Chapter 12 Marine Bio

What is the most common type of estuary?

Drowned river valleys, formed by the drowning of low land around river mouths when sea level rose after the last ice age.

Give an example of a drowned river valley estuary.

Chesapeake Bay.

What is a bar built estuary?

An estuary formed by the accumulation of sediments into sand bars or barrier islands.

Provide an example of a bar built estuary.

North Carolina near Cape Hatteras.

What are tectonic estuaries?

Estuaries formed as a result of land sinking due to movements of the Earth's crust.

Name an example of a tectonic estuary.

San Francisco Bay.

What are fjords?

Deep channels cut in the coastal zone as a result of retreating glaciers.

Give examples of regions with fjord estuaries.

Alaska and Norway.

Where are estuaries best developed?

In areas where the coastal plain is flat and the continental shelf is wide.

What are the worst areas for estuary development?

Areas with steep, narrow continental shelves and coastal plains.

What is the typical salinity range in estuaries?

Salinity can vary from 5 to 30 ppt.

What factors influence salinity in estuaries?

Distance from saltwater or freshwater input, storms, and depth.

What does it mean for an organism to be euryhaline?

It can tolerate a wide variety of salinities.

What are osmoregulators?

Organisms that have mechanisms for keeping their internal concentration stable.

What are osmoconformers?

Organisms whose internal concentrations vary with their surroundings.

How do flowering plants in estuaries deal with excess solutes?

They either expel excess solutes or concentrate solutes in specific tissues.

What is the substrate composition in estuaries?

Mostly fine sand or mud, which can be difficult to move through.

Why is water clarity poor in estuaries?

Due to suspended sediments and particles from rivers.

What are the predominant organisms in open water of estuaries?

Plankton, floating algae, fish, and many larval forms such as crabs and shrimp.

What is the role of estuaries as nurseries?

Many marine species spend at least a portion of their life in an estuary, mainly as larvae.

What vegetation predominates in saltmarshes?

Spartina species, with Juncus or needlerush found in low salinity areas.

Where are mangroves typically found?

In tropical and subtropical coastal areas, replacing saltmarshes.

What are pneumatophores?

Vertical root extensions in some mangrove species that assist with gas exchange.

What are seagrass beds?

Areas in some estuaries where seagrass can grow if water clarity permits.

What are oyster reefs?

Congregations of oysters that provide a hard substrate for other species to thrive.