Practice Questions for Exam 2 -- Answers at bottom of page
Note: No multiple choice examples are included because we covered these in the review session

Part 1.  Definitions
Please define the following terms and explain briefly why each term has significance in marine ecology (3 points each)

1. eurythermal

2. trophic group amensalism

Part 2.  Short answer.  Please fill in the blanks or circle the correct answer.  BE SURE TO ANSWER ALL PARTS OF EACH QUESTION (1.5 points for each correct answer)

1. Two regions of the ocean (be specific) where there are food webs based at least partially on chemosynthesis are:

2. Two possible functions of bioluminescence are:

3. American-type / European-type estuaries are dominated by extensive mud flats with few large plants.  In these estuaries the main source of autochthonous primary production is benthic diatoms / detritus from rivers / seagrass and these estuaries are
net sources / net receivers of energy.
 

Part 3. Multiple Choice (covered during review session)

Part 4. Short essay. Please provide concise but complete answers for the following questions:

1. Name and explain two of the older hypotheses for the diversity of the deep-sea benthos, and describe newer evidence
    that seems to refute each of them (4 points)

2. You really want a summer job working with a researcher who is trying to verify that the seastar, Pisaster is a keystone predator in
    the Pacific Northwest.  As preparation for the job interview, she asks you to design an experiment to examine the ecological effects
    of predation by Pisaster, in the rocky intertidal zone.  Your employment prospects hinge on the quality of your design.  Describe
    your experiment (3 points).

 3.  Biological interaction are extremely important in the Rocky intertidal zone.  Give two specific examples of organisms and their
     biotic interactions in temperate rocky intertidal ecosystems (3 points).

BONUS QUESTION (DUE 9 APRIL AT EXAM)

You visit an estuary and find the below salinity pattern.  This estuary could be classified as a                                  estuary.

salinity profile of estuary
 
 

FEEL FREE TO COME SEE ME IF YOU HAVE QUESTIONS!

Part 1.  Definitions
Please define the following terms and explain briefly why each term has significance in marine ecology (3 points each)

1. eurythermal
        Organisms that are able to tolerate a wide range of temperatures.
        Example of an acceptable significance: Eurythermal organisms can live higher up in the intertidal, where temperature
                variability can be extreme.
2. trophic group amensalism
        Exclusion of one trophic group by another, due to environmental modification by the second trophic group.  For example, burrowing
                deposit feeders often stir muddy sediments, excluding suspension feeders whose filtering apparati get clogged.
         Example of an acceptable significance:  Trophic group amensalism may help explain local abundance patterns.  It is a form of
                competition...

Part 2.  Short answer.  Please fill in the blanks or circle the correct answer.  BE SURE TO ANSWER ALL PARTS OF EACH QUESTION (1.5 points for each correct answer)

1. Two regions of the ocean (be specific) where there are food webs based at least partially on chemosynthesis are:
        possible answers:
        deep sea hydrothermal vents (deep sea is not specific enough, because most of the deep sea does not support chemosynthesis)
        cold seeps
        intertidal muddy shores (where the sediment is anoxic)

2. Two possible functions of bioluminescence are:
        possible answers:
           Counterillumination
            Lighing an area to sea prey
            Mate recognition
            Attraction of prey
            Burglar alarm hypothesis -- startling predators

3. European-typeestuaries are dominated by extensive mud flats with few large plants.  In these estuaries the main source of autochthonous primary production is benthic diatoms and these estuaries are net receivers of energy.

Part 4. Short essay. Please provide concise but complete answers for the following questions:

1. Name and explain two of the older hypotheses for the diversity of the deep-sea benthos, and describe newer evidence
    that seems to refute each of them (4 points)
        Possible answers
           (1) Stability-time hypothesis - says that the deep sea is very stable and there has been a long time for specialization
                    (and competitive niche partitioning).  Evidence that seems to refute this is that many benthic species are
                    generalists, not specialists, as would be predicted by this hypothesis.
            (2) Cropper disturbance hypothesis - says that any diversity that develops (via mutation...) is maintained because intense
                    predation or 'cropping' decreases the abundances of all organisms enough that it prevents high competition and
                    extinction due to competitive exclusion.  Evidence that seems to refute this is that few deep sea animals seem to
                    have adaptations to reduce predation, which would be predicted if predation/cropping pressure is high.
            (3) Area hypothesis - says that diversity is higher in the deep sea because it is so large.  Evidence that seems to refute this
                    is that species density and abundance are actually highest at intermediate depths, which aren't the biggest part
                    of the deep sea.

2. You really want a summer job working with a researcher who is trying to verify that the seastar, Pisaster is a keystone predator in
    the Pacific Northwest.  As preparation for the job interview, she asks you to design an experiment to examine the ecological effects
    of predation by Pisaster, in the rocky intertidal zone.  Your employment prospects hinge on the quality of your design.  Describe
    your experiment (3 points).

    Any kind of exclusion or addition experiments, perhaps coupled with field surveys, was fine.  People would
    lose points if they had no controls or if they didn't mention what they wanted to measure and compare in their experiments.  People should
    include REPLICATES.  When deciding what you were going to meaure, you should made it clear why your study would
    demonstrate something about the predation effects of Pisaster on the community or something about keystone predation.

3.  Biological interaction are extremely important in the Rocky intertidal zone.  Give two specific examples of organisms and their
     biotic interactions in temperate rocky intertidal ecosystems (3 points).
        There are TONS of these examples.  People would lose points if they didn't list specific organisms, or if they discussed interactions
        between organisms and their environment (abiotic interactions) instead of organisms with each other.

        Some examples:
            (1) The barnacles Chthamalus and Semibalanus compete for space.  Semibalanus will overgrow Chthamalus in some
                    zones, but C. can escape higher up because is less susceptable to desiccation.
            (2) Mussels outcompete barnacles by settling on them.
            (3) Gastropods eat Balanus, but can not withstand as much desiccation, so there is a refuge for the barnacle in the upper
                    intertidal.
            (4) Pisaster prefers to eat the Mytilus mussel, the dominant Northwestern U.S. rocky intertidal competitor, changing the
                    entire community (keystone predation).

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