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32 Cards in this Set
- Front
- Back
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Productivity |
- the rate of production of biomass - gC/m^2/year or gC/m^3/year |
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Biomass |
- mass of living material present at a given time - gC/m^2 or gC/m^3 - not necessarily a reflection of productivity |
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Standing crop |
- the total biomass of photosynthetic autotrophs - more production, more yield - less production, less yield |
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Productivity in coral reefs vs kelp forests |
- coral reefs: very high productivity, very small algal biomass - kelp forests: lower productivity than coral reefs, large algal biomass |
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Primary productivity |
- rate of carbon fixation by photosynthesis |
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Gross primary production |
= energy (or carbon) fixed by photosynthesis per unit time |
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Net primary production |
= energy (or carbon) fixed by photosynthesis - energy (or carbon) lost via respiration per unit time |
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Geographic variability in productivity |
- highest primary production in upwelling zones, continental shelves, and high latitudes - lowest primary production in the middle of ocean gyres |
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What is a low nutrient environment dominated by? |
- small phytoplankton like cyanobacteria |
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What is a high nutrient environment dominated by?
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- large phytoplankton like diatoms |
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What is the neritic zone dominated by? |
- drop off of the continental shelf - high nutrients - large phytoplankton - more phytoplankton - short food chains especially in upwelling zones - high fish biomass supports fisheries |
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Secondary productivity |
- rate of biomass production by consumers - herbivores, carnivores, detritivores - dependent on primary productivity and efficiency of energy transfer |
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Food chain |
- linear depiction of energy flow 1) primary producer- autotroph 2) primary consumer- herbivore 3) secondary consumer- carnivore 4) tertiary consumer- secondary carnivore |
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Food web |
- more realistic and complex than a food chain |
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How much energy is passed to the next trophic level? |
- 10% |
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How is energy lost at each trophic level? |
- some material is not eaten - not all that is eaten is converted into biomass |
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Production efficiency |
- proportion of E that is incorporated into the new biomass - varies by group - typically around 10% |
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What limits the length of food chains? |
- loss of energy at each level |
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What does having larger phytoplankton mean? |
- shorter food chains - less energy lost - more fish / higher biomass at top of chain - large phytoplankton are food for planktivorous fish which are food for piscivorous fish |
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What does having small phytoplankton mean? |
- longer food chains - more energy lost - less fish / lower biomass at top of chain - small phytoplankton are food for small zooplankton which are food for large zooplankton which are eaten by planktivorous fish which are eaten by piscivorous fish |
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Where is 90% of marine catch from? |
- continental shelves - greatest primary production in upwelling zones |
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Polar food webs |
- highly productive in the summer - high nutrients - simple, short food web |
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Southern ocean |
- krill is keystone species in southern ocean - trophic efficiency to top predators is lower than 10% - only 3 levels - when krill is low, dominated by copepods and amphipods |
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Open ocean |
- low nutrient levels - small phytoplankton - high number of phytoplankton - long food chains - low numbers and biomass of large animals |
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What does low nutrient levels do? |
- small phytoplankton - long food chains - open ocean |
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What do high nutrient levels do? |
- large phytoplankton - short food chains - continental shelves and upwelling zones |
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Bacteria in open ocean |
- increase efficiency of open ocean food webs - allow energy from dissolved organic matter to be recycled and used by higher tropic levels |
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How productivity and food webs vary in oceans |
- neritic zone: highest biomass of fish - epipelagic zone: much lower fish biomass - mesopelagic to abyssopelagic (deep sea): lowest fish biomass |
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Why is primary production usually limited to? |
- the epipelagic zone - except for chemosynthetic communities in the deep sea - organisms below rely on food that falls from above |
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Marine snow |
- collection of organic and inorganic material held together by extracellular polysaccharides - increases sinking rate of small organisms |
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Characteristics of deep sea |
- dark - cold - little food - high pressure - constant conditions - animals have adaptations for the conditions |
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Adaptations of mesopelagic fish |
- live from around 200 m to 1000 m (twilight zone) - large eyes - bioluminescence / counterillumination - red in color (appear dark grey or black) - large mouths and teeth, and large stomachs - lures to help catch prey - hermaphroditism and parasitic males |
