phytoplankton and primary production-1folk.uio.no/steinka/roya/marine botany 1-26jan.pdf · marine...
TRANSCRIPT
Marine pelagic ecology BIO 4400
Phytoplankton and primaryproduction-1
Bente Edvardsen 2009ka
Literature (Pensum):
Chap. 13, 14 in Garrison
Chap. 5 in Skjoldal
p. 3-50 in Paasche (or Chap 2 in Kaiser et al.)
Aims of learning - marine botanyGive an understanding and knowledge on:• Ecological role of phytoplankton• Primary production, photosynthesis and growth• Effects of ecological factors: light, nutrients,
temperature, salinity • Distribution in time and space• Ecological strategies• Phytoplankton diversity
Content
• Phytoplankton size groups• Primary production• Light• Photosynthesis and effect of light• Nutrients (C, N, P and Si)
Phytoplankton (Planteplankton)
Most are microscopically small, drifting, single celled algae. They are small to float and to have an efficient nutrient uptake. Some live in colonies.
Photo: Jahn Throndsen (JT)
Size variation of phytoplankton
The size of phytoplankton:< 2 µm picoplankton2-20 µm nanoplankton20-200 µm microplankton200-2000 µm mesoplankton
Plankton and size-groups
(Sieburt 1978)
Microplankton (20-200 μm)
CeratiumDinophysis
Guinardia
dinoflagellates diatoms
JTJT
Nanoplankton (2-20 μm)
ChrysochromulinaEmiliania huxleyi
haptophytes
cryptophytes
Identification in electron microscopy often needed
JT
Picoplankton (0.2-2 μm)
Micromonas pusilla
Prokaryota Eukaryota
Prochlorococcus
Synechococcus
Phytoplankton as primary producers
Half of the Earth’s primary productivity is by marine microbes
Phytoplankton
bacteria
protists
zooplankton
From Paasche 2005
Nutrition in microalgae (trophy)
• autotrophy: use CO2 as carbon source and light as energy• auxotrophy: autotrophy, but need some
organic compounds e.g. vitamins• heterotrophy: use organic carbon as
carbon source • phagotrophy: nutrition from organic particles• osmotrophy: nutrition from dissolved organic
material (DOM)• mixotrophy: both autotrophy and
heterotrophy
Primary production - definition
Formation of organic matter through assimilation of inorganic elements through photosynthesis or chemosynthesis
Photosynthesis
light6CO2 + 6H2O + -> C6H12O6 + 6O2
Garrison, Fig 13.2
Chemosynthesis in chemolithotrophic bacteriae.g. in sediments
Garrison, Fig 13.4
Chemolithotrophic bacteria
Beggiatoa is a sulfur-oxidizing bacteria
Keiser et al. Fig 2.7
Primary production in the sea
• phytoplankton 90-96%• benthic algae 2-5%• chemolithotrophic bacteria 2-5%
• c. 50 . 109 tonnes C per year in the sea• c. 60 . 109 tonnes C per year on land
• biomass 1-2 . 109 tonnes in the sea• c. 800 109 tonnes on land
Primary production:Carbon assimilationper area (or volume) and per time unit
Absolute units:g C· m -2 · day-1 (or y-1)or g C· L-1 ·h-1
Specific units:
g C· C-1 · day-1Garrison, Fig 13.5
Effect of environmental factors on primary production
• Light reaction in the photosynthesis: light, CO2
• Dark reaction (production of sugar, then lipids and proteins): nutrients and temperature
Photosynthesis:
RUBISCO
RUBISCO= Ribulosebiphosphate carboxylase/oxygenase
Light reaction
dark reaction
Calvin - Bensoncycle
Radiation (stråling) – visible light
Energy E, E= h f or E=hc/ λwhere f is frequency h is Plancks constant, c is light speed and λ (lambda) is wavelength of irradiance
Units for irradiance (innstråling)
Paasche Fig. 1
Irradiance varieswith latitude and through the year
Paasche 2005, Fig. 2 og 3
Light in the sea
Spectral distribution in water
Skjoldal
JT03
Light attenuation in water
Attenuation(svekking) of
light in varioustypes of water
Paasche Fig. 6
Pure sea water
Coastal water
Irradiance(Innstråling)
Euphotic zone = the well lit zonewith enough lightfor growth
Approx. 1% lightdepth (the depth where 1% ofsurface light remains)
Garrison, Fig 13.15
PigmentsAlgae can utilise irradiance of wave
lengths 350-700 nm = PAR photosynthetically available radiation≈ visible light (400-700 nm)
PS I + II: chlorophyll a
Accessory pigments:chlorophyll b, c• carotenoids (carotenes , fucoxanthin
etc, xanthofylls)• Phycobiliproteins (phycoerythrin,
phycocyanin, allophycocyanin)
“Sunglass pigments”:• carotenoids (diatoxanthin,
diadinoxanthin, zeaxanthin)WE
Photo: Wenche Eikrem
Absorption spectrum for chlorofyll a
= the amount of absorbed light at various wave lenghts
Absorption spectrum for some accessorypigments
they fill inn some of the “optical window”
Absorptionspectra and
action spectra
= photosynthesis(O2 development) at various wavelengths)
dinoflagellate
diatom
Sea lattice
kelp
Photosynthsis as a function of irradiance(P/E curve)
P photosynthesis
R respiration
I (=E) irradiance
Ik saturation irradiance
Ic compensation irradiance
Pmax light saturated photosynthesis
N nett
B gross
P/E curve
PBmax: Light saturated photosynthesis per biomasse (measured
as chlorophyll a)
α shows how efficient P is
Photoacclimation
High light adapted
Low light adapted
Irradiance
Photosynthesis vs. light and depth
DC = compensation depth
photosynthesis=respiration
photoxidation
average DC ≈ lower limit for euphotic zone
Compensation and critical depth
Euphotic zone
Kaiser et al.
Effect of environmental factors on primary production
• Light reaction in the photosynthesis: light, CO2
• Dark reaction (production of sugar, then lipids and proteins): nutrients and temperature
Elemental composition of algal cells
99% of the living biomass is made up of C, H, O and N
Dissolved inorganic carbon in sea water
Carbon dioxide• At 35 PSU and pH 8.2, 90% of inorganic
carbon occurs as HCO3-
• This is converted within the cell to CO2
• The supply of inorganic C for photosynthesis is rarely limiting in marine systems