Crab walking on beach (Shutterstock)
Changes to the ocean's chemistry brought on by carbon dioxide may be making it harder for shore crabs and other animals to survive. (Shutterstock)

Climate change is affecting the ocean and the animals in it.

The increase of carbon dioxide in the air is altering the chemistry of the ocean, making it harder for some animals to use smell to find prey and identify other animals, new studies show.

“Imagine you are a little crab, living on a shore with large rocks, deep pools and battled by tides and waves. The only way to find your lunchtime snack would be to smell it from a distance,” said Christina Roggatz, a lead researcher at the University of Hull in England, which has studied the problem.

If ocean creatures lose the ability to use smell to find food, avoid predators and mate because of higher CO2 levels, “it would be comparable to a world without light or sound for us humans,” she said.

Changes in the ocean could affect the 1 billion people around the world who rely on it for their primary source of protein.

Ocean acidification

The ocean absorbs human-generated carbon dioxide, which produces carbonic acid that changes ocean chemistry. Today’s ocean is 30 percent more acidic than the ocean was 200 years ago. Researchers estimate that by 2100 it could be 150 percent more acidic than today.

In that environment, shore crabs would not receive chemical signals to protect their eggs, according to Roggatz. Shrimp, barnacles, oysters and other creatures that depend on the same “smells” to hatch, find shelter and survive would also suffer.

Ocean acidification causes other problems, too. It can dissolve the calcium of shellfish such as oysters and clams, as well as the skeletons of coral. Coral reefs, which make up about 1 percent of the ocean floor, support an estimated one-fourth of all marine life.

Ocean acidification also makes it harder for sea snails to escape from their sea star predators, according to a second study from the University of California, Davis.

Everyone can help protect marine creatures, sometimes in innovative ways. For instance, surfers can use a Smartfin, a detachable surfing fin that collects data on near-shore acidity and other measurements, to fill a critical data gap.