Characteristics of major types of coastal zones

By Rema Faddoul

Estuary – Chesapeake Bay largest estuary in the United States is located off the Atlantic Ocean.

Salt Marshes Along the Heathcote River, Christchurch, New Zealand

Mud Flats Cobequid Bay, Nova-Scotia

Major Types Include:

Partly enclosed coastal body of water with one or more rivers/streams flowing into it and a free connection to the open sea

Economically significant as seaports, centers of ocean commerce and commercial fisheries

They exist today because sea level has risen approximately 120 m since the glaciers started melting 18,000 years ago

Estuaries

4 Major Classes of Estuaries

Coastal Plain Estuary

Form when sea level rises and floods existing river valleys

Ex. Chesapeake Bay in Maryland and Virginia

Fjord (pronounced Fee-yord)

Forms when sea level rises and floods a glaciated valley

Typically has a U-shape with steep walls

Common in Alaska, Canada, New Zealand, Chile and Norway

Bar-Built EstuaryShallow and separated from open ocean by sand bars parallel to the

coast

Lagoons that separate barrier islands from main land are bar

built estuaries.

Ex. Pamlico Sound in North Carolina

Tectonic EstuaryForms when faulting/folding of rocks creates a restricted down dropped area into which rivers

flow

Ex. San Francisco Bay due to movements along the San Andrea

Fault

Salt MarshesGeneral Information The Specifics

Intermittently submerged by ocean water

Support a variety of grasses

Serve as nurseries for commercially important fish

Stopover point for many species of waterfowl and migratory birds

Flounder and bluefish use marshes for feeding and protection in winter

Oysters, scallops, clams, eels and smelt are located in marshes

Efficient at cleansing polluted water from agricultural runoff and toxins

Salt Marshat Fort Fisher State Recreation Area

Generally found next to salt marshes and sheltered areas like bays, bayous, lagoons

Form when mud is deposited by tides and rivers

Most sediment within a mudflat is within the intertidal zone, thus submerged/exposed twice daily due to tidal flow

Organisms found in mud flats include eelgrass, turtle grass, crabs, mud snails and filter feeders due to presence of plankton.

Below the surface one can find burrowing animals such as clams, worms and crustaceans

Mudflats are under threat from predicted sea level rises, land claims for development and chemical pollution

Mud Flats

Teshekpuk LakeOn the Arctic Coast of Alaska