CO2, is there anything it can’t do? Add it to the list.

Over at WaPo, they call them “supersized”. From Counsel and Heal News (h/t to Gene Doebley):

Carbon To Blame for Oversized Blue Crabs

The use of genetic engineering or steroid enhancements to enlarge certain food products has been popular but highly controversial in the history of the food industry. Based on new research, it seems like certain animals, such as the blue crabs, have found another way of growing that does not require a lab setting. According to research, the side effects of pollution, particularly the emission of carbon dioxide, can lead to oversized blue crabs. Researchers found a link between the growing size of these crustaceans and the growing rate of carbon found in the waters. Although these crabs are growing bigger and faster without the help of scientists, this trend might not be safe for the marine environment.

Hmmm. They seem a little unclear on the giant crab mechanism:

Although carbon dioxide is emitted into the air, it dissolves into the water and saturates the oceans with carbon, which can change how these marine ecosystems work. Saturated waters become acidic, which is detrimental for certain marine animals, such as oysters and corals. These living creatures have calcium carbonate shells, which forms at a much slower rate when the waters become acidic, even if it is only by a small amount. Meanwhile, other creatures, particularly the blue crabs, thrive on the carbon in the water. … “Higher levels of carbon in the ocean are causing oysters to grow slower, and their predators – such as blue crabs – to grow faster,” said marine geologist, Justin Baker Ries from the University of North Carolina.

Full story here

Lessee, oysters grow slower, so they won’t reach breeding maturity and replace themselves as fast, and somehow this makes the crabs grow faster?

Maybe this is why it doesn’t make sense, from WaPo, it is recycled news:

The research showing the effects of carbon on marine organisms was published in the journal Geology in 2009. The study, led by Ries and co-authored with Anne L. Cohen and Daniel C. McCorkle, and found that crabs, lobsters and shrimp grew bigger more rapidly as carbon pollution increased. Chesapeake blue crabs grew nearly four times faster in high-carbon tanks than in low-carbon tanks.

Seafood lovers rejoice!

But, ah, another “not in the real world, aka ocean” experiment conducted in tanks. No mention of “giant, oversized, or supersized crabs” in the paper it seems. We’ve been down this road before with “tanked” experiments where they try to extrapolate captive life experiments to the real ocean.

Marine calcifiers exhibit mixed responses to CO 2 -induced ocean acidification

Abstract Anthropogenic elevation of atmospheric carbon dioxide (pCO 2 ) is making the oceans more acidic, thereby reducing their degree of saturation with respect to calcium carbonate (CaCO 3 ). There is mounting concern over the impact that future CO 2 -induced reductions in the CaCO 3 saturation state of seawater will have on marine organisms that construct their shells and skeletons from this mineral. Here, we present the results of 60 d laboratory experiments in which we investigated the effects of CO 2 -induced ocean acidification on calcification in 18 benthic marine organisms. Species were selected to span a broad taxonomic range (crustacea, cnidaria, echinoidea, rhodophyta, chlorophyta, gastropoda, bivalvia, annelida) and included organisms producing aragonite, low-Mg calcite, and high-Mg calcite forms of CaCO 3 . We show that 10 of the 18 species studied exhibited reduced rates of net calcification and, in some cases, net dissolution under elevated pCO 2 . However, in seven species, net calcification increased under the intermediate and/or highest levels of pCO 2 , and one species showed no response at all. These varied responses may reflect differences amongst organisms in their ability to regulate pH at the site of calcification, in the extent to which their outer shell layer is protected by an organic covering, in the solubility of their shell or skeletal mineral, and in the extent to which they utilize photosynthesis. Whatever the specific mechanism(s) involved, our results suggest that the impact of elevated atmospheric pCO 2 on marine calcification is more varied than previously thought.

Received 7 March 2009.

Revision received 16 July 2009.

Accepted 21 July 2009. PDF here: http://www.unc.edu/~jries/Ries_et_al_09_Geology_Mixed_Responses_to_Ocean_Acidification_full.pdf

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