MSCI 112 Study Guide

Fall 2003

TEST EXPECTATIONS AND POTENTIAL TEST QUESTIONS

There are two things making it tough for you to study for this test:  1) you’ve never had a test from me before, and 2) this last section is a community-by-community review of some things you’ve already learned and some things that are new, and none of it is in your book in a format for easy review.  So, my plan is to give you a number of potential test questions on this site, with the actual test being primarily a subset of those questions. 

These general topics went up last week:

    1. Modification of the substrate due to physical interactions with waves and currents
    2. Resulting substrate and/or sediment grain size
    3. Effect on habitat stability and required adaptations for organisms to live there
    4. Relative importance of infauna vs. epifauna, competition for space vs. food, and biomass vs. biodiversity
    5. How biological interactions (predation, competition, sybiotic relationships) interact with the physical environment to produce community function and zonation

These questions went up on Tuesday.  Below are some actual potential test questions.  Some of them will be on your test, others won’t.  I may add a few questions that aren’t on this page, but most of your test will be here first.  (I added a few more on Wed morning—see below.)

1. Compare rocky intertidal and sandy beach intertidal habitats.  Specifically, cover:

  1. how the geological structure of each is formed by physical forces
  2. how both of the above influence the chemical structure of each habitat
  3. how all of the above determine the structure of the biological community, including the types of species that live there, and they importance of various biological interactions between species.

 

2. List 4 physical (as opposed to biological) stresses for organisms living in the rocky intertidal zone.

 

3. Remember this one?  There could be another similar type question on the test:  For three imaginary species in the rocky intertidal zone, species A can survive out of water the longest (it only requires an hour or 2 underwater per day, although it does fine if submerged all day), species B is next (it can survive in the mid- and low- tidal range), and species C dries out fairly quickly (it can only survive in the low-tidal range).  In terms of competition for space, species B is the dominant competitor, and species C is the least effective competitor.  What pattern of vertical zonation within the intertidal zone would you predict?  (Hint:  You may want to sketch this out.  It is not necessarily the same example you had in lecture.)

  1. A dominant on top (upper tidal range), B dominant in the middle, C dominant on the bottom (lower tidal range)
  2. C dominant on the top, A dominant in the middle, B dominant on the bottom
  3. A dominant everywhere
  4. A dominant on top, B dominant everywhere else

 

4. Your buddy thinks the main impact of temperature on oceanic productivity is that warmer temperatures increase metabolic rates, so the highest productivity is associated with warmer temperatures.  Do you agree?  If not, explain what you think the main effect of temperature is on primary production rates in the open ocean.

 

5. Review your box model exercise

 

6. How does the food source differ for typical deep sea fauna, deep sea mobile predators, and deep sea hydrothermal vent organisms? 

 

7. In terms of maintaining high biodiversity, would resource partitioning be more important in an equilibrium community or a non-equilibrium community?  Explain briefly.

 

8. Darwin proposed that most coral reefs begin as fringing reefs.  Name and describe his next 2 stages in the evolution of coral reefs and explain how they develop.

 

9. Describe the mutualistic relationship between zooxanthellae and the coral polyp.  How does each help the other (be complete)?

 

10. In coral reef ecosystems, would (1) eutrophication and (2) overfishing of herbivorous fish have a similar or opposite impact on the reef community and biodiversity?  Explain briefly.

 

11. What’s the difference between the photic zone and the epipelagic zone?  (not reviewed in lecture, but I referred you to your book for these depth zone categories)

12. Imagine a world where the water density increases with temperature (warmer water is more dense).  All else is the same.  On a graph like we drew in the most recent class (with the months along the X-axis) , draw and clearly label 3 curves for the temperate latitude, North Atlantic surface waters:  (1) nutrient concentration, (2) light availability, and (3) primary production rate.  There is no scale on the y-axis, so I am more interested in the shape of the curve than the exact magnitude.

These questions were added on Wednesday morning.  The past few weeks have been all about applying what you know to understand structure and processes for whole systems.  Some of these questions ask you to do that with new scenarios.

13. Add salt marshes to the first question above (along with rocky intertidal and sandy beaches)

 

14. We talked in class about the processes that determine vertical zonation patterns on rocky intertidal zones.  What is different for fouling communities?

 

15. The famous white cliffs of Dover in England are made up largely of the remains of coccolithophores.  Explain how and where (in a rough sense) these layers were first formed.  How do you know?

 

16.     In a typical South Carolina salt marsh in the summer, an enormous amount of juvenile and adult nekton are living in the marsh.  These organisms crowd into intertidal creeks at high tide and their accumulated high excretion rates lead to a water column dominated by ammonium as the nitrogen source.  Larger phytoplankton, such as diatoms do not utilize ammonium well, so the system is dominated by smaller phytoplankton and bacterioplankton, which in turn are fed on by small zooplankton (micro-ciliates, etc.) and on up the food chain.  Also in the summer, the warmer temperatures promote faster bacterial decay processes. 

In the winter, most of the nekton have reached a larger size and move off shore.  With less excretion, the system is more dominated by nitrate and nitrite forms of nitrogen (from run-off and other sources).  This promotes a phytoplankton community with more large phytoplankton species that are fed on by larger zooplankton, etc…  Spartina growth is negligible in the winter. 

Total primary production is much higher in the summer in the marsh, and as described above, it tends to support different species and different food chains to varying degrees.  Now, for the question:  given these patterns, in which season might the energy from primary production be more efficiently transferred to higher trophic levels?  For the higher trophic levels, does this serve to dampen out the impact of annual fluctuations in primary production, or does it magnify the fluctuations, potentially leading to dramatic shifts in available resources?

 

17. Read the section on page 339 in your text on the Gulf of Mexico dead zone.  If eutrophication leads to increased levels of primary production, and photosynthesis adds oxygen to the water, why do we find large hypoxic zones forming?  Why does this phenomenon peak in summer?

 

18. The Chesapeake Bay gets similar anoxic zones over large portions of the bottom in the summer.  One way to improve DO would be to increase the amount of seagrasses on the bottom, but seagrasses have severely declined over the last century in the bay.  One reason is overharvesting of oysters.  Oyster populations used to be so large that they filtered the volume the entire bay in a matter of days, helping to improve water clarity.  Now the populations are smaller and take over a year to filter the bay.  With declining water quality and the loss of seagrasses, less sediment is stablilized by grasses, leading to further declines in water clarity and thus, further declines in seagrasses.  Ugly cycle, huh?  So, here’s the question:  can we fix this simply to going out and planting more sea grasses ourselves?  If so, what would be the chain of events that leads to success.  If not, why wouldn’t seagrasses succeed?