“We were surprised that some organisms didn’t behave in the way we expected under elevated CO2″…
News Release : In CO2-rich Environment, Some Ocean Dwellers Increase Shell Production
December 1 2009
Source: Media Relations
In a striking finding that raises new questions about carbon dioxide’s (CO2) impact on marine life, Woods Hole Oceanographic Institution (WHOI) scientists report that some shell-building creatures—such as crabs, shrimp and lobsters—unexpectedly build more shell when exposed to ocean acidification caused by elevated levels of atmospheric carbon dioxide (CO2).
The concern is that this process will trigger a weakening and decline in the shells of some species and, in the long term, upset the balance of the ocean ecosystem.
But in a study published in the Dec. 1 issue of Geology, a team led by former WHOI postdoctoral researcher Justin B. Ries found that seven of the 18 shelled species they observed actually built more shell when exposed to varying levels of increased acidification. This may be because the total amount of dissolved inorganic carbon available to them is actually increased when the ocean becomes more acidic, even though the concentration of carbonate ions is decreased.
“Most likely the organisms that responded positively were somehow able to manipulate…dissolved inorganic carbon in the fluid from which they precipitated their skeleton in a way that was beneficial to them,” said Ries, now an assistant professor in marine sciences at the University of North Carolina. “They were somehow able to manipulate CO2…to build their skeletons.”
Organisms displaying such improvement also included calcifying red and green algae, limpets and temperate urchins. Mussels showed no effect.
“We were surprised that some organisms didn’t behave in the way we expected under elevated CO2,” said Anne L. Cohen, a research specialist at WHOI and one of the study’s co-authors. “What was really interesting was that some of the creatures, the coral, the hard clam and the lobster, for example, didn’t seem to care about CO2 until it was higher than about 1,000 parts per million [ppm].” Current atmospheric CO2 levels are about 380 ppm, she said. Above this level, calcification was reduced in the coral and the hard clam, but elevated in the lobster
The “take-home message, “ says Cohen, is that “we can’t assume that elevated CO2 causes a proportionate decline in calcification of all calcifying organisms.” WHOI and the National Science Foundation funded the work.
Conversely, some organisms—such as the soft clam and the oyster—showed a clear reduction in calcification in proportion to increases in CO2. In the most extreme finding, Ries, Cohen and WHOI Associate Scientist Daniel C. McCorkle exposed creatures to CO2 levels more than seven times the current level.
This led to the dissolving of aragonite—the form of calcium carbonate produced by corals and some other marine calcifiers. Under such exposure, hard and soft clams, conchs, periwinkles, whelks and tropical urchins began to lose their shells. “If this dissolution process continued for sufficient time, then these organisms could lose their shell completely,” he said, “rendering them defenseless to predators.”
“Some organisms were very sensitive,” Cohen said, “some that have commercial value. But there were a couple that didn’t respond to CO2 or didn’t respond till it was sky-high—about 2,800 parts per million. We’re not expecting to see that [CO2 level] anytime soon.”
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.
1) Like Global Warming morphed into Climate Change, Ocean Acidification is morphing into Ocean Carbonation or something similar. The oceans simply aren’t acidifying. The oceans are becoming more saturated with Disolved Inorganic Carbon (DIC) – The stuff most shellfish use to make shells.
2) We now have indisputable evidence that the following things are beneficially affected by elevated CO2:
a) otoliths (fish ear bones)
b) coccoliths (phytoplankton)
c) “crabs, shrimp and lobsters”
d) “calcifying red and green algae, limpets and temperate urchins”
Anyone who ever took a carbonate geology class would have already known this; yet all of the above results were unexpected and contrary to the ocean acidification hypotheses that was being tested.
3) We have clear evidence that the following creatures are not adversely affected by elevated CO2 levels below 1000 to 2800 ppmv:
a) coral reefs, lobsters and hard clams below 1000 ppmv
b) “soft clams, conchs, periwinkles, whelks and tropical urchins” below 2800 ppmv.
4) Gorebot-inclined scientists are desperately looking for some evidence that anthropogenic CO2 emissions are acidifying the oceans and/or destroying carbonate shell building organisms.
5) Gorebot-inclined scientists keep “unexpectedly” finding that carbonate shell building organisms simply used the excess CO2 (in the form of DIC) to build more limestone.
I ponied up $25 to the GSA and bought the paper.
18 benthic species were selected to represent a wide variety of taxa: “crustacea, cnidaria, echinoidea, rhodophyta, chlorophyta, gastropoda, bivalvia, annelida.” They were tested under four CO2/Ωaragonite scenarios:
409 ppm (Modern day)
606 ppm (2x Pre-industrial)
903 ppm (3x Pre-industrial)
2856 ppm (10x Pre-industrial)
7/18 were not adversely affected by 10x pre-industrial CO2: Calcification rates relative to modern levels were higher or flat at 2856 ppm for blue crab, shrimp, lobster, limpet, purple urchin, coralline red algae, and blue mussel.
6/18 were not adversely affected by 3x pre-industrial CO2: Calcification rates relative to modern levels were higher or flat at 903 ppm for halimeda, temperate coral, pencil urchin, conch, bay scallop and whelk.
3/18 were not adversely affected by 2x pre-industrial CO2: Calcification rates relative to modern levels were higher or flat at 903 ppm for hard clam, serpulid worm and periwinkle.
2/18 had very slight declines in calcification at 2x pre-industrial: Oyster and soft clam.
The effects on calcification rates for all 18 species were either negligible or positive up to 606 ppm CO2.
That’s because oceanic pH doesn’t change a whole lot in response to changes in atmospheric CO2.
Average annual pH reconstructions and measurements from various Pacific Ocean locations:
60 million to 40 million years ago: 7.42 to 8.04 (Pearson et al., 2000)
23 million to 85,000 years ago: 8.04 to 8.31 (Pearson et al., 2000)
6,000 years ago to present: 7.91 to 8.28 (Liu et al., 2009)
1708 AD to 1988 AD: 7.91 to 8.17 (Pelejero et al., 2005)
2000 AD to 2007 AD: 8.10 to 8.40 (Wootton et al., 2008)
The low pH levels from 60 mya to 40 mya include the infamous Paleocene-Eocene Thermal Maximum (PETM); a period in which large scale subaerial and submarine flood basalt eruptions probably dislodged a massive volume of methane hydrates into the Atlantic Ocean, causing a shoaling of the lysocline (AKA ocean acidification). Even then, the oceans did not actually “acidify;” the lowest pH was 7.42 (still basic). PETM CO2 levels have been estimated to have been 1000 to 3000 ppmv from pedogenic carbonates… But fossil plant stomata suggest that CO2 levels in North America were not much different than today (300 to 400 ppmv).
A plot of CO2 vs pH from the Flinders Reef dataset (Pelejero et al., 2005) shows no statistically significant correlation between CO2 and pH from 1788-1988…