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Acidification and Animal Behavior

Acidification in the Chesapeake

The carbon we burn each year doesn’t just end up in the atmosphere; about one-fourth of it dissolves in the oceans, increasing the acidity of our waterways. That includes the Chesapeake Bay, where waters are acidifying three times more quickly than the open ocean. Add pollution to the mix, and you have a recipe for disaster.

The Bay’s complex food web is facing threats from the changing conditions of its waters. Research shows acidification can have alarming effects on two of the estuary’s most iconic inhabitants: the blue crab and the oyster. One study tested growth of oyster larvae in water containing high levels of acidity—levels, it should be noted, that are expected to occur this century. The results? Shells grew at only one-quarter the speed they did in low-carbon conditions, and they contained less calcium.

This could present a real problem for an oyster population that’s already diminished to 2 percent of what it was in colonial times. On a bigger scale, this could lead to trouble for the Bay itself. Oysters keep the Chesapeake clean and serve as a home for crabs and fish.

Meanwhile, highly acidified waters could beef up one of the oyster’s biggest predators: the blue crab. A 2009 study found that Chesapeake blue crabs grow almost four times faster in high-carbon conditions. When these crustaceans absorb the Bay’s carbon pollution, they molt more quickly and emerge bigger and possibly stronger, making them more challenging prey and fiercer predators.

In other words, while oysters are struggling to survive in the Bay’s altered state, its predators are thriving in it, establishing a dangerous ecosystem imbalance. And oysters aren’t the only ones. The population decline of several of the Bay’s fish species—including striped bass, American shad, alewife, menhaden and herring—has been linked with acidification.


So … What’s the Good News?

Oysters might be facing major challenges, but they also have a secret weapon to combat acidification: their shells. When their shells break down and dissolve, they release calcium carbonate—a base and the active ingredient in the antacid Tums—into the water, helping to balance out the acidic environment. This is just one of the reasons oyster reef restoration is so critical to protecting the Chesapeake Bay.

Local leaders are also taking steps to counteract the adverse effects of acidification. In April 2013, the Maryland General Assembly passed a bill to create a special task force to study the effects of acidification in the Chesapeake Bay and other state waters. In fact, our own chief conservation officer, Eric Schwaab, is serving as the task force’s chairman. Officially named Maryland’s Task Force to Study the Impacts of Ocean Acidification on State Water, this group of experts will follow up on their evaluation with recommendations on how to address the issue. You can expect a report on their findings in early 2015. (To learn more about this, check out Eric’s post on our blog.)

Your daily actions can help create a brighter future for the Chesapeake Bay and its inhabitants. By reducing your carbon footprint, you can contribute to the fight against acidification. Your commute is a great place to start making changes. Burning fossil fuels sends carbon dioxide into the air and ultimately into waterways, compounding the harmful effects of climate change and acidifying waters.

Reduce your impact by purchasing local products and taking mass transit, walking or biking whenever possible. You can also decrease your household energy consumption by lowering your thermostat, turning off the lights when they’re not in use and replacing incandescent lamps with fluorescent bulbs. The Bay—and your wallet—will thank you.

National Aquarium, Ocean Acidification: A Global Issue with Local Consequences
National Aquarium, Ocean Acidification: What You Need to Know
U.S. Environmental Protection Agency, 2011 TRI National Analysis: Large Aquatic Ecosystems: Chesapeake Bay
National Aquarium, Change for the Chesapeake
Natural Resources Defense Council, Ocean Acidification – East Coast Estuaries
Smithsonian Science, Rising Acidification of Estuary Waters Spells Trouble for Chesapeake Bay Oysters
Geophysical Research Letters, A Developmental and Energetic Basis Linking Larval Oyster Shell Formation to Acidification Sensitivity
New York Times, Oyster Shells are an Antacid to the Oceans
California Academy of Sciences, Oysters and Acidification
The Star Democrat, Bill to Study Effects of Acidification in Bay Passes
The Washington Post, Crabs Draw Strength from Pollution—a Gain that May be Bay’s Loss
Take Part, How the Ocean Grows its Own Medicine

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