Lecture 3 & 4 - Marine Primary Production

Question 1

What is marine primary production

Answer 1

Fixiation of carbon (c) from inoganic sources dissolved in the water column and turned into organic carbon

Question 2

What are the marine primary producers and which is most important (6)

Answer 2

Phytoplankton
Macroalgae (key)
Seagrass
Mangrove
Saltmarsh
Coral Reefs

Question 3

What is the equation for Photosynthesis

Answer 3

NOT CORRECT SYMBOLS

6 CO2 + 12 H2O –(light)–> C6H12O6 + 6 O2 + 6 H2O

Question 4

What is primary productivity so important (obvious answer)

Answer 4

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

Question 5

What is primary productivity so important (no so obvious)

Answer 5

Primary production controls the earths atmopshere and so has important implications with regards to global warming!

Question 6

Rate of 7 primary production centers in the maine enviorments and their production in

gC per meter squared per year

Answer 6

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)

Question 7

What two processes in Photosynethesis a coupling of?

Answer 7

1. The conversion of light energy into chemical energy

2. The conversion of inorganic carbons (eg CO2) into organic carbon

Question 8

What two key processes are involved with photosynthesis

Answer 8

The electron transport train

The Calvin Cycle

Question 9

What is the electron transport chain?

Answer 9

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).

Question 10

What occours in the ETC of chloroplasts

Answer 10

In chloroplasts, light drives the conversion of water to oxygen and NADP+ to NADPH with transfer of H+ ions across chloroplast membranes

Question 11

Draw the Basics of the ETC

Answer 11

use colours to make it better

Question 12

Draw the Calvin Cycle

Answer 12

Use colours !

Question 13

Explain light as a limiting factor

Answer 13

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

Question 14

What is the Beer-Lambery Equation

Answer 14

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

Question 15

What is Zeu and Zm

Answer 15

Zeu = This is the eupotic zone where photosynthesis can occour,
Zm = mixing depth which is needed to nutrient circulation

Question 16

How can the euphotic zone be measured with a Secchi Disk?

Answer 16

Zeu = 2.7 x Zs (where Zs is the depth of the secchi disk

Question 17

What is the photocompensation depth

Answer 17

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.

Question 18

What is the critical depth

Answer 18

The point where photosynthesis can no longer occour

Question 19

Explain the thermocline and mixing depth as a limitation of PS

Answer 19

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

Question 20

Could you draw thermal stratification, showing the mixing depth ?

Answer 20

maybe, maybe not

Question 21

Explain the situation that occurs when mixing depth < euphotic depth

Answer 21

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)

Question 22

Explain the situation that occours when mixing depth > eupotic depth

Answer 22

Photosynthesis can only occur up to the the Zeu, it will not extend down to the bottom on the Zm due to light limitation

Question 23

What six processes can influence the Zm (mixing depth) and therefore the introduction on nutrients into the Zeu (euphotic zone)

Answer 23

Tides
Surface Waves
Gyrals and Ekman Spiral
Langmuir circulation
Upwellings
Currents

Question 24

Explain what occours on upwelling and the example

Answer 24

The cold nutrient rich waters are forced up into the euphotic zone which allows for high primary production

Question 25

Explain nutrient limitation

Answer 25

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

Question 26

What are the two ways you can measure Primary production

Answer 26

1. Increase in Biomass
   a) Chlorophyll a
   b) Fluorescence signal
   c) remote sensing of spectra
2. Productivity
   a) evolution of 02
   b) increase in Carbon-14 update