L2 Primary productivity Flashcards Preview

Marine ecology and physiology > L2 Primary productivity > Flashcards

Flashcards in L2 Primary productivity Deck (18)
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1
Q

Difference between phyto and zoo plankton

A

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

2
Q

NPP

A

Net Primary Productivity

amount of inorganic co2 fixed into organic compounds by autotrophs.

3
Q

Which environments have greater productivity?

A
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
4
Q

Where is the highest terrestrial PP?

A

Rainforests - 460-1600

Temperate farmland - 550-700

5
Q

How does oceanic PP compare to terrestrial?

A

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.

6
Q

What is a coccolithophore?

A

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

7
Q

what seasonal patterns of PP are in the tropics?

A

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

8
Q

what seasonal patterns of PP are in the Temperate regions?

A

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

9
Q

what seasonal patterns of PP are in the polar regions?

A

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

10
Q

What determines phytoplankton species composition?

A

Different stressors in an area

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

11
Q

What causes a spring bloom?

A

increased light and nutrient availability

Water warmed so less dense, increasing stability and reducing overturn

12
Q

What is sea ice algae?

A

Mainly diatoms which live in brine channels

13
Q

What happens to fixed carbon if not eaten?

A

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

14
Q

How are nutrients released within the sea?

A

decomposition of organic matter

Upwelling replenishes nutrients

15
Q

How does equatorial upwelling occur?

A

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

16
Q

What affects Light limitation of PP?

A

By turbidity, prevents deeper penetration of light

Phytoplankton affect photic zone depth by shading.

17
Q

What is usually the limiting nutrient?

A

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.

18
Q

Where do phytoplankton have most favourable conditions??

A

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