Download - Estuaries
Estuaries
Estuaries• Estuaries are partially enclosed coastal bodies of
water• Examples of estuaries include:
– River mouths– Bays– Inlets– Gulfs– Sounds
• Formed by a rise in sea level after the last Ice Age
Southern California Watersheds
Classifying estuaries by origin
• Coastal plain• Fjord• Bar-built• Tectonic
Examples of estuaries
Pu‘uloa
Examples of estuaries
Fjord estuary (Norway)
Tectonic estuary (San Francisco, CA)
Coastal wetlands• Coastal wetlands are saturated
areas that border coastal environments
• Brackish water conditions• Two most important types of coastal
wetlands:1. Salt marshes (mid-latitudes)2. Mangrove swamps (low latitudes)
Coastal wetlands: Salt marshes and mangrove swamps
Salt Marshes are dominated
by dense stands of halophytic
(salt-tolerant) plants such as herbs, grasses, or low shrubs.
These plants are terrestrial in origin and are essential to the stability
of the salt marsh in
trapping and binding
sediments.
Infauna: • live within the sediment, mostly soft bottom; • mostly clams and worms (polychaetes) • burrow tubes for food scavenging and oxygen
supply• Primary producers: algae, mostly benthic
diatoms and dinoflagellates • cyanobacteria mats on mudflats • mud more productive than sand• macro- and meiobenthos, often detrivores,
living of deposits from seagrasses and marshes
• birds important grazers
32,000 polychaetes in sand/m2vs
50-500 earth worms in soil/m2
Ecological Role:• clean sediments • aerate soil
• Found from the Arctic to Southern Australia
• Salt marshes grow in muds and sands that are sheltered by barrier islands.
• Flood and ebb currents transport saltwater, nutrients, plankton and sediments in and out of the marsh.
Salt marshes play a large role in the aquatic food web and the
exporting of nutrients to coastal waters.
They also provide support to terrestrial animals such as
migrating birds as well as providing coastal protection