Marine pelagic ecology BIO 4400
Phytoplankton and primary
production-1
Literature (Pensum):
Chap. 13, 14 in Garrison
Chap. 5 in Skjoldal
p. 3-50 in Paasche (or Chap 2 in Kaiser et al.)
k
a
Bente Edvardsen 2009
Aims of learning - marine botany
Give 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
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Phytoplankton size groups
Primary production
Light
Photosynthesis and effect of light
Nutrients (C, N, P and Si)
Phytoplankton (Planteplankton)
Photo: Jahn Throndsen (JT)
Most are microscopically small, drifting, single celled
algae. They are small to float and to have an efficient
nutrient uptake. Some live in colonies.
Size variation of phytoplankton
The size of phytoplankton:
< 2 µm picoplankton
2-20 µm nanoplankton
20-200 µm microplankton
200-2000 µm mesoplankton
Plankton and size-groups
(Sieburt 1978)
Microplankton (20-200 μm)
dinoflagellates
diatoms
JT
JT
Dinophysis
Ceratium
Guinardia
Nanoplankton (2-20 μm)
Chrysochromulina
haptophytes
Emiliania huxleyi
JT
cryptophytes
Identification in electron microscopy often needed
Picoplankton (0.2-2 μm)
Prokaryota
Eukaryota
Prochlorococcus
Synechococcus
Micromonas pusilla
Phytoplankton as primary producers
zooplankton
Phytoplankton
Half of the Earth’s
primary
productivity is by
marine microbes
protists
bacteria
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
Garrison, Fig 13.2
light
6CO2 + 6H2O + -> C6H12O6 + 6O2
Chemosynthesis in chemolithotrophic bacteria
e.g. in sediments
Garrison, Fig 13.4
Chemolithotrophic bacteria
Keiser et al. Fig 2.7
Beggiatoa is a sulfur-oxidizing bacteria
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 assimilation
per 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:
Garrison, Fig 13.5
g C· C-1 · day-1
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:
Light reaction
Calvin - Benson
cycle
RUBISCO
dark reaction
RUBISCO= Ribulose
biphosphate carboxylase
/oxygenase
Radiation (stråling) – visible light
Energy E, E= h f or E=hc/ λ
where 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 varies
with latitude and
through the year
Paasche 2005, Fig. 2 og 3
Light in the sea
Spectral distribution in water
Skjoldal
Light attenuation in water
JT03
Attenuation
(svekking) of
light in various
types of water
Coastal water
Pure sea water
Paasche Fig. 6
Irradiance
(Innstråling)
Euphotic zone =
the well lit zone
with enough light
for growth
Approx. 1% light
depth (the depth where 1% of
surface light remains)
Garrison, Fig 13.15
Pigments
Algae 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 accessory
pigments
they fill inn some of the “optical window”
Absorption
spectra and
action spectra
Sea lattice
dinoflagellate
kelp
diatom
= photosynthesis
(O2 development)
at various wave
lengths)
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
α shows how efficient P is
PB max: Light saturated photosynthesis per biomasse (measured
as chlorophyll a)
Photoacclimation
High light adapted
Low light adapted
Irradiance
Photosynthesis vs. light and depth
photoxidation
DC = compensation depth
photosynthesis=respiration
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