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