Lecture 3 & 4 - Marine Primary Production Flashcards
What is marine primary production
Fixiation of carbon (c) from inoganic sources dissolved in the water column and turned into organic carbon
What are the marine primary producers and which is most important (6)
Phytoplankton Macroalgae (key) Seagrass Mangrove Saltmarsh Coral Reefs
What is the equation for Photosynthesis
NOT CORRECT SYMBOLS
6 CO2 + 12 H2O –(light)–> C6H12O6 + 6 O2 + 6 H2O
What is primary productivity so important (obvious answer)
Primary production always = the start of the food web suporting nearly all life on earth, marine production is of vital importance for socioeconomic and enviromental reasons
What is primary productivity so important (no so obvious)
Primary production controls the earths atmopshere and so has important implications with regards to global warming!
Rate of 7 primary production centers in the maine enviorments and their production in
gC per meter squared per year
Arctic Ocean (0.7-1) Antarctic Ocean (40-260) - more upwelling than ^^ temperate seas, uk (70-180) Temperate seas coastal (110-220) Coastal Upwellins (70-180)
Seagrass and kelp (550-1800) Coral reefs (1500-3700)
What two processes in Photosynethesis a coupling of?
- The conversion of light energy into chemical energy
2. The conversion of inorganic carbons (eg CO2) into organic carbon
What two key processes are involved with photosynthesis
The electron transport train
The Calvin Cycle
What is the electron transport chain?
An electron transport chain (ETC) is a series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions, and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. This creates an electrochemical proton gradient that drives ATP synthesis, or the generation chemical energy in the form of adenosine triphosphate (ATP).
What occours in the ETC of chloroplasts
In chloroplasts, light drives the conversion of water to oxygen and NADP+ to NADPH with transfer of H+ ions across chloroplast membranes
Draw the Basics of the ETC
use colours to make it better
Draw the Calvin Cycle
Use colours !
Explain light as a limiting factor
Light energy is absorbed exponentially with distance in the water column, much of the solar radiation is in the infarRED portion of the spectrum and is absorbed within the first 2m of the water colour
What is the Beer-Lambery Equation
This is used to calculate the penetrative depth of light and is:
E = Eo e^(-kz)
where Eo is light at surface and K is a constant and Z is depth
What is Zeu and Zm
Zeu = This is the eupotic zone where photosynthesis can occour, Zm = mixing depth which is needed to nutrient circulation
How can the euphotic zone be measured with a Secchi Disk?
Zeu = 2.7 x Zs (where Zs is the depth of the secchi disk
What is the photocompensation depth
The compensation point is the amount of light intensity on the light curve where the rate of photosynthesis exactly matches the rate of respiration. At this point, the uptake of CO2 through photosynthetic pathways is exactly matched to the respiratory release of carbon dioxide, and the uptake of O2 by respiration is exactly matched to the photosynthetic release of oxygen.
What is the critical depth
The point where photosynthesis can no longer occour
Explain the thermocline and mixing depth as a limitation of PS
This is the thermocline of the change of temp down through the water column, the around of work required to mix water of different densities is a function of the temperature, the larger the difference between the two water bodies the more energy needed
Could you draw thermal stratification, showing the mixing depth ?
maybe, maybe not
Explain the situation that occurs when mixing depth < euphotic depth
The eupothic zone is only as deep as the bottom of the mixing depth therefore the mixing depth (Zm) and nutrients therein become the limitation factor and will not extend down into the bottom of the euphotic depth (Zeu)
Explain the situation that occours when mixing depth > eupotic depth
Photosynthesis can only occur up to the the Zeu, it will not extend down to the bottom on the Zm due to light limitation
What six processes can influence the Zm (mixing depth) and therefore the introduction on nutrients into the Zeu (euphotic zone)
Tides Surface Waves Gyrals and Ekman Spiral Langmuir circulation Upwellings Currents
Explain what occours on upwelling and the example
The cold nutrient rich waters are forced up into the euphotic zone which allows for high primary production
Explain nutrient limitation
In marine systems the limiting nutrient is normally nitrogen, although it may be other. If too much is introduced (possibly man made) then eutrophication can occur in water systems
What are the two ways you can measure Primary production
- Increase in Biomass
a) Chlorophyll a
b) Fluorescence signal
c) remote sensing of spectra - Productivity
a) evolution of 02
b) increase in Carbon-14 update
