Estuaries
This presentation is the property of its rightful owner.
Sponsored Links
1 / 15

Estuaries PowerPoint PPT Presentation


  • 65 Views
  • Uploaded on
  • Presentation posted in: General

Estuaries. Form where river meets the sea Regions of constant environmental change Importance to marine ecosystems Organic material enriches ocean waters Protection from predators (ex: juvenile fish) Support many commercially important animals that humans rely on for food Fish nurseries

Download Presentation

Estuaries

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Estuaries

Estuaries


Estuaries

  • Form where river meets the sea

  • Regions of constant environmental change

  • Importance to marine ecosystems

    • Organic material enriches ocean waters

    • Protection from predators (ex: juvenile fish)

    • Support many commercially important animals that humans rely on for food

    • Fish nurseries

  • Fragile habitats

    • Pollution

    • Damage by dams Block freshwater supply


Physical characteristics of estuaries

Embayment: coastal area partially cut off from the rest of the sea

Freshwater mixes with saltwater to form an estuary

Physical Characteristics of Estuaries


Types of estuaries

Types of Estuaries

  • Coastal plain (drowned river valley)

    • Form between glacial periods

    • Form when rising water levels from melting glaciers flood coastal plains and low-lying rivers


Types of estuaries1

Types of Estuaries

  • Tectonic

    • Earthquakes caused land to sink, allowing seawater to cover it


Types of estuaries2

Types of Estuaries

  • Fjord

    • Form when glaciers carve large valleys in coastal areas

      • Filled with water after glaciers retreated


Types of estuaries3

Types of Estuaries

  • Bar-built

    • Form when geographic barriers form a wall between freshwater and saltwater


Salinity and mixing patterns

Salinity and Mixing Patterns

  • Salinity varies vertically and horizontally

    • Least salty near the mouth of the river

  • Freshwater flows over the seawater

  • Surface water is less dense and flows out to sea

  • Denser saltwater from ocean moves into estuary along the bottom

    • Called positive estuary

  • Negative estuary  lose more water through evaporation than the river is able to replace

    • Low in productivity (nutrient poor)


Estuaries

  • Salt-wedge estuary

    • In mouths of rivers flowing into saltwater

  • Well-mixed estuary

    • River flow is low and tidal currents play major role in water circulation


Estuaries

  • Partially mixed estuary

    • Have strong surface flow of freshwater and strong influx of seawater

  • Temperature

    • Changes rapidly with air temperature changes

    • Estuaries are heated by the sun


Estuarine productivity

Estuarine Productivity

  • High because of freshwater and saltwater mixing

  • Silt and clay deposits absorb any excess nutrients from surrounding water

    • Release back into water when nutrients are in short supply

  • Filter feeders remove more phytoplankton

    • Excess phytoplankton eliminated as pseudofeces

      • Large, semisolid particles


Life in an estuary

Life in an Estuary

  • Fewer species

    • Less competition for food and space

  • Feed on a variety of foods


Estuaries

  • Maintaining osmotic balance

    • Have body fluids with same concentration of salts as seawater

      • Isosmotic to surrounding water

      • Have tissues and cells that tolerate dilution (osmoconformers) or maintain optimal salt concentration in their tissues (osmoregulators)


Estuarine communities

Estuarine Communities

  • Many are euryhaline species

    • Can tolerate a broad salinity range

  • Oyster reefs  oysters growing on the shells of previous generations

  • Mud flats  contain rich deposits of organic material with small inorganic sediment grains


Estuaries

  • Seagrass meadows  extract nutrients from sediments

  • Salt marsh community

    • Temperate and subarctic regions

    • Low and high marsh regions

  • Mangrove communities

    • Tropical regions

    • Little wave action

      • Sediments accumulate that lack oxygen


  • Login