MASC Final (1)
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How does light change as it travels through seawater? What causes those changes?
Light decreases exponentially - hits 0% sunlight approximately 60% through photic zone.
Changes are caused by wavelength of light (blue and green penetrate most deeply)
Also affected by depth of light penetration w/ respect to photosynthesis (angle of incident light, suspended sediments and particles, productivity levels, presence of colored, dissolved materials). 4
What controls primary productivity in ocean? 4
- 1. Availability of nutrients (upwelling, coastal, gyres, etc)
- 2. Depth of sunlight
- 3. Extent of water mixing
- 4. Amount of pollution
How do physical factors influence primary productivity? What are requirements for primary productivity? (5)
- 1. Sunlight
- 2. CO2 levels
- 3. Nutrients: Nonlimiting - C, H, O, Mg. Limiting: N, P, Fe, Si. Needed in small amounts: Co, K, Cu, Zn, Mo (not considered limiting).
Also need chlorolphyll, amino acids, etc.
How do factors that limit primary productivity vary in different regions of the ocean?
How are general patterns of ocean circulation, underlying factors driving those patterns, and how these circulation patterns affect nutrient distribution & productivity related?
Solar radiation --> wind patterns. Wind is major driver of ocean circulation --> give example of upwelling region. Wind, distribution of dusts, El Nino, wind differences in open ocean and upwelling.
In photic zone, why is there lots of O2 in euphotic zone? Why is there a huge drop in O2 right underneath? Why does P mirror N? How do we know that we don't have an O2 beaker ocean?
- 1. Product of photosynthesis
- 2. Used in respiration
- 3. Organic matter + O2 --> CO2 + H2O.
4. If we did have beaker ocean, it would deplete exponentially, then decrase again.
What organisms are the most important primary producers in the ocean? 2
Phototrophs and chemolithoautotrophs in deep sea hydrothermal vents, etc.
What are ecological strategies of phytoplankton? (5)
Then 4 extras.
- Niche specialization:
- 1. Use different wavelengths or broad wavelengths of incoming light
- 2. Preference for diff depth layers with different light spectrums (prochlorococcus - can absorb deep blue light vs. synechococcus)
- 3. Even within same group of organisms, specialists for low & high light conditions.
- 4. High genetic diversity/variability within a genome to allow adaptations.
- 5. Seasonal - change in chlorophyll content increases as an adaption to lower light levels.
ALSO, in nutrient-limited areas: high SA:V ratio, smaller nutrient storage, lesser grazing defense, faster growing.
In nutrient-rich areas: larger cell sizes, better grazing defense, requier lots of nutrients to grow (ex diatoms).
What specific factors complicate our efforts to investigate marine organisms and marine environments, in particular deep sea and high latitude environments? Why is it difficult to accurately assess marine biodiversity in deep ocean? 5
- 1. Technology limitations
- 2. Sampling bias (alvin)
- 3.Mesopelagic zone is most difficult
- 4. We don't know extend of symbiosis which increases biodiversity by two
- 5. Seldom seen
What are examples of major groups of phytoplankton? (4)
1. Diatoms - singlecelled euk, frustule made of silica, dominate nutrient rich areas.
2. Dinoflagellates - unicellular eukaryotes, smaller than diatoms, some can produce toxic blooms, some are heterotrophs.
3. Coccolithophores - unicellular eukaryotes (smaller than diatoms and dinos), calcium carbonate shell, dominate less nutrient rich/productive areas.
- 4. Cyanobacteria: synechococcus (1 um - mysteriously motile found in oligotrophic ocean)
- prochlorococcus - 0.5 um, responsible for 30-80% of primary productivity in oligotrophic ocean.
- trichodesmium - heterocysts fix nitrogen (tropics/subtropics) also phytoplankton. crocosphaera - fixes N at night found in tropics. Dominant autotrophs due to abundance and efficiency in N Pacific.
What is the nature of food webs at hydrothermal vents?
Short food chains
Whta kinds of organisms are found at hydrothermal vents and why are they only found in these environments?
- Hydrothermal vents: chemolithoautotrophic metabolism.
- One example: bacteria that can do methanogenesis: CO2 + 4H2 --> CH4 (organic matter) + 2H2O.
- Chemolithoautotrophic microbes
- If we have methanogenesis, ANME
- (anaerobic methane oxidizers) archaea.
Sulfide-oxidizing: (H2S --> HSO4): beggiato, athioploca,thiomargarita
- Macrolife: Vent shrimp, vent
- polychate, tubeworms (riftia)
What is the basis of life at hydrothermal vents?
An inorganic e- donor (H2S, S, NH3, H2, Fe2+ or Mn2+) yields electron which are transferred to an electron acceptor (O2, NO3, Fe3+, Mn4+, SO42-, CO2) Requires ATP and makes organic material CH2O.
- 2. The energy yield of this rxn is saved as ATP
- 3. ATP is required for CO2 fixatno into biomass and synthesis of biomolecules that the bacterium requires for maintenance and growth.
Where do anaerobic reactants come from for chemolithoautotrophic metabolism? Which types of chemolithotrophs do not require O2?
Interactions of rock and water at high temperature. Methanogenic archaea and sulfate-reducing bacteria.
Provide example of sulfur-oxidizing bacteria
Beggiatoa - largest free-living sulfide-oxidizing bacteria.
Bacterioplankton & Microbial Loop
How are the activities of bacteria, circulation of water masses, and locations at which primary productivity occur linked together?
Higher primary productivity --> higher bacteria activity. Location - based on temperature. Degradation of organic matter etc. Also think about coasts - coastal & upwelling regions have tons of nutrients and primary productivity.
What is the role of heterotrophic bacteria in the microbial loop?
- 1. Repackaging organic matter and respiring organic matter
- 2. Regenerating nutrients - determines location & depth of nutrient regeneration (important for primary productivity).
Degradation of dead biomass & fecal pellets AND recycling of nutrients (N, P, minerals) to fertilize phytoplankton.
Carbon: Bacteria can transform DOC into CO2 or incorporate into bacterial biomass that is reintroduced into food chain.
What are links between life in the deep sea and its dependence on processes in the surface ocean in terms of carbon transport/transformation, oxygen availability, and sediment characteristics?
Organic rich sediments are found in higher areas of primary productivity - much more sinking, burying organic carbon (Gulf of Mexico).
The more active heterotrophic bacteria are --> less organic matter makes it to the deep.
- Oxygen: High in regions of high photosynthesis, then dips, then increases in water REMEMBER THESE PROFILES
- (primary productivity).
Bulge of nutrients - not being utilized bc not in photic zone.
What is the relationship between primary productivity and fisheries?
Most prolific fish yields are found in coastal & upwelling regions (most primary production per mg C/m^2 basis).
Increased primary productivity --> increased biomass, so in upwelling/coastal regions, food web is much shorter than open ocean --> larger zooplankton (diatoms) --> larger fish yield.
Describe global distribution of nutrients, light, and phytoplankon/zooplankton abundance in mid-latitudes, high latitudes, and tropical latitudes.
What are controls on biodiversity in the ocean?
Amount ofn utrients, primary productivity, temperature
What specific problems are associated with trying to harvest fish according to max sustainable yields?
- 1. We don't know original baseline population size
- 2. Doesn't take into account effect on entire ecosystem that target fish has role in.
- 3. Bycatch
- 4. Generally, maximum sustainable yields are optimistic.
What are differences between mesopelagic and bathypelagic zones?
Mesopelagic (200-1000 m) - receives light, but not enough for primary productivity. Affects animal behavior on diurnal schedule. Many species are vertical migrators (nocturnal).
Bathypelagic (1000-2000 m) vs. Bathyal: 200-2000 m. Blind animals, fulltime residents with minimum energy expenditure, less biomass
What is the impact of commercial fisheries on food webs? Think of specific examples of changes in trophic cascade.
Fishing down the food chain
Exaples of human impact on the marine environment/marine organisms
1. Pushing tuna farms into open waters off coast of US (shooting of sea lions - predators, overfishing of sardines).
3. Combustion of fossil fuels on calcium carbonate organisms.
How do organisms divide habitat and ecologic niche in mesopelagic zone? (4)
- 1. Vertical movement in water column
- 2. Timing - different species inhabit different depths -timesharing of water column.
- 3. Differential physiology and behavior of feeding and reproduction
- 4. Niche differentiation - don't be/eat in same place at same time
What kinds of organisms & biological processes have been discovered in the deep sea over the past several decades and why have they been a surprise to us? (think of specific examples)/
- 1. Deep sea cold water corals - thought only existed in tropical/temperate environments.
- 2. Deep sea can have seasons based on detritus from upper areas.
- 3. New species of shrimp thought to be extinct found in 2006.
What is the Gakkel Ridge?
Slowest spreading center
How do Arctic and Antarctic differ? How are they similar? 3
Animal life: Antarctica has rich sea life, but no terrestrial life past nematodes and microbes except for emperor penguin.
Arctic has relatively short marine food chain.
Territory and sovereignty - commercial exploitation, Norwegian etc.
In what ways may climate change in high latitude (polar) environments affect lower latitude environments? 3
- 1. Melting of glaciers (ice sheets-land and sea ice - ocean) increasing sea levels for everybody.
- 2. Putting freshwater into water column, causing density stratification and deeper thermocline.
- 3. Albedo effect
What evidence do we have for rapid climate change in the Arctic? (5)
- 1. Surface air temp rising in high latitudes
- 2. Spread of marine species (from South to North - invasive species)
- 3. Enhanced melting of Greenland ice sheet
- 4. Sea ice coverage has decrased by 50%
- 5. Changes in sea level out of sync with Arctic Oscillation
What evidence do we have for envr change in antarctica? 3 difficulties; 3 reasons
What role do morraines play?
Highly variable -difficult to pin down
- 1. Difficult to record temperature changes
- 2. No records on marine ice sheet thickness
- 3. Glaciers are far thicker than sea ice - determining changes in precipitation/loss is challenging.
There is evidence in Palmer peninsula (permanently manned stations) - changes in penguin pops, dramatic loss of ice shelves (Larsen B), more rapid movement of Pine Island Glacier near Larsen shelf after berakup.
Tidewater glaciers have shallower morraines. Once warmer water tops morraine, it can undercut glacier, causing grounding line to retreat.
What is the difference between photosynthesis and chemosynthesis?
Photosynthesis: Process of converting inorganic carbon into organic carbon and water. Requires light.
Chemosynthesis: biological conversion of inorganic carbon molecules and and nutrients into organic matter using oxidation of inorganic molecules (H2, H2S, CH4)
What are characteristics of the Arctic Ocean that distinguish the Arctin basin from other ocean basins?
- 1. Large influx of terrestrial material into Arctic basin (freshwater) Gets 10% of global riverine input
- 2. Bering strait prevents water mixing with Pacific, whereas there's a lot more exchange with Pacific via Norwegian Sea (Fram Strait)
What are the 7 types of chemolithotrophs? Which are the most common? Which do not require oxygen?
What is the general formula for methanogens?
- 1. Sulfur oxidizing
- 2. Sulfate reducing H2 (no o2)6.
- 3. Nitrifying
- 4. Methanogenic archaea H2 (No O2, uses CO2)
- 5. Iron & Magnesium oxidizing bacteria
- 6. Hydrogen-oxidizing bacteria H2
- 7. Methylotrophic bacteria (CH4)
CO2 + 4H2 --> CH4 + 2H2O
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