Coastal Areas —Why do we care?

Coastal Areas —Why do we care?

• Popular

• More than 60% of world’s population lives within 60 miles of the coast.

Coastal Areas —Why do we care?

• Popular

•Vulnerable

US Shoreline Erosion

Sea levels rose 10 inches over the past 100 yearsExpected to rise 2 more feet over next 100 years

Would rise more than 200 more feet if only Antarctica melted

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CHAPTER 11The Coastal Ocean

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Chapter Overview

• Coastal waters support about 95% of the total biomass in the oceans.

• Most commercial fish are caught within 320 km (200 miles) from shore.

• Coast waters are important also for shipping, oil and gas production, and recreation.

• Pollution is a major issue.

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Ocean Ownership

• In 1609 the sea was free to all (mare liberum).– Assumed fish resources are inexhaustible

• In 1702 the territorial sea area was declared under the coastal nation’s sovereignty (3 nautical miles from shore).– Distance of cannon shot

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United Nations Law of Sea

• United Nations Conference on the Law of the Sea– 1958– 1960– 1973–1982

• Treaties have undergone revisions.

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Law of the Sea• Coastal nations jurisdiction

– National sovereignty extends 12 nautical miles– Exclusive Economic Zone (EEZ) 200 nautical

miles (370 km) from land (mineral and fishing resources)

• Right of free passage for ships• Open ocean mining regulated by

International Seabed Authority• United Nations arbitrates disputes

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United States EEZ

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Characteristics of Coastal Waters

• Adjacent to land (to edge of continental shelf)

• Influenced by river runoff, wind, tides

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Characteristics of Coastal Waters

• Salinity variable– Freshwater runoff

• Can produce well-defined halocline

– Winds

– Mixing by tides

• Water may be

isohaline

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Characteristics of Coastal Waters

• Temperature variable– Low-latitudes – restricted circulation, very

warm– High-latitudes – sea ice

• Water may be isothermal at low and high latitudes.

– Seasonal changes– Prevailing winds– A strong thermocline may develop at middle

latitudes.

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Temperature Variation in Coastal Ocean

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Types of Coastal Waters

• Estuaries– Partly enclosed body

of water– Freshwater runoff

dilutes ocean water.

• Where FW meets SW

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Types of Estuaries

• Coastal plain estuary– Former river valley now flooded with seawater

• Fjord– Former glaciated valley now flooded with seawater

• Bar-built estuary– Lagoon separated from ocean by sand bar or

barrier island

• Tectonic estuary– Faulted or folded downdropped area now flooded

with ocean

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Types of Estuaries

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Water Mixing in Estuaries

• Vertically mixed– Shallow, low volume

• Slightly stratified– Deeper– Upper layer less salty; lower layer

more salty– Estuarine circulation

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Water Mixing in Estuaries

• Highly stratified– Deep, relatively strong halocline

• Salt wedge– Deep, high volume– Strong halocline

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Estuary Classification by Mixing

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Estuaries and Human Activities

• Important breeding grounds for many marine animals

• Protective nurseries

• Pressures from increasing human populations

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Columbia River Estuary

• Salt wedge estuary• Damage done by

flooding of agricultural areas

• Dams altered ecosystem

• Logging industry damage

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Chesapeake Bay Estuary• Slightly stratified• Seasonal changes in

salinity, temperature, dissolved oxygen

• Anoxic conditions below pycnocline in summer

• Major kills of commercially important marine animals

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Types of Coastal Wetlands

• Ecosystems intermittently inundated with ocean water

• Peat deposits and halophytic plants

• Salt Marshes– Between 30 and 65 degrees latitude

• Mangrove Swamps– Tropics

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Locations of Salt Marshes and Mangrove Swamps

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Characteristics of Coastal Wetlands

• Biologically important

–Nurseries, feeding grounds for commercially important marine animals

• Efficiently cleanse polluted water

• Absorb water from coastal flooding

• Protect shores from wave erosionIt is a good thing we really take good care of our Estuaries, right???????

Global Patterns of Primary Productivity

Global Primary Production• Upwelling areas

– Very productive but smallest area• Coastal areas

– Intermediate productivity and area• Open ocean

– Least productive, but largest area– As productive as deserts on land

• Estuaries – As productive as the most heavily cultivated areas

on land

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Loss of Coastal Wetlands

• Half of U.S. coastal wetlands lost to development (housing, industry, agriculture)

• U.S. Office of Wetland Protection, 1986– Minimize loss of wetlands– Protect or restore wetlands

• Predicted rise in sea level over next 100 years will destroy or shift wetlands inland

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Loss of Coastal Wetlands

Estuary

• Where SW meets FW

• Of the 32 largest cities in the world, 22 are located on estuaries. For example, New York City is located at the opening of the Hudson River estuary.

Estuary

• Tidal Influence means flushing

• New water in with high tide = nutrients, food, oxygen

• Water leaves at low tide removes waste and CO2

• Flushing rate: high (fast) or low (slow)

Estuary

• Chesapeake Bay once had an oyster population that was able to filter the entire water system in 2 weeks.

• Now it takes about 1 year.

Salt Marsh

Wednesday Next Monday

Pollution Part 1 Pollution Part 2

Wednesday March 30EXAM #3

Chap 9, 10, 11 +

Long Island +

Pollution