CHESAPEAKE BAY

Chesapeake as an EstuaryChesapeake as an Estuary

An An estuaryestuary is: is:• a semi-enclosed body of a semi-enclosed body of

water that has a free water that has a free connection with the seaconnection with the sea

• where seawater is mixed with where seawater is mixed with freshwater runoff from the freshwater runoff from the land.land.

.

-4- Estuary Types-4- Estuary Types• Drowned River ValleyDrowned River Valley• Bar-Built EstuaryBar-Built Estuary• Tectonic EstuaryTectonic Estuary• FjordsFjords

Estuary Estuary TypesTypes

Drowned River ValleyDrowned River ValleyThis is the most common type of This is the most common type of

estuary. estuary.

• Forms during an ice age from Forms during an ice age from glacial melt. glacial melt.

• The Chesapeake Bay is a drowned The Chesapeake Bay is a drowned river valley river valley (Susquehanna(Susquehanna))

• 12,000 – 18,000 years ago12,000 – 18,000 years ago

Bar-Built Estuaries• Found whereFound where

sand barssand bars

and barrierand barrier

islands form.islands form.

(Outer Banks of NC)(Outer Banks of NC)

Bar-Built Estuaries• The shallow The shallow water behind water behind these barrier these barrier islands forms islands forms low salinity low salinity estuariesestuaries.

Tectonic Estuaries• These These estuaries estuaries form where form where the land sank the land sank (subsided).(subsided).

Fjords!• Fjords were Fjords were

created created when when retreating retreating glaciers cut glaciers cut deep in the deep in the earth.earth.

Fjords!• Where in the Where in the United United States might States might we find we find fjords?fjords?

A A watershedwatershed is the is the drainage area for a drainage area for a

region.region.

Virginia’sVirginia’s WatershedsWatershedsThere are 3 Different Watersheds There are 3 Different Watersheds in VA.in VA.

–The Chesapeake BayThe Chesapeake Bay

–The Gulf of MexicoThe Gulf of Mexico

–The North Carolina The North Carolina SoundsSounds

Gulf of Gulf of MexicoMexico

Chesapeake Chesapeake BayBay

North Carolina North Carolina SoundsSounds

Facts About The Chesapeake Bay

The Chesapeake Bay is the largest estuary in the United States.

•Can you name the Can you name the 6 states6 states that make that make up the watershed up the watershed of the Chesapeake of the Chesapeake Bay?Bay?

• VirginiaVirginia

• MarylandMaryland

• West VirginiaWest Virginia

• DelawareDelaware

• New YorkNew York

• PennsylvaniaPennsylvania

Chesapeake Chesapeake Bay WatershedBay Watershed

Maryland

DelawareDelaware

New York

District of Columbia

Virginia

West Virginia

Pennsylvania

The water The water from over from over

5050 rivers rivers empties into empties into

the Bay. the Bay. Can you Can you

name the name the 55 major riversmajor rivers that flow into that flow into

the bay?the bay?

• From South to NorthFrom South to North

• JamesJames

• YorkYork

• RappahannockRappahannock

• PotomacPotomac

• SusquehannaSusquehanna

(JYRPS!)(JYRPS!)

Susquehanna Susquehanna RiverRiver

Potomac RiverPotomac River

Rappahannock RiverRappahannock River

York RiverYork River

James RiverJames River

The Susquehanna RiverThe Susquehanna River

provides about provides about 50%50% of the of the fresh water coming into the fresh water coming into the Bay.Bay.

• The river empties an average The river empties an average of of 19 million gallons of water 19 million gallons of water per minute.per minute.

• The Bay holds 18 trillion gal.The Bay holds 18 trillion gal.

The bay is shallow. Can The bay is shallow. Can you guess its average you guess its average

depth?depth?• 106 ft.106 ft.

• 21 ft.21 ft.

• 9ft.9ft.

THE ANSWER!THE ANSWER!• 21 feet is the correct answer.21 feet is the correct answer.

• The deepest spot in the bay The deepest spot in the bay is 174 feet near Annapolis is 174 feet near Annapolis Md.Md.

Colonization of Estuaries

• For those For those organisms that organisms that can survive the can survive the extremes of the extremes of the estuary, (temp., estuary, (temp., salinity, oxygen) salinity, oxygen) there is a great there is a great deal of food.deal of food.

Bay OrganismsBay Organisms• The Bay is home to over The Bay is home to over

3600 living organisms!3600 living organisms!

2700 – plants2700 – plants

348 – finfish348 – finfish

173 - shellfish173 - shellfish

Marsh DwellersMarsh Dwellers• Marsh dwellers Marsh dwellers

are located in are located in and around and around tidal mudflats. tidal mudflats. They include They include small fish, small fish, birds, and birds, and marsh marsh grasses.grasses.

SAV CommunitiesSAV Communities• Submerged Aquatic Submerged Aquatic

Vegetation Vegetation CommunitiesCommunities are are important for many important for many reasons. They reasons. They provide shelter for provide shelter for organisms organisms including fish including fish ducks, crabs, and ducks, crabs, and eelgrass.eelgrass.

Plankton CommunityPlankton Community• The plankton The plankton community community includes the includes the drifters drifters of the of the Bay. Bay.

Plankton CommunityPlankton CommunityIncludes Includes phytoplankton, phytoplankton, bacteria, and bacteria, and zooplankton.zooplankton.

Benthic CommunitiesBenthic Communities• Benthic refers Benthic refers

to the bottom of to the bottom of the Bay. Benthic the Bay. Benthic organisms organisms include oysters, include oysters, clams, clams, barnacles, and barnacles, and mud crabs.mud crabs.

Nekton CommunitiesNekton Communities• Nekton refers Nekton refers

to the to the swimmers of swimmers of the Bay,the Bay,

many of which many of which use the Bay use the Bay as a nurseryas a nursery

The Bay area is home to over 15,000,00015,000,000 people!

• About

50,00050,000 commercial vessels enter the Bay each year.

• All of these people and activities put a strain on the Bay ecology.

Bay Problems

Nutrient PollutionNutrient Pollution• Fertilizers, manure & sewage Fertilizers, manure & sewage

add nitrogen and add nitrogen and phosphorus to the Bay.phosphorus to the Bay.

• These cause increased algae These cause increased algae growth (algal bloom)growth (algal bloom)

• Algae blocks sunlight Algae blocks sunlight from bottom dwellers.from bottom dwellers.

• As the algae dies, it uses As the algae dies, it uses up oxygen.up oxygen.

• Not enough oxygen left Not enough oxygen left for animals.for animals.

Sources of NutrientsSources of Nutrients

FarmsFarms

Urban Urban AreasAreas

Wastewater Wastewater treatment treatment plantsplants

Bay ProblemsLoss of Submerged Aquatic Loss of Submerged Aquatic

Vegetation (SAV)Vegetation (SAV)• Plants that are found on the Plants that are found on the

bottom of the bay provide food bottom of the bay provide food and shelter for organismsand shelter for organisms

• These plants are dying because These plants are dying because of pollution and sedimentation.of pollution and sedimentation.

Bay ProblemsToxinsToxins

• Harmful chemicals can be Harmful chemicals can be added to the bay from added to the bay from industries, roads, farms and industries, roads, farms and homes.homes.

Examples: pesticides, Examples: pesticides, herbicides, chemicals, oil herbicides, chemicals, oil productsproducts

Pollution Sources• Point Sources-Point Sources- pollutants pollutants

that come from a specific that come from a specific source that can be identified source that can be identified (factories,(factories,

sewagesewage

outflows)outflows)

• Non-point Sources-Non-point Sources- pollutants pollutants that come from a large region that come from a large region and can’t be identified from a and can’t be identified from a specific site (ex- farm runoff or specific site (ex- farm runoff or sedimentssediments

LawnsLawns

Parking lotsParking lots

Pesticides)Pesticides)

Bay ProblemsBay Problems Exotic SpeciesExotic Species

• Some plants and animals are Some plants and animals are accidentally or intentionally accidentally or intentionally introduced into the Bay Area introduced into the Bay Area (ex. Zebra mussel, snakehead, (ex. Zebra mussel, snakehead, water milfoil, Rapa whelk)water milfoil, Rapa whelk)

• Have no natural predators so Have no natural predators so they are hurting the ecosystem.they are hurting the ecosystem.

http://nas.er.usgs.gov/mollusks/images/zebra4b.jpg