Photosynthetic Capacity in Coral Photosynthetic Capacity in Coral Reef Systems: Applications for the Reef Systems: Applications for the

Underwater PAM FluorometerUnderwater PAM Fluorometer

Adrian Jones & William DennisonAdrian Jones & William Dennison

Thanks to the students of Coral Reef Biology & Geology (ID211) of Thanks to the students of Coral Reef Biology & Geology (ID211) of 1996 and Terrestrial & Marine Environmental Physiology (BT230) of 1996 and Terrestrial & Marine Environmental Physiology (BT230) of

19971997

Marine BotanyMarine BotanyThe University of QueenslandThe University of Queensland

AimsAims

• Generate photosynthesis versus irradiance (PI) Generate photosynthesis versus irradiance (PI) curves using Pulse Amplitude Modulated curves using Pulse Amplitude Modulated (PAM) fluorescence techniques (PAM) fluorescence techniques

• For a variety of marine macroalgae, determine For a variety of marine macroalgae, determine relationships between PI curves and various relationships between PI curves and various environmental factors environmental factors

• Use ecophysiological responses to infer light Use ecophysiological responses to infer light availability, desiccation stress and nutrient statusavailability, desiccation stress and nutrient status

PAM FluorometerPAM Fluorometer

Fibre OpticFibre OpticCableCable

Leaf ClipLeaf Clip

SubmersibleSubmersibleHousingHousing

• PAM generates saturating pulse of light which is used to PAM generates saturating pulse of light which is used to measure photosynthetic ratesmeasure photosynthetic rates

PAM FluorescencePAM Fluorescence(Pulse Amplitude Modulation)(Pulse Amplitude Modulation)

HeatHeat FluorescenceFluorescence

LightLight

PhotochemistryPhotochemistry

PQPQ PSIPSI

FFmaxmax -- FFinitialinitial ==

SaturatingSaturatingPulse from PAMPulse from PAM

PQPQPSIIPSII

PhotosyntheticPhotosyntheticYieldYield

PhotosyntheticPhotosyntheticYieldYield

Absorbed Absorbed LightLight

Electron Transport Rate Electron Transport Rate (ETR; µmol e(ETR; µmol e-- m m-2-2 s s-1-1))

xx ==

/ F / F maxmax(( ))

Rapid Light CurveRapid Light Curve

0

1000

2000

3000

4000

Inci

dent

Lig

ht

(µm

ol q

uant

a m

-2 s

-1)

Time (s)Time (s)1010 2020 3030 4040 5050 6060 80807070 909000

1 Second 1 Second Saturating PulseSaturating Pulse

10 Second 10 Second Actinic IrradianceActinic Irradiance

}

Rapid Light CurveRapid Light Curve

0

5

10

15

20

25

30

35

40

0 200 400 600 800 1000 1200 1400 1600

Photosynthetically Active Radiation (PAR)(µmol quanta m-2 s-1)

Ele

ctro

n T

rans

port

Rat

e (E

TR

)

(µm

ol e

- m-2 s

-1 )

PhotoinhibitionPhotoinhibition

Maximum ETR

Study SiteStudy Site

AustraliaAustraliaBrisbaneBrisbane

GreatGreat BarrierBarrier ReefReef

HeronHeronIslandIsland

HeronHeronIslandIsland

HeronHeronReefReef

WistariWistariChannelChannel

Heron IslandHeron IslandSouthern Reef FlatSouthern Reef Flat

Species ComparisonSpecies Comparison

0

50

100

0 500 1000 1500

Marine SpeciesMarine Species

ZooxanthallaeZooxanthallae

(Acropora)(Acropora)

0

50

100

0 500 1000 1500

ChlorodesmisChlorodesmis

PAR (µmol quanta m-2 s-1)

Terrestrial SpeciesTerrestrial Species

0

50

100

0 500 1000 1500

PAR (µmol quanta m-2 s-1)

ArgusiaArgusia

0

50

100

0 500 1000 1500

PisoniaPisonia

ET

R

(µm

ol e

- m-2 s

-1 )

ET

R

(µm

ol e

- m-2 s

-1 )

Experimental DesignExperimental Design(Reef Transect)(Reef Transect)

• Photosynthesis in Photosynthesis in ChlorodesmisChlorodesmis was measured along a was measured along a transect from 15m depth along the reef flat to the beachtransect from 15m depth along the reef flat to the beach

Reef FlatReef Flat ReefReefCrestCrest

BeachBeach

200m200m

GutterGutter 15m15m

20

30

40

50

60

70

80

0 20 40 60 80 100 120 140 160 180 200 220 2 5 10 15

Max

imu

m E

TR

(µ

mol

e- m

-2 s

-1)

Transect of Max ETR in Transect of Max ETR in ChlorodesmisChlorodesmis

BeachBeach

Reef Reef CrestCrestGutterGutter

Distance from Beach (m) Depth (m)

0

20

40

60

80

0 500 1000 1500PAR (µmol quanta mPAR (µmol quanta m-2-2 s s-1-1))

5m 10m 15m

ET

RE

TR

(µm

ol e

(µm

ol e

-- m m-2-2 s s

-1-1))

Experimental DesignExperimental Design(Desiccation)(Desiccation)

• Chlorodesmis Chlorodesmis collected from the reef flat and 15m collected from the reef flat and 15m was subjected to desiccation and fluorescence was monitored.

Reef FlatReef FlatReefReefCrestCrest

BeachBeach

200m200m

GutterGutter15m15m

0

10

20

30

40

50

0 20 40 60 80

Time (mins)

Max

imu

m E

TR

(µm

ol e

- m-2 s

-1)

Reef Flat 15m

Desiccation and RecoveryDesiccation and Recovery

DesiccationDesiccation RecoveryRecovery

Experimental DesignExperimental Design(Shading)(Shading)

• Several species of macroalgae and coral Several species of macroalgae and coral were shaded and the change in fluorescence were shaded and the change in fluorescence measured over 5 days.measured over 5 days.

50% PAR Shading50% PAR Shading

0

20

40

60

80

0 500 1000 1500 2000

Day 1 Day 2 Day 3 Day 4

ChlorodesmisChlorodesmis

ET

R (

µm

ol e

- m-2 s

-1 )

PAR (µmol quanta m-2 s-1)

0

60

120

180

0 500 1000 1500 2000

ChnoosporaChnoospora

Day 1 Day 2 Day 3 Day 4

ET

R (

µm

ol e

- m-2 s

-1 )

PAR (µmol quanta m-2 s-1)

0

20

40

60

80

100

0 200 400 600 800 1000 1200 1400PAR (µmol quanta m-2 s-1)

ET

R(µ

mol

e- m

-2 s

-1)

UV ScreenedControl

UV ShadingUV Shading

PadinaPadina

Experimental DesignExperimental Design(Fertilisation)(Fertilisation)

• Several species of macroalgae and coral were incubated Several species of macroalgae and coral were incubated for 10 days in flow-through aquaria with added for 10 days in flow-through aquaria with added nitrogen (88g mnitrogen (88g m-2-2) and phosphorus (22g m) and phosphorus (22g m-2-2) )

FertilisationsFertilisations

NutrientNutrientSufficiency StatusSufficiency Status

0

10

20

30

40

50

0 500 1000 1500 2000

FertilisedUnfertilised

PadinaPadina

ET

R (

µm

ol e

- m-2 s

-1 )

PAR (µmol quanta m-2 s-1)

0

5

10

15

20

25

30

0 200 400 600 800 1000 1200 1400

FertilisedUnfertilised

ChlorodesmisChlorodesmis

PAR (µmol quanta m-2 s-1)

0102030405060

0 500 1000 1500 2000

FertilisedUnfertilised

ColpomeniaColpomenia

ET

R (

µm

ol e

- m-2 s

-1 )

PAR (µmol quanta m-2 s-1)

FertilisationsFertilisations

0

20

40

60

80

100

0 500 1000 1500

FertilisedUnfertilised

AcroporaAcropora

PAR (µmol quanta m-2 s-1)

SummarySummary

• Rapid light curves in terrestrial and marine plants can be Rapid light curves in terrestrial and marine plants can be used to assess a variety of ecophysiological responsesused to assess a variety of ecophysiological responses

• Ability to generate Ability to generate in situ in situ PI curves rapidly, non PI curves rapidly, non destructively to determine relationships with various destructively to determine relationships with various environmental factorsenvironmental factors

• Ecophysiological responses to environmental gradients such Ecophysiological responses to environmental gradients such as desiccation, light, and depth can be ascertainedas desiccation, light, and depth can be ascertained

• PI responses can be used to infer a nutrient sufficiency status PI responses can be used to infer a nutrient sufficiency status