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Light climate and PP in the Arctic > Geir > Flashcards

Geir Flashcards

We will come back too that

1
Q

Describe the food web in the Barents sea.

A

Virus > bacteria > phytoplankton > ciliates > copepods (C. finmarchicus (Atlantic) or C. glacialis (Arctic) > Little auk (coast) / Herrings (open water) > Minkes whale (open water)

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2
Q

What are ice algae and give two specie?

A

Phytoplankton that grows in relationship with sea ice (Duh!). Eg. Nitzschia frigida, Polarella glacialis, Navicula sp.

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3
Q

Geir likes to talk about red calcarous algae, why?

A

Because little is known about them (and I suppose he as a lot of cool underwater picture of them)

By the way, they are found at 50-60 m depth

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4
Q

Why does the macroalgae of Svalbard displays low/missing zonation pattern?

A 
Because there is a strong competition for a place to live, light, nutrients, because of: 
Light regime limitations
Nutrient limitations
Substrate limitations
Epigrowth
Sedimentation
Ice-scouring
Grazers (sea-urchins)
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5
Q

At what depth are the kelp forest in Svalbard?

A

Light limitation at 5-30 m depth

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6
Q

How does macroalgae survives the polar night?

A

Some species need only a few days of positive photo-­
synthesis to survive and grow during the polar night.

New findings: Brown, green and red macroalgae can perform photosynthesis during the
polar night if light is provided

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7
Q

What biological processes are affected by light climate as a function of time?

A
  • Photosynthesis
  • Respiration
  • Behaviour– incl DVM
  • Occurrence
  • Reproduction
  • Development & growth
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8
Q

What is included in the light climate?

A 
intensity = irradiance (E, umol quanta m-2 s-1)
colour = spectral irradiance (E(landa), umol quanta m-2 s-1 nm-1) 
day length  (d, h)
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9
Q

What is the biological importance of the kelp forest?

A

What happens beneath the kelp lamina:
Shelter and food during reproduction period for ghost shrimps
Juvenile polar cod in kelp forest in January – abundance of food
• Kelp forest an important habitat for the “dark lords” in
the polar night

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10
Q

Name the marine key-stone organisms of the Barents Sea.

A 
Phytoplankton (Plankton algae and cyanobacteria)
Copepods (and other zooplankton)
Krill
Polar cod
Capelin
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11
Q

What is the role/importance of primary producers (phyto, ice algae and macroalgae)?

A

Food source for different trophical levels(zooplankton, fish, birds, marine mammals)
Prod O2/uptake of CO2 (in light). Note respiration in light versus dark.
Biological carbon pump- takes up enormous amounts of CO2 through photosynthesis
Equilibrium between [CO2 in atmosphere and water
Climate: How do temperature and pH affect photosynthesis and respiration?

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12
Q

How does light is attenuated as a function of depth?

A

Light absorption and scattering of water.
Light absorption and scattering of particles
Light absorption of dissolved organic matter

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13
Q

Name a new gadget that Geir loves a lot. What instruments are include in that lovely thing? What does it does?

A

AUV <3
include and CTD, ecotriplet, irradiance meter, altimeter, accoustics things, sonar, GPS
It swims and take measurment

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14
Q

What is the impact of climate warming on global circulation (very basic)?

A

Abrupt climate change induce by weakening of the global circulation because of increse in arctic precipitation, river runoff, melting snow and ice.

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15
Q

Why does the Arctic warms faster than lower latitude?

A

Because of the albedo positive feedback.

  1. As snow and ice melt, darker land and ocea surface absorbe more solar E.
  2. More of the extra trapped E goes directly into warming rather than evaporation.
  3. The atm layer that has to warm in order to warm the surface is shallower in the Arctic.
  4. as sea ice retreats solar heat absorbed by the ocea is more easily transfered to the atm
  5. Alterations in atm and oceanic circulation can increase warming
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16
Q

What is irradiance?

A

Irradiance is defined as a “photon flux” (can use the term mol) per unit time and area

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17
Q

How does the solar angle influence irradiance?

A

At low sun angle the light received on the
surface have to pass a thicker layer of air than
at higher sun elevation

Lowering of the sunangle lowers the direct
radiance from the Sun compared to indirect
radiance from gas molecules and particles

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18
Q

What is the influence of clouds on irradiance?

A

Nice weather with few clouds yields a higher surface irradiance
than a clear sky.

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19
Q

What are the factors influencing spectral irradiance underwater?

A
  • Reflection of irradiance is high at low sunangles and no wave activity.
    -Cloud cover
    -Aerosol
    -Depth/ice thickness
  • Clean (clear) sea water attenuates the
    different colors of visible light (400-700
    nm) differently as a function of depth, and
    the blue photons may travel far, in contrast
    to the high attenuation of the red photons.
  • Phytoplankton absorbs highly in the
    blue, blue-green and in the red part of the
    visible spectrum - leaving green light
    unabsorbed.
  • Yellow substances (humic acids,
    DOC) absorbs highly wavelengths in the
    blue and in the UV- region
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20
Q

Ocean colour varies as a function of:

A

a) Phytoplankton
b) cDOM
c) TSM

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21
Q

What phytoplankton groups dominates in the Barents Sea?

A

The diatoms dominates the spring bloom in the Barents Sea. The
other groups is dominated by the prymnesiophyte Phaeocystis cf. pouchetii

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22
Q

Why do diatioms dominate?

A
  1. Needs silicate to build cell wall.
  2. No flagella - non motile.
  3. Green light specialists (e.g. planktonic forms under ice and ice algae).
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23
Q

What is special with Phaeocystis?

A
  1. May form massive blooms (several billions cells m-3)
  2. May form big mucus colonies (up to 2 mm in diameter)
  3. Contains Chlorophyll c3, characteristic for harmful and bloom
    forming prymnesiophytes.
  4. Blue-green light specialist.
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24
Q

What are the 3 major groups of pigments?

A
  1. Chlorophylls (8 major types).
  2. Carotenoids (xanthophylls and carotenes; >100 types).
  3. Phycobiliproteins (4 major groups, only found in cryptophytes,
    cyanobacteria and red algae).
25
Q

How does the chla participates in photosynthesis?

A

By being:

  • A light harvesting pigment (in vivo abs maxima at 440 and 675 nm).
  • Part of the reaction center of PS II were oxygen is split from water.
  • All eucaryotic phototrophs (and Cyanobacteria) contains Chl a.
26
Q

What can be the different functions of pigments?

A
  1. Light harvesting (photosynthetic pigments)

2. Photoprotection (sunglas pigments)

27
Q

What influence absorption characteristics of an algal cell?

A
  1. Pigment composition
  2. Pigment-protein complexes
  3. Intracellular self shading (=package effect)
    - these properties varies with light regime
28
Q

What parameter can help to obtain the biomass after normalization with photosynthetic parameters?

A
  • Chlorophyll a
  • Total pigments
  • Carbon (organic)
  • Cell
  • Volume
29
Q

What factors influence algal growth rate?

A

Physical factors (weather related):
- Light regime (irradiance, its spectral composition and day length)
- Temperature (eg. biochemical reactions, temp gradients)
- Wind/current speed and direction
Chemical:
- Nutrient supply and composition (N, P, Si etc.)
- Salinity
Biological:
- Predation/grazing/competition
-Physiology/morphology/molecular build up

30
Q

What are the methods to measure photosynthetic performance?

A
  1. 14C-isotope
  2. Oxygen measurements (electrodes, titration)
    3.Fluorescence kinetics (Pulse Amplitude
    Modulated fluorometry).
31
Q

Name an effect that can cause problem for AOP measurements.

A

The light flickering effect

32
Q

What are the inherent optical properties (IOP)?

A

IOP´s are those properties that depend only on the medium and thus are independent of the ambient light field. The IOP include
absorption and scattering, which are additive properties of the medium.
While IOP are easy to interpret, historically, they have been
difficult to measure.

33
Q

What is the impact of temperature on growth rate?

A
  • Temperature alters photosynthesis, respiration and thus growth rate.
  • Enzymatic activity slows down with corresponding lowering of temp and thus respiration.
  • The light rx in photosynthesis is not dependent on enzyme
34
Q

What is the ice edge effect?

A

Ice melting northwards
New nutrients exposed
Favorable light regime for photosynthesis
Stabilization of surface water masses
Termoklin & nutriklin
Seeding stock of ice algae and associated phytoplankton

35
Q

Where is the biggest difference in salinity occuring in the phytoplankton’s habitat?

A

Inside and under the sea ice

36
Q

What can influence phytoplankton buoyancy?

A
  • Small species sinks slowly compared to big one
  • Production of oil droplet inside the cell
  • Big fraction of light ions (Na, Mg) vs heavy ones (K, Ca)
  • Varying shape/form

The viscosity of water diminishes as the temperature gets higher

37
Q

What is the critical depth?

A

The critical depth is found were the total (integrated) photosynthesis and respiration in the water column above that given depth is equal.

38
Q

How does the critical depth is related to the bloom?

A

A bloom can only develop if the vertical mixing depth is lower that the critical depth

39
Q

What are the different type of chls?

A

chla, chlab, chlc1, chlc2 and chlc3

40
Q

Describe the carotenoids.

A

The carotenoids are of two type: carotenes and xanthophylls. The carotenes, which are rather few, are hydrocarbons, while the xanthophylls contain at least one atom of O and make up the majority of the carotenoids. The simplest carotenois are found in cyanobacteria. The most important light harvesting carotenoids of algae are fucoxanthin and its derivates as well as peridinin.

In addition to their light harvesting functions (ie being accessory pigments), some carotenoids also acts as photoprotective pigments.

41
Q

What is the role of photo-protective carotenoids?

A

Protect chls and thus the cell from harmful effects due to hight irradiance in the presence of oxygen.

42
Q

In which class is violaxanthin/zeaxanthin present?

A

Prasinophytes, chlorophytes, Phaeophyte

43
Q

In which class is diadinoxanthin/diatoxanthin present?

A

Diatoms, dinoflagellates, prymnesiophytes, euglenophyte, chrysophyte

44
Q

Describe the phycobiliproteins.

A

The are four major types of phycobilioroteins: Phycocyanin, Phycoerythrin, Allophycocyanin and Phycoerythrocyanin. These are light harvesting pigments int the cyanobacteria, chryptophycea and Rhodophycea.

They are water soluble protein and their covalent bond is not broken when the pigments are extract (instead of chls and carotenoids)

45
Q

What are the long-term photoacclimative processes?

A

(i) changes in the amounts and ratios of light-harvesting pigments and photoprotective carotenoids,
(ii) photosynthetic parameters,
(iii) enzymatic activities involved in photosynthesis and respiration, and finally,
(iv) cell volume and chemical composition

  • Chloroplast size, number, morphology and distribution
  • Light-harvesting complexes and thylakoid membranes
  • Pigment composition and function
46
Q

What happen in the viola cycle when there is too much light?

A

The drop in pH activate viola de-epoxidase to transform violaxanthin in Antheaxanthin to zeaxanthin

47
Q

What happen in the diadino cycle when there is too much light?

A

The drop in pH activate diadino de-epoxidase to transform diadinoxanthin in diatoxanthin

48
Q

What are the factors influencing bio-optical properties in a phytoplankton cell?

A
  1. Pigment composition.
  2. Cell size, shape or morphology.
  3. Chloroplast size, shape, number, morphology and distribution.
  4. The degree of stacking and optical properties of the thylakoid membranes.
49
Q

What are the use of bio-optical measurement?

A
  1. Pigment composition (photosynthetic and photoprotective)
  2. In vivo bio-optical characteristics (spectral light absorption and fluorescence):
    A) Light harvesting and utilization
    B) Bio-optical taxonomy
    C) Biomass
    n Laboratory
    n Remote (laser induced) & in situ sensed fluorescence
    n Profiling instruments
    n Time-series
  3. Photosynthetic parameters (Pulse Amplitude Modulated fluorometry).
  4. Changes in physiological status as a function of
    6 nutrient composition
    6 temperature
    6 salinity
    6 light regime
50
Q

What characterize hight-light adapted cell?

A
  1. Low pigment content
  2. High amounts of photoprotective pigments
  3. Low amounts of light-harvesting pigments
  4. High chl a-specific light absorption
  5. High respiration rates
51
Q

What characterize low light adapted cells?

A
  1. High pigment content
  2. Low amounts of photoprotective pigments
  3. High amounts of light-harvesting pigments
  4. Low chl a-specific light absorption (high intracellular self shading)
  5. Low respiration rates/
52
Q

What are the fundamental principle of light absorption?

A
  1. Any molecule can absorb only one photon at a time
  2. this photon causes the excitation of only one electron.
  3. Each electron can be driven away from its ground state in the positively charged nucleus at a distance corresponding to an energy exactly equal to the energy of the absorbed photon.
  4. The pigment molecule is then in an excited stade (only for a short period)
  5. The excitation E can be lost by heat release or fluorescence
53
Q

What is fluorescence?

A

An electronically excitated molecule (e.g. Chl a), after
undergoing the radiationless transition to the lowest energy
level of the lowest excited singlet state, can then undergo a
transition to one of the vibrational/rotational levels of the
ground state by re-emitting a photon of light

54
Q

When talking about fluorescence, it is important to discriminate between…?

A

In vivo fluorescence
In vitro fluorescence
Fluorescence yield & intensity

55
Q

When light hit a phytoplankton cell, what are the thing that can happen and with what instrument can you detect it? (ok gimme a break I’m tired) (the drawing of the cell is the answer)

A 
Scattering
(Spectrophotometer,
Flow-cytometer)
Absorption
(Spectrophotometer)
Fluorescence
(Spectrofluorometer,
Flow-cytometer, PAM)
Heat
(IR-detector)
Photochemistry
(Spectrofluorometer,
PAM)
56
Q

On what depend the photosynthetic rate?

A
  1. Available photons absorbed and transported to the
    photosystems
  2. The conversion of light energy to chemical energy
  3. The amount of chl a per PSU (q)
  4. The minimum turnover time for electrons in PSU
57
Q

How do you calculate ΦIIe (and what is it)?

A

The maximum quantum yield of stable charge separation (seen by chl
a f luorescence) in PSII ( fluorescence yield) can be calculated as one
minus the ratio between the fraction of open and closed reaction centres in darkness:
ΦIIe =1− F0/Fm
= Fv/Fm
(15 min in darkness)

58
Q

What is the difference between the in vivo absorption spectrum VS in vivo fluorescence excitation spectrum?

A

An in vivo absorption spectrum indicates absorption of all pigments. In contrast, an in vivo fluorescence excitation spectrum indicates the
absorbed light to PSII, or more precisely, the transfer of light energy by LHPII to PSII. (Photopigment book)

59
Q

How is the in vivo excitation spectrum of chla comparable to an oxygene action spectrum?

A

In the reaction centres of PSII, the water-splitting complex (evolving photosynthetic oxygen from water) is tightly connected to reaction center-Chl a
emitting light (fluorescence) as a function of discrete wavelengths absorbed and funnelled to the reaction centres. Because of this relationship, the shape of an
in vivo fluorescence excitation spectrum resembles that of an oxygen action spectrum (Photopigment book)

Light climate and PP in the Arctic (5 decks)

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