Marine Biology (Castro), 8th Edition

Chapter 13: Life on the Continental Shelf

Chapter Quiz

1
The shelf break occurs at which depth?
A)The lowest tide mark
B)About 40 m
C)150 m
D)1000 m
2
Waters over the continental shelves are relatively unproductive because nutrients sink to the shelf bottom and become unavailable to most producers.
A)True
B)False
3
There usually are more species in subtidal than in intertidal soft bottoms largely because subtidal conditions are less variable.
A)True
B)False
4
In Antarctica, there are no intertidal communities because of
A)Very cold water.
B)Scouring by ice.
C)Low nutrients.
D)Low primary productivity.
5
Like most cold-water areas, the continental shelf off Antarctica is dominated by kelps.
A)True
B)False
6
Patchy distributions of subtidal animals can develop if the larvae sense adults and prefer to settle near them.
A)True
B)False
7
Which feature would you NOT expect to see on the continental shelf off the mouth of the Mississippi River?
A)Lithogenous sediment
B)Abundant nutrients in the water
C)Constant water temperature year-round
D)Water with a greenish tint
8
Animals of soft-bottom subtidal communities must cope with
A)Desiccation.
B)Drastic changes in temperature.
C)Turbulence.
D)Salinity changes.
9
As a general rule, members of the meiofauna do not
A)Have long and slender bodies.
B)Eat detritus.
C)Live between sand grains.
D)Build tubes made from particles of sediment.
10
The "sweet potato", Molpadia, is a sea cucumber. It is a deposit feeder that creates mounds of disturbed sediment. The sweet potato is considered to be an example of a
A)filter-feeder.
B)Bioturbator.
C)Primary producer.
D)Scavenger.
11
A fish that feeds on infauna is the
A)Flounder.
B)Reef shark.
C)Ray.
D)Sea horse.
12
An animal that eats seagrass leaves is the
A)Manatee.
B)Queen conch.
C)Starfish.
D)tube-dwelling polychaete.
13
Near a seagrass bed, one could expect to find all of these conditions but which one?
A)Reduced turbulence
B)Fine sediment being deposited
C)Lots of detritus
D)Many rocks
14
On a rocky subtidal bottom, competition is largely for
A)Oxygen.
B)Food.
C)Space.
D)Nutrients.
15
Giant kelps grow over a depth range limited by wave action at the upper end and by light at the lower end.
A)True
B)False
16
Seaweeds tend to dominate on steeply sloping bottoms and vertical walls, where they out-compete sessile animals for space.
A)True
B)False
17
Most of the productivity of the giant kelps enters the food chain as fragments (detritus) rather than as whole plants directly eaten by herbivores.
A)True
B)False
18
Subtidal seagrass beds are among the most productive communities in the oceans because
A)Seagrasses, unlike algae, have roots capable of absorbing nutrients from the sediments.
B)All parts of a seagrass, including the roots, are photosynthetic.
C)Seagrasses have no herbivores to eat them.
D)Seagrasses can live in nutrient-poor water.
19
If you wanted to grow kelp on rocks in the Caribbean Sea, could you do so?
A)Yes, because the water is clear.
B)Yes, because there are plenty of rocks on which it can grow.
C)No, because the water is too warm.
D)No, because the water is too shallow.
20
Kelps of the understory generally
A)Form a canopy.
B)Adapt to reduced light levels.
C)Have large pneumatocysts.
D)Are encrusting forms.
21
All of the following explanations but which one have been suggested for the decline of kelp beds in Southern California?
A)Heavy fishing on lobsters and crabs
B)Decrease in the amount of drift algae
C)Overfishing on cod
D)Unusually warm currents and severe storms
22
Even though they do not eat kelp, fishes often are seen to nibble at the blades. What might they be eating?
A)Hermit crabs
B)Bryozoans
C)Epiphytic algae
D)Meiofauna
23
Sea urchin barrens may be the result of all of these reasons but which one?
A)Higher survival of sea urchin larvae
B)Absence of sea otters
C)Sewage pollution
D)A "La Ni–a" event
24
There may be a link between overfishing of sea urchins in the Gulf of Maine and
A)An increase in the number of lobsters.
B)An increase in the number of cod.
C)Die-offs of sea otters.
D)Growth of giant kelp.
25
A commercially valuable species that may inhabit seagrass beds is the
A)Atlantic bay scallop.
B)Topsmelt.
C)Halibut.
D)Sand dollar.
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