205 Chapter 14—Estuaries
Chapter 14—Estuaries
MULTIPLE CHOICE
1. Drowned river valley estuaries were formed by:
a.
tectonic activity.
b.
the scoring effect of glaciers.
c.
rising sea levels after glacial periods.
d.
both a and b.
e.
none of the above.
2. Estuaries in which river flow is strong and prevents the flow of seawater upstream are called:
a.
fjords.
b.
salt-wedge estuaries.
c.
well-mixed estuaries.
d.
tectonic estuaries.
e.
drowned river valleys.
3. When retreating glaciers carved deep coastal valleys they created:
a.
fjords.
b.
salt-wedge estuaries.
c.
well-mixed estuaries.
d.
tectonic estuaries.
e.
drowned river valleys.
4. An example of a salt-wedge estuary is:
a.
the Mississippi Delta.
b.
Delaware Bay.
c.
Chesapeake Bay.
d.
Puget Sound.
5. San Francisco Bay was created by:
a.
rising sea levels.
b.
retreating fjords.
c.
erosion of the coastline.
d.
tectonic activity.
e.
glaciers.
6. Where rivers slow and drop their sediment load they form deltas termed:
a.
dendritic.
b.
coastal plain.
c.
tidal flats.
d.
sand bar.
e.
tombolos.
7. When sediment removal is less than input we often find:
a.
fjords.
b.
tectonic estuaries.
c.
tidal flats.
d.
bar-built estuaries.
e.
drowned river valleys.
8. In a well-mixed estuary, river flow is ____ tidal currents.
a.
greater than
b.
less than
c.
perpendicular to
d.
equal to
9. What causes tidal overmixing in estuaries?
a.
strong tidal currents.
b.
strong river flow.
c.
an unstable water column.
d.
downwelling.
e.
animal migrations.
10. When dense seawater sinks below lighter fresh water we observe a condition called:
a.
downwelling.
b.
salt wedge.
c.
tidal overmixing.
d.
upwelling.
e.
convection current.
11. An estuary where freshwater inflow is greater than evaporation is called a:
a.
negative estuary.
b.
positive estuary.
c.
reversible estuary.
d.
neutral estuary.
12. An example of a negative estuary is:
a.
Delaware Bay.
b.
Puget Sound.
c.
Laguna Madre.
d.
San Francisco Bay.
e.
Chesapeake Bay.
13. It is common for negative estuaries to be:
a.
lower in salinity than the ocean.
b.
nutrient poor.
c.
nutrient rich.
d.
lower in temperature than the ocean.
e.
brackish.
14. In a salt-wedge estuary the relationship between salinity and depth is that salinity:
a.
is even from top to bottom.
b.
increases with depth.
c.
changes abruptly with depth.
d.
varies horizontally.
e.
decreases with depth.
15. In a partially mixed estuary the salinity
a.
is extremely variable from place to place.
b.
is stratified with lower salinity near the bottom.
c.
is lower than the ocean but relatively homogenous.
d.
increases with depth.
16. In estuaries at high latitudes, which of the following factors strongly influences mixing?
a.
Oxygen concentrations
b.
Nutrient concentrations
c.
Carbon dioxide concentrations
d.
Temperature
e.
Turbidity
17. Estuaries tend to be well supplied in the following limiting nutrient(s) of the open ocean:
a.
phosphorus.
b.
nitrogen and silica.
c.
phosphorus and silica.
d.
nitrogen and phosphorus.
e.
carbon and oxygen.
18. Pseudofeces are:
a.
semisolid deposits containing un-digested material.
b.
semisolid deposits of digested material.
c.
solid deposits containing un-digested material.
d.
solid deposits containing digested material.
19. The concentration of nutrients in estuaries causes____ productivity.
a.
extremely low
b.
low
c.
average
d.
medium
e.
high
20. The number of resident species in estuaries tend to be ___________ relative to nearby aquatic
ecosystems.
a.
an order of magnitude higher
b.
greater
c.
about the same
d.
fewer
21. Which factor currently tends to regulate abundance of commercially valuable estuary species such as
oysters and crabs?
a.
Competition
b.
Predation
c.
Human activities
d.
Normal seasonal die off
e.
Disease
22. All of the following tend to hold nutrients in estuaries for use by other organisms except:
a.
adsorption onto silt particles.
b.
reduced numbers of filter feeders.
c.
the formation of pseudofeces.
d.
overturn.
23. An animal that maintains a constant salt concentration in their body is called:
a.
an osmoconformer.
b.
an osmoregulator.
c.
hyperosmotic.
d.
hypo-osomotic.
24. An example of an osmoregulator at low salinities and an osmoconformer at higher salinities is a(n):
a.
blue crab.
b.
salmon.
c.
oyster.
d.
sea squirt.
e.
tuna.
25. The animals that remain isosmotic to the surrounding seawater are called:
a.
osmoconformers.
b.
osmoregulators.
c.
hyperosmotic.
d.
hyposmotic.
e.
euryhaline.
26. An example of an osmoconformer is:
a.
a crab.
b.
a polychaete worm.
c.
a fish.
d.
a sea squirt (tunicate).
27. All of the following are adaptations against excessive water and salt exchange between animals and
their surrounding environment except:
a.
having very permeable tissues.
b.
covering body with mucus.
c.
living inside a tube that can be isolated from the external environment.
d.
covering the body with a hard exoskeleton.
e.
actively absorbing salt ions with gills.
28. All of the following are adaptations to remain stationary in the ever-shifting soft bottom of estuaries
except:
a.
extensive roots and rhizomes.
b.
holdfasts.
c.
sessile lifestyle.
d.
operculum.
e.
byssal threads.
29. Estuaries for many transient species are considered:
a.
a place to spawn.
b.
nurseries.
c.
too full of predators for juveniles.
d.
very stable environments.
30. An example of a species that uses the estuary as a nursery ground is the:
a.
Atlantic eel.
b.
seal.
c.
shad.
d.
lobster.
e.
tuna.
31. A euryhaline species can tolerate:
a.
a wide range of temperatures.
b.
a narrow range of temperatures.
c.
a wide range of salinities.
d.
a narrow range of salinities.
32. All are true of oyster reefs except
a.
they are oriented perpendicular to currents.
b.
they are concentrated in lower salinity areas.
c.
they are important habitats for other organisms.
d.
they are adversely affected by rapid changes in salinity.
e.
they are increasing in the Chesapeake Bay.
33. Larval oysters attach themselves to:
a.
They do not have specific requirements.
b.
any available solid substrate.
c.
other oyster shells.
d.
both b and c
e.
sand.
34. Oysters generally settle at right angles to tidal currents. These currents:
a.
carry food away from the oysters.
b.
clear sediments from the oysters.
c.
help them avoid oyster drills.
d.
deposit sediments among the oysters.
35. Ecologically mud flat areas are a focal area of:
a.
nutrient recycling.
b.
primary production.
c.
tertiary consumers.
d.
nutrient sink.
e.
sessile epifauna.
36. The energy base on mud flats is:
a.
phytoplankton.
b.
detritus.
c.
marsh plants.
d.
algae.
e.
chemosynthesis.
37. Most of the animals of mud flats are:
a.
planktonic.
b.
epifaunal.
c.
oysters.
d.
infaunal.
e.
nektonic.
38. Many of the burrowing animals of the mud flat must actively
a.
keep digging to exchange gasses.
b.
circulate water through their burrows.
c.
live near natural breaks in the sediment for gas exchange.
d.
maintain an anaerobic environment.
39. Ghost shrimp live:
a.
in burrows.
b.
under rocks on the mud flat.
c.
on the surface of the mud.
d.
in the water above the mud flat.
e.
symbiotically with bivalves.
40. Ghost shrimp and mud shrimp play an active role in:
a.
compacting the sediment.
b.
reducing species through competition.
c.
decomposition of seagrass roots.
d.
oxygenating the sediments.
e.
consuming marsh plants.
41. Seagrasses can reach high productivity levels with the aid of:
a.
oxygen brought to their roots via mud shrimp burrows.
b.
symbiotic, nitrogen-fixing bacteria.
c.
their leaves, cleared of epiphytes by grazers.
d.
fertilization by manatees.
e.
eutrophic water conditions.
42. Seagrasses are important in all the following except:
a.
nutrient recycling.
b.
providing a habitat for animals.
c.
stabilizing sediments.
d.
being consumed by most estuarine herbivores.
43. A common direct consumer of eelgrass (Zostera) is:
a.
snails.
b.
waterfowl.
c.
sea cucumbers.
d.
manatees.
e.
sea stars.
44. Caribbean seagrasses are extensively fed on by all except
a.
manatees.
b.
green sea turtles.
c.
some sea urchins.
d.
sea cucumbers.
45. The dominant plant species closest to the water line of salt marsh communities is:
a.
cordgrass.
b.
pickleweed.
c.
spike grass.
d.
salt wort.
e.
mangroves.
46. Marsh plants are important in all of the following except:
a.
trapping sediments.
b.
serving as a refuge for animals.
c.
being directly consumed food.
d.
stabilizing sediments.
47. Pneumatophores of black mangroves are:
a.
prop roots.
b.
aerial roots.
c.
germinated seeds.
d.
pores on leaves.
e.
salt-excreting structures.
TRUE/FALSE
48. All estuaries are diluted by freshwater runoff.
49. Estuaries are immune from larger temperature variations.
50. Seawater and fresh water do not mix very well in fjords.
51. The major source of nitrogenous nutrients in estuaries is incoming seawater.
52. The species diversity in estuaries is high, but the number of individuals is low.
53. Estuaries are important nurseries because of the relatively low numbers of predators in these areas.
54. Mud flats are typically low in organic matter.
55. Most burrowing animals of estuaries exchange gases with their environment through their skin.
56. Seagrasses are usually consumed directly by grazers in estuaries.
57. Salt marsh communities predominate in temperate and subarctic areas.
58. Salt marsh plants play an important role in expanding the terrestrial environment.
59. Mangrove forests predominantly occur in temperate regions.
MATCHING
Match the mangrove ecosystem species with its most closely associated trophic level.
a.
heterotrophic bacteria
b.
mangrove
c.
amphipod
60. Primary producer
61. Detritivore
62. Secondary consumer
Match the plant with its most closely associated substrate attachment method.
a.
algae
b.
red mangrove
c.
seagrasses
d.
black mangrove
63. Prop roots
64. Rhizomes
65. Holdfast
66. Pneumatophores
Match the process/epoch with its most closely associated estuary type.
a.
glacial formed
b.
land movement
c.
inter-glacial periods
67. Coastal plain
68. Fjord
69. Tectonic
Match the process with its most closely associated result.
a.
sediment based barrier islands
b.
water-filled, steep-sided valleys
c.
sediment deposition at the upper river mouth
70. Tidal flats
71. Bar-built
72. Fjord
Match the words with those they are most closely associated with.
a.
Scandinavia estuaries
b.
Long Island Sound
c.
Cape Hatteras region
73. Drowned river valley
74. Bar-Built estuaries
75. Fjord
Match the process with its most closely associated estuarine mixing type.
a.
Evaporation can exceed freshwater input.
b.
Fresh water flows over seawater.
c.
Dense surface seawater mixes into freshwater below.
76. Tidal overmixing
77. Positive estuary
78. Negative estuary
Match the area with the type of estuary.
a.
Puget Sound
b.
Delaware Bay
c.
Sacramento River mouth in San Francisco Bay
79. Salt-wedge estuary
80. Well-mixed estuary
81. Partially-mixed estuary
Match the species with its most closely associated salinity concentration type.
a.
Nereis polychaetes
b.
tunicates
c.
hermit crab
82. Osmoconformer
83. Osmoregulator
84. Both osmoconformer and osmoregulator
Match the genus with its most closely associated common name.
a.
Mya
b.
Urosalpinx
c.
Ulva
85. Oyster drill
86. Green algae
87. Soft-shelled clam
Match the primary producer with its most closely associated herbivore.
a.
soft-shell clam
b.
waterfowl
c.
green turtles
88. Thalassia
89. Zostera
90. Diatoms
ESSAY
91. Outline 3 human uses of estuaries that impact their ecology.
92. Define the following terms:
•
Estuary
•
Tidal flat
•
Salt-wedge estuary
93. Define the following terms:
•
Coastal plain estuary
•
Tectonic estuary
•
Fjord
94. How does temperature-driven vertical turnover occur, and what is its importance?
95. What properties of estuaries make them highly productive areas?
96. Describe the difference between an osmoregulator and an osmoconformer.
97. Considering that species diversity in estuaries is limited by constant changes in salinity, temperature,
and water movement, where, vertically, in an estuary would one expect to find the greatest species
diversity? The least species diversity?
98. What horizontal part of an estuary would you expect to show the greatest species diversity?
99. Even though estuaries support large numbers of organisms, there are relatively few numbers of species
that live in estuaries. Why is this the case?
100. Why are estuarine environments ideal locations for the development of juveniles of many species of
marine animals?
219 Chapter 14—Estuaries
101. Oyster reefs are usually oriented at right angles to the currents in estuaries. How do you think this
could be an advantage to the oysters living in this community?