An estuary is a partially enclosed body of water where fresh water from rivers and streams mixes with salt water from the ocean. Estuaries are areas of transition between the land and the sea. They are often called bays, harbors, inlets or sounds.
What are the dimensions of the bay:
Length of the bay: Bay itself is about 200 miles long, stretching from Havre de Grace, Maryland, to Virginia Beach, Virginia
Width Range: 4 mi to 30 mi
Volume: 800 trillion gallons
Depth Range: 21 ft to 174 ft
Average Depth: 21 ft
How many miles of shoreline make up the bay; 11,684 miles of shoreline
What is the total surface area of the bay: 4,480 square miles
What was the initial event that lead to the Bay’s creation:
About 35 million years ago, a rare bolide – a comet- or asteroid-like object from space – hit the area that is now the lower tip of the Delmarva Peninsula, near Cape Charles, Virginia. The bolide created what geologists call the “Exmore Crater,” which they believe was as large as Rhode Island and as deep as the Grand Canyon.
During the last Ice Age, mile-thick glaciers stretched as far south as Pennsylvania, and the Atlantic coastline was about 180 miles farther east than it is today.
Approximately 18,000 years ago, the glaciers began to melt, carving streams and rivers that flowed toward the coast. Sea level continued to rise, eventually submerging the area now known as the Susquehanna River Valley. This drowned river valley became the Chesapeake Bay
What three geological areas contribute geology of the bay? What specific characteristics do they add:
Atlantic Coastal Plain
The coastal plain is supported by a bed of crystalline rock covered with southeasterly dipping wedge-shaped layers of sand, clay and gravel. Water passing through this loosely compacted mixture dissolves many of the minerals. The most soluble elements are iron, calcium and magnesium.
Several types of dense crystalline rock, including slates, schists, marble and granite compose the eastern side of the ridge. This variety creates a very diverse topography. Water from the eastern side of the Piedmont is low in calcium and magnesium salts. The western side of the Piedmont consists of sandstones, shale and siltstones layered over by limestone. this limestone bedrock contributes calcium and magnesium, making the water “hard”. Water from the western side of the ridge flows into the Potomac River.
These areas are characterized by mountains and valleys, and they are rich in coal and natural gas. Sandstone, siltstone, shale and limestone form the bedrock.
What three rivers contribute 80% of the Bay’s freshwater:
The Potomac River, the Susquehanna River and the James River
Describe how the salinity of the Bay changes as you travel from the North to the South? Why does this occur?
In general, the lower Chesapeake Bay is salty and the upper Bay is fresh. Salinity decreases as you move north towards the river inlets that provide fresh water to the Bay and increases as you move south closer the ocean which provides the salt water to the Bay.
Why does the chemical composition of freshwater vary place to place:
The composition of fresh water varies depending upon the soil and rocks the water has come into contact with.
What are the three sources that contribute to the chemical composition of fresh & salt water:
Bacteria and other microorganisms decompose dead organisms and release compounds into the water. Live organisms also release compounds directly into the water. Additionally, dissolved materials enter the Bay from its rivers and the ocean.
What two gases are most important for organisms in the Bay:
Draw two of any of the fish and one of the shellfish presented on this page. Describe their defining characteristics (click on their picture for this information):
Chin with 3-5 pairs of small barbells and 5 pores.
Caudal fin double concave.
Body is elongate and somewhat compressed.
Dorsal fin deeply notched, with 10 spines in the anterior portion and 1 spine and 26-30 soft rays in the posterior portion.
Upper dorsal side with numerous brassy spots that from wavy bars (less distinct in large individuals).
The species is easily recognized because of its large spiny head and wide mouth filled with fang-like teeth.
Monkfish have very broad, depressed heads (head is as wide as the fish is long)
They have enormous mouths with long, sharp teeth.
Monkfish have a modified spine called an "esca."
This spine is quite mobile and can be angled forward so it can dangle in front of the fish's mouth and be wiggled like bait to lure its prey.
These animals get their name from their general horseshoe shape.
They have a hard exoskeleton like a crab.
They are brown with a slender pointed tail.
A horseshoe crab's tail, while menacing, is not a weapon. Instead, the tail is used to plow the crab through the sand and muck, to act as a rudder, and to right the crab when it accidentally tips over.
Unique looking, with nothing else that looks much like them in existence today.
What are the two broad categories that encompass crabs and shellfish? What are their defining characteristics and examples:
Arthropods have an external skeleton—or exoskeleton—that they molt to grow. Crustaceans like crabs, shrimp and barnacles are the Bay's most common arthropods. Horseshoe crabs are arthropods, but not crustaceans: they are more closely related to spiders and scorpions
Mollusks include bivalves, gastropods (snails) and cephalopods (squid). Most mollusks have at least one shell that protects and supports the animal’s soft body. They also have a foot, which allows them to move.
Using links, provide a quick description of each habitat:
Forests now only cover about 58% of the watershed. Forests provide vital habitats for wildlife, filter pollution keeping the waterway cleaner and act as natural sponges that absorb runoff.
Wetlands are transitional areas between land and water. There are two categories, tidal and non-tidal. Tidal wetlands, found along the Bay’s shores, are filled with salt or brackish water. Non-tidal wetlands contain fresh water.
Streams & Rivers
Streams and rivers provide the bay with fresh water as well as providing many aquatic species with critical habitats.
Shallow waters are the areas of water from the shoreline to about 10 ft. deep. Shallow waters are constantly changing with the tides and weather throughout the year. The shallows support plant life, fish, birds and shellfish.
Tidal marshes in the Bay’s shallows connect shorelines to forests and wetlands. Marshes provide food and shelter for the wildlife that lives in the Bay’s shallow waters. Freshwater marshes are found in the upper bay, brackish marshes in the middle Bay and salt marshes in the lower Bay
Aquatic reefs are solid three-dimensional habitats made up of densely packed oysters. the reefs form when oyster larvae attach to larger oysters at the bottom of the bay
Open waters are beyond the shoreline and the shallows. Aquatic reefs replace underwater bay grasses, which cannot grow where sunlight cannot penetrate deep waters. Open water provides vital habitat for pelagic fish, birds and invertebrates
Using links, give a quick description of how each of the following puts pressure on the Bay:
Land & People:
The increase in human population has reduced the amount of land available for native species and has reduced the sustainability of the plants and animals that live in the Bay. Wastewater from sewage treatment plants also increase nutrients into the bay and its tributaries, contributing to algal bloom.
Air & Water Pollution:
Air pollution from cars, trucks and other burning of fossil fuels pollutes the bay when the harmful gases are absorbed by the waters. Chemical contaminants, such as pesticides, pharmaceuticals, metals, household cleaners all harm the ecosystem of the Bay by killing off species.
Commercial fisheries have overharvested many of the once populous species, such as oysters and shad, two vital organisms to the Chesapeake Bay, endangering the balance of the ecosystem.
Storms can upset the balance of the ecosystem as habitats are altered from erosion and flooding. Diseases, such as viruses, and reduce populations of vital species, such as the oysters.
Invasive species can cause harem when they establish themselves at the expense of native plants and animals, using up resources.
Climate change has been lined to rising seas, warming water temperature and prolonged periods of extreme weather. More immediate effects include a rise in coastal flooding, shoreline erosion and changes in wildlife abundance and migration patterns.
Using the links, describe how each of the following helps the bay:
By reducing graywater by using biodegradable soaps, using toxic-free paints, reducing runoff, and conserving water, the water that flows into the bay is cleaner, restoring water quality
By using fertilizers properly, reducing, recycling and reusing, by planting plants to prevent erosion, and by composting, the pressures on the habitats can be reduced, allowing them to return to their natural balance.
By limiting or restricting the numbers of catch and the time of catch, fish can have a chance to regain the optimal population for the health of the bay.
Because watershed feed directly into the Bay, human actions in the watershed areas have a direct effect on the Bay’s health.