L2 Primary productivity

Question 1

Difference between phyto and zoo plankton

Answer 1

Phyto - photosynthesise, all algae. mostly near to continents
Zoo - Consume phytoplankton. more abundant where phytoplankton are.

Question 2

NPP

Answer 2

Net Primary Productivity

amount of inorganic co2 fixed into organic compounds by autotrophs.

Question 3

Which environments have greater productivity?

Answer 3

Ocean and land pretty much equal 
Benthic usually more than pelagic.
Highest is coral reefs, 1500-3700
Salt marshes also high - 250-2000
Arctic ocean and cntral ocean gyres lowest

Question 4

Where is the highest terrestrial PP?

Answer 4

Rainforests - 460-1600

Temperate farmland - 550-700

Question 5

How does oceanic PP compare to terrestrial?

Answer 5

Similar annual NPP
Oceanic rapid turnover of autotrophic biomass and very small biomass involved.
Entire global population of phytoplankton is replaced every 2-6 days.

Question 6

What is a coccolithophore?

Answer 6

Organism with CaCO3 skeleton
Reflective, can be seen from space
20micrometers diameter.
can double population in a day

Question 7

what seasonal patterns of PP are in the tropics?

Answer 7

always nutrient limited
Small peaks due to change in composition of organisms over the year.
Coccolithophores and diatoms always present
Dinoflagelltes in summer

Question 8

what seasonal patterns of PP are in the Temperate regions?

Answer 8

Winter autumn - light limited and cold
Spring - bloom Thalassiosira, Chaetoceros
Summer - becomes nutrient limited so drops. Chaetoceros, Skeletonema
similar fluctuations to FW lakes

Question 9

what seasonal patterns of PP are in the polar regions?

Answer 9

Autumn, winter, light limited.
Spring, summer bloom
Much overturn so more productive

Question 10

What determines phytoplankton species composition?

Answer 10

Different stressors in an area

Different species can tolerate different stressors, so have impact on species selection.

Question 11

What causes a spring bloom?

Answer 11

increased light and nutrient availability

Water warmed so less dense, increasing stability and reducing overturn

Question 12

What is sea ice algae?

Answer 12

Mainly diatoms which live in brine channels

Question 13

What happens to fixed carbon if not eaten?

Answer 13

Falls to sea bed. may be broken down before reaching the floor.

Question 14

How are nutrients released within the sea?

Answer 14

decomposition of organic matter

Upwelling replenishes nutrients

Question 15

How does equatorial upwelling occur?

Answer 15

Prevailing winds meet at equator and merge to run parallel
Ekman transport moves water away from equator towards N and S, and upwelling occurs along equator.
V V important

Question 16

What affects Light limitation of PP?

Answer 16

By turbidity, prevents deeper penetration of light

Phytoplankton affect photic zone depth by shading.

Question 17

What is usually the limiting nutrient?

Answer 17

N.
NO3- is an important source of N
Some phytoplankton eg cyanobacteria and Trichodesmium can fix N
Adding N artificially can enhance HAB and O2 defecient dead zones.

Question 18

Where do phytoplankton have most favourable conditions??

Answer 18

Neritic - Shallow so light, and nutrients cant sink too far