Estuaries Understanding Check

Check your understanding by matching the correct estuary example with its geologic origin.

Rising sea floods a river valley:

Sea level rises and floods a valley formed by glaciers:

Sand builds up into bars or barrier islands creating a lagoon that migrates shoreward as sea level rises:

rising sea levels flood down-dropped areas formed by tectonic activity along faults or folded formations:

Rising sea floods a river valley: coastal plain estuary

Sea level rises and floods a valley formed by glaciers: fjord

Sand builds up into bars or barrier islands creating a lagoon that migrates shoreward as sea level rises: bar built estuary

rising sea levels flood down-dropped areas formed by tectonic activity along faults or folded formations: tectonic estuary

Check your understanding: Salinity increases with depth in all types of estuaries except one.  Which one has the same salinity water from top to bottom at any given point?

Vertically Mixed Estuary

Check your understanding: which of the following words best characterizes the abiotic factors in most estuarine habitats?

change

Check your understanding:  Which of the following is not a role of oyster reefs in the estuary?

• Serve as a food source

• Increase turbidity

• Provide habitat for other species

• Improve water quality

increase turbidity in estuaries.

Check your understanding: Estuaries are dynamic ecosystems with detritus-based food webs that are under pressure from natural and man-made change.

true

You've just collected oysters and shrimp from a sampling station in Pamlico Sound.  As you record salinity measurements at the site you notice the salinity is nearly the same from the surface to the seabed.  This tells you you are in which type of estuary?

Question 1Select one:

fjord

highly stratified estuary

salt wedge estuary

bar-built estuary

vertically mixed estuary

vertically mixed estuary

Match the estuarine inhabitants with the conditions for which they are adapted.

• marine species that can tolerate salinities in most of the estuary

• species limited to the middle reach of the estuary where salinities range from around 5 to 18.

• marine species at the mouth of the estuary that cannot tolerate salinities below 25-30.

• species limited to the head of an estuary where salinities do not exceed 5

choices: abyssal species, euryhaline marine, stenohaline marine, brackish species, freshwater species

• marine species that can tolerate salinities in most of the estuary: euryhaline marine

• species limited to the middle reach of the estuary where salinities range from around 5 to 18.: brackish species

• marine species at the mouth of the estuary that cannot tolerate salinities below 25-30.: stenohaline marine

• species limited to the head of an estuary where salinities do not exceed 5: freshwater species

The sediments in most estuaries are muddy because

Select one:

strong currents outwell the sand from the system, leaving only silt behind.

suspended silt flocculates from river water in estuaries where conditions become salty.

oysters are becoming rare and no longer remove silt from estuaries.

high energy flow suspends sand in the water of rivers.

suspended silt flocculates from river water in estuaries where conditions become salty.