Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms Abstract Nature
Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms
James C. Orr
1, Victoria J. Fabry
2, Olivier Aumont
3, Laurent Bopp
1, Scott C. Doney
4, Richard A. Feely
5, Anand Gnanadesikan
6, Nicolas Gruber
7, Akio Ishida
8, Fortunat Joos
9, Robert M. Key
10, Keith Lindsay
11, Ernst Maier-Reimer
12, Richard Matear
13, Patrick Monfray
1,
19, Anne Mouchet
14, Raymond G. Najjar
15, Gian-Kasper Plattner
7,
9, Keith B. Rodgers
1,
16,
19, Christopher L. Sabine
5, Jorge L. Sarmiento
10, Reiner Schlitzer
17, Richard D. Slater
10, Ian J. Totterdell
18,
19, Marie-France Weirig
17, Yasuhiro Yamanaka
8 & Andrew Yool
18
Today's surface ocean is saturated with respect to calcium carbonate, but increasing atmospheric carbon dioxide concentrations are reducing ocean pH and carbonate ion concentrations, and thus the level of calcium carbonate saturation. Experimental evidence suggests that if these trends continue, key marine organisms—such as corals and some plankton—will have difficulty maintaining their external calcium carbonate skeletons. Here we use 13 models of the ocean–carbon cycle to assess calcium carbonate saturation under the IS92a 'business-as-usual' scenario for future emissions of anthropogenic carbon dioxide. In our projections, Southern Ocean surface waters will begin to become undersaturated with respect to aragonite, a metastable form of calcium carbonate, by the year 2050. By 2100, this undersaturation could extend throughout the entire Southern Ocean and into the subarctic Pacific Ocean. When live pteropods were exposed to our predicted level of undersaturation during a two-day shipboard experiment, their aragonite shells showed notable dissolution. Our findings indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously.
Ocean Acidification - Google Books
Volcanic carbon dioxide vents show ecosystem effects of ocean acidification Abstract Nature
Volcanic carbon dioxide vents show ecosystem effects of ocean acidification
Jason M. Hall-Spencer
1, Riccardo Rodolfo-Metalpa
1, Sophie Martin
2, Emma Ransome
1, Maoz Fine
3,
4, Suzanne M. Turner
5, Sonia J. Rowley
1, Dario Tedesco
6,
7 & Maria-Cristina Buia
8
The atmospheric partial pressure of carbon dioxide (
pCO2) will almost certainly be double that of pre-industrial levels by 2100 and will be considerably higher than at any time during the past few million years
1. The oceans are a principal sink for anthropogenic CO2 where it is estimated to have caused a 30% increase in the concentration of H+ in ocean surface waters since the early 1900s and may lead to a drop in seawater pH of up to 0.5 units by 2100 (refs
2,
3). Our understanding of how increased ocean acidity may affect marine ecosystems is at present very limited as almost all studies have been
in vitro, short-term, rapid perturbation experiments on isolated elements of the ecosystem
4, 5. Here we show the effects of acidification on benthic ecosystems at shallow coastal sites where volcanic CO2 vents lower the pH of the water column. Along gradients of normal pH (8.1–8.2) to lowered pH (mean 7.8–7.9, minimum 7.4–7.5), typical rocky shore communities with abundant calcareous organisms shifted to communities lacking scleractinian corals with significant reductions in sea urchin and coralline algal abundance. To our knowledge, this is the first ecosystem-scale validation of predictions that these important groups of organisms are susceptible to elevated amounts of
pCO2. Sea-grass production was highest in an area at mean pH 7.6 (1,827
atm
pCO2) where coralline algal biomass was significantly reduced and gastropod shells were dissolving due to periods of carbonate sub-saturation. The species populating the vent sites comprise a suite of organisms that are resilient to naturally high concentrations of
pCO2 and indicate that ocean acidification may benefit highly invasive non-native algal species. Our results provide the first
in situ insights into how shallow water marine communities might change when susceptible organisms are removed owing to ocean acidification.
Real information on ocean acidification at these three sites, not flap yapping of pretend scientists.