Coastal Habitats - Estuaries, Lagoons, Salt Marshes and Mangroves

A comprehensive set of vocabulary flashcards covering the formation, circulation, and biological characteristics of estuaries, lagoons, salt marshes, and mangroves.

Coast

A broad term including habitats and ecosystems associated with terrestrial and marine processes, beyond just the shoreline.

Estuary

A semi-enclosed body of water where freshwater mixes with seawater.

Drowned river valley

An estuary formed via sea level rise as a result of deglaciation during the Holocene, where seawater floods river valleys.

Fjord

An estuary where glacial advance carves steep-sided valleys and rising sea level breaches the moraine to infill the valley.

Bar-built estuary

An estuary formed when the deposition of coastal sediments from longshore currents creates a sand bar or spit across an embayment.

Tectonic estuary

An estuary formed in tectonically active areas where faulting and folding processes at plate boundaries create basins that become infilled with seawater.

Salt-wedge estuary

A highly stratified estuary characterized by high river discharge and small tidal input, featuring a landward directed bottom current and seaward surface current.

Partially-mixed estuary

An estuary with small river discharge and large tidal input where water mixing occurs via tide-generated turbulence, resulting in a weakly developed halocline.

Well-mixed estuary

A tide-dominated estuary with limited freshwater inputs where water mixes completely, resulting in no halocline and salinity increasing from the head to the mouth.

Coriolis Effect (Northern Hemisphere Estuaries)

A force that tends to drive higher salinity water to the right side of wide estuaries and lower salinity water to the left side.

Chesapeake Bay

A partially mixed, drowned river valley estuary in the USA that is approximately $300\,km$ long, less than $65\,km$ wide, and has an average depth of $10\,m$.

Rocky Substrate Benthic Fauna

Sessile filter feeders such as bivalves, oysters, sponges, and barnacles.

Epifauna

Benthic organisms that live on the surface of mud or sand substrates, such as sea urchins, sea stars, and snails.

Infauna

Benthic organisms that live buried within mud or sand substrates, such as polychaete worms and clams.

Lagoon

A shallow body of coastal water that receives little to no freshwater inflow and whose salinity varies from brackish to hypersaline depending on climate.

Isothermal

A condition in tropical lagoons where the water temperature does not vary with depth.

Salt marshes

One of the most productive environments on Earth, consisting of intertidal flats covered by vegetation, commonly found in protected areas with moderate tidal ranges.

Low marsh

A salt marsh zone extending from mean low water to neap high water.

High marsh

A salt marsh zone extending from neap high water to the highest spring tide.

Mature marsh

A stage in salt marsh evolution reached when about one-half of the salt marsh consists of high marsh.

Old marsh

A stage in salt marsh evolution where vertical growth from sediment deposition has resulted in dominantly high-marsh communities and infilled channels.

Spartina alterniflora

A type of salt marsh grass specifically associated with the low marsh zone.

High marsh grasses

Plant species such as Spartina patens, Salicornia sp., and Distichlis spicata.

Mangroves

Large woody trees with dense, complex root systems growing downward from branches; they are the dominant plants of tropical and subtropical intertidal areas.

Mangrove Reproduction Cycle

A process where a seedling grows on a branch, matures, drops into the water, and floats until it takes root on a shallow mud bank.

Manatees

Large sea mammals living in the tidal creeks of mangrove forests that face threats from habitat destruction, pollution, and propeller strikes.