Lecture 15- Ocean Primary Production I

Question 1

why study primary production?

Answer 1

• Base of the food web
• Essential element of the global carbon cycle
• Represents half of the total global photosynthesis

Question 2

why is the global carbon a big topic?

Answer 2

it is closely related to our global warming problem

Question 3

photosyntheis

Answer 3

consumes carbon dioxide gas to form the particulate carbon of algae

Question 4

respiration

Answer 4

by all organisms produces carbon dioxide gas

Question 5

difference between photosynthesis and respiration by all of the organisms

Answer 5

is what sinks to the ocean floor

Question 6

half of oxygen comes from

Answer 6

photosynthesis in the ocean

Question 7

global carbon cycle- atmosphere

Answer 7

0.5%

Question 8

global carbon cycle- respiration and decay

Answer 8

0.01%

Question 9

global carbon cycle- lithosphere

Answer 9

99.5%

Question 10

Plankton

Answer 10

small organisms that drift with the ocean currents

Question 11

Phytoplankton

Answer 11

small cells (often single cells but sometimes chains or colonies of many cells) that contain chlorophyll and drift with ocean currents

Question 12

glucose from photosynthesis

Answer 12

serves as the energy source for all subsequent biochemical reactions

Question 13

Photosynthesis only depends on

Answer 13

the availability of water, carbon dioxide, and sunlight

Question 14

Primary production of photosynthesis requires

Answer 14

the uptake of plant nutrients for the construction of complex molecules that are needed to form new cellular components

Question 15

magnitude of the primary production

Answer 15

depends on the availability of essential plant nutrients as well as sunlight

Question 16

Net Primary Production (NPP)

Answer 16

• difference between the amount of CO2 consumed by photosynthesis and the amount of CO2 produced by respiration
• also known as the net gain or net loss of carbon within the cell

Question 17

primary production effectively consumes carbon dioxide and forms

Answer 17

particulate organic carbon that can sink into the deep ocean

Question 18

primary production

Answer 18

• makes oxygen

- requires light AND essential plant nutrients such as nitrogen, phosphorous, Si, and Fe

Question 19

phytoplankton

Answer 19

single celled organisms that carry out the vast majority of primary production in the ocean via chlorophyll

Question 20

diatoms

Answer 20

require silica

Question 21

Flagellates

Answer 21

mobile so they are able to avoid sinking in calm waters

Question 22

photosynthetic bacteria

Answer 22

• able to grow at very low nutrient concentrations

- main photosynthesizers

Question 23

At compensation light level

Answer 23

photosynthesis is on the speed of respiration

Question 24

photosynthesis increases with

Answer 24

intensity of light but respiration is constant

Question 25

At light levels below the compensation light level

Answer 25

- phytoplankton cells do not have sufficient light to photosynthesize fast enough to meet their basal metabolic needs - respiration exceeds photosynthesis

Question 26

below compensation light level

Answer 26

Negative values of net primary production

Question 27

At low light level

Answer 27

phytoplankton are light limited

Question 28

At optimal light levels

Answer 28

phytoplankton are light saturated

Question 29

At very high light levels

Answer 29

phytoplankton are photoinhibited

Question 30

compensation depth

Answer 30

depth at which the ambient light intensity is equal to the compensation light intensity

Question 31

The amount of nutrient needed for growth by an individual phytoplankton cell is proportional to

Answer 31

the cell's mass or equivalently to the cell's volume

Question 32

amount of nutrient that can be transported into a cell is proportional to

Answer 32

the cell's surface area

Question 33

smaller cells

Answer 33

can grow better at lower nutrient concentrations

Question 34

4 Phytoplankton Nutrients of Interest

Answer 34

- Nitrogen - Phosphorous - Silica (for diatoms) - Iron

Question 35

main source of nitrogen, phosphorous and silica

Answer 35

vertically mixing or upwelling of nutrient rich deep water to the surface

Question 36

What do you expect to happen to ocean primary production under a global warming scenrtio that enhances only temperatures of the surface layer of the ocean and leaves the deep layer cold (strengthens the thermocline/pcynocline)?

Answer 36

decrease

Question 37

thermocline

Answer 37

- hold phytoplankton near the sunlit surface ocean - significant barrier to upward mixing of nutrient rich deep water - stronger the thermal stratification, the stronger the inhibition of nutrient mixing

Question 38

Source of Iron

Answer 38

- Main source of iron input to the surface ocean is from dust blowing off of continents - Not abundant in the deep ocean

Question 39

Iron Limited Regions

Answer 39

Southern Ocean

Question 40

Primary production is enhanced

Answer 40

- high light | - high nutrients