June-Aug Fv/Fm 998 Remote Sensing of phytoplankton photosynthetic rates and production from measurements of ocean colour. Jim Aiken, Gerald Moore, James Fishwick, Claudia Omachi, Tim Smyth, Plymouth Marine Laboratory, Prospect Place, Plymouth, UK. Conceptually, ocean colour (Rrs), an inverse function of the light absorbed, should be functionally related to primary production, a direct function of the light absorbed. Data on phytoplankton pigment composition from the equatorial Pacific Ocean (IronEx II), the Southern Ocean (SOIREE), the Atlantic Ocean (Atlantic Meridional Transect; AMT) and European shelf seas are shown to correlate with photosynthetic quantum efficiency (PQE, F v /F m ) determined by Fast Repetition Rate Fluorometer (FRRF). We conclude:. Chlorophyll a to total pigment fraction () is significantly correlated to PQE, generally and more so within provinces or within seasons. is a proxy for PQE.. Plants when stimulated to grow, synthesise in preference to other accessory pigments and decrease synthesis relatively when stimulation wanes. Evidence from laboratory culture experiments is consistent with these observations. 3. is maintained at a level needed to sustain maximum phytoplankton growth rates in their environment, in response to the limitations imposed by other growth substrates. 4. Within a province, is variable; it has a seasonal cycle related to production. 5. has a distinct optical signature, detectable in ocean colour spectra. Fast Repetition Rate Fluorometer Jim Aiken, Gerald Moore, James Fishwick, Claudia Omachi, PML Phytoplankton Photosynthetic Quantum Efficiency (PQE, F v /F m ) is related to pigment composition, providing a proxy for the remote sensing of photosynthetic rates from ocean colour. Fast Repetition Rate Fluorometer, Kolber & Falkowski Photosynthetic Quantum Efficiency (PQE, F v /F m ) Results IronEx II (Eq. Pacific, 95) & SOIREE (S Ocean 99), show PQE is a dynamic parameter. Results from natural ecosystems, AMT (N S Atlantic) & L4 (W English. Chan., ) show similar interesting results. June-Aug Fv/Fm 998 Is there a functional relationship between PQE & Pigment ratios? Is there an optical signature (remote sensing determinand) for Chlorophyll fraction and a proxy for PQE? Bang
FRRF profiles Photosynthetic Quantum Efficiency, PQE, F v /F m FRRF vertical profiles, Celtic Sea, 4 May. Cast 43,.8 GMT, 4/5/ Surface chlorophyll DAWN, Cast 3, 4.9 GMT, /5/ F v /F m σ psii F m PAR Cast 43,.8 GMT, 4/5/ F v /F m σ psii F v /F m vs PAR F v /F m x PAR vs PAR E k FRRF profiles, PQE, F v /F m. Stratified, sub-surface maximum Station E W. English Channel AMT-, Station 3 (SATL). Omachi sub-surface max. at m. PAR ( ue.m -.s - ) 3 6 9 Fm T & F m T & F v /F m,l,d T & PAR F m Depth ( m ) 3 4 Depth ( m ) 3 4 5 PA R 5 FmD Temperature FmL Depth ( m ) 6 9 3 5 7 Temperature ( o C )..4 Fv/Fm.6 3 4 5 6 T & F v /F m,l,d Fv/FmL Temp 9 3 5 7 Temperature ( o C ) Fv/Fm*PAR ( ue.m -.s - ) 6 F v /F m x PAR E k Dark Chamber Light Chamber PAR ( ue.m -.s - ) σ psii Sub-surface max. at ca m. layers populations values
Aiken, et al. IronEx II: Photosynthetic Quantum Efficiency (PQE, F v /F m ), (mg/m 3 ) 4.5 4 3.5 3.5.5 TPig IronEx II 4 6 8 4 Iron injections Conclusion. is correlated with PQE (F v /F m ) and a proxy for PQE? (Data sparse). Plants synthesise preferentially when stimulated into growth. Fv/Fm,.6.4..4 5 /TPig IronEx II 4 6 8 4 IronEx II y = 9x.97 R =.636, n=, p=.6..4.6 Boyd et al, Nature,. SOIREE:.5 deg C 6 S; low light Aiken et al, SOIREE: Pigments, and PQE, F v /F m SOIREE: Southern Ocean Iron Enrichment Experiment, - Feb 999., (mg/m 3 ).5.5 5.5. SOIREE 4 6 8 4 SOIREE y = 9x.7 R = 79, n=, p=...4 Conclusion. SOIREE same as IronEx II, but data sparse. synthesised preferentially, when growth is stimulated. Fv/Fm,.4 SOIREE /TPig. 4 6 8 4 F v /F m rises from. to.43 within 4 h and remains at ca.43-.48 for 4-3 d. fraction rises from.3-5. Both F v /F m and fraction remain low outside Fe-enriched patch. SOIREE a(49), b b (49) 3
AMT-6 SeaWiFS Chlorophyll AMT-6, 998 Cape Town to UK. Pigments, and PQE, F v /F m..6.4 5 AMT6 All, (mg.m -3 ) 6 4 8 6 4 a. A-6 (all regions) Ben! SAT! NA 3 4 5 6 Stn. y =.734x. R = 36 5.4.6.6.4 5 AMT6 Ben y =.9x 78 R = 3E-6 S. Ben N. Ben Fv/Fm,.7.6.4 y =.9466x.9 R = 35 5.4.6 b. A-6 (all regions) Ben! SAT! NA 3 4 5 6.6 AMT6 NASA Stn. y =.958x.4 R = 63.4 SAT 5 y = 3x.8 R = 6 NA 5.4.6 Conclusion 3. AMT-6: significantly correlated with F v /F m, within regions. In natural ecosystems, plants increase the fraction of, to sustain maximum growth rates in their environment, subject to other limiting substrates. a) Chlorophyll-a and Total pigments. b) and PQE. Chlorophyll a ( mg.m -3 ) In SS period, values of PQE obtained for surface layer and thermocline max. &.. W English Channel, Station L4, measurements throughout. Phytoplankton pigments & PQE, F v /F m 8. 6. 4....7.65.6.4 5 LW-SB SS (Tm) AB-EW WEC 3 periods: LW-SB SS (Tm) AB-EW 4 4 6 6 8 8 4 4 6 6 8 sdy 8 sdy 4 4 6 6 8 8 3 3 3 Strat 3 34 34 36 36. Late winter, spring bloom (LW-SB).. Summer stratified (SS). with sub-surface thermocline maximum (Tm). 3. Autumn bloom, early winter (AB-EW) 4
W English Channel Station L4. Phytoplankton pigments, PQE, F v /F m.65.6 LWSB.65.6 L4 all y =.87x.36 R = 5.4 5.4 = m (Fv/Fm) c Season m c R n p L4all:.87.36 5 36. LWSB:.7.46.78 <. LWSB SS:.88.5 9 <. LWSBSS-ssm:..8.73 3 <. ABEW:.9 -.65 8 <..65 LWSBSS-ssm.6.4 y =.7x.46 R =.78 5.4.4 y =.x.8 R =.73 5.4 Conclusion 4. Station L4. As AMT, correlated to PQE generally & within seasons. Plants increase their fraction to sustain maximum growth in their environment, subject to other limiting substrates. Summary: Phytoplankton pigments & PQE, F v /F m IronEx II, end point, Eq Pac. May 95 SOIREE, out-of-patch, S Ocean, /99.7.65.6 /.4 Esur L4 Pro 5/ Dis 6/99 AMT- 6 Essm x Lab cultures x AMT-6, N S Atlantic, May-Jun 998 Disco, N. Sea, June 999 5 x Iron-end Propheze, Celtic Sea, May L4-LWSBSS, WEC, Esur, Essm, WEC, Conclusion 5. Is there a generalised relationship? Is there a site, season specific relationship? Is there a functional link between PQE and (not ).5. x S-oop..5 5.4.6.65.7 5
Aiken et al. PQE & Phytoplankton Pigments Conclusions:. IronEx II. PQE increases rapidly when phytoplankton are stimulated to grow. PQE is a dynamic parameter; FRR fluorometer is a Bloom Detector.. IronEx II & SOIREE. is correlated with PQE (F v /F m ); i.e. is a proxy for PQE. Plants synthesis preferentially when stimulated to grow. i.e. there is a coupled physiological-biological (functional) response. 3. AMT-6. significantly correlated with Fv/Fm, within regions. In natural ecosystems, plants increase the fraction of to, to sustain maximum growth rates in their environment, subject to other limiting substrates. 4. Station L4. significantly correlated with Fv/Fm, within seasons. 5. Is there a functional link between PQE and (not )? PQE or are dynamic parameters of phytoplankton production. 6. has a bio-optical signature, detectable in satellite colour data, using precise bio-optical algorithms. 6