the food chain, we don’t have much food for” bigger fish, he said, using graphics and videos of fish to illustrate his points. “That’s going to have a major effect.”
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Corals and Climate Change

VIRGINIA KEY, FL (August 13, 2007) — A modest new lab at the Rosenstiel School is the first of its kind to tackle the global problem of climate change impacts on corals. Fully operational this month, this new lab has begun to study how corals respond to the combined stress of greenhouse warming and ocean acidification. The lab is the first to maintain corals under precisely controlled temperature and carbon dioxide conditions while exposing them to natural light conditions.
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Marine photosynthesis and oceanic pH

Based on four theoretical constructs – a geochemical model, an ocean general-circulation model, an IPCC CO2 emissions scenario for the 21st century, and a logistic function for the burning of earth’s post-21st century fossil-fuel reserves – Caldeira and Wickett (2003) calculated that earth’s atmospheric CO2 concentration could approach 2000 ppm around the year 2300, leading to a concomitant surface oceanic pH reduction of 0.7 units, a change they describe as being much more rapid and considerably greater “than any experienced in the past 300 million years.”

What will be the result for earth’s coral reefs and other calcifying marine organisms if this unprecedented – but purely theoretical – surface oceanic pH reduction actually comes to pass? Kleypas et al. (1999) and Buddemeier et al. (2004) have claimed that the projected increase in the air’s CO2 content, together with its simulated decline in surface ocean water pH, will dramatically decrease coral calcification rates, which they say could lead to a major slow-down, or even reversal, of reef-building and the potential loss of reef structures. There are, however, some good reasons for believing otherwise.
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Coccolithophore productivity response to greenhouse event of the Paleocene–Eocene Thermal Maximum

During the Paleocene–Eocene Thermal Maximum (PETM), rapid release of isotopically light C to the ocean–atmosphere system elevated the greenhouse effect and warmed temperatures by 5–7 °C for 105 yr. The response of the planktic ecosystems and productivity to the dramatic climate changes of the PETM may represent a significant feedback to the carbon cycle changes, but has been difficult to document. We examine Sr/Ca ratios in calcareous nannofossils in sediments spanning the PETM in three open ocean sites as a new approach to examine productivity and ecological shifts in calcifying plankton.

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Group Seeks States’ Help on Ocean Acid

ANCHORAGE, Alaska — A conservation organization has requested that Alaska and six other states add bodies of water to their list of impaired waterways: the Pacific and Atlantic oceans.

The Center for Biological Diversity, based in San Francisco, requested that Alaska, Washington, Oregon and Hawaii list the Pacific Ocean as impaired under the federal Clean Water Act. The group wants New York, New Jersey and Florida to list the Atlantic.

The reason: ocean acidification, the changing of sea water chemistry because of absorption of carbon dioxide produced by humans.

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