OC211(OA211) Phytoplankton

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OC211(OA211) Phytoplankton Primary Production

• Dr Purdie SOC (566/18) email DAP1_at_soc.soton.ac.u
  k

LECTURE 4 Week 4 I)The algal cell pigments,
sampling and preservation (ii) Major Marine
Microalgal Taxonomic Groups (iii) Definitions of
Primary Production
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ALGAL CLASSIFICATIONAND TAXONOMY

• General Features of Algae
• Size single celled 1mm phytoplankton to 30 m
  (Kelp)
• No tissue differentiation into root, stem, flower
• Primary classification is based on 5 criteria
  however final classification depends on a
  combination of several characteristics
• 1) Photosynthetic pigments
• 2) Food storage products e.g. lipids, starch
  leucosin
• 3) Cell wall composition, cellulose, pectin,
  mineralisation e.g. silica (diatoms) calcite
  (coccolithophores), mucilage.
• 4) Flagella position length form and number
• 5) Other cellular features e.g. nuclear membrane
  , vacuole

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PIGMENTS

• Pigments are soluble in lipid type solvents
  (acetone methanol) and are enclosed in
  chloroplast or plastic (except prokaryotic forms)
• All photoautotrophs contain chlorophylls and a
• number have been recognised i.e. a, b, c, d.
• Auxiliary pigments carotenoids e.g. carotenes
  and
• xanthophylls. Can capture and utilise different
• wavelengths of light.
• Biliproteins are water soluble found only in
  three
• divisions
• cyanophyta (blue green algae)
• Rhodophyta (red) and Cryptophyta. Phycocyanin,
  phycoerythrin, allophycocyanin
• )

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FLAGELLA
Figure from Sleigh Protozoa
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Organisation of the Eukaryotic algal cell

• e.g. a flagellated organism
• outer cell covering of cellulose, silica,
  protein, calcite or organic scales,
• Nucleous- most of the genetic nucleic acid in
  cell,
• Mitochondria- site of cellular aerobic oxidation
  i.e. respiration.
• Golgi- form waste material polysaccharide
  production
• Endoplasmic reticulumn ribosomes - site of
  protein production
• Chloroplast thylakoid membranes containing
  pigments
• Pyrenoid- proteinaceaous area of chloroplast site
  of CO2 fixation, chloroplast also contains some
  DNA
• Vacuoles
• Flagella

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THE MICROALGAL CELL
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ALGAL CLASSIFICATION AND TAXONOMY

• Bacillariophyta (Diatoms)
• unicellular or loose colonies no flagella
• silica impregnated cell wall
• The FRUSTULE is in two halves upper epitheca
  (large)and lower hypotheca (small)
• contain fucozanthin - brown pigment colour and
  chlorophyll c
• centric (centrales) discoid or Pennate
  (Pennales)linear form
• Cell division produces cells from one side of
  cell reduced in size
• Shape and morphology determines genera/species

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DIATOM DIVISION
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ALGAL CLASSIFICATION AND TAXONOMY

• Dinophyta (Dinoflagellates)
• mostly unicellular some chains
• paired flagella longitudinal in groove- Sulcus-
  transverse- Cingulum or girdle
• Two halves to body Upper Epicone, Lower Hypocone
• Theca or cell wall often covered in cellulose
  plates (armoured)
• chloroplasts yellow green or yellow brown
• characteristic xanthophyll is Peridinin

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ALGAL CLASSIFICATION AND TAXONOMY

• Dinophyta (Dinoflagellates)

A desmokont B dinokont
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ALGAL CLASSIFICATION AND TAXONOMY

• Chrysophyta
• yellow green or brown in colour
• small unicellular with 2 flagella
• several characteristic carotenoids
• contain 2 chloroplasts
• some species have scales
• others naked e.g. Pavlova

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ALGAL CLASSIFICATION AND TAXONOMY

• Haptophyta or Prymnesiophyta
• unicellular or colonial usually motile
• reserve products lipids
• 2 or sometimes 4 chloroplasts
• contain chlorophyll a and c
• e.g. Phaeocystis, Emiliania (Coccolithophore)
  Isochrysis

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ALGAL CLASSIFICATION AND TAXONOMY

• Cryptophyta
• small unicellular ovoid or slipper shaped
• 2 flagella
• contractile vacuole
• 2 chloroplasts
• contain chlorophyll a and c plus phycobilins as
  accessory

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ALGAL CLASSIFICATION AND TAXONOMY

• Chlorophyta
• mainly freshwater forms
• micro and macro examples
• chlorophyll a and b
• cellulose in cell wall
• starch as storage product

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ALGAL CLASSIFICATION AND TAXONOMY

• Euglenaphyta (Euglenoids)
• ovoid unicellular
• chlorophyll a and b
• 1 or 2 flagella

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ALGAL CLASSIFICATION AND TAXONOMY

• Cyanophyta (Bluegreen algae)
• prokaryotes small, bacteria sized
• no cellular bound organelles
• no flagella
• cellulose cell wall
• chlorophyll a and phycobilins
• some contain gas vacuoles
• some (mostly freshwater forms)
• have heterocysts for N2 fixation
• e.g.Trichodesmium

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ALGAL CLASSIFICATION AND TAXONOMY

• Prochlorophytes
• unicellular prokaryotic
• chlorophyll a and b
• some motile using flagella
• can only be detected with a
• flow- cytometer not visible
• under a microscope

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Phytoplankton sampling preservation

• Diversity is immense and representatives of most
  algal divisions are found in the ocean.
• Collection of phytoplankton
• (I) Nets- concentrates cells but only provides
  qualitative indication of important larger
  species. Useful to observe cells in live state.
• (ii) Water sample add preservative and
  concentrate by sedimentation
• Preservatives
• Lugols iodine acidic solution of iodine (acid
  denatures protein and iodine is a heavy ion)
• Glutaraldehyde solution (buffered) preserves
  pigment fluorescence for use with epifluorescent
  microscope and used with more delicate organisms
  and calcareous species.

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Definitions of Primary Production Terms

• Photoautotrophic Biomass or Standing Crop
  concentration of plant material per unit volume
  (g m-3)
• Biomass can be measured as wet weight, dry
  weight, ash-free dry weight or organic carbon.
• In phytoplankton studies chlorophyll is used as a
  biomass indicator although the carbon
  chlorophyll ratio is not a constant.
• From phytoplankton microscopic cell counts can
  use cell dimensions to calculate volume of
  cytoplasm and hence cell carbon.
• Yield is the increase in plant biomass over time
• (units g m-3)
• Yield Net photosynthesis Excretion Grazing
  - Export

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Definitions of Primary Production Terms

• Use of the term PRODUCTION versus PRODUCTIVITY
• Production (or rate of production) is a
  quantitative term e.g. the annual production
  was
• Productivity (i.e. fertility) is a qualitative
  term
• e.g. a period of high productivity

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Definitions of Primary Production Terms

• Carbon Based Definitions
• Gross Primary Carbon Production (PgC) is the
  organic carbon produced by the reduction of
  carbon as a consequence of the photosynthetic
  process over some specified period of time.
• Net Primary Carbon Production (PnpC) is gross
  primary carbon production minus the losses in
  carbon due to photoautotrophic respiration.
• PnpC PgC - RaC
• Net Community Carbon Production (PncC) is gross
  primary carbon production minus all losses in
  carbon due to respiration.
• This includes Photoautotrophic respiration (RaC)
  and Heterotrophic respiration (RhC)
• PncC PgC - RaC - RhC

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Definitions of Primary Production Terms

• Photosynthetic Quotient
• The molar ratio of the rate of oxygen production
  to rate of carbon fixation
• PQ O2 gt1
• - CO2

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• Phytoplankton Production Possible Methods
• ..must be accurate and precise (or sensitive)
• 1)Gas Flux Measurements
• 2)CO2 changes TCO2, pCO2, pH
• 3)O2 Changes
• 4)Isotopes
• 14CO2 3H2O
• 18O2
• 15NO3 or 15NH4
• 33PO4 or 32PO4
• 5) Biomass changes organic carbon or chlorophyll
• 6) Fluorescence Kinetics