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.
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"
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