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Bio 124 Fall 2009: Study guide/questions for lecture material covered since Midterm#2
Below I have provided an outline of the material covered since midterm 2 along with some
important vocabulary and study questions (bullet points) that you should be able to define/answer
from your lecture and reading notes. This material will constitute HALF of the final exam (100
points), the other half will be on material covered by midterms #1 and #2 (100 points).
Come prepared to the exam review session (lecture on Thursday 12/3) with questions and notes.
Come prepared to the exam with a 100 question scantron & a #2 pencil.

Polar Oceans & Adaptations
I. Polar oceans: physical environment
  A. Seasonality
      Describe the light regime in the polar regions. What season is the most productive?
  B. Ice
      Describe the following types of sea ice: a) slush, b) pancake ice, c) ice floe, d) iceberg, e)
         anchor ice, f) platelet ice.
      Which type of ice do you think has the greatest impact (positive or negative) on polar
         marine organisms?
      In Antarctica, the presences of sea ice leads to zonation in shallow waters. Describe how
         the 3 zones differ from each other.

II. Polar marine organisms & adaptations
      How does species diversity in polar regions compare with tropical regions?
      Why are marine organism population sizes higher in polar regions compared to tropical
      List 3 characteristics of polar subtidal organisms. Describe why one of these
         characteristics is likely to have developed.
      Polar fishes exhibit two different adaptations that allow them to survive amongst the ice:
         one based on their hemoglobin content in their blood and the other based on special
         proteins. Briefly describe each and how they keep fish from freezing.
      Many polar organisms are not subtidal; they are air-breathers but use the ocean as a
         habitat and source of food. Describe two of these animals and list 2 adaptations of each
         that allow them to thrive in polar regions.

III. Threats to polar marine life
    Name 3 different ways that global warming is impacting polar organisms (name one organism
      being affected for each impact).

The Mesopelagic/Twilight/Midwater Zone
At a given depth, temperature varies less than in epipelagic – but this is the zone of main
thermocline, so temperature varies with depth.
Light still occurs, but at levels too low for photosynthesis to occur.

A. Life in the Mesopelagic
    What are two abundant zooplankton in the mesopelagic?
    List two larger invertebrates that occur in the mesopelagic. What is one adaptation they
       commonly have?

B. Mesopelagic Adaptations
Wide-ranging species from given depth often have very similar adaptations, unlike surface waters,
where adaptations vary widely
      1. Feeding & food webs
          What percentage of the food produced in epipelagic is transferred to the
          What are 3 adaptations of mesopelagic fish that allow them to deal with this low
             food availability?
      2. Mobility
              What is the Deep Scattering Layer? When and why does it change depth?
              There are two major groups of mesopelagic animals: non-migrators & migrators.
                 List 1 example from each and compare adaptations that benefit their lifestyle.
      3. Coloration & body shape
          Camouflage is very important in the mesopelagic, especially since they can’t afford
             energetic costs of fast swimming, defensive spines & scales. List 3 different ways
             that mesopelagic organisms can ‘hide’ in the mesopelagic.
      4. Sensory
          Describe two different ways that eyes have evolved to be more effective in the low
             light regime of the mesopelagic.
      5. Bioluminescence
          List two purposes for bioluminescence.
          There are 3 different ways that mesopelagic and deep sea animals create
             bioluminescence: photophores, specialized cells, and fluids. Briefly describe each one
             and note one animal that uses each.
          Where are photophores generally located in mesopelagic fishes?
      6. Oxygen
          The oxygen minimum zone is a well-defined layer of water at about 500 m depth
             where oxygen is much lower than it is either above or below in the water column.
             Why is oxygen depleted at this level only?
          How do fish living near this zone handle the low oxygen levels?

Deep Sea
largest habitat on earth – 75% of ocean volume
I. Deep Sea – Pelagic
   A. Zones
          List depth ranges of the following zones: bathypelagic, abyssopelagic, hadopelagic
   B. Physical environment
          Describe the physical characteristics of deep sea environment in terms of: 1) light, 2)
            pressure, 3) oxygen source, 4) source of nutrients, 5) temperature, 6) salinity
   C. Biological adaptations
                 Describe specific adaptations of deep sea pelagic organisms in terms of:
                1. Biomass
                2. Color
                3. Bioluminescence
                4. Eyes
                5. Low food levels
                6. Reproduction
                7. Pressure
          List at least 4 characteristics of deep sea fishes (e.g., body size, muscle & skeletal
                development, feeding adaptations, activity level,..)
          Name one deep sea fish and describe how it is adapted to live in the deep sea

   II.      Deep Sea – Benthos
         Benthos = sea floor; Benthic organisms – live on sea floor
    Of the 270 mil miles2 of deep sea floor only about 500 m2 have been sampled. Why such a
     small area?
   A. Environment
          Describe the sea floor – what kind of habitat makes up the majority?
   B.     Food sources
          What is the major source of food for deep sea organisms?
          What is a bait fall? Why are they declining?
   C.     Animals
          Provide one example of each of the following deep sea benthic animals and describe how
            they feed and how they are adapted to live in the deep sea.
          1. Meiofauna
          2. Macrofauna
          3. Benthic deep sea fishes
          How does the decomposition rate of deep sea bacteria differ from bacteria in shallow

III.       Hydrothermal vents
           A. Discovery: 1977 by geologists on a research expedition in the Galapagos Rift
              (Atlantic mid-ocean ridge system), 2700 m deep

        B. Physical Characteristics
       Describe 4 physical characteristics distinct to hydrothermal vents (pressure,
        temperature, pH, chemistry)

        C. Formation of vents
       Where are vents found?
       Describe how hydrothermal vents are formed, citing plate tectonics, sea floor spreading,
        and the roles of magma, water flow, and minerals.

           D. Life at deep sea vents
          What is the basis of life (source of energy & organism capturing it) in this lightless
          How does chemosynthesis differ from photosynthesis?
          There are 3 major food chains in deep sea vent communities: suspension, benthic, and
           symbiotic. List the trophic structure (major animals & their prey) in each.
          Describe one hydrothermal vent organism and its unique adaptations for living here.
          Are the same species found at all hydrothermal vents?

           E. Death of a vent
       List 3 causes for the demise of a hydrothermal vent.

           F. Significance
       List 2 things that make hydrothermal vents of interest to scientists/the medical

IV.        Cold seeps & Whale falls
         Usually along continental margins or sediment-rich basins (Gulf of Mexico) where
          hydrogen sulfide (H2S) and methane (CH4) produced by decay of organic matter seep out
          from sea floor.
         Chemosynthetic prokaryotes can use this to support distinct communities
         Also occurs at whale falls – after scavengers finish, H2S & CH4 produced by decomposer
         Whale/fish/animal carcasses may be an important ‘stepping stone’ between vent & seep
          communities & whaling may have limited this.

Life on the Continental Shelf
  Why are waters & benthos over continental shelf so highly productive?
I. Physical characteristics of the shelf environment
   Subtidal = sublittoral zone ->Benthic life (vs. above planktonic life in neritic zone)
  What are the physical boundaries of the continental shelf?
  Does shelf width and depth vary greatly across the globe?
  How does the fact that shelf environments are relatively shallow impact the water motion,
    sediment load, thermocline and regimes of nutrients, temperature, and salinity?

 II. Continental shelf benthic communities
   A. Soft bottom subtidal communities
       Distinguish epifauna and infauna and list some examples of them in soft bottom benthic
       Why are infauna restricted to the top layer of sediment?
       List 2 adaptations for living interstitially.
       Deposit feeders are common in soft-bottom communities. List 2 examples.
       What is bioturbation? Provide examples of 2 animals that cause it.
       List 2 suspension/filter feeders and 2 predators of soft bottom communities.

B. Seagrass Beds
       Seagrass is a flowering plant – how do they differ from marine algae?
       Why are seagrass beds important ecologically?
       List one grazer, one detritus feeder, one filter feeder, and one predator that you might
              find in a seagrass bed.
       Define epiphyte.

C. Rocky-bottom subtidal communities (not coral reefs)
       List 2 important factors that determine the distribution of seaweeds in the ocean.
       Why are epifauna uncommon on rocky-bottom subtidal areas? Give an example of one
              and briefly describe how it burrows.
       List 4 ways that seaweeds can defend themselves against grazers.

Reproduction of ocean animals
       Why might it be beneficial to be hermaphroditic in the ocean?
       What is broadcast spawning?
       What is a bipartite life cycle? Why is it beneficial for marine organisms?
       What cues do planktonic larvae use to determine where to settle?
       Distinguish between catadromous and anadromous fish. Provide one example of each.
       Name two different marine animals that make large scale migrations in order to

Marine resource extraction
I. Oil (Dr. Riki Ott lecture)
      Crude oil (petroleum) is a complex mixture of hydrocarbons (long chains of carbon &
       hydrogen) & other chemicals. The chemical make-up of crude oil varies depending on where
       it was extracted from, so the impacts can sometimes be hard to predict.
      Most of components of oil are insoluble in water & float on surface or sink & accumulate on
       sediments, but lighter components evaporate and become airborne.

        Why was the Exxon-Valdez oil spill an important event?
        List 2 long-term effects of the Exxon-Valdez oil spill
        How did this oil spill change the way we study and understand ecotoxicology?
        Why did this oil spill cause fisheries collapses?
        List 2 impacts of oil exposure to marine mammals or birds and 2 impacts to fish or
        List one impact of oil spills to human health and one to human economy.
        If oil is biodegradable, why do we still find it on beaches 20 yrs after an oil spill?

II. Fisheries
   A. Importance of fisheries
        Which communities of people are most dependent upon seafood?
        Which part of the sea is most productive for fisheries?
   B. Fishing methods
        Briefly describe each of the following methods of fishing, listing one type of fish
           targeted with this method and one negative impact of the method on the marine
           environment: 1) purse seines, 2) gill nets, 3) bottom trawls, 4) traps, 5) longlines
  C. Fishing Effort & Historical Views
      World fishery catches increased steadily and dramatically until the late 1980’s, but have
              since stabilized and are now largely in decline. Briefly discuss why catches increased
              and why they have leveled off or are in decline.
 D. Ecosystem Impacts of fishing
    What does ‘fishing down the food web’ mean?
    Describe a trophic cascade
 E. Management
    What is a renewable resource?
    Maximum Sustainable Yield is a management concept that seeks to obtain the highest yield
       of fish while still maintaining a constant, high population size of fish. Why has this been
       difficult/impossible to achieve?
    What defines a ‘collapsed’ fishery?
    List 3 different management methods.

Ocean Resources/Technology/Impacts…Future of the Oceans
More people now live within 100 km of coastlines than the entire global population in 1950.
Now > 6.5 billion people on the planet (that’s a lot!) and increasing exponentially.
    Make a graph of the exponential increase in human populations (don’t need numbers, just
       label the x and y-axes). What does it mean to be exponentially increasing?
I. Habitat Modification
    List 2 direct & 2 indirect impacts of humans on coral reefs and on the deep sea floor.
    What kind of animal communities are selected for (encouraged to occur) when an area of
       the sea floor is continually trawled? (give specific examples of one type of organism
       selected for and one that is likely to die-off)
II. Habitat Restoration
    If a ship ran across a coral reef and crushed it, what method would you recommend to
       restore the area? (specifically, what type of substrate would you lay down and how would
       you encourage coral reef animals to colonize it?)
    List two different reasons to place an artificial reef in the ocean.
III. Invasive species
    Define an invasive species.
    What characteristics would make an introduced species be more successful than the native
       species that live in an area?
    Name two intentional and two accidental ways that species can become introduced to a
       different ecosystem.
    What is one method that can be used to limit unintentional species introductions?

   Examples of invasive species
   1. Asian Clam (Potamocorbula amurensis) into SF Bay accidentally after trade opened with
      China in late 1980s, went from 0 to >10,000 clams per m2!
   2. Comb jelly into Black Sea (Mnemiopsis leidyi), first recorded there in 1982 and has since
      devastated the fishery because competes with fish for zooplankton and feeds on fish eggs
      & larvae
   3. Lionfish in Caribbean – no predators there, a voracious & successful predator itself.
   4. Seaweeds

IV. Pollution: The introduction into the environment of substances that decrease environmental
quality. Most are land-based (development, industry, agriculture, forestry, power), <20% come
from sea (shipping, drilling).
   1. Trash/solid wastes
          Why is trash concentrating in the Garbage Patch?
          What happens to plastics that are thrown into the ocean?
          What is ‘ghost fishing’ and what impact does it have on marine organisms?

2. Sewage
        List 3 things that can occur in human sewage besides natural human waste products.
        What is one impact of sewage release into the oceans?
        Describe two different methods of sewage treatment.
        If chemical treatment of sewage is so effective in reducing bacteria and viral
   infections, why do many countries/communities not use it?
        How does sewage release into the ocean cause hypoxic/anoxic conditions?

3. Nutrient input
    Define eutrophication.
    Why are hypoxic zones now more common and larger? List one coastal area where they
      have become a problem.
4. Nutrient limitation
 How can dams & reservoirs impact the nutrient and the sediment flux into the ocean?

5. Persistent Toxic Substances
 What does it mean for a substance to be non-biodegradable? If a substance is
   biodegradable, does that mean it will cause no harm to the environment?
 Why are toxic substances often concentrated in the polar regions, far from where they
   were released into the environment?
      a. Pesticides (many are chlorinated hydrocarbons such as DDT, chlordane)
          How are pesticides introduced to the ocean?
          What is biomagnifications?
          Why did the brown pelican become endangered? What has led to its recovery?
          We have an ‘Endangered Species List’ which creates federal regulations regarding
            species that are in immediate risk of extinction. Is this the best time to take
            action to protect a species? If not, what signal would you look for to warn you of
            future danger to an organism?
      b. PCBs – polychlorinated biphenyls
          Name two sources of PCBs in the marine realm.
           What is the danger of PCBs to marine or human life?
      c. Dioxins (also are chlorinated hydrocarbons)
          Name one source of dioxins into the environment and one impact.
      d. Heavy metals
          List 3 different heavy metals that can become toxic if accumulate in an organism.
      e. Radioactive wastes
          Why is nuclear waste dangerous?
           Knowing what you now know about sea floor geology, ocean chemistry, and marine
          organisms, what do you thing may happen to the containers of waste deposited in the
   6. Thermal pollution
 What is one source of thermal pollution in the ocean?
 Which marine organisms are most likely to be impacted by thermal pollution?

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