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1 SOES1008 earth and ocean systems > ocean primary production > Flashcards

ocean primary production Flashcards

1
Q

what is primary production in the oceans?

A

Global primary production- fixing of gaseous or dissolved CO2 to produce organic matter

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2
Q

what plant dominates terrestrial production?

A

Vascular plants dominate terrestrial production with only minor contributions from algae

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3
Q

how much do oceans contribute to the global primary production

A

Oceans contribute around half of global primary production

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4
Q

what is oceanic primary production dominated by?

A

Oceanic primary production is dominated by unicellular algae known as the phytoplankton
Phytoplankton from the basis of all major oceanic food webs

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5
Q

what is phytoplankton?

A

Phytoplankton: biomass dominated by 3 single celled algae.

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6
Q

what are diatoms?

A

Diatoms have a silicon shell made of opal. They are the largest phytoplankton, desirable as food for larger zooplankton and small herbivorous fishes.

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7
Q

what are dinoflagellates?

A

Dinoflagellates: smaller than diatoms, weak motile. Readily decomposable cellulose cell wall, but none have hard parts. Tend to dominate the phytoplankton when silica is unavailable.

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8
Q

what are coccolithophores?

A

Coccolithophores: mosaic of calcite plates covering cell walls. Less abundant than diatoms. Tend to favour warm ocean waters.

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9
Q

what is a diatom algae?

A

Diatom algae:
Cell wall made of opal. The oceans main primary producer. Often colonial, booms can form large tangled masses. Fossil records since 185Ma.

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10
Q

why do diatoms have a simica cell wall?

A

Diatoms- why a silica cell wall?
Less energy to make than organic cell wall
Mechanical strength, finest pores prevent penetration of viruses. Are used for nanotechnology. Due to their cell walls.

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11
Q

why do dinoflagellates have an organic cellulose wall?

A

Dinoflagellates: organic cellulose wall.
May be autotropic, or heterotrophic.
Have 2 flagella, giving them motility
No hard parts in the cell, but produce cysts in fossil record.
Serious allergic reactions to swimmer
Render shellfish toxic.

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12
Q

how small are dinoflagellates?

A

Very small, 2 um to 2 mm.

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13
Q

what are harmful algal blooms?

A

Red tides “harmful algal blooms”, some species contain toxins, concentrations may kill fish.

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14
Q

what do dinoflagellates hold for predators?

A

Bioluminescent s an alarm call, predator is illuminated.

Predator itself is eaten by something bigger.

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15
Q

what are coccolithophores algae?

A

Coccolithophores algae:
Unicellular algae secrete tiny calcite platelets.
Widespread

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16
Q

why are coccolithophores abundant in ancient warmer seas?

A

Abundant in ancient warmer seas

May have problems with ocean acidification

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17
Q

what colour are coccolithophorid?

A

• Coccolithophorid blooms give distinct pale “chalky” colour. Large areas in the summer, which can be seen by satellite.

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18
Q

what is chalk made of?

A

What chalk is made of: abundant in ancient warmer periods. Vast deposits in Europe from warm Cretaceous age shelf seas. Chalk also contains opaline flints which are the remains of siliceous algae.

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19
Q

what controls primary production?

A

Controls on primary production:

• Light is key prerequisite for photosynthetic primary production.

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20
Q

what elements are readily obtained from dissolved CO2 and sea water?

A

Of the major elemental building blocks of life, H, C, O, and S, are readily obtainable from dissolved CO2 and sea water. P and N are hard to come by. Therefore these 2 limit production

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21
Q

what is the ratio of C:N:P?

A

Occur in constant ratio in phytoplankton organic matter C:N:P 106:16:1. “redfield” ratio. Also found in deep waters

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22
Q

what is the ratio of C:N:S:P due to diatoms cell walls?

A

Diatoms form their cell walls of silica so Si or silica acid is a key limiting nutrient from them C:S:N:P 106:15:16:1.

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23
Q

what are the key essential metal ions?

A

Key essential metal ions: iron, magnesium, copper and manganate. Iron is limited.

24
Q

how do you track the oxygenation of the atmopshere and oceans?

A

Tracking the oxygenation of the atmosphere and oceans:
• Progressive oxygenation of oceans- effect on elemental abundancies.
• Reflect 2-phase oxygenation of atmosphere.

25
Q

what des photosynthesis depend on?

A

Production in the oceans:
• Photosynthesis depends on the availability of light energy.
• The Photic Zone/ Euphotic Zone.

26
Q

what is compensation depth?

A

Compensation depth= base of photic zone. Depth at which the respiration consumption of oxygen exceeds the photosynthetic production of oxygen generally takes as 1% light level.

27
Q

what is the light intensity percentage at the depth of 100m

A

Penetration of light: in clear ocean waters, light intensity is reduced to about 1 % at the depth 100m.

28
Q

why are red and violet ends faster absorbed than blue?

A
  • Red and voilet ends of the spectum are absorbed faster tahn blue and green
    • Base of photic zone is defined at 1% light level
    • Coincides with depth of mixed layer base.
29
Q

what controls primary production?

A

Controls of primary production:
• Wherever there is sufficient light phytoplankton will grow, so in id and high latitudes increase of light in spring will kick start primary production- the spring bloom.

30
Q

what controls phytoplankton growth?

A
  • Phytoplankton growth will continue until nutrients becomes limiting.
    • Well-lit surface waters of the ocean will always will be depleted in nutrients. Unless there are mixing events- which may occur by- wind driven upwellings, eddies, fronts, storms.
    • Coastal upwelling of nutrients generate high productivity.
31
Q

what is the phytoplankton distribution in the oceans?

A

Phytoplankton distribution:
A lot less in Sargasso sea. Much more productive in shelf water. Change in the groups, more diatoms which grows 2 or 3 ties fast. In open ocean, more coccolithophores and dinoflagellates.

32
Q

what is Nutricline?

A

During summer at high and mid latitudes, the thermocline coincide with a nutricline.
Nutricline is delimited by a reduction in nitrate.
All major nutrient profiles reflect surface productivity demand.

33
Q

how do you get nitrogen?

A

A lot of nitrogen about, but it had a very strong triple bond and hence cannot use it. However, there are nitrogen fixer species, which strip the nitrogen to produce ammonia from just cellular mechanisms.

34
Q

which process changes air nitrogen to ammonia?

A

Faber process. Nitrogen in the air to liquid ammonia.

35
Q

what is trichodenium?

A

Trichodenium- a filamentous colonial cyanobacteria, has the enzyme nitrogenase in it, grows in sheaves of colonial trichomes. Forms significant blooms in tropical and subtropical nitrate poor waters.

36
Q

what is Diatom diazotrph associatons?

A

Diatom diazotroph associations- lives inside the diatom cell. Intracellularis. Forms massive blooms in the north pacific subtropical gyre.

37
Q

what happens to nitrogen when oxygen concentrations get low?

A

Nitrate reduction, when oxygen is low, then nitrate in demand as oxidant.
Nitrate concentrations in ocean reflect high demand in surface mixed layer, euphotic zone and age of formation of deep water. Phosphate limitation as well, and silicon limiation, the concentrations reflect deep water circulation.

38
Q

what are profiles and conveyer?

A

Controls on nutrient distribution in surface waters- profiles and conveyer. Nutrient profiles reflect position on conveyer.

39
Q

what is the nutrient distribution like?

A

silicate, like nitrate and phosphate, does follow conveyor in north pacific. But elsewhere, much more depleted. Only concentrated in southern ocean. Silicate is trapped in the southern ocean, due to the diatom production using much of the available silicate.

40
Q

what are iron micronutrients?

A

Micronutrients- iron is a limiting micronutrient. Iron profiles just like nutrient profiles.
Iron release in southern ocean simulates a diatom bloom.

41
Q

what is the fate of primary production?

A

What is the fate of primary production?
• It gets eaten.
• Copepods: evolved from benthic ancestors and colonised pelagic realm.
• Dominate zooplankton biomass in modern ocean.
• Very fast. Very strong. Very good jumper.
• Watery arms race has developed over millions of years.
• Diatoms- evolved stress-resistant silica cells.
• Copepods evolved silica mandibles to crush and snap.

42
Q

what is zooplankton?

A

Zooplankton:
• Are larvae or juveniles of larger invertebrates or fish
• Are holoplankton if they live all their lives as plankton
• Species include euphausiids such as krill, calcium carbonate, etc.
• Holoplanktons also include jellyfish, and salps.
Zooplanktons that are eggs, larvae, or juveniles of species that are bethos or nekon as adults are meroplankton

43
Q

what is Nekton?

A

Nekton:
• Organisms that live in the water column that are able to swim actively so they are no just swept along by currents are nekton.
They include- fish, squid, other cephalopods, marine mammals, and a few marine reptiles and birds

44
Q

what gets exported from the surface layer?

A

What gets exported from the surface layer?
• Export from phytoplankton blooms, some is self-export. When nutrients run out, diatoms form gelatinous aggregates and settle rapidly.
• Setting aggregates known as marine snow.
• Resting spores are robust.

45
Q

what happens with nutrients run out?

A

When nutrients run out, some diatoms form resting spores.
Export from phytoplankton blooms, some is crap. Zooplankton and fish produce faecal pellets that settle, however lots of marine life like this- coprophagy, a snack.

46
Q

wat is recycled production?

A

Recycled production and microbial loop:

• In the marine ecosystem, must production is recycled, in the microbial loop, in part by bacterial meditation.

47
Q

what steps are formed for recycling production?

A

Biological pump and carbon draw down. The critical step for the carbon cycle is the export of organic carbon from the surface layer of the ocean. When the carbon is broke down into molecules, it is known an DOC. We think of the system as a number of boxes.

48
Q

what is dissolved inorganic carbon?

A

Dissolved inorganic carbon DIC- in the ocean, most of the inorganic carbon is in the form of bicarbonate ion HCO3-. We now need to consider the process of calcification.

49
Q

what are the 2 pumps working in oppoiste directions?

A

2 distinct pumps working in opposite directions- 2 distinct pumps working in opposite directions. The process of calcification generates CO2. growth and flux of most phytoplankton draws down the CO2 from the atmosphere.

50
Q

what is the carbonate counter pump?

A
  • Carbonate counter pump, when you make shell, you kick out Co2.
    • Organic carbon pump
51
Q

what is the ocean circulation pump?

A

In addition the organic carbon pump and the carbonate counter pump there is the ocean circulation “pump”, that dictates changes in carbon storage in the deep sea, or changes in the ocean ventilation. Ocean circulation has a major control on CO2 “storage” versus outgassing.
Ocean circulation dictates changes in carbon storage in the deep sea or changes in ocean ventilation.

52
Q

what is the global context of this issue?

A
  • The main carbon reservoirs which needs to be taken into account in the greenhouse warming debate
    • The atmosphere CO2 gas
    • The ocean- dissolved inorganic carbon
    • Biosphere- organic carbon
    • Geological reservoir- fossil fuels
53
Q

what are the fluxes between these reservoirs which deterime the build up and decrease in each reservoir?

A
  • Atmopshere
    • Ocean DIC
    • Ocean DOC
    • Living biomass
    • Sous
    • Fossil fuels
    • Sedimentary rocks
54
Q

what is the atmosphere concentration worries?

A

Past natural variability during glacial- interglacial cycles was around 80 ppmv. Increasing and we mass 400 ppmv in may 2013. why are CO2 concentrations going up: rates and sources of global anthropogenic fossil fuel CO2 emissions. Rise of atmospheric CO2 account for 50% of emissions. Ocean has taken up 35%, missing 10-20%, some say rapid forest growth, mangroves etc.

55
Q

what are the ocean concentration worries?

A

Organic carbon cycle, biological pump of carbon into the sea. Target for geo-engineering. Increase primary production, and CO2 drawn from the atmosphere. Inorganic carbon cycle, equilibrium with an atmosphere with enhanced CO2 will cause higher pCO2 throughout the ocean.
The ocean, in particular the deep sea, becomes more acidic and more corrosive to carbonates

56
Q

what does DIC stand for?

A

dissolved inorganic carbon

1 SOES1008 earth and ocean systems (30 decks)

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