Week 2: Primary productivity Flashcards
Primary productivity is
The synthesis of organic materials from inorganic substances by photosynthesis or chemosynthesis
Primary producers are often called
Autotrophs or Lithotrophs
Autotrophs are able to
Produce their own food from energy and inorganic molecules
Lithotrophs are derived by greek terms
Litho (rock) and troph (consumer) meaning eaters of rock
Photosynthesis: light reaction
Traps light energy and converts it to chemical potential energy
Photosynthesis: dark reaction
Uses chemical potential energy to fix carbon via the Calvin cycle
Energy from light used to reduce carbon from CO2 and to split H2O is an
Electron Donor
Photosynthesis in the ocean provides
Oxygen and energy, which would result in little marine life without it
Photosynthesis provides what for us
Food and oxygen
The enzyme that fixes CO2 into organic carbon and is probably the most important enzyme on earth
Rubisco
Collects light energy for photosynthesis
Chlorophyll
Pigments occur in
The light harvesting complex
Through excitation, pigments funnel energy to
The reaction centre
Organisms that undergo chemosynthesis convert
One or more carbon molecules into organic matter using the oxidation of inorganic compounds (such as Sulphide) or methane as a source of energy
Many organisms for fisheries obtain a portion of their diet from
Chemosynthetic food sources
Seagrass habitats provide
Chemosynthesis-based ecosystem services
Primary productivity is expressed in
Grams of carbon bound into organic material per square metre of ocean surface area per year (c/m^2/yr)
Percentage of contribution to primary productivity
90% phytoplankton
2-5% seaweed
?% sea grass
2-5% chemosynthesis
The ocean makes up what percentage of the earths surface
93%
Overall contribution to earths primary productivity from the ocean
50%
90% of our fish comes from what percent of the ocean (also percentage of coastal waters)
7%
Coastal waters contribute to what percent of marine productivity
25%
Importance of primary productivity
- Fixes carbon and is the base of marine food webs
- Provides oxygen that we and fish like to breathe
- Role in carbon controlling atmospheric CO2 and climate (e.g biological pump)
Limitation of productivity
Law of the minimum
Main limitation to primary productivity
Light
Euphotic zone
- Section of the ocean where primary productivity occurs
- characterized as the depth at which 1% of surface light remains
- Enough light for positive growth and productivity when costs of respiration are accounted for
Euphotic zone depth
200m at its clearest
Coastal seas have much _____ photic zone than offshore oceanic water
Shallower
