Increasingly Acidified Waters Could Prompt Mass Shellfish Dissolution
by Jeremy Elton Jacquot, Los Angeles on 11. 4.07
If present acidification trends in the world's oceans continue unabated, mussels, oysters and other shellfish could become extinct as early as 2100. Carol Turley, a researcher at the Plymouth Marine Laboratory, is warning that these mass casualties could have severe repercussions for humans and the health of ocean ecosystems. "A lot of shellfish are an important food source for fish as well as humans. The impacts of shellfish disappearing could be massive," she explained in a recent address.
Increasing levels of dissolved carbon dioxide hinder the ability of shellfish to build their protective shells by significantly reducing the amount of free carbonate in the water. Shellfish typically absorb calcium carbonate from their surroundings and deposit it around their bodies to make their shells; higher levels of carbon dioxide, however, limit the amount of available carbonate - which otherwise could bind to free calcium ions - by forming more bicarbonate ions.
This effect is especially pronounced in deeper waters, where extremely low levels of carbonate ions, paired with higher hydrogen ion concentrations, have caused shellfish shells to actively dissolve. Indeed, several recent studies have noted a worrying rise in the Carbonate Compensation Depth (CCD), a level below which the rate of supply of calcium carbonate equals that of dissolution.
For very much the same reason, coral reefs are also likely to be hit hard as coral polyps struggle to build the tough skeletons they need to protect themselves and provide habitats for a wide variety of organisms. Fish are also likely to not escape unscathed as acidification harms their ability to fertilize their eggs.
Via ::The Daily Telegraph: Mussels face extinction as oceans turn acidic (newspaper)
See also: ::Increasing Ocean Acidification Eroding Coral Reefs, ::Never Mind Future Temperature Increases: CO2 Emissions Deserve EPA's Attention NOW, ::Live from Pop!Tech: For Ocean Health, "Climate Change More Important than Fishing Practices"
Image courtesy of Misserion via flickr
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About a year ago, The New Yorker ran a great piece about ocean acidification and how it affects animals with calcium carbonate shells. It was a great summary of one researcher's findings that I could easily understand, and I have nothing more than a high school education. I was thoroughly impressed with the article, but moreso with the actual findings of the researcher, which only further convinced me to move on the path of environmentalism.
All I could find was the abstract, unfortunately. Here it is:
http://www.newyorker.com/archive/2006/11/20/061120fa_fact_kolbert
Regarding the New Yorker article referenced above
The following link was retrieved via google search of "The Darkening Sea," The New Yorker, November 20, 2006,
http://igbp-scor.pages.unibe.ch/gfx/NewYorker.pdf
The final paragraph bears a theme worthy of highlighting here..."Actions that might appear
utterly unrelated—say, driving a car down
the New Jersey Turnpike and secreting a
shell in the South Pacific—turn out to be
connected."
This is quite honestly ridiculous. The atmosphere has or will have more CO2 then any time in the past 100 thousand years but in the last 10-15 million years there have been times when their has been *much* more CO2 in the atmosphere. Shell fish have been around much longer then that. They lived and survived quite well in a world with a higher CO2 content then today.
Speculation such as this just adds fuel to the people who already think the environmentalists are a bunch of people yelling "the sky is falling".
RE: "someone" (above)
Maybe. maybe not.
While "They lived and survived quite well in a world with a higher CO2 content then today. "
may in itself, be a true statement, it needs to be taken in the context of evolutionary processes that took place over millions of years. The often-understated concern of anthropomorphic climate change is that it is occurring at rates that do not allow for adaptation via natural selection.
In other words, a given change in any one parameter over millions of years may allow for species to adapt their cellular machinery and produce an adequate shell structure, but a change over 200 years won't. It is the rate of change that offers the threat, not the magnitude of change itself.
To give yourself a better sense of scale when dealing with such disparate time frames, do this exercise which converts time into the more palpable terms of relative distance.
If you set 100 years to equal one centimeter, each 10 million years is 1 kilometer long.
Picture the distance of something a Km (0.62 miles) away in relationship to the width of your pinky finger.
This is the time frame over which you are talking about historic CO2 levels compared with the approx. 1 century of the industrial age.
The fact is, we don't know for certain what will happen.