Article

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

Photograph by Edward Mattis, MyShot

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

By Stuart Thornton

Thursday, November 4, 2010

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, the surface waters at the end of the pier have increased 3 degrees Fahrenheit since people began collecting data from the site in 1938.

Secor believes if little action is taken to slow global warming, the Chesapeake Bay could have summer water temperatures comparable to Florida’s by the year 2100. Global warming is the increase in the average temperature of the Earth’s air and oceans. The release of carbon emissions into the atmosphere, mostly through industrial agriculture and burning fossil fuels, probably contributes to global warming.

“If we do nothing—which is probably the simplest way to think about this—in 50 year’s time, we are looking at at least a 3-degree Fahrenheit rise,” he says. “In 80 years time we could be looking at a 6- to 8-degree Fahrenheit change.”

The Chesapeake Bay is an estuary off the Atlantic Ocean that stretches north into the 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 500 years ago. Oysters, fish, crabs, and wild rice were part of the diet of the Powhatan, the Native Americans of 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 the most important fishery in the area.

Secor admits at this time he can only predict what might happen to the region’s ecology and economy as the bay’s temperatures continue to climb. He thinks that climate change might cause declines in species that are already stressed by disease and poor water quality.

Hot Water for Fishes and Plants

Secor says he suspects that Atlantic sturgeon and shortnose 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 pollution. Runoff from farms and industry, as well as overfishing, have threatened sturgeon populations in the Chesapeake Bay region.

“The combination of warm water and maybe frequent droughts, which are in the offing in the future, could be the final nail in the coffin for species like sturgeon,” Secor says.

Secor also suspects that fish that thrive in cooler waters, including shad and striped bass, could experience decreases in population brought about by a warmer climate.

“These species are already very stressed by water quality, by watershed development, by impervious surfaces, by dams,” he says. “A stress like warming could produce a threshold condition that causes very rapid declines in these species.”

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.

“Blue crabs and peeler crabs go into the grass to molt, so when they lose that protection they are more susceptible to predation,” Dennison says.

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 manatees in the Chesapeake Bay as an example of a species from a warmer climate appearing. Manatees, an endangered species, are marine mammals usually found in tropical waters of the Caribbean Sea. 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 says 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.

With warming waters, more exotic species could become prevalent. “We sometimes see things like piranhas [in the Chesapeake Bay] that people release from aquariums,” Secor says. “Currently, when we come across one, we can be confident that winter temperatures will kill those fish. If winters become milder, then some of these invasives that are introduced through the aquarium trade could take hold.”

Reinventing Ecosystems

At this point, Secor admits he doesn’t know how the Chesapeake Bay will change as its waters warm.

“There’s a lot of discussion about what is the ecosystem [is] going to look like,” he says. “We just can’t say we are going to look just like a South Carolina estuary or a North Carolina estuary or something like that. What we will be doing is kind of reinventing these systems. There will be some species that can adapt to these trends most assuredly, and then others that will be colonizing into the Chesapeake.”

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

agriculture

Noun

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

Encyclopedic Entry: agriculture

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 released into the air through 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.

climate

Noun

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

Encyclopedic Entry: climate

climate change

Noun

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

Encyclopedic Entry: climate change

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.

drought

Noun

period of greatly reduced precipitation.

Encyclopedic Entry: drought

ecology

Noun

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

Encyclopedic Entry: ecology

economy

Noun

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

ecosystem

Noun

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

Encyclopedic Entry: ecosystem

eelgrass

Noun

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

endangered species

Noun

organism threatened with extinction.

Encyclopedic Entry: endangered species

estuary

Noun

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

Encyclopedic Entry: estuary

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.

global warming

Noun

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

Encyclopedic Entry: global warming

impervious surface

Noun

boundary that does not allow water to penetrate it.

invasive species

Noun

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

Encyclopedic Entry: invasive species

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.

pollution

Noun

introduction of harmful materials into the environment.

Encyclopedic Entry: pollution

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.

river

Noun

large stream of flowing fresh water.

Encyclopedic Entry: river

runoff

Noun

overflow of fluid from a farm or industrial factory.

Encyclopedic Entry: runoff

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 animal that has a shell.

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.

tributary

Noun

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

Encyclopedic Entry: tributary

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.

Credits

Media Credits

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Writer

Stuart Thornton

Editors

Kara West
Jeannie Evers

Producer

Caryl-Sue, National Geographic Society

Source

Chesapeake Sea Level Rise and Storm Surge: Public Awareness and Response (CSSPAR)

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