Estuaries

Shore

Zone between low tide and highest area on land affected by waves

Coast

Extends inland as far as ocean related features are found

Coastline

Boundary between shore + coast

- Relatively shallow waters overlying continental shelf

- Adjoin continents or islands

- Influenced by river runoff, wind, tides

- Open ocean lies beyond

What are some characteristics of coastal waters?

Halocline

Area in water that has a changed salinity (can be strong at coastal waters)

- Freshwater runoff

- Winds

- Tides

Salinity in coastal waters are impacted by...

Isohaline

Same/constant salinity

- Visable

- Well-defined

- Sometimes easily observed at surface or depth

- Can to the other direction(vertical stacking/horizontal siding)

What are haloclines?

- Winds

- Insolation

- Currents

- Atmosphere

Temperatures in coastal waters are impacted by:

- A layer of rapidly changing temperature

- Can sometimes be seen or felt

What are thermoclines?

Partially enclosed body of water in which freshwater runoff dilutes ocean water

What are estuaries?

highly productive marine ecosystems

Estuaries are...

Head of an estuary

End of an estuary where freshwater enters

Mouth of an estuary

Where it opens to saltwater/coastal waters and it enters

mixes

We can classify estuaries by how the saltwater + freshwater ...

Coastal plain estuary (drowned river)

Former river valley now flooded with seawater (bc of the rising sea level)

Fjords

Former glaciated valley now flooded with seawater (bc of rising sea level + global warming)

Bar built estuaries

Lagoon separated from ocean by sand bar or barrier island

Tectonic estuaries

Faulted/folded down dropped area now flooded with ocean. Formed bc of tectonic activity

- Shallow

- Freshwater input low volume

- Net flow head to mouth

- Wind + tidal mixing

What are characteristics of water mixed vertically in estuaries?

- 2-level flow

- Upper layer less salty; lower layer more salty

- Estuarine circulation-mixing by wind + tides

What are characteristics of water mixed slightly stratified in estuaries?

- Deep

- Surface salinity increases

- Bottom salinity uniform

- Relatively strong halocline

- Entrainment at interface

What are characteristics of water mixed highly stratified (fjords/deep) in estuaries?

- High volume river

- Surface fresh from head to mouth

- Salinity gradient at depth (horizontal + vertical)

What are characteristics of water mixed salt wedge in estuaries?

- Low to no river flow

- High evaporation

- Salinity in upper later decreases towards mouth

- Salinity in lower layer increases towards head

- Vertical salinity profiles show gradual increase from the surface to the bottom

What are the characteristics of an negative estuary (rare)?

- Dominated by tidal flushing

- Determined by tides + wind

- Food currents flow on "right side" (east)

- Influenced by Coriolis effect, N hemisphere

- Ebb current flow on "left side" (west)

- Isohalines slosh with tides

What are the daily patterns of change?

Spring freshets or other fluctuations in freshwater input

The seasonal pattern are dominated by...

anoxia and fish kills

Stratification and circulation patterns change with the seasons and it can cause

- Salinity

- Oxygen

- Temperature

- Suspended sediment

- Light

Living organisms must adapt to oscillations in:

Steno

Narrow

Eury

Wide

Brackish water species

Species that evolved to tolerate the in between of fresh + salty water

- Margins of estuaries

- Other coastal areas support wetlands

.... support wetlands

Ecosystems with water table close to surface

What are wetlands?

- Salt marshes (mid-and high latitudes)

- Mangrove forests (low latitudes)

What are the 2 most important types of coastal wetlands?

Salt marsh

Found from the Arctic to Southern Australia

Barrier islands

Salt marshes grow in muds and sands that are sheltered by...

- Water

- Nutrients

- Plankton

- Sediments

Tidal currents transport ..... in and out

high and low

Salt marsh can be divided in .... marsh

The region above high tide

The high region of the salt marsh is..

Flooded daily

The low region of the salt marsh is...

Distinctive vegetation

Each region of the salt region has its only...

- Important habitat

- Nurseries for more than 1/2 of commercially important fish in SE US

- Help preserve water quality, filter pollutants

- Reduce erosion

- Prevent storm damage

- Aesthetics and recreation

What are the different values of marshes?

Mangrove forests

A community dominated by trees and shrubs that grows in salt water

- Individual plants

- Leaves are tough + succulent

- Represent 8 families and 12 general

What are the mangrove forests characteristics?

- Fisheries

- Timber and plant products

- Coastal protection

- Tourism

What are the values of mangrove forests?

Home to a large variety of fish, crab, shrimp, and mollusk species

What are fisheries?

resistant

Mangrove wood is ... to rot and insects, making it extremely valuable

construction material

Many coastal and indigenous communities rely on the wood for ... as well as for fuel

sediments

The dense root systems of the mangrove forests trap ... flowing down rivers down rivers and off the land

erosion

This helps stabilizes the coastaline and prevents ... from waves and storms