EPA 903-R-00-001 CBP/TRS 232/00 April 2000 Chesapeake Bay NTRODUCTION to an o- 3- 3 c o = ~ ^ 2. w n O ILS.EPAKegicnill pl Center lor Environmental 1G50 Arcli Street (o?M32i CA> Callinectes sapidus Fossil Shark Tooth Chesapeake Bay Program Oxyrhina desori EPA Report Collection Regional Center for Environmental Information U.S. EPA Region III Philadelphia, PA 19103 ------- 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 ------- 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 ------- The Chesapeake Bay Watershed L_ j Chesapeake Bay Watershed ------- 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 ------- Striped Bass Potamogeton perfoliatus ------- |