Deck 17: The Shallow Coastal Subtidal: Sea Grass Beds, Rocky Reefs, Kelp Forests, and Coral Reefs

Question 1

Sea grasses such as eel grass

A) Can spread populations only by rhizome extension
B) Are flowering plants that are pollinated by flying insects at the time of low tide
C) Are flowering plants that are fertilized by pollen that is spread by water currents
D) Are flowering plants with self-fertilization only

Answer 1

C

Question 2

Sea grasses such as eel grass

A) Have their lower depth limited strictly by light
B) Have their lower depth limited by herbivore pressure by fish grazing
C) Can live at great depths, as much as 10 m
D) Cannot grow in soft sediment such as mud because the pore waters lack oxygen

Answer 2

A

Question 3

Sea grasses

A) Are rather indigestible so only a restricted number of herbivore species can subsist on them
B) Are always strongly controlled by grazing by herbivores
C) Are digestible by invertebrates but not vertebrates
D) Tend to grow right up to the edge of patch reefs in the Caribbean

Answer 3

A

Question 4

Green turtles

A) Decimate turtle grass flats and encourage the growth of seaweeds
B) Feed only on grass tips and encourage grass growth
C) Do not feed on sea grasses, only the invertebrates within the beds
D) Have increased because of the increase of sea grasses in the Caribbean

Question 5

If suspension feeding bivalves are abundant

A) Sea grasses are abundant because the bivalves feed and increase transmitted light to the seabed
B) Sea grasses decline because they are inundated with bivalve pseudofeces
C) Sea grasses are not affected
D) Sea grasses decline because of predation on bivalves

Question 6

In the 1930s

A) Eel grass increased greatly owing to the relaxation of overfishing
B) Eel grass declined owing to sewage
C) Eel grass declined because of a disease
D) Decreasing light caused a decline of eel grass

Question 7

How does eel grass affect sedimentation?

A) It slows currents and increases sedimentation
B) Leaves decompose and increase sedimentation of organic material
C) It encourages the growth of surface algae and seaweeds and increases sedimentation
D) All of the above

Question 8

Subtidal rocky reefs

A) Tend to be dominated by solitary animal species, such as barnacles
B) Have faunas that are very similar to the fauna of rocky shores
C) Contain very homogeneous assemblages of invertebrates
D) Are usually dominated by colonial invertebrates

Question 9

On subtidal rocky reefs

A) Urchins are usually absent
B) Urchins are found more abundantly on horizontal than vertical benches
C) Urchins are found more abundantly on vertical than horizontal benches
D) Carnivores are largely absent

Question 10

On subtidal rocky reefs

A) Dominant colonial invertebrates generally have lecithotrophic larvae, so recruitment only occurs over short distances
B) Dominant colonial invertebrates generally have planktotrophic larvae so settlement is from distant areas
C) Mussels dominate to great depths
D) Dominant colonial invertebrates have crawl-away larvae

Question 11

Subtidal rocky reef communities

A) Are associated with kelp forests in the tropics
B) Are associated with kelp forests in cool water coastal environments
C) Are dominated by species consisting of single individuals
D) Are rarely patchy

Question 12

Kelps

A) Grow well in low nutrient concentrations
B) Are confined to the tropics
C) Grow very slowly
D) Are limited to cooler and cold marine waters

Question 13

If an Alaskan kelp forest is left undisturbed

A) A well-developed multistory canopy will develop eventually
B) Only a relatively low-lying kelp species will come to dominate and eliminate most other kelp species
C) Urchins will stop consuming seaweeds
D) Sea otters will switch to feeding on kelp

Question 14

What is the large kelp plant that we see?

A) An asexual sporophyte
B) A very large gametophyte
C) The only stage of a plant that is nonsexual
D) A benthic stage of a planktonic gametophyte

Question 15

Kelp forests are an example

A) Of an environment with little herbivory
B) Of an environment where water flow is not an important factor
C) Of an environment with a strong trophic cascade
D) Of a group of species adapted to warm, turbulent waters

Question 16

A barrens is liable to form when

A) Sea otters are very abundant
B) Urchins are very abundant
C) Storms are infrequent
D) Kelps grow too rapidly

Question 17

El Niños

A) Are very beneficial for kelp forest growth
B) Have no effect on kelp forest growth
C) Negatively affect kelp forest growth
D) Kill kelps because of the very cold water they bring

Question 18

If a disease exterminated all of the sea otters

A) Kelps would soon greatly increase in abundance
B) Sea urchins would be short of their preferred food
C) Competition among species of kelps would be reduced
D) Urchin populations would continue to increase indefinitely

Question 19

Zooxanthellae

A) Are never found outside of their coral hosts
B) Are found only in hermatypic corals
C) Are found in a number of invertebrate animal groups
D) Cannot reproduce while in their hosts

Question 20

Coral atolls

A) Are found strictly in the Pacific
B) Are formed by rising of the earth's crust
C) Are formed by sinking of the earth's crust
D) Grow in higher latitudes than coastal reefs

Question 21

Zooxanthellae benefit their coral hosts

A) Principally by removing nitrogenous wastes
B) Mainly by supplying oxygen in an oxygen-poor environment
C) By protecting them from uv light
D) By transferring carbohydrates to their hosts, which is used for food

Question 22

Mass spawning of many species on coral reefs is beneficial because

A) It guarantees cross-fertilization among species
B) It increases the probability of fertilization for each species separately
C) It allows suspension feeders to feed on gametes from the water column
D) It guarantees the distant transport of gametes from the parents

Question 23

Many sessile species often coexist on coral reefs because

A) Space is never limiting
B) Predation always reduces population sizes
C) Interspecific mechanisms of competition are complex and often non-hierarchical
D) They could never require the same space for attachment

Question 24

Corals growing slowly on reefs

A) Are always overgrown by faster growing corals, so they survive only by high larval recruitment
B) May maintain themselves by aggressive responses toward neighbors
C) Live only on the undersides of other corals
D) Tend to grow tall so as to shade out their neighbors

Question 25

Global warming is likely to affect coral reefs

A) By decreases in pH, which will reduce calcification
B) By rises in sea level, which may drown some reefs
C) By high temperature stress, which may cause bleaching
D) All of the above

Question 26

In corals, disease is associated with

A) Bleaching
B) The presence of coral carnivores
C) The presence of unusually dense concentrations of zooxanthellae
D) None of the above

Question 27

In regions with coral reefs

A) Diseases are spread only locally within a reef
B) Only corals have been found to be affected by disease
C) Disease has been found to play an insignificant role in coral reef ecology
D) Diseases can be spread by currents over large areas

Question 28

Coral diseases

A) Are strongly suppressed when sea water is unusually warm
B) Are strongly correlated with bleaching
C) Are positively correlated with zooxanthellae concentration
D) Have been on the decline in recent decades