Carbon Emissions Create Giant Crabs: Oyster Industry in Trouble

A lot of things in America are supersized: our portions, our drinks and now, apparently, our crabs. New research reveals that crabs can grow much faster and larger when water is saturated with carbon. This means that as greenhouse gas emissions grow, so will these crustaceans.

Carbon pollution is emitted by power plants, factories and vehicles, pouring into our atmosphere. Yet these emissions don't only mix with our air. Like sugar dissolving into a cup of coffee, the carbon pollution also mixes and dissolves into our water; this changes the composition and dynamics of underwater ecosystems.

Increased CO2 in water causes it to become slightly acidic. This is bad news for creatures--like oysters and corals--with calcium carbonate shells. As the water becomes more acidic, these shelled creatures actually form their shells more slowly. This, in turn, makes them more vulnerable to predators.

While other creatures grow more slowly, though, crabs seem to be thriving. They eat, grow and molt their shells, revealing soft, new ones which eventually harden. In fact, the increased carbon helps speed up this molting process so that the crabs have larger and possibly stronger shells which make them less vulnerable to predators.

"Higher levels of carbon in the ocean are causing oysters to grow slower, and their predators--such as blue crabs--to grow faster," said Justin Baker Ries, a marine geologist at the University of North Carolina, in an interview with The Washington Post.

Because crabs are voracious predators, they could potentially decimate populations of oysters, scallops and other shellfish. Oysters in particular are effective filter feeders; they can filter up to 50 gallons of water a day as they eat algae and remove dirt and nitrogen pollution. If their populations begin to shrink due to excess predation and thinner shells, it's possible that waterways could become more polluted and could exacerbate existing issues.

It's not just crabs that are benefitting from a growth spurt, though. Lobsters and shrimp will also grow bigger and more rapidly as carbon pollution increases.

Currently, states are attempting to promote oyster recovery. Viewing them as a highly valuable resource and a means to clean up water, Maryland has poured $50 million into its oyster recovery effort over the past 16 years, according to The Washington Post. Whether numbers will help oysters battle the tide of larger crabs, though, remains to be seen.

The findings are published in the journal Geology.