Estuaries

What is an estuary?

Freshwater meeting saltwater habitats.

What are some properties of estuaries?

Productive, low diversity with high biomass, variable conditions - tides, rain etc, rocky intertidal, large human impact and provide habitat.

Why are estuaries good nurseries?

Good nursery because of lack of diversity means there is a lack of predators to eat the babies.

What are the different types of estuaries?

Classified by how they’re formed. Coastal plain estuaries, bar-built estuaries, tectonic estuaries and fjords.

What are characteristics of coastal plain estuaries? How are they formed?

Aka Drowned river valleys. Formed by “drowning” of low land with freshwater rivers. Most common type of estuary. Ex: Chesapeake Bay, mouth of Delaware river.

What are characteristics of bar-built estuaries? How are they formed?

Accumulation of sediments into sand bars or barrier islands. Ex: North Carolina.

What are characteristics of tectonic estuaries? How are they formed?

Formed as a result of land sinking due to movement in earth’s crust. Ex: San Francisco Bay.

What are characteristics of fjords? How are they formed?

Glacier-carved estuaries. Deep channels cut into coastal zone. Ex: Alaska, Norway.

What does brackish mean?

Meaning that the salinity is between freshwater and saltwater. Mix!!

In an estuary where is it most fresh?  Where is it more salty?  Depth-wise, where is it more salty? 

More fresh closer to freshwater input. More salty near saltwater input and deeper.

What’s a salt wedge?

Due to salt sinking, it will be closer to freshwater input, called salt wedge.

What is a negative estuary and what are tidal bores?

Estuaries that have low fresh water input with high evaporation that causes extremely high salinity, over 35 ppt. Tidal bores are massive waves coming into estuaries at higher tides due to thin space.

What is the most common substrate in estuaries?

Mud.

What does anoxic mean?  Where in the estuary can you commonly find anoxic conditions?

Lack of oxygen. In deep mud in estuaries due to water having a hard time flowing through.

Why is water clarity so poor in estuaries? 

Due to large amounts of sediment from rivers.

Who does most of the primary production in estuaries? Why is it more difficult for algae and plankton in the water to do primary production?

Primary production from flowering plants. More difficult for algae and plankton due to lack of light to photosynthesize.

Why are estuaries so productive?

Large amount of flowering plants!!

What does euryhaline and stenohaline mean?

Euryhaline means an organism can survive in a wide variety of salinities. Stenohaline means organisms that can only survive in a narrow range of salinity.

What are osmoregulators and osmoconformers?

Two ways that organisms are euryhaline. Osmoregulators are organisms that have mechanisms for keeping their internal salinity stable. Osmoconformers are organisms that changes their inner salinity to match with outer.

Where can you find the least amount of organisms? Why?

Brackish water due to the need for specific adaptations to live in fluctuating salinity.

What are two ways that flowering plants deal with salinity in estuaries?

Can expel excess solutes by using salt glands or concentrate solutes in specific tissues(and discard them).

What are the main photosynthetic organisms within mudflats? What feeding type dominates here among the inhabitants?

Alternately submerged and exposed by tides. Mainly diatoms and bacteria. Mainly deposit feeders, can be anoxic

What is a salt marsh? What is a wetland?

A type of wetland. Intertidal grasslands of the estuary. Wetlands are areas that get some saltwater input.

What does halophytic mean?

Salt tolerant.

Why are salt marsh plants said to provide the food base for estuaries? When is the only time these plants are submerged?

As plants die off, they provide a food base for other organisms as detritus. Only submerged during the high tide.

Where are salt marshes found?

Salt marshes are found in colder/temperate regions

Where are mangrove forests found?

Mangrove forests are found in tropical and subtropical coastal areas, warmer water.

What are pneumatophores and what organism has them? Why do they need them?

Mangroves have pneumatophores, vertical root extensions that assist the plant with exchange of gases in anoxic mud, because they would not be able to get oxygen.