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, 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 and short nose sturgeon 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.”

 

Warming Waters
Even a minute change in ocean temperature can devastate species such as algae, plants, and animals.

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

Noun

the art and science of cultivating land for growing crops (farming) or raising livestock (ranching).

benthic
Adjective

having to do with the bottom of a deep body of water.

blue crab
Noun

crustacean with a greenish body and blue legs, native to North America.

carbon emission
Noun

carbon compound (such as carbon dioxide) released into the atmosphere, often through human activity such as the burning of fossil fuels such as coal or gas.

caviar
Noun

delicacy made from the eggs of sturgeon or other fish.

Chesapeake Bay
Noun

large, shallow estuary of the Susquehanna and other rivers that flow through the U.S. states of Maryland, Virginia, West Virginia, Delaware, Pennsylvania, and New York and the capital of Washington, D.C., before emptying in the Atlantic Ocean.

Noun

all weather conditions for a given location over a period of time.

Noun

gradual changes in all the interconnected weather elements on our planet.

crustacean
Noun

type of animal (an arthropod) with a hard shell and segmented body that usually lives in the water.

cue
Noun

hint or marker.

dam
Noun

structure built across a river or other waterway to control the flow of water.

Dermo
Noun

fatal disease among oysters caused by the germ Perkinsus marinus.

Noun

period of greatly reduced precipitation.

Noun

branch of biology that studies the relationship between living organisms and their environment.

economy
Noun

system of production, distribution, and consumption of goods and services.

Noun

community and interactions of living and nonliving things in an area.

eelgrass
Noun

type of seagrass with long, thin leaves. Also called tape grass.

Noun

organism threatened with extinction.

Noun

mouth of a river where the river's current meets the sea's tide.

exotic species
Noun

non-native species.

facility
Noun

a building or room that serves a specific function.

fishery
Noun

industry or occupation of harvesting fish, either in the wild or through aquaculture.

fossil fuel
Noun

coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.

Noun

increase in the average temperature of the Earth's air and oceans.

impervious surface
Noun

boundary that does not allow water to penetrate it.

Noun

type of plant or animal that is not indigenous to a particular area and causes economic or environmental harm.

manatee
Noun

threatened marine mammal native to the Caribbean Sea and Atlantic Ocean.

migrate
Verb

to move from one place or activity to another.

molt
Verb

to shed fur, skin, feathers, or other body covering.

MSX
Noun

(multi-nucleated sphere unknown) fatal disease among oysters caused by the germ Haplosporidium nelsoni.

offing
Noun

part of a body of water that touches the horizon.

overfish
Verb

to harvest aquatic life to the point where species become rare in the area.

pier
Noun

platform built from the shore and extending over water.

piranha
Noun

carnivorous, freshwater fish native to South America. Also called caribe.

Noun

introduction of harmful materials into the environment.

Powhatan
Noun

people and culture native to the mid-Atlantic region of the U.S.

predation
Noun

behavior of one animal feeding on another.

prevalent
Adjective

common or widespread.

Noun

large stream of flowing fresh water.

Noun

overflow of fluid from a farm or industrial factory.

settler
Noun

person who migrates and establishes a residence in a largely unpopulated area.

shad
Noun

type of fish, related to the herring.

shellfish
Noun

any aquatic organism that has a shell or exoskeleton.

stress
Verb

to strain or put pressure on.

sturgeon
Noun

type of marine or freshwater large, long, bony fish.

susceptible
Adjective

able to be influenced to behave a certain way.

threshold
Noun

point in a process that must be met to start a new stage in the process.

Noun

stream that feeds, or flows, into a larger stream.

tropical
Adjective

existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.

watershed development
Noun

construction or preparation of land for housing, industry, or agriculture near a river or flood plain.