Warming Waters

Warming Waters

As the Chesapeake heats up, native species may be forced to migrate.


9 - 12+


Biology, Ecology, Earth Science, Meteorology, Oceanography

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From the end of a pier jutting into Maryland’s Patuxent River, scientists at the Chesapeake Biological Laboratory have determined that the region’s water temperatures are warming.

According to David Secor, a professor from the University of Maryland Center for Environmental Science who works at the facility, by 2010 the surface waters at the end of the pier had increased 3°F (1.7°C) since people began collecting data from the site in 1938.

In 2010, Secor and his colleagues published an article in the journal Estuarine, Coastal and Shelf Science looking at potential impacts of climate change on the Chesapeake Bay. Secor and his colleagues estimate that the Chesapeake Bay could see increases in water temperature of between 2° to 6°C (3.6° to 10.8°F) by the end of the century. Climate change refers to long-term shifts in temperature, precipitation, and other weather patterns. Scientists have documented an increase in the average temperature of Earth’s air and oceans, known as global warming. The release of carbon emissions into the atmosphere, mostly through industrial agriculture and burning fossil fuels, contributes to global warming.

The Chesapeake Bay is an estuary off the Atlantic Ocean that stretches north into the U.S. states of Virginia and Maryland and supports a variety of animal and plant species. More than 100 rivers and streams from New York, Delaware, Pennsylvania, and West Virginia flow into the bay.

The plants and animals of the Chesapeake Bay have supported people since the first European settlers arrived in the area more than 400 years ago. Oysters, fish, crabs, and wild rice were part of the diet of the Powhatan, the Native Americans living in the region. Chesapeake Bay still produces more fish and shellfish than any other estuary in the United States. The blue crab (Callinectes sapidus), the “state crustacean” of Maryland, is a keystone species in the Bay’s food web, as well as one of the area’s most commercially valuable fisheries.

Though they can only predict what might happen to the region’s ecology and economy as the Bay’s temperatures continue to climb, Secor and his colleagues think that climate change might cause declines in some fish and shellfish species. Some of these species are already stressed by disease and poor water quality.

Hot Water for Fishes and Plants
Secor says he suspects that Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) and shortnose sturgeon (Acipenser brevirostrum) will be affected by the changes in the Chesapeake Bay. Sturgeon are huge fish, native to most rivers that feed the Chesapeake Bay, including the James and the Susquehanna Rivers. Sturgeon, a cold-water fish also native to Russia, are mostly harvested for their eggs, or caviar. Sturgeon are a benthic species, meaning they live near the bottom of rivers.

Sturgeon are particularly sensitive to pollutionRunoff from farms and industry, as well as overfishing, have threatened sturgeon populations in the Chesapeake Bay region. Species like sturgeon can also be threatened by warming waters and more frequent droughts. Climate change is likely to contribute to these conditions.

Secor also suspects that fish that thrive in cooler waters, such as striped bass, could experience decreases in population brought about by a warmer climate. “Maybe we’ll see higher production of some things like blue crabs, but we may see diminished production of fish that don’t do so well in warmer waters such as striped bass, perch and black sea bass,” he says.

According to Bill Dennison, the vice president for science application at the University of Maryland Center for Environmental Science, the Chesapeake Bay’s rising water temperatures could also change the makeup of the region’s plant communities. He cites an unusually warm summer in 2005 that caused a mass die-off of eelgrass, a marine plant that is commonly found along the mouths of tributaries that flow into the bay from Virginia.

If eelgrass were to die out in the Chesapeake Bay due to warming water temperatures, its disappearance would affect other species in the region. For example, some species, such as blue crabs, hide in the eelgrass to molt. When they lose that protection, they are more likely to be caught by predators.

According to Secor, increasing water temperatures in the bay can also cause species there, including striped bass, shad, and river herring, to misread environmental cues. “These species migrate into the Chesapeake Bay according to certain reproduction and feeding schedules,” he says. “With warming, those schedules can get miscued due to environmental conditions.”

Invasive Species
The Chesapeake Bay’s changing water temperatures might affect more than just native plants and animals. The change could also make conditions more favorable for non-native or invasive species.

Secor points to recent sightings of Florida manatees in the Chesapeake Bay as an example of a species from a warmer climate appearing. Florida manatees, an endangered species, are marine mammals primarily found in the warm waters around the Florida peninsula and the surrounding southeastern states. More sightings of manatees in the Chesapeake Bay area could be a sign of the animal moving northward due to changing water conditions. The bay ecosystem, including marine grasses on which manatees feed, may not be able to support the animals.

Secor and his colleagues identified another invasive species benefitting from warmer Bay waters. The parasites that cause the oyster diseases MSX and Dermo seem to flourish in the warmer and drier conditions that are part of global warming, the latest instance of climate change on Earth.

Reinventing Ecosystems
Secor and his colleagues can make educated guesses, but they can’t say for certain exactly how the Chesapeake Bay will change as its waters warm. One important variable is how humans respond to climate change.

As Secor and his colleagues state in a study: “Although it is very likely that climate change impacts will occur, it is also clear that the severity of these impacts are directly under human control. Efforts to reduce CO2 [carbon dioxide] emissions now will thus reduce future climate change impacts on the Chesapeake Bay and other estuaries.”

Fast Fact

The Chesapeake Biological Laboratory is the oldest state-supported marine laboratory on the United States East Coast.

Media Credits

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Stuart Thornton
Jeannie Evers, Emdash Editing, Emdash Editing
Kara West
Chesapeake Sea Level Rise and Storm Surge: Public Awareness and Response (CSSPAR)
National Geographic Society
Last Updated

April 3, 2024

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