Lecture 9- Ocean primary productivity

Question 1

What is the function of photosynthesis?

Answer 1

-light energy is captured by chlorophylls and stored in chemical bonds of carbohydrates (e.g glucose) -6CO2+6H2O= C6H12O6+ 6O2

Question 2

How much of primary productivity occurs in the oceans?

Answer 2

-1/2

Question 3

What is meant by primary productivity?

Answer 3

-taking inorganic material and changing them into organic (sunlight into energy)

Question 4

What is respiration in relation to photosynthesis?

Answer 4

-the opposite reaction -C6H12O6+602=6CO2+6H2O -there must be more photosynthesis than respiration

Question 5

What does chlorophyll in an environment indicate?

Answer 5

-photosynthesis -but not at night! they then respire

Question 6

How does the distribution of chlorophyll change seasonally?

Answer 6

• it is more abundant in areas that are experiencing summer (mostly)
• dark blue= no chlorophyll

Question 7

What organism contribute to marine primary productivity?

Answer 7

-algae (green, brown and red) -plants (seagrasses) -phytoplankton(bacterial and eukaryotic)

Question 8

What is the algal contribution to marine primary productivity?

Answer 8

-they are limited in their growth by depth -only up to 50m as they have to be attached to the sea floor -only in coastal areas, not a major contributor to marine primary productivity, more habitats though!

Question 9

What is the plants’ contribution to marine primary productivity?

Answer 9

-also only around coast -non-significant contributors

Question 10

Who are the biggest contributors to primary marine productivity?

Answer 10

-phytoplankton as they are not limited by depth, can float

Question 11

How large can phytoplankton blooms be?

Answer 11

-1000s of kilometers

Question 12

What are the non-photosynthetic primary producers in the sea?

Answer 12

-chemoautotrophic bacteria by the volcano vents, not a major contributor to marine primary productivity

Question 13

What are the characteristics of cyanobacteria? (type of cell, cell wall type and single celled?)

Answer 13

-part of phytoplankton -prokaryotes -gram negative cell walls -can be single celled, filamentous, or form thalli

Question 14

In what ways can cyanobacteria be motile?

Answer 14

-can be motile (flagellar, gas vesicles=so they float, gliding) -gliding= freshwater

Question 15

What colour are cyanobacteria and why?

Answer 15

-typically blue-green due to phycobiliproteins -aslo chlorophyll a

Question 16

What element can cyanobacteria fix?

Answer 16

N2 -key nutrient for protein, these can take it out of the air and capture it so others can use it too

Question 17

Is it true that cyanobacteria form toxins?

Answer 17

-some do -often freshwater that doesn’t move very much

Question 18

Give an example of a cyanobacteria?

Answer 18

-Prochlorococcus -one of the most important organisms in the oceans

Question 19

Can cyanobacteria form colonies?

Answer 19

• Trichodesmium
• common in tropical waters -colonies of aggregated filaments
• forms visible blooms
• in warmer waters
• can control their buoyancy and can float on the top

Question 20

What is the colour and structure of diatoms?

Answer 20

-golden brown due to accessory pigments (chlorophyll c) -surrounded by intricate structures made out of glass= their cell wall -second most important primary producers after cyanobacteria -build a frostule= glass house, pure glass -little holes= for gas exchange, as glass nonpermeable

Question 21

What is the structure of the glass house of diatoms?

Answer 21

• glass houses made up of two valves, (like a petri dish, one smaller and fits into the other one)
• then divides and form new 2 valves on the inside (so four cells now)
• but there is quite lot of variation, some insert girdle bands=make it possible to grow longer

Question 22

What are the two major groups of diatoms?

Answer 22

1.Centric diatoms 2.Pennate diatoms

Question 23

What are the characteristics of centric diatoms?

Answer 23

• radial symmetry -nonmotile= do not have flagellas
• planktonic(means they float around carried by the currents etc.)

Question 24

What are the characteristics of pennate diatoms?

Answer 24

-bilateral symmetry -motile(gliding system) -sessile on rocks and ice -only sperm cells have flagellas -non-planktonic

Question 25

What do centric diatoms have spines for?

Answer 25

-some centrics have long spines= helps them in the currents -the spines when divide hold cells together= colony

Question 26

What is the structure and motility system of the pennate diatoms?

Answer 26

-pennates, have long slits that goes almost down to the middle -this slit secretes carbohydrate= this will help it stick to a surface, then motor molecules in the membrane and then pull the cell along -leave a little goo train, more an more on and then other organisms eat it biofoulling -they store some of the carbs they photosynthesise= lipids and chrysolaminarin sugar -important in arctic regions, not as important in coastal and warm oceans

Question 27

Where do lot of pennate diatoms grow?

Answer 27

-grow beneath polar sea ice -estimated to contribute 20% of primary productivity of Southern Ocean

Question 28

What is the lifecycle of diatoms?

Answer 28

• Form resting stages and spores to survive conditions unsuitable to growth
• cytoplasm is dense with lipid droplets and poly-phosphate granules
• can be dormant for decades
• when the ice melts= they float= form resting spores, withstand until ice forms again

Question 29

What is the colour of haptophytes?

Answer 29

-golden brown due to accessory pigments (chlorophyll c)

Question 30

What is the haptophytes’ cell wall made of?

Answer 30

-calcium carbonate scales (coccoliths)

Question 31

What is the way of getting energy for haptophytes?

Answer 31

-they are both heterotrophic and autotrophic (some)