FINAL EXAM REVIEW (WITH ANSWERS!)

The final will consist of:

  1. A series of multiple choice questions covering the entire course. These questions are based on what an educated person (yourself hopefully) should know after completing an oceanography course.

  2. A series of short answer questions and definitions covering new material, shoreline processes and marine ecology

  3. Two essay questions (with some degree of choice). One essay will be from previous material (marine geology or ocean circulation) and one will be from marine ecology.

Study questions for new material

N.B. These are brief answers designed to make sure that you are on the right track. You should use your notes and book to augment these answers. I do not want to see verbatim regurgitation of these answers on the exam. That would be plagiarism!
  1. Name the five primary nutrients in seawater. Name a secondary (macro) and a tertiary (micro) nutrient. Which two primary nutrients usually limit primary productivity? Why do these nutrients limit primary productivity?

    2. C,H,O,N,P; N and P are limiting; Secondary: K, Ca, Si; Tertiary: Fe, Zn, Cu (in Flintstone vitamins!)
  2. Describe the nitrogen and phosphorous cycles.

    3. Although cyanobacteria can fix molecular nitrogen, N2, most plants need ammonium NH4, nitrite NO2 or nitrate NO3. Because the rate of fixing of N2 is slow (and human activity such as fertilizer manufacture now accounts for over 50% of worldwide fixing of N2), most N is recycled in the nitrogen cycle. Few nitrogen salts are produce by weathering of rock, and few are lost to sediments, so geologic processes are not major players. Organisms excrete some ammonium directly. Other ammonium is liberated in the first step of bacterial decay of dead organic material. A second bacterial step converts ammonium to nitrite and a third bacterial step in needed to produce nitrate. If the material has sunk below the thermocline by the time these steps complete, some nitrogen is lost from the photic zone and must be returned at upwelling zones.

    The phosphorous (phosphate) cycle is more open and relies less on recycling than the N cycle. There are many inorganic sources of phosphates including weathering of rock. Phosphate enters the biological system and is recycled very rapidly. There is also rapid loss of phosphates from the biological system into sediments.

  3. Sketch a simple diagram of the open ocean Antarctic trophic pyramid. What is the most important organism in the second trophic level here? Describe it! About how much energy is transmitted from one trophic level to the next? How would a trophic pyramid in temperate coastal waters differ?

    4. This is a three level trophic pyramid with primary producers on the bottom, krill (euphausids) on the primary grazer level and baleen whales and birds on the third level. (actually we could add a fourth level for seals and killer whales that eat penguins and each other!). Between 15% –20% of the energy is transferred up from on level to the next. Studies suggest that energy transfer is more efficient in these regions than in the oligotrophic waters of the open ocean. A temperate coastal ecosystem would have a taller pyramid with more trophic levels, and the energy transfer would be lower, about 10%, between layers. Thus a given biomass of primary producers would support a smaller biomass of primary consumers, etc.
  4. Describe the seasonal cycles of primary productivity in the tropics, mid-latitudes and polar seas. How does standing crop vary with primary productivity? Be able to graph the seasonal vertical variation of water temperature in temperate latitudes. What is the mixed layer?

    5. Tropics: low productivity...plenty of light but stong shallow thermocline isolates nutrients out of photic zone..the exception is in upwelling zones.

    Polar: Vigorous bloom of productivity in the short summer...high angle light is only available then...nutrients are seldom the limiting factor.

    Mid-latitudes: Big bloom in spring...winter has mixed the surface waters into an isothermal layer, removing the shallow thermocline and bringing the nutrients into the euphotic zone and the length of the day, and sun angle increases. Bloom dies by early summer as a strong thermocline develops isolating nutrients below the oxygen compensation depth. Small bloom in Fall when storms remix the isothermal layer. Then winter hits and too little daylight and low angle sun again limit productivity.

    Standing crop doesn't vary much... as productivity rises, so does the population of the organisms that graze on the phytoplankton so the total mass of primary biomass is fairly stable. So standing stock rises and falls like standing crop, but with a slight time delay.
  5. Describe how fresh water and salt water fish have adapted to the salinity of their environments.

    6. Fresh water fish (hypertonic) don’t drink water and they urinate large volumes. Salt water fish (hypotonic) urinate very small volumes and drink salt water from which they remove the salt with glands on the gill slits. Marine invertebrates are isotonic, they have the same salinity as their surroundings.
  6. Name and describe two major groups of zooplankton that are primary grazers. Be able to sketch these.

    7. Copepods and Euphusids (Krill) , Know their approximate sizes and be able to sketch them. Copepods are about 0.5-1 mm and  Euphusids are 1-2 cm in length, both are shown in figure 14.5, and krill are shown life sized in figure 17.8.
  7. What is the difference between holoplankton and meroplankton? Give some examples of each. How are plankton classified by size?

    8. Holoplankton spend their entire life cycle as plankton, meroplankton are larval and juvenile stages of species that develop into nektonic or benthic adults. Most meroplankton are zooplankton, such as crab larvae and fish eggs.

    By size, we distinguish macroplankton (jellyfish, krill), microplankton (diatoms, copepods, dinoflagellates), nannoplankton and picoplankton (bacteria).
  8. What are the three major divisions of marine organisms based on habitat and locomotion?

    9. Nekton, Plankton, Benthos
  9. Be able to list or sketch the major Pelagic and Benthic environments. Why are the photic and aphotic zones better called the epipelagic and mesopelagic zones respectively?

    10. Figure 13.15. The photic zone is hard to define since light penetration depends on turbidy, productivity and seasonal variations in sun angle. The aphotic zone contains organisms that can sense and respond to the light levels found there, as evidenced by the Deep Scattering Layer which demonstrates diurnal depth cycles.

  10. Describe two differences between lunging and cruising fish and give an example of each.
    11.

    Muscle tissue (high capillary density in cruisers gives red tissue, well developed myomeres in lungers), aspect ratio of the fins, shape of the caudal fin and mouth position Tuna is a cruiser, Grouper is a lunger. Be ready to sketch these differences.
  11. Describe the Gran method (light-bottle/dark-bottle) of determining both net and gross primary productivity. What is another way to measure primary productivity? What is the oxygen compensation depth and why is it more important than the depth of the photic zone?

    12. The Gran method uses light-bottles and dark-bottles and measures productivty indirectly by measuring changes in dissolved oxygen content. In addition to the Gran method, radioactively "tagged" carbon (14C) can be introduced into the bottles, then the phytoplankton are strained out of the water and their radioactivity is measured. 

    Above the oxygen compensation depth, there is positive net primary productivity. Thus net oxygen is being added to the water, and productivity by plants exceeds their own needs. Below the oxygen compensation depth, respiration and decay remove more oxygen than photosynthesis create. Plants beneath this depth are not able to produce beyond their own needs.
  12. Compare the productivity of open ocean to that of major upwelling zones, continental shelves, coral reefs and estuaries in terms of gC/m2/yr. Explain the enhanced productivity in estuaries and upwelling zones. How many apples equal a pumpkin?

    13. Open ocean (these are called oligotrophic waters) approximately 30 gC/m2/yr or less

    Upwelling zones (these are called eutrophic waters) approximately 150-300 gC/m2/yr

    Continental shelves 150 gC/m2/yr

    Coral reefs 2000-5000 g/C/m2/yr at reef face, but surrounding waters are usually oligotrophic

    Estuaries approximately 1000 gC/m2/yr

    In estuaries, water is shallow so nutrients cannot sink beneath the photic zone.

    Make sure to look at figures 14.15 and 14.26
  13. Why do we estimate that there is very slow diffuse upwelling throughout the open ocean. What is the main effect of this form of upwelling.

    14. The background productivity (oligotrophic waters) is not zero. Even places like the Sargasso sea maintain productivities that average 50gC/m2/yr. In addition major upwelling regions do not upwell as much water as is downwelling but there must be a balance so the "missing" upwelling is distributed throughout the oceans. Finally, the thermocline in the tropics is stable despite continual surface heating due to this slow upwelling of deeper, colder water.
  14. What are the major divisions of marine mammals? What are baleen whales? What are pinnepeds? Which marine mammal has readapted to the sea most recently? 
    15.

    Sea otters, Pinnepeds, Sirenians, and Cetaceans ( Odontoceti and Mysticeti). Baleen whales are largest whales, strain krill with large sheets of fiberous material in mouth. Pinnepeds are "feather-footed" mammals (seals, sea lions, and walrus). Sea otters or Polar Bears show least adaption to marine life.
  15. You take your 4 year old daughter to SeaWorld and she asks "is that a porpoise or a dolphin?" What do you say?

    16. Shut up and watch the show, or the answer to question 5 of Q&A in chapter 15.

  16. What is coral bleaching?

    17. The coral polyp incorporates photosynthetic dinoflagellates called zooxanthellae into its tissue establishing a symbiotic relationship. The brownish color of the zooxanthellae give the coral its color. When stressed by environmental changes, particularly too warm water or pollution, the coral polyps expel the zooxanthellae causing the coral to loose its color or "bleach." The coral polyps can no longer continue to secrete CaCO3 to form their skeletal material.

  17. What are the two most common minerals in beach sand?
    18.

    Quartz and feldspar
  18. Explain the formation of longshore current. Which direction is the dominant longshore current on the Pacific and Atlantic coasts of the U. S.

    19. Longshore currents result from flow of water within the zone of breaking waves. Where waves are not breaking, the water doesn’t flow, it simple orbits in place. As soon as the wave breaks, the orbits are disrupted and water flows. When a wave breaks, water moves up the beach in the direction the wave was moving. In general this is not perpendicular to the shoreline. The backwash of water off of the beach is generally perpendicular to shore. This results in a zig-zag motion of water in the breaker zone with a net movement of water parallel to the shoreline. Since most wave are generated by storm activity in the northern Atlantic and Pacific, waves tend to come on shore from the north and the longshore currents move from north to south.
  19. Draw a cross section of a high–profile barrier island showing the major subdivisions of the beach, dunes and island flat. Discuss the impact of a tropical storm on a high–profile barrier island. Compare this to a low-profile barrier island.

    20. During a tropical storm, the large, vegetated foredunes of a high profile barrier island are eroded but are only occasionally breached. Thus, after the storm, the dunes rebuild and the island is stable or migrates seaward over long periods of time. Low profile barrier islands have small, poorly vegetated, foredune fields. During a tropical storm, large amounts of sand are moved from the beach side of the low-profile island into the lagoon. The net result is a landward migration of the island over time. Low profile islands are characteristic of coastal areas where sediment supply is low. South Padre Island, and Galveston Island are low-profile (except for the portions of Galveston where the sea wall was constructed after the 1900 hurricane). North Padre Island and Mustang Island are high-profile islands today.
  20. What is eustatic sea level change?
  21. Describe the interplay between geologic processes and oceanic processes that control the nature of a coastline.

    Eustatic sea level changes are important, but local oceanic processes include wave amplitude and local currents. Geologic factors include tectonic activity (faults, subduction), resistance of bedrock to erosion, location and nature of streams and rivers and the nature and amount of sediment delivered to the coast.
  22. What are some key differences between emergent and submergent coastlines? Give an example of each in the U.S.
  23. Why is the coast of Norway an emergent coastline despite rising eustatic sea level for the last 18,000 years?

    Although eustatic sea level has risen over 100m in the last 18,000 years, the continental surface is rising faster due to isostatic rebound. As the glacial sheets melted and retreated, that weight was removed from the continental crust. Asthenospheric flow beneath the continent has allowed it rebound upward.
  24. Which way do the predominant longshore currents flow along the east and west coasts of the U.S.? Along the Texas coast?

    Longshore currents on both the east and west coasts of the US flow predominantly southward since most storm activity in the Pacific and Atlantic occurs at higher latitudes. Locally, the shape and orientation of the shoreline is the major influence on the direction of the longshore currents. The Texas coast is gently curved. Along the upper Texas coast (Beaumont, Galveston) the predominant flow is southwest. Along the lower Texas coast (Brownsville, South Padre Island) the predominant flow is northeast. In the central Texas coast (coastal bend region, Corpus Christi) these currents converge, so the flow alternates. This is responsible for the increased amounts of shore debris along the central Texas coast.
  25. What is an estuary?
  26. Describe the vertical distribution of dissolved oxygen in the ocean. What are typical values of oxygen concentration?

    At the surface, oxygen concentration is governed by equilibrium with the atmosphere. Through the upper photic zone oxygen concentration increases until the oxygen compensation depth and then begins to decrease with depth as respiration and decay remove more oxygen than is added. Oxygen concentration decreases until a well defined oxygen minimum is reached, typically at depths of 500-700m. Oxygen concentration then begins to increase as intermediate and deep waters bring cold, oxygenated waters via thermohaline circulation. Values of  oxygen concentration are measured in ppm. Well oxygenated waters have values between 5-10 ppm. The oxygen minimum is typically around 1-2 pm. Values less than 3 ppm make respiration difficult for marine organisms.

    27.