Deck 12: Estuaries: Where Rivers Meet the Sea

Question 1

In an estuary,salinity of the water increases as:

A)One moves inland.
B)Depth decreases.
C)Evaporation decreases.
D)Freshwater flow from a river increases.
E)Depth increases.

Answer 1

E

Question 2

The salt wedge in the water column of an estuary:

A)Moves inland as tide moves in.
B)Is found in shallower water as one moves inland.
C)Decreases the average salinity of the estuary.
D)Decreases the distribution of marine organisms along the bottom of the estuary.
E)Spreads further into the estuary as the flow of freshwater increases.

Answer 2

A

Question 3

The amount of hydrogen sulfide in the sediment increases as the following factors increase except one:

A)Oxygen.
B)Decrease in the space between sediment particles.
C)Decrease in the size of sediment particles.
D)Amount of decomposing bacteria.
E)Amount of detritus.

Answer 3

A

Question 4

The most common type of substrate in estuaries:

A)Mud.
B)Rock.
C)Coarse sand.
D)Fine sand.
E)None of the choices are correct.

Question 5

Most of the primary production on mud flats is due to:

A)Diatoms.
B)Green algae.
C)Brown algae.
D)Red algae.
E)Sulfur bacteria.

Question 6

Fjords are formed as a result of the:

A)Subsidence of land.
B)Lowering of sea level.
C)Formation of sand bars and barrier islands.
D)The coast is cut by a river.
E)Raising of sea level and glaciation.

Question 7

Well-formed estuaries are least likely to be formed by:

A)Sea level rise.
B)Retreating glaciers.
C)Active continental margins.
D)Passive continental margins.
E)Accumulation of sediments.

Question 8

Coastal plain estuaries were formed when:

A)Sand bars formed along the coast as the result of an accumulation of sediment.
B)The ocean invaded lowlands and river mouths.
C)Retreating glaciers cut a valley along the coast.
D)Sea level fell during glaciation.
E)Land subsided along the coast.

Question 9

Osmoconformers survive changes in salinity by:

A)Maintaining the salinity of their body fluids constantly.
B)Moving up and down the water column in order to spend most of the day in the salt wedge.
C)Pumping water in as salinity decreases.
D)Allowing the salinity of their body fluids to vary with that of the surrounding water.
E)Increasing the amounts of salts in their body fluids no matter what the salinity of the surrounding water is.

Question 10

Succulents are plants that:

A)Excrete salts by way of salt glands.
B)Lose water and salts.
C)Accumulate water in their tissues.
D)Take in salts to compensate for the loss of water.
E)Do not have any roots to minimize water loss.

Question 11

The greatest importance of estuaries to the entire world oceanic ecosystem is as:

A)Reservoirs for nutrients.
B)Breeding grounds for many marine species.
C)Sources of freshwater for dilution of salinity.
D)Buffers against storm surge for man-made structures.
E)Discharge areas for human waste products.

Question 12

The most important difference between muddy intertidal shores and the mud flats of estuaries:

A)Type of substrate.
B)Variation in salinity.
C)Amount of light.
D)Exposure to wave action.
E)Size of sediment particles.

Question 13

The infauna of mud flats feeds mostly on:

A)Epifauna.
B)Sulfur bacteria.
C)Filter feeders.
D)Plankton.
E)Detritus.

Question 14

Euryhaline species:

A)Are less common in estuaries than stenohaline species.
B)Need less oxygen to survive.
C)Tolerate only a narrow range of salinities.
D)Can survive changes in salinity.
E)Only tolerate small temperature changes.

Question 15

Zonation in an estuary is made evident by:

A)Large number of worms in the mud.
B)Presence of different species along different horizontal levels in relation to tides.
C)Tide pools along the mud flats.
D)Absence of life in black sediments.
E)High concentration of plants in salt marshes.

Question 16

Good examples of bar-built estuaries are found here:

A)Coast of Norway.
B)Pacific coast of the United States.
C)Atlantic coast of the United States.
D)Chesapeake Bay.
E)St.Lawrence River.

Question 17

The zonation of plants in salt marshes is determined mostly by:

A)Temperature fluctuations.
B)Geographical location.
C)Height of the tide.
D)Amount of oxygen in sediments.
E)Detritus in the water.

Question 18

The food web in salt-marsh communities is characterized by high primary production.Most of this production is made available to other communities in the form of:

A)Plant tissue eaten by grazers.
B)Plankton eaten by filter feeders.
C)Detritus.
D)Plants eaten by herbivores.
E)Plants eaten by zooplankton.

Question 19

Large organisms of the mudflats are more likely to be:

A)Infauna.
B)Endofauna.
C)Epifauna.
D)Meiofauna.
E)Midfauna.

Question 20

Blood rich in hemoglobin is an adaptation to:

A)Fluctuating salinities.
B)Wide variations in temperature.
C)Soft sediments.
D)Feeding in detritus.
E)Low oxygen concentrations.

Question 21

The most extensive mangrove forests can be found in:

A)Caribbean.
B)Mediterranean.
C)Atlantic.
D)Indo-West Pacific.
E)Eastern Pacific.

Question 22

Mangroves belong to one of the following groups:

A)Green algae.
B)Brown algae.
C)Seagrasses.
D)Flowering plants.
E)Kelps.

Question 23

In many tropical areas extensive areas of mangrove forests have been cleared or destroyed in order to raise:

A)Mussels.
B)Oysters.
C)Salmon.
D)Tuna.
E)Shrimp.

Question 24

Pneumatophores are used for:

A)Excretion of excess salts.
B)Horizontal growth.
C)Aeration of plant tissues.
D)Reproduction.
E)Downward growth.

Question 25

The world-wide distribution of mangrove forests is mostly determined by:

A)Salinity.
B)Type of sediment.
C)Temperature.
D)Wave action.
E)Height of tide.

Question 26

The area of salt marsh just above the mean low tide is most likely to be dominated by:

A)Cordgrass.
B)Salt marsh hay.
C)Pickleweed.
D)Rushes.
E)Salt grass.

Question 27

Which of these resources is most likely to be in short supply in the open water of an estuary?

A)Nutrients
B)Substrate
C)Oxygen
D)Space
E)Prey

Question 28

A sub-environment native to the estuaries of the Atlantic coast of North America.

A)Kelp beds.
B)Mussel aggreations.
C)Oyster reefs.
D)Coral heads.
E)Tectonic rifts.

Question 29

The loss of estuaries and mangrove forests is particularly serious since these ecosystems:

A)Provide nesting or resting areas to many seabirds.
B)Are among the most productive of all marine ecosystems.
C)Provide habitats to many species.
D)Directly or indirectly provide food to many species.
E)All of the choices are true.

Question 30

Outwelling in estuaries is most important since it:

A)Maintains high primary production.
B)Provides living space to many species.
C)Releases much oxygen.
D)Provides food and nutrients to other communities.
E)Allows plants to survive despite wide fluctuations in salinity.