EPA 903-R-00-001
CBP/TRS 232/00
April 2000
Chesapeake Bay
NTRODUCTION
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EPA Report Collection
Regional Center for Environmental Information
U.S. EPA Region III
Philadelphia, PA 19103
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Regional Center for Fm ironmenlal Information
US EPA Region III
1650 Arch St.
Philadelphia, PA 19103
Note: This edition of Chesapeake Bay: Introduction to an Ecosystem is an update of the 1994 edition
and includes information through December 1999.
1994 Version
Editor
Kathryn Reshetiloff
Illustrations and Layout
Sandra Janniche
Reviewers
Richard Batiuk
Peter Bergstrom
Carin Bisland
Walter Boynton
Sherri Cooper
Eugene Cronin
Richard Everett
Douglas Forsell
Eileen Setzler-Hamilton
Michael Hirshfield
Carl Hershner
Frederick Howard
Steven Jordan
Robert Lippson
Lori Mackey
Tamara McCandless
Kent Mountford
Kate Naughten
Robert Orth
Nita Sylvester
Christopher Victoria
Chesapeake Bay Program
) Recycled/Recyclable—Printed with Vegetable Oil Based Inks on Recycled Paper (30% Postconsumer)
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
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Contents,
al Center for Environmental
Information
1650 kroh Street (3PM52)
Philadelphia, PA 19103
THE CHESAPEAKE BAY ECOSYSTEM 1
The Watershed 1
The Chesapeake Bay—An Important Resource 2
A Threatened Resource 3
GEOLOGY OF THE CHESAPEAKE 5
Geologic History 5
The Chesapeake Bay 5
Erosion and Sedimentation 6
WATER & SEDIMENTS 8
Water: Salinity, Temperature and Circulation 8
Suspended Sediments: Composition and Effects 10
Chemical Make-up 10
HABITATS 14
Islands and Inlands 14
Freshwater Tributaries 14
Shallow Water 15
Open Water 15
LIVING RESOURCES & BIOLOGICAL COMMUNITIES 16
Wetlands 17
Underwater Bay Grasses 18
Plankton 20
The Swimmers 21
Life at the Bottom 22
FOOD PRODUCTION & CONSUMPTION 24
The Food Web 25
Direct and Detrital Pathways 26
PRESERVING THE CHESAPEAKE BAY: THE BIG PICTURE 28
Be Part of the Solution, Not Part of the Problem 29
For More Information 30
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The Chesapeake Bay
Watershed
L_
j Chesapeake Bay Watershed
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The Chesapeake Bay Ecosystem
The physical processes that drive the Chesapeake Bay
ecosystem sustain the many habitats and organisms
found there. Complex relationships exist among the living
resources of the Bay watershed. Even the smallest of crea-
tures plays a vital role in the overall health and production of
the Bay. Forests and wetlands around the Bay and the entire
watershed filter sediments and pollutants while supporting
birds, mammals and fish. Small fish and crabs find shelter
and food among lush beds of underwater Bay grasses. Unno-
ticed by the naked eye, phytoplankton and microzooplankton
drift with the currents, becoming food for copepods and
small fish. Clams and oysters pump Bay water through their
gills, filtering out both plankton and sediment. During the
fall and winter, waterfowl by the thousands descend upon the
Bay, feeding in wetlands and shallow waters. Bald eagles
and osprey, perched high above the water, feed perch, men-
haden and other small fish to their young. The spectrum of
aquatic environments, from freshwater to seawater, creates a
unique ecosystem abundant with life.
The relentless encroachment of people threatens the eco-
logical balance of the Bay. More than 15 million people live,
work and play in the watershed. Each individual directly
affects the Bay by adding waste, consuming resources and
changing the character of the land, water and air that sur-
round it. However, through the choices we make everyday,
we can lessen our impact on the Bay's health. We must nur-
ture what scientist Aldo Leopold once termed as our "wild
rootage"—a recognition of the fundamental connection and
dependency between society and the environment. As advo-
cates for the Bay and its many living resources, we can
preserve the Chesapeake for years to come.
The Watershed
The Chesapeake Bay receives about half its water volume
from the Atlantic Ocean. The rest drains into the Bay from an
enormous 64,000 square-mile drainage basin or watershed.
The watershed includes parts of New York, Pennsylvania,
West Virginia, Delaware, Maryland and Virginia and the entire
District of Columbia. Freshwater from springs, streams, small
creeks and rivers flows downhill, mixing with ocean water to
form the estuarine system. Soil, air,
water, plants and animals, including
humans, form a complex web of
interdependencies that make up the
ecosystem. The people living in the
Chesapeake watershed play an
important role in this ecosystem.
The activities and problems occur-
ring throughout the entire watershed
significantly impact the functions
and relationships of the Bay. We
must choose whether our role will
be destructive or productive.
BAY FACT
Everyone in the
watershed lives
just a few minutes
from one or more
than 100,000
streams and rivers
draining into the
Chesapeake Bay.
POPULATION: Chesapeake Bay Watershed
2020
(projected)
2000
(projected)
1980
6 8 10 12
Millions of People
14
16
18
Chesapeake Bay Ecosystem 1
-------
Waterman handtonging
for oysters.
The Chesapeake Bay—
An Important Resource
BAY FACT
Through the years, residents and visitors alike
have found the Chesapeake Bay imposing, yet hos-
pitable. The Algonquin Indians called it "Chssepi-
ooc," meaning great shellfish bay. Spanish
explorers described the Bay as ". . . the best and
largest port in the world." Captain John Smith, an
English explorer, extolled, "The country s not
mountainous nor yet low but such pleasant plain
hills and fertile valleys . . . rivers and brooks, all running most
pleasantly into a fair Bay." All were impressed with its size,
navigability and abundance of wildlife and food.
Today, the Bay is still one of this country's most valuable
natural treasures. Even after centuries of intensive use, the Bay
remains a highly productive natural resource. It supplies mil-
lions of pounds of seafood, functions as a major hub for ship-
ping and commerce, provides natural habitat for wildlife and
offers a variety of recreational opportunities for residents and
visitors.
Oysters and blue crabs are famous Bay delicacies. From the
1950s to the 1970s, the average annual oyster catch was about
25 million pounds per year. Since the early 1980s, however, the
catch has declined dramatically due to overharvesting, disease
and loss or degradation of habitat. As for Etay blue crab har-
vesting, it averaged 80 million pounds annually from 1993 to
1998, contributing more than a third of the nation's catch.
Although this figure is consistent with past harvests, fishing
pressure, both commercial and recreational, continues to grow.
The states of Maryland and Virginia have pledged to jointly
manage the Bay's blue crab harvests through pot limits, gear
Prior to the late
1800s, oysters
were $o abundant
that some oyster
reefs posed
navigational
hazards to Boats,
restrictions and license restrictions. Harvesting of
soft-shelled clams and an extensive finfish indus-
try, primarily based on menhaden and striped bass,
round out the Chesapeake's commercial seafood
production. In 1997, the dockside value of com-
mercial shellfish and finfish harvests was close to
$196 million.
The hospitable climate, lush vegetation and
natural beauty of the Chesapeake have made it an
increasingly popular recreational area. Boating,
crabbing, swimming, hunting and camping are
major attractions. Both power and sail boating have grown
dramatically. In Maryland and Virginia, more than 428,000
pleasure boats and other personal craft were registered in 1998.
Sportfishing is another major recreational activity in the
Chesapeake region. The National Marine Fisheries Service
estimates that close to 1.4 million anglers took fishing trips in
Maryland and Virginia in 1998.
The Chesapeake is also a key commercial waterway, with
two major North Atlantic ports located here. The Hampton
Roads Complex, which includes Portsmouth, Norfolk, Hamp-
ton and Newport News, dominates the mouth of the Bay.
Hampton Roads ranks second in the nation for metric tons of
exports. At the northern end, the Port of Baltimore is ranked
eleventh in volume of exports in foreign trade. In all, these two
ports handled more than 70 million metric tons of both imports
and exports in 1997. Both Baltimore and Hampton Roads are
near the coal-producing regions of Appalachia, making them
essential to exporting coal.
Shipbuilding and other related industries also depend on the
Bay. Industries and power companies use large volumes of
water from the Bay for industrial processes and cooling.
Chesapeake Bay: Introduction to an Ecosystem
-------
Perhaps the Chesapeake's most valuable function, yet
most difficult to put a price tag on, is its role as habitat
for living resources. The Bay and its surrounding
watershed provide homes for a multitude
of plants and animals.
Waterfowl and other birds migrating along the
Atlantic Flyway stop here, finding food and shelter
in coves and marshes. The Chesapeake is the winter
home for tundra swans, Canada geese and a variety
of ducks, including canvasbacks, pintails, scoters,
eiders and ruddy ducks. On average, nearly a million
waterfowl winter each year on the Bay. It is also a
major nesting area for the threatened bald eagle.
The nation's largest population of another raptor,
the osprey, is in the Bay region.
The Chesapeake's tidal freshwater tributaries
provide spawning and nursery sites for several
important species offish, such as white and yellow
perch, striped bass, herring and shad. During the
warmer months, numerous marine species,
including bluefish, weakfish, croaker, menhaden,
flounder and spot, enter the Bay to feed on
its rich food supply.
A Threatened Resource
The Chesapeake Bay, the largest
estuary in the United States, is part
of an extremely productive and
complex ecosystem. This ecosystem
consists of the Bay, its tributaries and the
living resources it supports. Humans, too, are a part of this
ecosystem. We are beginning to understand how our activi-
ties affect the Bay's ecology. Growing commercial, indus-
trial, recreational and urban activities continue to threaten
the Bay and its living resources.
Overharvesting and loss of habitat threaten fish and shell-
fish species. These two factors, plus disease, have decimated
the oyster population. Excess sediment and nutrients endan-
ger the Bay's water quality. Hypoxia (low dissolved oxygen)
and anoxia (absence of dissolved oxygen) are particularly
harmful to bottom-dwelling (benthic) species. Chemical con-
taminants, particularly high in industrialized urban areas,
accumulate in the tissues of birds, fish and shellfish. Three
areas, known as Regions of Concern, where living resources
likely are being affected by chemical contaminants are the
Baltimore Harbor/Patapsco River in Maryland, the Anacostia
Canada goose
(Branta canadensis)
BAY FACT
The Chesapeake is
fairly shallow. A
person six feet tall
could wade over
700,000 acres
of the Bay
without Becoming
completely
Canvasback
(Aythya valisineria)
Osprey
1 (Pandion haliaetus)
Great blue heron
(Ardea herodias)
Tundra swan
(Cygnus columbianus)
Chesapeake Bay Ecosystem
-------
River in the District of Columbia and the Elizabeth
River in Virginia.
To find the causes of and potential remedies for
these problems, it is necessary to see the Bay from
an ecological perspective. All too often we think of
ourselves as external to our environment and ignore
the many relationships that link people, other living
creatures and the surrounding habitat. If we ignore
these connections when seeking solutions to prob-
lems, more and greater problems may result
For example, agricultural activities and res idential develop-
ment increase the amount of sediment and nutrient-rich fertil-
izers entering the Bay through runoff. Water clarity is reduced
and rivers are silted in. Excess nutrients cause algal blooms that
block sunlight from reaching critical underwater Bay grasses
known as submerged aquatic vegetation or SAV. As Bay grass
acreage declines, so does the food, shelter and nursery grounds
for many aquatic species. Solutions to these environmental
problems can only be effective if complex relationships among
all components of the ecosystem also are considered.
When environmental problems are approached from an
ecosystem perspective, both living and non-living components
BAY FACT
More than a
third of the
nation's catch of
blue crabs comes
from the Bay,
are considered when recommending solutions.
A truly effective solution not only corrects the
problem, but avoids damaging other relation-
ships within the ecosystem. This approach
makes problem-solving a great deal more
challenging, but leads to more effective envi-
ronmental management.
The Chesapeake Bay as we know it today
is the result of thousands of years of continu-
ous change. The Chesapeake, less than 10,000 years old,
continues to change. Nature, like a dissatisfied artist, is con-
stantly reworking the details. Some modifications enhance
the Bay; others harm it. All affect the ecosystem and its inter-
dependent parts. Some changes are abrupt, while others take
place over such a long time that we can only recognize them
by looking back into geologic history.
Humans are becoming more involved in the reshaping
process, often inadvertently initiating chains of events that
reverberate through the Bay's ecosystem. Because our
actions can have devastating effects on the entire system, it
is essential that we develop an adequate understanding of the
Bay's geological make-up and fundamental characteristics.
Chesapeake Bay: Introduction to an Ecosystem
-------
Geology of the Chesapeake
Geologic History
During the latter part of the Pleistocene
epoch, which began one million
years ago, the region that is now the
Chesapeake was alternately exposed and
submerged as massive glaciers advanced
and retreated up and down the North Amer-
ican continent. Sea levels rose and fell in con-
cert with glacial contraction and expansion.
The region still experiences changes in sea
levels, easily observed over the duration of
a century.
The most recent retreat of the glaciers,
which began about 18,000 years ago, marked
the end of the Pleistocene epoch and brought
about the birth of the Chesapeake Bay. The rising
waters from melting glaciers covered the conti-
nental shelf and reached the mouth of the Bay
about 10,000 years ago. Sea level continued to
rise, eventually submerging the area now
known as the Susquehanna River Valley. The
Bay assumed its present dimensions about
3,000 years ago. This complex array of
drowned streambeds forms the Chesapeake basin
we know today.
The Chesapeake Bay
The Bay proper is approximately 200
miles long, stretching from Havre de
Grace, Maryland, to Norfolk, Virginia. It
varies in width from about 3.4 miles
near Aberdeen, Maryland, to 35 miles at
its widest point, near the mouth of the
Potomac River. Including its tidal tributaries,
the Bay has approximately 11,684 miles of
shoreline.
Fifty major tributaries pour water into the
Chesapeake every day. Eighty to 90% of the
freshwater entering the Bay comes from the
northern and western sides. The remaining
10 to 20% is contributed by the eastern
shore. Nearly an equal volume of saltwater
enters the Bay from the ocean.
D3
A
Broad Ribbed scallop
(Lyropecten santamaria)
Turret snail (Turritella plebia)
Ark (Anadora stammea)
Shark teeth
1 (Otoc/as obliquus)
2 (/-/em/pr/st/i serra)
3 (Oxyrhina desori)
On average, the Chesapeake holds more
than 15 trillion gallons of water. Although
the Bay's length and width are dramatic,
the average depth is only about 21 feet.
The Bay is shaped like a shallow tray,
except for a few deep troughs believed
to be remnants of the ancient Susque-
hanna River. The troughs form a deep
channel along much of the length of the Bay.
This channel allows passage of large com-
mercial vessels. Because it is so shallow,
the Chesapeake is far more sensitive to
temperature fluctuations and wind than
the open ocean
To adequately define the Chesapeake
ecosystem, we must go far beyond the
shores of the Bay itself. Although the Bay
lies totally within the Atlantic Coastal Plain,
the watershed includes parts of the Pied-
mont Province and the Appalachian
Province The tributaries provide a mixture
of waters with a broad geochemical range to
the Bay. These three different geological
provinces influence the Bay. Each con-
tributes its mixture of minerals, nutrients
and sediments.
The Atlantic Coastal Plain is a flat,
low land area with a maximum eleva-
tion of about 300 feet above sea level.
It is supported by a bed of crystalline
rock, covered with southeasterly-
dipping wedge-shaped layers of rela-
tively unconsolidated sand, clay and gravel.
Water passing through this loosely com-
pacted mixture dissolves many of the
minerals. The most soluble elements are
iron, calcium and magnesium.
The Atlantic Coastal Plain extends
from the edge of the continental shelf, to
the east, to a fall line that ranges from 15
to 90 miles west of the Bay. This fall line
forms the boundary between the Piedmont
Plateau and the Coastal Plain. Waterfalls
and rapids clearly mark this line, which is
close to Interstate 95. Here, the elevation
Geology of the Chesapeake
-------
THE CHESAPEAKE BAY_
WATERSHED/'"'
'^~->
I Appalachian Province
| Piedmont Plateau
^;4 Atlantic Coastal Plain
rises to 1,100 feet. Cities such as Fredericksburg and Rich-
mond in Virginia, Baltimore in Maryland, and the District of
Columbia developed along the fall
line taking advantage of the poten-
tial water power generated by the
falls. Since colonial ships could not
sail past the fall line, cargo would
be transferred to canals or overland
shipping. Cities along the fall line
became important areas for
commerce.
The Piedmont Plateau ranges
from the fall line m the east to the Appalachian Mountains in
the west. This area is divided into two geologically distinct
BAY FACT
More than
600 species are
fossilized in the
sediments of
Culvert Cliffs
in Maryland,
regions by Parrs Ridge, which traverses Carroll, Howard
and Montgomery counties in Maryland and adjacent coun-
ties in Pennsylvania. Several types of dense crystalline
rock, including slates, schists, marble and granite, com-
pose the eastern side. This results in a very diverse topog-
raphy. Rocks of the Piedmont tend to be impermeable, and
water from the eastern side is low in the calcium and mag-
nesium salts. This makes the water soft and easy to lather.
The western side of the Piedmont consists of sandstones,
shales and siltstones, underlain by limestone. This lime-
stone bedrock contributes calcium and magnesium to its
water, making it hard. Waters from the western side of Parrs
Ridge flow into the Potomac River, one of the Bay's largest
tributaries.
The Appalachian Province lies in the western and north-
ern parts of the watershed. Sandstone, siltstone, shale and
limestone form the bedrock. These areas, characterized by
mountains and valleys, are rich in coal and natural gas
deposits. Water from this province flows to the Bay
mainly via the Susquehanna River.
The waters that flow into the Bay have different chem-
ical identities, depending on the geology of the place
where the waters originate. In turn, the nature of the Bay
itself depends on the characteristics and relative volumes
of these contributing waters.
Erosion and Sedimentation
Since its formation, the Bay's shore has undergone con-
stant modification by erosion, transport and deposition of
sediments. In this process, areas of strong relief, like penin-
sulas and headlands, are eroded and smoothed by currents
and tides, and the materials are deposited in other parts of the
Bay. Sediments may be deposited in channels. Sediments,
carried by the river currents, also are left at the margins of
the Bay and major tributaries, resulting in broad, flat
deposits of mud and silt. Colonization of these areas by
hydrophytic (water-loving) vegetation may stabilize the sed-
iments and wetlands can develop. Recently, however, wet-
lands along shorelines have been retreating inland as sea
level has risen. The speed at which these actions progress
depends on numerous factors, including weather, currents,
composition of the affected land, tides, wind and human
activities.
Many of the islands that existed in the Bay during colonial
times are now submerged. Poplar Island, in Talbot County,
Maryland, illustrates the erosive forces continuing today. In
the early 1600s, the island encompassed several hundred
Chesapeake Bay: Introduction to an Ecosystem
-------
acres. Over the centuries, rising sea level eroded the perimeter
of Poplar Island. Though still populated by the 1940s, only
200 acres remained and the island had been cut in two. Today,
a chain of small islands is all that remains of the original
Poplar Island. Efforts are under way to stabilize the remnant
acres. In addition, the island's original landmass will be rebuilt
by creating marshes that will protect the island from further
erosion and provide a haven for birds and other wildlife.
In contrast, sedimentation also has altered the landscape.
By the mid 1700s, some navigable rivers were filled in by
sediment as more land was cleared for agriculture. Joppa-
town, Maryland, once a seaport, is now more than two miles
from water. The forces of erosion and sedimentation con-
tinue to reshape the details of the Bay.
Mid-19th Century
725 acres
Late 1940s
200 acres
COACHES
ISLAND
POPLAR ISLAND: ISLAND EROSION
—^^
POPLAR
ISLAND
JEFFERSON
ISLAND
1993 Remnants
100-125 acres
COACHES
ISLAND
Geology of the Chesapeake
-------
Water & Sediments
Water . . . approximately 70% of Earth's surface is cov-
ered by it. It makes up about 80% of our total body
weight. Without it, we cannot live. Perhaps, because its pres-
ence is so pervasive in our lives, we tend to think of water as
uniform rather than a substance with extremely diverse char-
acteristics and properties.
In the natural environment, water is never pure. It tends to
hold other substances in solution and easily enters into vari-
ous chemical reactions. As the universal solvent, water is an
important environmental medium. Water normally contains
dissolved gases, such as oxygen, and a variety of organic
(containing carbon) and inorganic materials. The concentra-
tion and distribution of these substances car vary within a
single body of water. Add differences in temperature and cir-
culation, which can enhance or retard certain chemical reac-
tions, and the variety of possible water environments vastly
increases.
Of all bodies of water, estuanne systems offer the great-
est physical variability in water composition. An estuary,
according to the late oceanographer Donald W. Pritchard, is
a "... semi-enclosed body of water which has free connec-
tion with the open sea and within which seawater is measur-
ably diluted by freshwater from land drainage." Within an
estuary, freshwater mixes with saltwater, with each con-
tributing its own chemical and physical characteristics. This
creates a range of environments that support a wide variety
of plants and animals.
Water: Salinity, Temperature and Circulation
The distribution and stability of an estuarine ecosystem,
such as the Chesapeake Bay, depend on three important
physical characteristics of the water: salinity, temperature
and circulation. Each affects and is affected by the others.
SPRING
SALINITY
in parts per
thousand
AUTUMN
SALINITY
in parts per
thousand
Isohalines mark the salt content of surface water. The salinity gradient varies during the year
due to freshwater input: fresher during spring rains, saltier during the drier months of autumn.
Chesapeake Bay: Introduction to an Ecosystem
-------
ZONE OF MAXIMUM
TURBIDITY
'•'•""'"'" ' " °
Salinity is a key factor influencing the physical make-up
of the Bay. Salinity is the number of grams of dissolved salts
in 1,000 grams of water. Salinity is usually expressed in parts
per thousand (ppt). Freshwater contains few salts (less than
0.5 ppt) and is less dense than full ocean strength seawater,
which averages 25 to 30 ppt. Salinity increases with depth.
Therefore, freshwater tends to remain at the surface.
Seawater from the Atlantic Ocean enters the mouth of the
Bay. Salinity is highest at that point and gradually decreases
as one moves north. Salinity levels within the Chesapeake
vary widely, both seasonally and from year to year, depend-
ing on the volume of freshwater flowing into the Bay. On a
map, isohalines or salinity contours mark the salt content of
surface waters. Because the greatest volume of freshwater
enters the Bay from northern and western tributaries, isoha-
lines tend to show a southwest to northeast tilt. The rotation
of Earth also drives this salinity gradient. Known as the Cori-
olis Force, it deflects flowing water to the right in the North-
ern Hemisphere so that saltier water moving up the Bay is
deflected toward the eastern shore.
Temperature dramatically changes the rate of chemical
and biological reactions within the water. Because the Bay is
so shallow, its capacity to store heat over time is relatively
small. As a result, water temperature fluctuates throughout
the year, ranging from 34 to 84 degrees Fahrenheit. These
changes in water temperature influence when plants and ani-
mals feed, reproduce, move locally or migrate. The tempera-
ture profile of the Bay is fairly predictable. During spring and
summer, surface and shallow waters are wanner than deeper
waters with the coldest water found at the bottom. Often tur-
bulence of the water helps to break down this layering.
BAY QUOTE
".,. the tide is
also governed fry
the wind. South"
east makes the
highest flood and
wrtftwest the
lowest ef>f>"
Rev, Hugh Jones, 1697
Just as circulation moves
much-needed blood throughout
the human body, circulation of
water transports plankton, fish
eggs, shellfish larvae, sediments,
dissolved oxygen, minerals and
nutrients throughout the Bay. Cir-
culation is driven primarily by the
movements of freshwater from the
north and saltwater from the
south. Circulation causes nutrients
and sediments to be mixed and
resuspended. This mixing creates a zone of maximum tur-
bidity that, due to the amount of available nutrients, is often
used as a nursery area for fish and other organisms.
Weather can disrupt or reinforce this two-layered flow.
Wind plays a role in the mixing of the Bay's waters. Wind
also can raise or lower the level of surface waters and occa-
sionally reverse the direction of flow. Strong northwest
winds, associated with high pressure areas, push water away
from the Atlantic Coast, creating exceptionally low tides.
Strong northeast winds, associated with low pressure areas,
produce exceptionally high tides.
Together, salinity, temperature and circulation dictate the
physical characteristics of water. The warmer, lighter fresh-
water flows seaward over a layer of saltier and denser water
flowing upstream. The opposing movement of these two
flows forms saltwater fronts or gradients that move up and
down the Bay in response to the input of freshwater. These
fronts are characterized by intensive mixing. A layer sepa-
rating water of different densities, known as a pycnocline, is
Water & Sediments
-------
The change in temperature and salinity divides the Bay into saltier bottom
water and lighter, fresher surface water. A blurry mixing layer, known as the
pycnocline, divides the two. Strong winds can pile surface water against one
shore of the Bay. To reestablish equilibrium, the bottom layer flows up into
shallower water.
^
;• PYCNOCUNE
| SALT CONTENT
i (parU/lhou&and)
I
TEMPERATURE
(degrees Celsius)
formed. This stratification varies within any season depend-
ing on rainfall. Stratification is usually highest in the spring
as the amount of freshwater in the Bay increases due to melt-
ing snow and frequent rain. Stratification is maintained
throughout summer due to the warming of surface waters.
In autumn, fresher surface waters cool faster than deeper
waters and sink Vertical mixing of the two water layers
occurs rapidly, usually overnight. This mixing moves nutri-
ents up from the bottom, making them available to phyto-
plankton and other organisms inhabiting upper water levels.
This turnover also distributes much-needed dissolved oxygen
to deeper waters. During the winter, water temperature and
salinity are relatively constant from surface to bottom.
Suspended Sediments:
Composition and Effects
The waters of the Chesapeake and its tributaries transport
huge quantities of sediments. Although sediments are a nat-
ural part of the Bay ecosystem, accumulation of excessive
amounts of sediments is undesirable. Accumulation of
sediments can fill in ports and waterways.
This sedimentation process already has
caused several colonial seaports, like Port
Tobacco, Maryland, to become landlocked.
As they settle to the bottom of the Bay, sed-
iments can smother bottom-dwelling plants
and animals, such as oysters and clams.
Sediments suspended in the water column
cause the water to become cloudy, or turbid,
decreasing the light available for underwa-
ter Bay grasses.
Sediments also can carry high concen-
trations of certain toxic materials. Individ-
ual sediment particles have a large surface
area, and many molecules easily adsorb or
attach to them. As a result, sediments can
act as chemical sinks by adsorbing metals,
nutrients, oil, pesticides and other poten-
tially toxic materials. Thus, areas of high
sediment deposition sometimes have high
concentrations of nutrients, persistent
(long-lasting) chemicals and contaminants,
which may later be released.
In the upper Bay and tributaries, sedi-
ments are fine-grained silts and clays that
are light and can be carried long distances.
These sediments are carried by the fresh,
upper layer of water. As they move into the
Bay, the particles slowly descend into the
denser saline layer. Here, the particles may reverse direction
and flow back up toward tidal tributaries with the lower layer
of water. As the upstream flow decreases, the sediments set-
tle to the bottom.
Sediments in the middle Bay are mostly made of silts and
clays. These sediments mainly are derived from shoreline
erosion. In the lower Bay, by contrast, the sediments are
sandier and heavier. These particles result from shore erosion
and inputs from the ocean. Sediments drop to the bottom
fairly rapidly, remain near their original source and are less
likely to be resuspended than finer silts.
Chemical Make-up
Like temperature and salinity, the chemical composition
of the water also helps determine the distribution and abun-
dance of plant and animal life within the Bay. The waters of
the Chesapeake contain organic and inorganic materials,
including dissolved gases, nutrients, inorganic salts, trace
elements, heavy metals and potentially toxic chemicals.
10
Chesapeake Bay: Introduction to an Ecosystem
-------
DISSOLVED INORGANIC
COMPOUNDS tN
SEAWATSR
im parts ppr million)
TfSACf HIMfNIS
,95 ppm
Q PURE WATER
H CHEMICAL MAKE-UP
M1NOK COMPONENTS
1 MA ppm
380 ppm WO ppm
* I
MAJOR COMPONCNTS
1350 ppm
* 4
The more saline waters are chemically similar to seawater.
Major constituents include chlorides, sodium, magnesium,
calcium and potassium. Dissolved salts are important to the
life cycles of many organisms. Some fish spawn in fresh or
slightly brackish water and must move to more saline waters
as they mature. These species have internal mechanisms that
enable them to cope with the changes in salinity.
Seawater also contains hundreds of trace elements that are
important in many biological reactions. For example, living
organisms require minute quantities of cobalt to make vita-
min B-12. Metals such as mercury, lead, chromium and cad-
mium also occur in low concentrations.
The composition of seawater is relatively constant from
place to place. Freshwater, however, varies depending upon
the soil and rocks with which the water has come in contact.
Both fresh and saltwater contain a myriad of natural dis-
solved materials. These come from several sources.
Microorganisms, such as bacteria, decompose dead organ-
isms and release compounds into the water. Live organisms
also release compounds directly into the water. In addition,
dissolved material enters the Bay via its tributaries and the
ocean.
BAY FACT
Due to a lack of
oxygen in the
water, hundreds
of blue crabs
meat run out onto
land. TMs rare
phenomena 1$
known as A
*cra6 fuAttee."
Dissolved oxygen is essential for most animals
inhabiting the Bay. The amount of available oxygen is
affected by salinity and temperature. Cold water can
hold more dissolved oxygen than warmer water, and
freshwater holds more than saline water. Thus, con-
centrations of dissolved oxygen vary, in part, with both
location and time. Oxygen is transferred from the
atmosphere into surface
waters by diffusion and the
aerating action of the wind. It
also is added as a byproduct
of photosynthesis. Floating
and rooted aquatic plants and
phytoplankton release oxy-
gen when photosynthesizing.
Since photosynthesis requires
light, production of oxygen
by aquatic plants is limited to
shallow water areas, usually
less than six feet deep. Sur-
face water is nearly saturated with oxygen most of the
year, while deep bottom waters range from saturated to
anoxic (no oxygen present).
During the winter, respiration levels of organisms
are relatively low. Vertical mixing is good, and there is
little salinity or temperature stratification. As a result,
dissolved oxygen is plentiful throughout the water col-
umn. During the spring and summer, increased levels
of animal and microbial respiration and greater stratification
may reduce vertical mixing, resulting in low levels of dis-
solved oxygen in deep water. In fact, deep parts of some trib-
utaries like the Patuxent, Potomac and Rappahannock rivers
and deep waters of the Bay's mamstem can become anoxic
in summer. In the autumn when surface waters cool, vertical
mixing occurs and deep waters are re-oxygenated.
Carbon dioxide, another dissolved gas, is important to the
well-being of the Bay's aquatic environment. It provides the
carbon that plants use to produce new tissue during photo-
synthesis and is a byproduct of respiration. Carbon dioxide
is more soluble in water than oxygen. Its availability also is
affected by temperature and salinity in much the same fash-
ion as oxygen.
Nitrogen is essential to the production of plant and animal
tissue. It is used primarily by plants and animals to synthesize
protein. Nitrogen enters the ecosystem in several chemical
forms and also occurs in other dissolved or particulate forms,
such as in the tissues of living and dead organisms.
Some bacteria and blue-green algae can extract nitrogen
gas from the atmosphere and transform it into organic nitro-
Water & Sediments
-------
Sunlight
Minimal
Phosphorus &
Nitrogen Inputs
Excessive
Phosphorus &
Nitrogen Inputs
Sunlight
• • Healthy
' • Oyster Reef v-'
;:; -,Bent" ^ofBenthlccommunrty :'
• ff
gen compounds. This process, called nitrogen fixation,
cycles nitrogen between organic and inorganic; components.
Other bacteria release nitrogen gas back into the atmosphere
as part of their normal metabolism in a process called deni-
trification. Denitrification removes about 25% of the nitro-
gen entering the Bay each year.
Phosphorus is another key nutrient in the Bay's ecosys-
tem. In the water, phosphorus occurs in dissolved organic
and inorganic forms, often attached to particles of sediment.
This nutrient is essential to cellular growth and reproduction.
Phytoplankton and bacteria assimilate and use phosphorus in
their growth cycles. Phosphates (the organic "orm) are pre-
ferred, but organisms will use other forms of phosphorus
when phosphates are unavailable.
In the presence of oxygen, high concentrations of phos-
phates in the water will combine with suspended particles.
These particles eventually settle to the Bay bottom and are
temporarily removed from the cycling procesis. Phosphates
often become long-term constituents of the bottom sedi-
ments. Phosphorus compounds in the Bay generally occur in
greater concentrations in less saline areas, such as the upper
part of the Bay and tributaries. Overall, phosphorus concen-
trations vary more in the summer than winter.
Nutrients, like nitrogen and phosphorus, occur naturally
in water, soil and air. Just as the nitrogen and phosphorus in
fertilizer aids the growth of agricultural crops, both nutrients
are vital to the growth of plants within the Bay. Excess nutri-
ents, however, are pollutants. Sewage treatment plants,
industries, vehicle exhaust, acid rain, and runoff from agri-
cultural, residential and urban areas are additional sources of
nutrients entering the Bay. Nutrient pollution is the number
one problem in the Bay system.
Excess amounts of nitrogen and phosphorus cause rapid
growth of phytoplankton, creating dense populations or
blooms. These blooms become so dense that they reduce the
amount of sunlight available to underwater Bay grasses.
Without sufficient light, plants cannot photosynthesize and
produce the food they need to survive. Algae also may grow
directly on the surface of Bay grasses, blocking light.
Another hazard of nutrient-enriched algal blooms comes
after the algae die. As the blooms decay, oxygen is used up
in decomposition. This can lead to dangerously low oxygen
levels that can harm and even kill aquatic organisms.
Chesapeake Bay: Introduction to an Ecosystem
-------
Besides nutrients, people add other substances to the
Bay's water, creating serious pollution problems. Heavy
metals, insecticides, herbicides and a variety of synthetic
products and byproducts can be toxic to living resources.
These contaminants reach the Bay through municipal and
industrial wastewater, runoff from agricultural, residential
and urban areas and atmospheric deposition.
This situation is improving. In some cases, industrial
wastewater can be treated to remove contaminants. The use
of especially damaging synthetic substances, like DDT and
Kepone, has been banned.
In an effort to control nutrient pollution, Maryland, Penn-
sylvania, Virginia and the District of Columbia agreed to
reduce the total amount of controllable nutrients entering the
Bay by 40% by 2000. Controllable sources include runoff
from agricultural, suburban and urban areas, wastewater
treatment plants and industry. A ban on laundry detergents
containing phosphates has reduced phosphorus levels. New
technologies at many sewage treatment plants remove some
phosphorus and nitrogen before the effluent is discharged
into rivers. Other efforts include maintaining forested or
other vegetated buffer strips along water sources, reducing
fertilizer use on farms and lawns and managing animal
waste.
BAY FACT
During the
1600s, wolves,
cougars, elk and
Buffalo still
inhabited the
Ray watershed.
Water & Sediments
13
-------
Habitats
The Bay provides food, water, cover and nesting or nurs-
ery areas, collectively known as habitat, to more than
3,000 migratory and resident wildlife species All plants and
animals have specific habitat requirements that must be sat-
isfied in order to live and thrive. Food, temperature, water,
salinity, nutrients, substrate, light, oxygen and shelter
requirements vary with each species. These physical and
chemical variables largely determine which species can be
supported by a particular habitat.
As a highly productive estuary, the Chesapeake Bay pro-
vides an array of habitats. Habitat types range from hard-
wood forests of the Appalachian mountains to saltwater
marshes in the Bay. These habitats are influenced by climate,
soils, water, plant and animal interactions and human activi-
ties. Four major habitat areas are critical to the survival of the
living resources of the Bay.
Islands and Inlands
Lands near water sources support a multitude of species,
from insects, amphibians and reptiles to birds and mammals.
Streambanks, floodplains and wetlands form the
transition from water to land. These areas act as
buffers by removing sediments, nutrients, organic
matter and pollutants from runoff before these sub-
stances can enter the water. Forests and foiested
wetlands are particularly important to wateifowl,
other migratory birds and colonial waterbirds.
Forested uplands and wetlands are nesting and
resting habitat for neotropical migratory Dirds.
These birds breed in the United States but winter in
Central and South America. Some neotropical
birds breed in the forests found in the Bay water-
shed. The Bay lies within the Atlantic Flyway, a
major migration route for neotropical migrants and
migrating waterfowl, and is a significant resting
area for birds.
Surrounded by water and cut off from most
large predators, Bay islands are a haven for colo-
nial waterbirds (terns and herons), waterfowl
(ducks) and raptors (osprey and bald eagles).
Islands also can protect underwater Bay grasses
and shallow water areas from erosion and sedi-
mentation. However, islands themselves are erod-
ing at alarming rates, mostly due to sea level rise
and the erosive force of wind and waves.
Freshwater Tributaries
Within the Chesapeake Bay watershed, five major
rivers—the Susquehanna, Potomac, Rappahannock, York
and James—provide almost 90% of the freshwater to the
Bay. These rivers and other smaller rivers, along with the
hundreds of thousands of creeks and streams that feed them,
provide habitat necessary for the production of many fish
species. Anadromous fish spend their adult lives in the ocean
but must spawn in freshwater. Anadromous fish species in
the Bay include striped bass (rockfish), blueback herring,
alewife, American and hickory shad, shortnose sturgeon and
Atlantic sturgeon. Semi-anadromous fish, such as white and
yellow perch, inhabit tidal tributaries but also require fresh-
water to spawn.
While all of these species have different habitat require-
ments, all must have access to freshwater spawning grounds.
However, due 1o dams and other obstacles, many historical
spawning grounds are no longer available to fish. Fish not
only need access to spawning grounds but require good
stream and water quality conditions for the development and
14
Chesapeake Bay: Introduction to an Ecosystem
-------
survival of eggs and juvenile fish. Nutrients,
chemical contaminants, excessive sediment
and low dissolved oxygen degrade spawn-
ing and nursery habitat.
Shallow Water
BAY QUOTE
Open Water
"In sommer no
place affordetfi
more plentie of
sturgeon, nor in
winter more abun-
dance of foule. .."
John Smith, 1607-08
Shallow water provides habitats for many
life stages of invertebrates, fish and water-
fowl Shrimp, killifish and juveniles of
larger fish species use Bay grass beds, tidal
marshes and shallow shoreline margins as nursery areas and
for refuge. Vulnerable, shedding blue crabs find protection in
grass beds. Predators, including blue crabs, spot, striped bass,
waterfowl, colonial waterbirds and raptors, forage for food
there. Along shorelines, fallen trees and limbs also give cover
to small aquatic animals. Even unvegetated areas, exposed at
low tide, are productive feeding areas. Microscopic plants
cycle nutrients and are fed upon by crabs and fish.
Striped bass, bluefish, weakfish, American shad,
blueback herring, alewife, bay anchovy and Atlantic
menhaden live in the open, or pelagic, waters of the
Bay. Although unseen by the naked eye, microscopic
plants and animal life (plankton) float in the open
waters. These tiny organisms form the food base for
many other animals. Hundreds of thousands of win-
tering ducks, particularly sea ducks like scoters, old-
squaw and mergansers, depend on open water for the
shellfish, invertebrates and fish they eat during the winter
months. Open water also supports oysters and other bottom-
dwellers. Oysters and other filter feeders help maintain water
quality by filtering suspended organic particles out of the
water. The oyster reef itself is a solid structure that supports
other shellfish, finfish and crabs
Habitats
15
-------
Living Resources &
Biological Communities
Within every habitat, communities of organisms
exist in close relationship to each other. Commu-
nities may be as small as an oyster bar or as large as the
entire Bay. The relationships among species form a com-
plex web. Some organisms produce food ard others
serve as prey. Some communities, such as underwater
Bay grasses, provide both food and cover. Many
organisms fit into more than one of these categories.
The functions within a given community are almost
endless, and the Chesapeake Bay supports countless
communities both large and small.
Change is characteristic
of ecological systems,
including the Bay. Germi-
nation of plant seeds, birth
of animals, growth, local
movement and migration
affect the species composi-
tion of each community, as
do changes in water quality, loss of habitat
or overharvesting.
Some variations, such as seasonal
changes, follow a predictable pattern.
Every year, waterfowl migrate to the Bay
to spend the winter feeding in uplands, wet-
lands and shallow water areas. Then, each spring,
they return to northern parts of the continent
to breed. After mating each summer, female
blue crabs migrate to the mouth of the Bay to
spawn, while the males remain in the
upper and middle Bay. Anadro-
mous fish, like shad and her-
ring, spend most of their lives
in the ocean, but each spring
enter the Bay and migrate into
freshwater to spawn. These are
just a few of the seasonal vari-
ations that occur.
Some Bay communities
are prone to rapid population
fluctuations of one or more
species. This is particularly true of
plankton. Rapid changes in plankton diversity
Sea Nettle
(Chrysaora quinquecirrha)
Striped bass
(Morone saxatilis)
American oyster
(Crassosfrea
virgmica)
Blue crab
(Callmectes sapidus)
and abundance may occur hourly or
daily due to the interaction of biolog-
ical, physical and chemical
factors.
Many species exhibit
long-term patterns in popula-
tion abundance and distribu-
tion. For example, croakers
suffer high mortalities during
exceptionally cold weather.
This fish was abundant in
the Bay during the late
1930s and early 1940s. It is
believed that relatively mild
winters in the late 1930s and
early 1940s promoted the
high numbers of croak-
ers. Human-induced
pressures can affect
long-term patterns.
Striped bass declined rap-
idly in the late 1970s and
through the 1980s due to
overharvesting and subse-
quent reproductive failure.
However, successful man-
agement measures led to a
restored stock in 1995.
Individual species may
belong to a variety of commu-
nities and use different habitats
throughout their life cycles.
Habitats are connected and
communities often overlap.
Changes in a particular habi-
tat not only may affect the
communities it supports but other
habitats and communities as
well.
In the Chesapeake, wetlands,
grass beds, plankton, fish and bot-
tom-dwellers are biological commu-
nities supported by the Bay's diverse
16
Chesapeake Bay: Introduction to an Ecosystem
-------
habitats. Wetlands are transitional areas between water and
land. Bay grass beds range from mean low tide to a depth of
about six feet or where light becomes limiting to plant
growth, although some freshwater species thrive in water up
to nine feet deep. Open water supports the plankton commu-
nity, composed mostly of minute creatures that float and drift
with the movement of the water, and the nekton community,
the fish and other swimmers that move freely throughout the
Bay and its tributaries. The bottom sediments support ben-
thic organisms.
Wetlands
Wetlands are environments subjected to periodic flooding
or prolonged saturation, producing specific plant communi-
ties and soil types. The presence of water affects
the type of soil that develops and the types of
plants and animals that live there. Wetlands are
characterized by hydrophytic vegetation (water-
loving plants adapted to wet soils) and hydric
soils (saturated or periodically flooded soils).
There are two broad categories of wetlands in the
Bay watershed. Wetlands within the reach of tides
are considered tidal. Salinity in tidal wetlands
ranges from fresh to saltwater. Nontidal or palus-
tnne wetlands are freshwater areas unaffected by
the tides. Wetlands receive water by rain, ground-
BAY FACT
are
among &e
most productive
ecosystems in the
world, producing
more food (In the
form of detritus)
than many
agricultural fields.
water seepage, adjacent streams and, in the case of tidal wet-
lands, tides. Salinity, substrate and frequency of flooding
determine the specific plant and animal life a wetland can
support.
Tidal wetlands are dominated by nonwoody or herba-
ceous vegetation and are subjected to tidal flooding. These
wetlands have a low marsh zone (flooded by every high tide)
and a high marsh zone (flooded by extremely high tides).
Plants such as smooth cordgrass are found in the low marsh
zone of brackish and saltwater marshes. The high marsh
zone may be dominated by saltmeadow cordgrass, black
needlerush, saltgrass or marsh elder. Freshwater marshes
also have low and high zones. Along the water's edge, you
may find wild rice, arrow arum, pickerel weed and pond lily.
In the high zone, cattail and big cordgrass may be prevalent.
Nontidal wetlands frequently contain bul-
rush, broad-leaved cattail, jewel weed, spike
rushes and sedges. Forested wetlands, often
referred to as swamps, may have permanent
standing water or may be seasonally flooded.
Trees commonly found in forested wetlands
include red maple, black gum, river birch,
black willow, Atlantic white cedar and bald
cypress. Willows, alders and button bushes are
types of shrubs present in forested wetlands.
Approximately 1.5 million acres of wet-
lands remain in the Bay watershed, less than
A Button bush
(Cephalanthus occidentalis)
B Big cordgrass
(Spartina cynosuroides)
C Narrow-leaved cattail
(Typha angustifolia)
D Black needlerush
(luncus roemerianus)
E Saltmeadow cordgrass
(Spartina patens)
F Wild rice
(Zizania aquatica)
C Widgeon grass
(Ruppia maritima)
Living Resources & Biological Communities
-------
A Black willow
(Salix nigra)
B Red maple
(Acer rubrum)
C River birch
(Betula nigra)
D Jewelweed
(Impatiens capensis)
E River bulrush
(Sdrpus fluviatilis)
F Broad-leaved cattail
(Typha latifolia)
half of the wetlands that were here during colonial times. Of
the remaining wetlands, 13% are tidal and 87% are nontidal.
Often viewed as wastelands, wetlands were drained or
filled for farms, residential developments, commercial build-
ings, highways and roads. Over the past several decades, our
understanding and appreciation of wetlands has increased.
Plant diversity, biochemical reactions and hydrology of
these habitats make them extremely productive. Wetlands
support large quantities of plant biomass. The huge amount
of visible plant material in wetlands makes up only the
above-ground biomass. The below-ground biomass, com-
posed of root and rhizome material, is often more than dou-
ble the above-ground biomass. This creates a tremendous
reservoir of nutrients and chemicals bound up in plant tissue
and sediments.
Many of the Bay's living resources depend on these wet-
land habitats for their survival. Tidal wetlands are the win-
tering homes for great flocks of migratory \vaterfowl. Other
wildlife, including muskrats, beavers, otters, songbirds and
wading birds, rely on wetlands for food and cover. Fish and
shellfish, many of which are commercially valuable, use
wetlands as spawning or nursery areas. Thousands of aquatic
animals, including reptiles,
amphibians, worms, insects, snails,
mussels and tiny crustaceans,
thrive in wetlands and are food for
other organisms.
The abundance of food and
shelter provided by wetland vege-
tation is essential to other members
of this community. A host of inver-
tebrates feed on decomposing
plants and animals. This nutrient-
BAY FACT
Two-thirds of
the nation's
commercial fish
and shellfish
depend on
wetlands as
nursery or
spawning grounds.
rich detritus is also available to juvenile stages of fish and
crabs. A dense layer of microscopic plants and animals,
including bacteria and algae, coats the land surface and
serves as food. Stems of larger plants provide another good
source of food. Decomposing plants and animals are the
major food source for other wetland inhabitants.
Wetlands are also important for controlling flood and
storm waters. Fast-moving water is slowed by vegetation and
temporarily stored in wetlands. The gradual release of water
reduces erosion and possible property damage. Coastal wet-
lands absorb the erosive energy of waves, further reducing
erosion.
Poised between land and water, wetlands act as buffers,
regulating the flow of sediments and nutrients into rivers and
the Bay. As water runs off the land and passes through wet-
lands, it is filtered. Suspended solids, including sediment
pollutants, settle and are trapped by vegetation. Nutrients,
carried to wetlands by tides, precipitation, runoff and
groundwater, are trapped and used by wetland vegetation. As
plant material decomposes, nutrients are released back into
the Bay and its tributaries, facilitated by floodwaters or tides.
Economically, wetlands provide opportunities for fishing,
crabbing and hunting. Other popular activities include hik-
ing, birdwatching, photography and wildlife study. People
are lured by the beauty of wetlands to enjoy the sights and
sounds that these areas can offer.
Underwater Bay Grasses
In the shallow waters of the Bay, underwater grasses sway
in the aquatic breeze of the current. Known as submerged
aquatic vegetation or SAV, these amazing plant communities
provide food and shelter for waterfowl, fish, shellfish and
18
Chesapeake Bay: Introduction to an Ecosystem
-------
invertebrates. Like other green plants, Bay grasses produce
oxygen, a precious and sometimes lacking commodity in the
Bay. These underwater plants also trap sediment that can
cloud the water and bury bottom-dwelling organisms like
oysters. As waves roll into grass beds, the movement is
slowed and energy is dispelled, protecting shorelines from
erosion. During the growing season, Bay grasses take up and
retain nitrogen and phosphorus, removing excess nutrients
that could fuel unwanted growth of algae in the surrounding
waters.
Like a forest, field or wetland, a grass bed serves as habi-
tat for many aquatic animals. Microscopic zooplankton feed
on decaying Bay grasses and, in turn, are food for larger Bay
organisms. Minnows dart between the plants and graze on
tiny organisms that grow on the stems and leaves. Small fish
seek refuge from larger and hungrier mouths. Shedding blue
crabs conceal themselves in the vegetation until their new
shells have hardened. Thus, grasses are a key contributor to
the energy cycling in the Bay. Bay grasses are a valuable
source of food, especially for waterfowl. In the fall and win-
ter, migrating waterfowl search the sediment for nutritious
seeds, roots and tubers. Resident waterfowl may feed on
grasses year-round.
There are 14 common species of grasses commonly found
in the Bay or nearby rivers. Salinity, water depth and bottom
sediment determine where each species can grow. Survival
of Bay grasses is affected most by the amount of light that
reaches the plants. Poor water quality resulting in less light
penetration is the primary cause for declining grasses.
Factors that affect water clarity, therefore, also affect the
growth of Bay grasses. Suspended sediment and other solids
cloud the water, blocking precious sunlight from the grasses.
Excessive amounts of suspended sediment may cover the
plants completely. Sources of suspended sediments include
runoff from farmland, building sites and highway construc-
tion. Shoreline erosion also adds sediment to the Bay. Land
development, boat traffic and loss of shoreline vegetation
can accelerate natural erosion.
Nutrients, although vital to all ecosystems, can create
problems when present in excessive amounts. Major sources
of nutrients include sewage treatment plants, acid rain, agri-
cultural fields and fertilized lawns. High levels of nutrients
stimulate rapid growth of algae, known as blooms. Algal
blooms cloud the water and reduce the amount of sunlight
reaching Bay grasses. Certain types of algae grow directly on
the plants, further reducing available sunlight.
Common Underwater Bay Grasses
Widgeon grass
(Ruppia maritima)
Eelgrass
(Zostera marina)
Wild celery
(Vallisneria americana)
Redhead grass
(Potamogeton perfoliatus)
Living Resources & Biological Communities
19
-------
Historically, more than 200,000
acres of grasses grew along the
shoreline of the Bay. By 1984, a
survey of Bay grasses documented
only 37,000 acres in the Bay and its
tidal tributaries. Declining water
quality, disturbance of grass beds
and alteration of shallow water
habitat all contributed to the Bay-
wide decline. The absence of
grasses translates into a loss of food
and habitat for many Chesapeake
Bay species. However, Bay grasses
have rebounded steadily since the
low point in 1984. In 1998, 63,495
acres of grasses were documented.
Water quality is the key to restor-
ing grasses. Scientists have identi-
fied the water quality conditions
and requirements necessary for the
survival of five grass species: wild
celery found in freshwater, sago
pondweed, redhead grass and wid-
geon grass found in nore estuarine
water and eelgrass found in the
lower Bay in saltier water. Each
species is an important source of
food for waterfowl. EJay grasses are
making a comeback, however.
Water quality is beginning to
improve due to the ban of phos-
phates in detergents, reduction of
fertilizer use by farrrers and home-
owners, protection of shallow water
habitat and the reduction of nutri-
ents in sewage effluent.
Plankton
Mainly unseen by the naked eye,
a community made up of predomi-
nantly microscopic organisms also
fuels the Bay ecosystem. These tiny
plants and animals, called plankton,
drift at the mercy of the currents
and tides. Some of the tiny crea-
tures move up and down in the
water column to take advantage of
light. Others will drop below the
BAY FACT
Owe drop of Bay
water may contain
thousands of
phytoplankton.
pycnochne, an intermediate layer where the increase in
salinity is more pronounced, to avoid being washed out to
the ocean.
Phytoplankton are tiny single-celled plants. Like higher
plants, phytoplankton require light to live and reproduce.
Therefore, the largest concentrations occur near the surface.
Salinity affects phytoplankton dis-
tribution with the largest number of
species preferring the saltier waters
near the mouth of the Bay. The
amount of nutrients in the water is a
major determinant to the abundance
of these plants. The largest concen-
trations of phytoplankton in the
Bay occur during the spring when
nutrients are replenished by freshwater runoff from the
watershed. These high concentrations produce the character-
istic brown-green color of estuarine and near-shore waters.
Although there are many species of phytoplankton, the major
types in the Bay are diatoms and dinoflagellates. When
dinoflagellates dominate the water, a red-tinted bloom,
called a mahogany tide, may be produced. Mahogany tides
typically occur on warm, calm days, often following ram.
Diatoms, which are present throughout much of the year,
may account for 50% of total algal production.
Changes in chemical conditions, such as the addition of
nutrients, can cause rapid increases in the amount of algae.
These algal blooms can have serious consequences. They
block light from reaching SAV beds. Even after they die,
they can cause problems. Deposition and subsequent decom-
position of large masses of plankton in the mainstem of the
Bay can deplete dissolved oxygen, suffocating other estuar-
ine animals.
Phytoplankton are the major food source for microscopic
animals called zooplankton. Dominating the zooplankton are
the copepods (tiny crustaceans about one millimeter long)
and fish larvae. Zooplankton are distributed according to
salinity levels. Distribution patterns also are related to those
of their main food source—the phytoplankton. Zooplankton
also feed on other paniculate plant matter and bacteria.
Tiny larvae of invertebrates and fish also are considered
zooplankton. Although this planktonic stage is only tempo-
rary, the larvae are a significant part of the community. These
larvae are consumed by larger animals, and may, as they
grow, consume copepods.
Another group of zooplankton found in the Bay are the
protozoa. These single-celled animals feed on detritus and
bacteria. They, in turn, become food for larvae, copepods and
larger protozoa.
20 Chesapeake Bay: Introduction to an Ecosystem
-------
Bacteria play an important function in the Bay. They are
essentially the decomposers. Their primary function is to
break down dead matter, particularly plants. Through this
process, nutrients in dead plant and animal matter again
become available for growing plants. Bacteria are eaten by
zooplankton and other filter-feeding animals in the Bay.
Bacteria can be residents of the Bay or can be introduced
through various pathways, including human sewage and
runoff from the land. Coliform bacteria are normal resident
bacteria found in the intestines of mammals. The presence of
coliform in a body of water indicates that human or other
animal wastes are present. Coliform bacteria are an indicator
that disease-producing pathogens may be present in the
water.
Clearly visible to the unaided eye, jellyfishes and comb
jellies are the largest zooplankton. Some of these gelatinous
creatures swim, though they are still at the mercy of the
water currents. Jellyfishes have tentacles with stinging cells
used to stun prey. The most famous jellyfish in the Chesa-
peake is the sea nettle. Sea nettles feed voraciously on other
zooplankton, including fish larvae, comb jellies and even
small fish. Because of the large volume of water in their bod-
ies, few animals except sea turtles prey on sea nettles. Comb
jellies, lacking the stinging cells of nettles, capture prey with
adhesive cells. They, too, consume vast quantities of small
copepods and zooplankton, especially oyster larvae.
The Swimmers
Swimmers comprise the nekton community. These organ-
isms can control and direct their movements. This group
includes fish and some crustaceans and other invertebrates.
Approximately 350 species of fish can be found in the
Chesapeake Bay. They can be divided into permanent resi-
dents and migratory fish. The residents tend to be smaller in
size and do not travel the long distances that migratory
species do.
Smaller resident species, such as killifish, normally occur
in shallow water where they feed on a variety of inverte-
brates. The bay anchovy, the most abundant fish in the Bay,
is a key player in the Chesapeake food web. Bay anchovies
feed primarily upon zooplankton. Adult anchovies also may
consume larval fish, crab larvae and some benthic species. In
turn, the bay anchovy is a major food source for predatory
Bay anchovy
(Anchoa mitchllli)
Weakfish
(Cynoscion regalis)
Striped killifish
(Fundulus majalis)
Bluefish
(Pomatomus saltatrix)
Striped bass
(Morone saxatilis)
Living Resources & Biological Communities
-------
fish like striped bass, bluefish and weakfish, as
well as some birds and mammals.
Migratory fish fall into two categories:
anadromous, which spawn in the Bay or its trib-
utaries, and catadromous fish, which spawn in
the ocean. Anadromous fish migrate varying dis-
tances to spawn in freshwater. Some can even be
considered Bay residents. For instance, during
the spawning season, yellow and white perch
travel short distances from the brackish water of
the middle Bay to freshwater areas of the upper
Bay or tributaries. Striped bass also spawn in the tidal fresh-
water areas of the Bay and major tributaries. Some remain in
the Chesapeake to feed while others migrate to ocean waters.
Shad and herring are truly anadromous, traveling from the
ocean to freshwater to spawn and returning to the ocean to
feed. Eels are the only catadromous species in the Bay.
Although they live in the Bay for long periods, eels eventu-
ally migrate to the Sargasso Sea in the central North Atlantic
to spawn.
Other fish utilize the Bay strictly for feeding. Croaker,
drum, menhaden, weakfish and spot journey into the Bay
while still in their larval stage to take advantage of the rich
supply of food. The abundance of menhaden supports a com-
mercial fishing industry and provides food for predatory fish
and birds. Bluefish enter the Bay only as young adults or
mature fish.
Besides fish, crustaceans and invertebrates may be part of
the nekton community. Larger animals like sharks, rays, sea
turtles, and occasionally marine dolphins and whales enter
the Bay.
The blue crab is difficult to place in any one community,
needing a variety of aquatic habitats, from the mouth of the
BAY FACT
Oysters are
alternate
hermaphrodites,
meaning they can
sense gender
imbalances and
change their sex.
Bay to fresher rivers and creeks, in order to
complete its life cycle. Throughout the year,
crabs may burrow into the Bay bottom, shed and
mate in shallow waters and beds of Bay grasses
or swim freely in open water. The first life stage
of a blue crab, called the zoea, is microscopic
and lives a planktonic free-floating existence.
After several molts, the zoea reaches its second
larval stage: the megalops. Another molt and a
tiny crab form is apparent. Both juvenile and
adult blue crabs forage on the bottom and hiber-
nate there through the winter. In spring, the crab quickly
begins migrating from the southern part of the Chesapeake to
tidal rivers and northern portions of the Bay. During the rest
of the year, adult blue crabs are dispersed throughout the
Bay, swimming considerable distances using their powerful
paddle-like back fins.
Life at the Bottom
The organisms that live on and in the bottom sediments of
the Bay form complex communities. Known as benthos, these
bottom-dwellers include animals, plants and bacteria. Benthic
organisms often are differentiated by their habitat. Epifauna,
like oysters, barnacles and sponges, live upon a surface
Worms and clams, considered infauna, form their own com-
munity structure beneath the bottom sediments, connected to
the water by tubes and tunnels. The roots and lower portions
of Bay grasses supply the physical support for a variety of epi-
phytic organisms. An oyster bar, and the many species it sup-
ports, is another example of a benthic community. Benthic
communities that exist on or in bare, unvegetated substrate are
made up of mollusks, worms and crustaceans.
LIFE STAGES OF A BLUE CRAB
Zoea
Immature
Crab
Chesapeake Bay: Introduction to an Ecosystem
-------
BENTHIC COMMUNITY
A A Hard clam (Mercenana mercenana)
B Atlantic oyster drill (Urosalpmx cinerea)
C Common clam worm (Nereis succinea)
D Red ribbon worm (Micrura leidyi)
E Soft-shelled clam (Mya arenaria)
F Glassy tubeworm (Spiochaetopterus oculatus) J Oyster spat
G Black-fingered mud crab (Panopeus herbstii)
H Whip mudworms (Polydora ligni)
I Sea squirts (Molgula manhattensis)
K Ivory barnacle (Balanus eburneus)
L Skilletfish (Gobiesox strumosus)
M American oyster (Crassosfrea virgimca)
','.".•••••.•'.•".
.<•<:•. * :-°-*-°
As with all aquatic life in the Bay, salinity affects the dis-
tribution of bottom-dwellers, but sediment type also plays a
role. Neither coarse sand nor soft mud support rich benthic
populations. The best sediment for diverse benthic commu-
nities consists of a mixture of sand, silt and clay. Some
organisms require specialized substrates. Oysters need a
clean hard surface, preferably another oyster shell, on which
the larval spat can attach or set. Oysters form a reef commu-
nity that is important habitat for other benthic species.
The benthic community affects the physical and chemical
condition of the water and sediments. Some build tubes or
burrows through which they pump water. Infaunal deposit
feeders, such as worms, plow through the sediments in
search of food. Many benthic animals bind sediments
together as fecal pellets that remain at the bottom. Predators,
such as adult blue crabs, scurry across bottom searching for
food. These activities stir the sediments, increasing the rate
of exchange of materials into the water column. This mixing
also increases diffusion of oxygen into the sediments.
Filter feeders, like oysters and clams, pump large volumes
of water through their bodies and extract food from it. As
they filter water for food, they also remove sediments and
organic matter, cleaning the water. Since many chemical
contaminants often are present in sediments, benthic fauna
often are exposed to and can be harmed by these pollutants.
Some benthic organisms are widely distributed. Others
are limited more by salinity. For example, hard clams and
oysters require higher saline waters. Mid-salinity waters sup-
port soft-shelled clams. Brackish water clams also are found
in lower salinities, along with freshwater mussels. Salinity
also determines the distribution of certain benthic predators,
parasites and diseases. MSX, a lethal parasite, and Dermo, a
disease caused by another parasite, have decimated oyster
populations of the mid and lower Bay, respectively. Oyster
drills and starfish, which feed on oysters, are less of a prob-
lem in upper Bay waters because of their intolerance to low
salinities.
Living Resources & Biological Communities
-------
Food Production & Consumption
The most important relationship among Chesapeake Bay
species is their dependence upon each olher as food. We
are all carbon-based creatures. Carbon is the basic element
of organic compounds, such as proteins, carbohydrates,
lipids and nucleic acids. These compounds are the building
blocks of life that make up the bodies of living organisms.
Feeding is the process by which organisms cycle energy-rich
carbon through the ecosystem. Each organism supplies the
fuel needed to sustain other life forms.
Plants and some bacteria can produce their own food
through a process known as photosynthesis. Using energy
from the sun, carbon dioxide and water are combined to form
high-energy organic compounds. These organic compounds
and other necessary chemicals form a plant's cellular struc-
ture, allowing it to grow. Because of this ability to use car-
bon dioxide and sunlight to produce their own food, plants
are called autotrophs or self-feeders. They are the primary
food producers. All other organisms must feed, directly or
indirectly, on organic material produced by plants.
Animals cannot process carbon via photosynthesis.
Instead, they acquire carbon by eating the organic matter
contained in plant and animal tissue or dissolved in water.
The animal breaks this organic material down into com-
ponents it can use for energy and growth. Animals are
heterotrophs or other-feeders.
CARBON-OXYGEN CYCLE
Sunlight
BAY FACT
Each year,
cra&fars catch
approximately
two-thirds of
the adult blue
crab population
in the Bay.
Every biological activity, such as reproduction, growth,
movement and bodily functions, requires energy. Whether
organisms produce food themselves or ingest it from other
sources, they all must break down organic molecules to use
the carbon and energy contained within. This process is
called respiration.
Aerobic respiration uses oxygen
and releases carbon in the form of
carbon dioxide. It compliments
photosynthesis, which uses carbon
dioxide and produces oxygen.
Together, aerobic respiration and
photosynthesis compose the
carbon-oxygen cycle.
All living things respire, but
autotrophs carry out photosynthesis
as well. Plants usually release more oxygen than they con-
sume, and animals use that excess oxygen for respiration. In
turn, animals release carbon dioxide, which plants require
for photosynthesis.
While carbon and oxygen are two of the most prevalent
elements in our physical make-up, many others are needed.
Nitrogen and phosphorus are two such elements. They are
crucial to the operation of the Bay's life support system.
Nitrogen is a major component of all organisms, prima-
rily as a key ingredient in protein. When an organism dies,
bacteria breaks down proteins into amino acids. Bacteria
then remove the carbon, converting the acids into ammonia.
Plants are able to use ammonia as a source of nitrogen. In the
presence of oxygen, bacteria can convert ammonia to nitrite
and nitrate, also good sources of nitrogen. Under low oxygen
conditions, some bacteria convert nitrate to gaseous nitrogen
that is unavailable to most aquatic organisms. However, in
tidal freshwater, some blue-green algae are able to use
gaseous nitrogen directly.
Phosphorus is another element essential to plant growth.
During decomposition and in the presence of oxygen, bacte-
ria convert organic phosphorus to phosphate. Phosphates are
readily used by plants. However, phosphate also attaches to
sediment particles and settles out of water very quickly. The
resulting decrease in available phosphorus can limit plant
growth.
Temperature, sunlight, carbon dioxide and usable nitro-
gen and phosphorus control the rate of photosynthesis. Since
plants are the only organisms able to produce new food from
inorganic matter, the rate of photosynthesis determines the
24
Chesapeake Bay: Introduction to an Ecosystem
-------
FOOD CHAIN
Producers
Decomposers &
Detritus Feeders
production of organic carbon compounds and, ultimately, the
availability of food in the Bay ecosystem.
To illustrate how these factors affect the productivity of
the Bay, let's look at the Chesapeake's most abundant food
producer—the phytoplankton. Like all plants, phytoplankton
require sunlight, nutrients and water. In the Bay, water is
never a limiting factor. However, the amount of sunlight and
nutrients can limit phytoplankton growth. The amount of
sunlight available to an aquatic plant depends on the sun's
altitude, cloud cover, water depth and turbidity (cloudiness
of water). Temperature also controls the rate of photosynthe-
sis.
Nutrients in the form of carbon dioxide and usable nitro-
gen and phosphorus are rarely available in the exact propor-
tions required by plants. Normally, one nutrient is in short
supply compared to the others and is considered the limiting
nutrient. If a limiting nutrient is added, a growth spurt may
occur. Conversely, reducing the amount of a limiting nutrient
causes plant production to decline.
Phosphorus controls the growth of some phytoplankton
species in the spring, especially in the tidal freshwater and
brackish areas. Nitrogen is the prime limiting factor at higher
salinities, particularly during warm months. Carbon dioxide
limitations may control the rate of photosynthesis during
algal blooms in tidal freshwater.
The Bay's life support system depends on maintaining the
delicate balance between the living and non-living compo-
nents. Although the Chesapeake's potential production
capacity is massive, it is also finite. Problems affecting the
simplest producers dramatically affect the survival of con-
sumers.
The Food Web
As one organisms eats another, a food chain is formed.
Each step along a food chain is known as a trophic level, and
every organism can be categorized by its feeding or trophic
level. The most basic trophic level is made up of producers:
plants and algae that make their own food. Organisms that
eat plants or other animals are consumers. Decomposers
digest the bodies of dead plants and animals and the waste
products of both. An example of a simple food chain starts
with phytoplankton converting sunlight and nutrients into
living tissue. They, in turn, are eaten by copepods—members
of the zooplankton community. The copepods then are con-
sumed by bay anchovies, which are eaten by bluefish and
striped bass. These fish can be harvested and eaten by peo-
ple. This illustrates how organic carbon compounds origi-
nally produced by a plant pass through successively higher
trophic levels.
Food production and consumption in the Bay are rarely
this simple or direct. Seldom does one organism feed exclu-
sively on another. Usually, several food chains are inter-
woven together to form a food web. Decomposers appear
throughout the food web, breaking organic matter down into
nutrients. These nutrients are again available to producers.
Food Production & Consumption
-------
This complex network of feeding continuously cycles
organic matter back into the ecosystem.
The transfer of energy from one organism to the next is,
however, inefficient. Only about 10% of the available energy
is transferred from one trophic level to the next. For exam-
ple, only a portion of the total amount of phytoplankton car-
bon ingested by zooplankton is assimilated by the
zooplankton's digestive system. Some of that is used for res-
piration, bodily functions and locomotion. A small fraction is
used for growth and reproduction. Since these are the only
functions that produce additional tissue, only this fraction of
energy is available to the consumer at the next trophic level.
Economically important foods like fish and shellfish
depend upon lower trophic level organisms. For every pound
of commercial fish taken from the Chesapeake, almost 8,000
pounds of plankton had to be produced. An ecosystem must
be enormously productive to support substantial populations
of organisms at the highest trophic levels. Massive quantities
of plants are required to support relatively few carnivores,
such as the striped bass or bluefish. Because producers are
the basis of all food, they influence the production of other
organisms. However, an overabundance of producers like
algae also can be detrimental, causing a loss of Bay grasses
and reducing the amount of dissolved oxygen available to
other organisms.
Toxic substances in contaminated prey also can be passed
on to the consumer. Heavy metals and organic chemicals are
stored in the fatty tissues of animals and con-
centrate there. As a result, an animal's body
may contain a much higher concentration
of the contaminant than did its food. This
phenomenon is known as bioaccumula-
tion. The severe decline of the bald
eagle during the 1950s, 1960s and
1970s was attributed to bioaccumula-
tion. During World War II, a chemical
pesticide, DDT, was used to control
insects and agricultural pests. Fish and
small mammals that fed on these pests
were in turn contaminated with higher
concentrations. Eagles eating contami-
nated prey concentrated even higher /
levels of DDT and its by-product DDE.
The DDE caused the birds to lay extremely thin shells, so
thin that most eggs broke in the nest and many eagle pairs
failed to produce young. As a result of the DDT ban in
1972 and protection provided by endangered species
status, bald eagles have been able to recover to the pop-
ulation we have today.
Direct and Detrital Pathways
Two basic pathways dominate the estuarine food web.
The direct pathway leads from plants to lower animals to
higher animals. The detrital pathway leads from dead
organic matter to lower animals then to higher animals. The
detrital pathway is dominant in wetlands and Bay grass beds.
The direct and detrital pathways coexist and are not eas-
ily separated. Higher plants, such as eelgrass, widgeon grass,
saltmarsh grass and cordgrass, contribute most of their car-
bon as detritus. However, epiphytic algae growing on these
grasses is usually eaten by consumers, putting them in the
direct food web.
In deeper waters, detritus from dead phytoplankton, zoo-
plankton and larger animals, as well as detritus from upland
drainage, wetlands and Bay grasses, continually rains down
on the benthos. Bottom-dwelling animals, such as oysters,
clams, crustaceans, tube worms, shrimp and blue crabs, feed
on it.
A Harpacticoid
(Scottolana canadensis)
B Calanoid
(Acart/a c/aus/j
C Cyclopoid
(Oithona colcarva)
BAY FACT
Most larval fish consume
huge amounts of
zooplankton to survive.
A gallon of Bay water
can contain mare than
500,000 zooplankton.
26
Chesapeake Bay: Introduction to an Ecosystem
-------
The direct pathway dominates the plankton
community. The smallest of phytoplankton,
known as nannoplankton, are fed upon by larger
microzooplankton. Larger phytoplankton, like
most diatoms and dinoflagellates, provide food
for larger zooplankton and some fish. Bacteria,
fungi, phytoplankton and possibly protozoa pro-
vide food for oysters and clams.
Copepods, a dominant form of zooplankton,
play a key role in the food web between phyto-
plankton and animals. Copepods feed on most
phytoplankton species and occasionally on the
juvenile stages of smaller copepods. In marine waters, most
animal protein production from plant material is carried out
by copepods. Copepods and a related organism, krill, are the
world's largest stock of living animal protein. Larger carni-
vores feed voraciously on them. Herring, for example, may
consume thousands of the tiny creatures in a single day.
Most of the Bay's fish are part of the direct food web, but
their feeding habits are complex. Some experts contend that
BAY FACT
Oysters were once
so plentiful they
could filter the
entire volume of
Bay water in a
few days. This
process now takes
aver a year.
menhaden are the dominant fish in the Bay's
intricate food web. The extremely fine gill rakers
of menhaden act as a filtering net. Adult men-
haden swim with their mouths open, consuming
any plankton in their paths. In turn, menhaden are
a major food of striped bass, bluefish and osprey.
They also support a large commercial fishery that
utilizes the fish for animal feed and for products
containing fish meal and oil.
Like menhaden, anchovies and all fish larvae
are primarily zooplankton feeders. Adult striped
bass, bluefish and weakfish feed mainly on other
fish. Striped bass and other predators also may feed upon
young of their own species. Many fish are omnivorous, eat-
ing both plants and animals. Omnivores, like eels and croak-
ers, feed on planktonic copepods, amphipods, crabs, shrimp,
small bivalves and small forage fish. Small forage fish, like
killifish and silversides, often feed upon the epifauna and
epiphytes along wetlands and in shallow water communities.
Food Production & Consumption
27
-------
Preserving the Chesapeake Bay:
the Big Picture
If we want to preserve the Chesapeake Bay and its many
delights for future generations, we must change our per-
spectives. We must view not only what occurs in the Bay
itself, but what happens on the land surrounding
it. It is not enough to protect shorelines, regulate
fisheries and prevent direct disposal of pollu-
tants. We must take into account all of the activi-
ties that occur throughout the watershed from
Cooperstown, New York, to Virginia Beach, Vir-
ginia, and from Pendleton County, West Virginia,
to Seaford, Delaware. Released into this water-
shed, fertilizers, sediment and chemical contam-
inants from agricultural, residential and urban
areas travel downstream to the Bay.
However, even a watershed perspective is not
adequate without personal responsibility. Even
though we acknowledge that activities in ihe watershed
affect the Bay ecosystem, we must also realize that indi-
vidual actions impact the Bay everyday: Fertilizers and
THE BAY'S
FUTURE
"Vihen we see
the land as a
community to
which we belong,
we may begin to
use it with love
and respect."
Aldo Leopold, 1945
pesticides from yards and gardens affect the Bay as much as
those from large farms. Excessive use of cars produces more
exhaust with nitrogen oxides, which contribute to elevated
nitrogen levels in the Bay. Indiscriminate use of
water results in more water that must be treated
and then discharged into the Bay system.
If we want a clean, healthy Bay that can sus-
tain biological diversity and be economically
stable, we must identify, alter and, if possible,
eliminate our own individual actions that impact
the Bay. People alter ecosystems. The solutions
to problems threatening the Bay are in the
lifestyles we choose. The Bay ecosystem is one
unit where forests are linked to oyster reefs,
housing developments to Bay grasses and
choices to responsibility. Education also is
required. Informed people choose actions that are beneficial
for themselves, their culture, their community and the
Chesapeake Bay.
28
Chesapeake Bay: Introduction to an Ecosystem
-------
BE PART OF THE SOLUTION, NOT PART OF THE PROBLEM
Reduce your nutrient input to the Bay.
Limit the amount of fertilizers spread
on gardens and lawns. Plant native
vegetation that requires less fertilizer
and water. Leave grass clippings on
lawns and gardens. Maintain your
septic system. Start a compost pile,
instead of using a garbage disposal.
2
Reduce the use of toxic materials
around your house and yard, including
pesticides.
Use safer, non-toxic alternatives for
cleaning and for controlling pests.
3
Reduce erosion.
Plant strips of native vegetation along
streams and shorelines. Divert runoff from
paved surfaces to vegetated areas.
ave water.
Use water-saving devices in toilets and
sinks. Turn off water when not in use.
Wash cars in grassy areas to soak up
soapy water.
Drive less.
Join a carpool or use public transporta-
tion.
6
Obey all fishing, hunting and harvesting
regulations.
Be a responsible boater.
Avoid disturbing shallow water areas and
Bay grass beds. Pump boat waste to an
onshore facility.
* Get involved.
Talk to your elected officials about your
concerns. Join or start a watershed asso-
ciation to monitor growth and develop-
ment locally. Participate in clean-up
activities.
FOR MORE INFORMATION
ABOUT THE
CHESAPEAKE BAY
ECOSYSTEM, VISIT
www.chesapeakebay. net
Preserving the Chesapeake Bay
29
-------
For more information about the Chesapeake Bay and its rivers contact:
Chesapeake Bay Program
(800) YOUR-BAY/(410) 267-5700
www.chesapeakebay.net
D.C. & STATE AGENCIES
Chesapeake Bay Commission
(410)263-3420
www.chesbay.state.va.us
District of Columbia Department
of Health
(202)645-6617
www.environ.state.dc.us
District of Columbia Public Schools
(202)442-4016
www.k!2 dc us
Maryland Department of Education
(888)246-0016
www.msde.state.md.us
Maryland Department of the
Environment
(800)633-6101
www.mde.state.md.us
Maryland Department of Natural
Resources
(410)260-8710
www dnr.state.md.us
Pennsylvania's Chesapeake Bay
Education Office
(717)545-8878
www.pacd org
Pennsylvania Department of
Conservation and Natural Resources
(717)787-9306
www.dcnr.state.pa.us
Pennsylvania Department of Education
(717)783-6788
www pde.psu.edu
Pennsylvania Department of
Environmental Protection
(717)787-2300
www dep.state.pa.us
Virginia Department of Conservation
and Recreation
(804)786-1712
www.state.va.us/-dcr/
Virginia Department of Education
(800)292-3820
www.pen.kl2.va.us
Virginia Department of Environmental
Quality
(800) 592-5482/(804) 698-4000
www.deq.state va.us
FEDERAL AGENCIES
National Oceanic and Atmospheric
Administration
Chesapeake Bay Office
(4: 0)267-5660
www.noaa.gov
National Park Service
(4 0) 267-5747
www.nps.gov
Natural Resources Conservation Service
(202) 205-0026
www.nrcs.usda.gov
U.S. Army Corps of Engineers
District office in Baltimore
(410)962-7608
www nab usace.army mil
U.S. Army Environmental Center
(410)436-7113
www. hqda.army.mil
U.S.D.A. Forest Service
(410)267-5706
www.fs.fed.us
U.S. Department of Education
(800) USA-LEARN
www ed.gov
U.S. Environmental Protection Agency
Chesapeake Bay Program Office
(800) YOUR-BAY
www.epa gov/r3chespk
U.S. Fish and Wildlife Service
Chesapeake Bay Field Office
(410)573-4500
www.fws.gov/r5cbfo
U.S. Geological Survey
(703)648-4000
www.usgs.gov
ACADEMIC ORGANIZATIONS
Maryland Sea Grant
(301)405-6371
www.mdsg.umd.edu
Pennsylvania State University
(814)865-4700
www.psu edu
University of the District of Columbia
(202) 274-5000
www.wrlc.org/udc.htm
University of Maryland Cooperative
Extension Service
(301)405-2072
www.agnr.umd.edu
University of Maryland Center for
Environmental Science
(410)228-9250
www umces.edu
Virginia Cooperative Extension
(540)231-6704
www.ext.vt.edu
Virginia Institute of Marine Science
(804) 684-7000
www.vims.edu
Virginia Tech
(540)231-6000
www vt.edu
NONPROFIT ORGANIZATIONS
Alliance for the Chesapeake Bay
Chesapeake Regional Information Service
Hotline
(800) 662-CRIS
www acb-onhne org
Chesapeake Bay Foundation
(410)268-8816
www.cbf org
Chesapeake Bay Trust
(410)974-2941
www.baytrust.org
30
Chesapeake Bay: introduction to an Ecosystem
-------
Chesapeake Bay Program
THE CHESAPEAKE BAY PROGRAM
A Watershed Partnership
The Chesapeake Bay Program, formed in 1983 by
the first Chesapeake Bay Agreement, is a unique
regional partnership that's leading and directing the
restoration of the Chesapeake Bay—the largest estuary
in the United States. The Bay Program partners include
Maryland; Pennsylvania; Virginia; the District of
Columbia; the Chesapeake Bay Commission, a tri-state
legislative body; the U.S. Environmental Protection
Agency (EPA), which represents the federal govern-
ment; and participating citizen advisory groups. The
Bay Program's highest priority is the restoration of the
Bay's living resources—its finfish, shellfish, Bay grass-
es and other aquatic life and wildlife.
The second Chesapeake Bay Agreement, adopted in
1987 and amended in 1992, established an overall vision
for the restoration and protection of the Bay. One of its
main goals is to reduce the nutrients nitrogen and phos-
phorus entering the Bay by 40% by the year 2000. In the
1970's, scientific and estuarine research on the Bay had
pinpointed nutrient over-enrichment as an area requiring
attention. In the Amendments, partners agreed to main-
tain the 40% goal beyond the year 2000 and to attack
nutrients at their source—upstream in the tributaries.
The Chesapeake Executive Council, made up of the
governors of Maryland, Pennsylvania and Virginia; the
mayor of the District of Columbia; the EPA adminis-
trator; and the chair of the Bay Commission, guided the
restoration effort in 1993 with five directives address-
ing key areas of the restoration, including the tributar-
ies, toxic chemicals, underwater Bay grasses, fish pas-
sages and agricultural nonpoint source pollution. In
1994, partners outlined initiatives for habitat restora-
tion of aquatic, riparian and upland environments;
nutrient reduction in the Bay's tributaries; and toxics
reductions, with an emphasis on pollution prevention.
The 1995 Local Government Partnership Initiative
engaged the watershed's 1,650 local governments in
the Bay restoration effort. The Executive Council fol-
lowed this in 1996 by adopting the Local Government
Participation Action Plan and the Priorities for Action
for Land, Growth and Stewardship in the Chesapeake
Bay Region, which address land use management,
growth and development, stream corridor protection,
and infrastructure improvements. A 1996 riparian for-
est buffers initiative furthers the Bay Program's com-
mitment to improving water quality and enhancing
habitat with the goal of increasing riparian buffers on
2,010 miles of stream and shoreline in the watershed by
the year 2010. In 1997, the Bay Program renewed its
commitment to meet the 40% nutrient reduction goal
by 2000 and adopted initiatives that addressed the
acceleration of current nutrient reduction efforts,
expanded wetlands protection and support for commu-
nity-based watershed restoration efforts.
Now, the Bay Program, advisory committees, all
levels of government and other Bay stakeholders have
set their sights on Chesapeake 2000, a renewal of the
Chesapeake Bay Agreement and one of the four direc-
tives signed at the 1998 Executive Council meeting. As
always, the Bay Program's highest priority is the
restoration of the Bay's living resources. Chesapeake
2000 will assess the progress made since 1987 and,
among other objectives, will identify new science and
emerging challenges related to the Bay's health.
Another directive—the Bay Program's Education
Initiative—will bring information, data and the goals of
the Bay region's restoration into classrooms. The other
two 1998 directives address innovative technologies in
Bay restoration and regional management of the use
and transport of animal waste.
S A 1' I A K 1-
2000
The Renewed Agreement
CHESAPEAKE BAY PROGRAM
410 Severn Avenue, #109, Annapolis, MD 21403
1-800-YOUR BAY • www.chesapeakebay.net
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Striped Bass
Potamogeton perfoliatus
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