Our fancy dinner oysters can tell us a lot about how our oceans are changing.

Find out why some baby oysters can't form strong shells.

Oysters. We love 'em.

You can imagine why people love oysters so much: They're a low-fat, high-protein food with a fresh, briny flavor — nature's perfect bar snack.

New York Times food writer Mark Bittman is a fan, too. When he moved from the Big Apple to San Francisco in January, trips to a raw bar at a local market became part of his weekend routine.


But "there are troubled waters ahead for oysters," according to Bittman.

Image via Mark Bittman: California Matters.

Oysters are threatened by ocean acidification.

When we use fossil fuels, it not only endangers animals in the ocean with oil spills, but it also changes the actual chemistry of the ocean.

The extra carbon dioxide that burning fossil fuels adds to the environment causes ocean acidification, which lowers the water's pH level and can affect the skeletons and shells of sea creatures. The extra CO2 also affects the level of calcium carbonate minerals, which are important components of the shells of oysters and other shellfish.

Here's a visual of how the ocean is changing over time because of fossil fuel use.

The future has more jellyfish, fewer healthy coral reefs, and sick little shellfish on the bottom of the acidified ocean. Source: ClimateCentral.org, used with permission.

Ocean acidification means baby oysters can't form strong shells.

Without their calcium carbonate homes, the soft, naked bodies of oysters don't do so well. Oysters and other shellfish have evolved to protect themselves from predators with their shells. Clams without clam shells are not very tough.

Though acidification affects oceans worldwide, some of the early effects are being felt on the West Coast of the U.S. and Canada.

One family of oyster farmers has already moved away Washington to Hawaii. A shellfish farmer in British Columbia reported the loss of 10 million scallops due to ocean acidification.

The reason the West Coast is being hit with ocean acidification is also one of the reasons why it's such an abundant ecosystem. The area experiences "upwelling," a term for a pattern of water moving in the ocean.

As the cold water currents deep in the ocean hit obstacles (like the coast of California), that layer of cold water moves up toward the surface. The cold water from the deep brings up nutrients that support animal life, but it is also more acidified than the warmer surface of the ocean.

Experts expect the effects of upwells to worsen as we continue to burn fossil fuels in the coming decades.

Researchers are seeing the impact of ocean acidification firsthand.

In the video below, Mark Bittman discusses the future of oysters with researchers from the University of California, Davis. He visits them at the Hog Island Oyster Farm, an hour and a half drive north of San Francisco, to understand how climate change is affecting one of his favorite items on the menu.

The cure for ocean acidification? Leave fossil fuels in the ground.

By cutting the use of fossil fuels such as coal, we can help stop the ocean acidification already underway. Do it for the shellfish. Or do it because you love seafood snacks. Either way, it's a healthier ocean.

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