SMS 598: Application of Remote and In-situ Ocean Optical Measurements to Ocean Biogeochemistry

Quick biology overview and

Phytoplankton – taxonomic classification, pigments, photo-adaptation

Mary Jane Perry5 July 2007

All you wanted to know about biology, but were afraid to ask

All you wanted to know about biology, but were afraid to ask

Three Super Kingdoms:Eukaryotes Eubacteria Archaea

single cells and metazoans

Prokaryotes:

single cells and consortia

Bottom line: great diversity of organisms that interact with light in the ocean

All you wanted to know about biology, but were afraid to ask

Four basic functions of all organisms:

Eat Avoid being eaten Defecate Reproduce

energy & materials * light * reduced inorganics * organic C

All you wanted to know about biology, but were afraid to ask

Four basic functions of all organisms:

Eat Avoid being eaten Defecate Reproduce

toxinsswimming bioluminescencemorphology (spines, chains)etc.

All you wanted to know about biology, but were afraid to ask

Four basic functions of all organisms:

Eat Avoid being eaten Defecate Reproduce

dissolved organics(e.g., glycolate at high light)

All you wanted to know about biology, but were afraid to ask

Four basic functions of all organisms:

Eat Avoid being eaten Defecate Reproduce

vegetative (asexual)sex – spore/cyst formation – diatom size – other?

All you wanted to know about biology, but were afraid to ask

Four basic functions of all organisms:

Eat Avoid being eaten Defecate Reproduce

energy & materials * light – “primary producers”

(phytoplankton; other photon users) * reduced inorganics – “primary producers” (chemosynthetic) * organic C – “consumers” (or secondary producers)

consume DOM or POM; mixotrophs

For the rest of this morning, will focus on “what’s a phytoplankton?”

Photosynthetic (pigmented)

Aerobic (oxygenated environment)

Oxygenic (oxygen producing; use sunlight)

Small, single-celled particle (usually)

Three points:1. Introduce you first to phytoplankton,

and a little bit about their role in the ocean2. What are the proxies based on interaction with light?

– particles scatter light– pigments absorb light– chlorophyll a and phycoerythrin fluoresce light

3. How physiology changes the relationship between phytoplankton and their optical proxies

Phytoplankton as particles– in the ocean, size matters <–> related to function

Size* efficiency of dissolved solute capture* motion – Brownian vs. intentional swimming* efficiency of encounter – surface area for contact* processing – if and how predator handles prey (match/not)* efficiency of aggregation* settling – Stokes Law (implications for carbon cycling)* carbon content* interaction with light – b: scattering (cross sectional area) – a: absorption (volume affects absorption efficiency)

Two food webs (with interconnections)

big

little

big particle vs. little particle energy/material cycling

“Phytoplankton” as species

What we call phytoplankton span the three Super Kingdoms: Archaea – rhodopsin (ATP); really phytoplankton? Eubacteria – cyanobacteria - oxygenic

aerobic, anoxygenic, bacterial chlorophyll anaerobic, anoxygenic (sulfur bacteria)

Eukaryotes – protists (very diverse) chlorophytes

Do species matter?

Some functions are species independent:photosynthesis and carbon fixationsize - sinking and nutrient uptake

Some functions are species specific:N2 fixation (Trichodesmium)toxins (domoic acid, PSP, etc.)dominate oceanic carbon flux (diatoms)

For optical identification, some pigments aretaxon specific

Synechococcus(~ 1 micron)

arrow denotes thylakoid membrane which has both photosynthetic and respiratory functions

Diagnostic: phycoerthyrin pigment fluoresces orange (in contrast to chlorophyll, which fluoresces red

Prochlococcus~ 0.7 microns

Diagnostic: very small size,lack of orange fluorescence,divinyl chlorophyll a & b

Trichodesmium (cyanobacterial nitrogen fixer; warm waters; patchy; Fe may regulate abundance)

Prasinophyte

Centric Diatoms, Thalassiosira and Chaetoceros

Pseudonitzschia (some species have toxin, domoic acid)

Alexandrium tamarense

CeratiumDinoflagellates

Coccolithophorid, with calcite plates or coccoliths;

look at the SeaWiFS website - blooms visible from space

Phaeocystis (colonical and single cell)famous for producing foam on northern European beaches

Chyrsophyte with silica scales

Pigments

definition: absorbing compound

role: light harvesting for photosynthesis (PS)light protection when too much light (PP)

types chlorophylls

chlorophyll a - primary PS pigment in all oxygen producers chlorophyll b or c - accessory PS pigments; expand range;transfer energy to chlorophyll a

(divinyl chl a and b) carotenoids

light harvesting for photosynthesis (PS) light protection when too much light (PP) phycobilins

water soluble pigments; phycoerythrin can fluorescence

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

http://www.nyu.edu/pages/mathmol/library/photo/

www.ch.ic.ac.uk/local/projects/ steer/cloroads.gif

Chlorophyll a(absorption peaks will vary,depending on environment –protein complex in membrane, polarity of solvent); in vivo fluorescence

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

porphyrinring w/Mg++

phytoltail

Degraded pigments: Pheophytin lost Mg++; peak shifts to ~415

Pheophorbidelost Mg++ and phytol tail

Accessory pigments:

Chl b and c

inside chl a max peaks minor modification of ring in vitro fluorescence

Chl c lacks phytol tail

Carotenoids

conjugated double bonds; role in photosynthesis (PS - absorb blue-green-yellow s) and photoprotection (PP - absorb excess photons, quenching free radicals, triplet oxygen); some taxon specificity

Phycobilins (phycobiliproteins) – water solublecyanobacteria and chryptomonads

PUB phycourobilin

PE (fluoresces orange)phycoerthyrin

PCphycocyanin

APCallophycocyanin