P roduction R ates in the Southern California Current System David Munro University of Washington 1 Acknowledgements Paul Quay Mark Haught Johnny Stutsman and Jackie Leung UW Laurie ID: 531790
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Slide1
B
iological Production Rates in the Southern California Current System
David MunroUniversity of Washington
1Slide2
AcknowledgementsPaul Quay, Mark Haught, Johnny Stutsman, and Jackie Leung (UW)Laurie
Juranek, Cynthia Peacock (NOAA), Deirdre Lockwood, Hilary PalevskyRalf Goericke, Dave Wolgast, and CalCOFI research associates (SIO)2Slide3
AcknowledgementsFunding sourcesFirst year graduate fellowship from the Program on Climate Change
Office of Naval Research (NDSEG) fellowshipNASA WA space grant fellowshipNational Science Foundation support for sample supplies and analysis3Slide4
Primary Production and Carbon Export in the Coastal OceanGlobal aquatic PP from satellites ~45-50 Pg
C y-1 (Carr et al., 2006)Based on derived Chl a, PAR, SST, and calibrated with 14C PP Estimates vary by a factor of 2 (Campbell et al., 2002; Carr et al. 2006)~20% of ocean PP occurs in continental margins (50-2000 m depth) (Carr et al., 2002; Muller-Karger et al., 2005) 40 to 50% of global C export flux occurs in continental margins (Muller-Karger et al., 2005; Dunne et al. 2007)Eastern Boundary Currents (EBC’s) <1% of ocean surface area but ~20% of global fish catchSlide5
Sea surface chlorophyll5
From Sarmiento and GruberSlide6
Net Primary Production6
From Sarmiento and GruberSlide7
Air-Sea C Flux in the Coastal Ocean
Globally, coastal seas may be a small net sink, high variability -0.22±0.16 Pg C y-1 (Cai et al. 2006)Global ocean ~ -2.0 Pg C y-1High variability, many poorly characterized systemsTable 1 and Fig. from Cai et al. 2006
7Slide8
Productivity termsGOP – Gross O2 production; photosynthetic O
2 production via water-splitting reactions in PSIINCP – Net community production; net production of O2 or C in surface ocean after demands of autotrophic and heterotrophic communities have been metNPP – Net primary production (Gross C production minus respiration by phytoplankton)Estimated using 14C-PP and VGPMNCP/GOP ratio – An estimate of the fraction of gross production available for export in terms of O2.NCP/NPP – equivalent to e-ratio or ef-ratio; fraction of NPP in C terms available for export8Slide9
Study Goals I: Spatial and seasonal variability of PP rates
Determine variability of PP and NCP and its impact on coastal C system using in situ methodsGross oxygen production (GOP) using 17Δ of dissolved O2Net community production (NCP) NOP = GOP – (Community Resp) using (O2/Ar)measuredExport efficiency (NOP/GOP)Comparison to incubation-based 14C-PPValidation of satellite-based PP in the coastal ocean9Slide10
Study Goals II: Variability in C export over the last three decades
Estimate NCP using four different approachesMixed layer O2 budgetMixed layer nitrate budget15N uptake f-ratios combined with 14C-PPSatellite-based (VGPM) x export algorithmsDunne et al. (2007); Laws et al. (2000) O2-NCP from biological O2 saturation based on O2/Ar measurementsEvaluate interannual and decadal variability in NCP10Slide11
Study Site: CalCOFI
Annual Mean Surface Chl a in mg m-3 from Photobiology Group (SIO)
CalCOFI grid coded by region17D O2
/Ar Samples collected during 6 cruises
11Slide12
14C PP: why another method?
In vitro effects are a big unknown (Marra, 2002)Uncertainty in what it actually measures (Marra, 2002)Something between GCP and NCP, closest to net primary production (NPP)Recycling of labeled CSome labeled C is dissolved (depending on methodology either included/excluded)Snapshot estimate (6 to 24 hours)Logistical constraintsSlide13
17Δ in situ GOP Method
Uses a mixed layer O2 and O2-isotope budget to estimate GOP in the mixed layerLuz and Barkan (2000)GOP = Kgas* [O2]sat *17D not sensitive to respirationMore terms in the coastal ocean (i.e. coastal upwelling, curl-driven upwelling, horizontal transports)Must convert from O2 to CNot based on an incubation(
17Δdiss – 16) (249 – 17Δdiss)13Slide14
Ocean Range of 17Δ Values
Purely Photosynthetic O2
249±15 per meg
Purely Gas Exchange O2
16±2 per meg
Half Photo + Half Gas Exchange O
2
132 per meg
Measuring
17
Δ yields a direct estimate of the
proportion
of O
2
from air and photosynthesis.
14Slide15
Locations of
17D measurements to date, from Juranek and Quay (2013)15Slide16
O2/Ar in situ NCP method
NCP estimates (in O2 terms) are based on mixed layer budgets for [O2] and [Ar]NCP = Kgas * [O2]sat * ( – 1)NCP/GOP a measure of export efficiency from one measurement Does NOT depend on gas exchange (Kgas)NCP/GOP is comparable to f-ratio2x N/G ~ f-ratio (new production/net primary production)
(O2/Ar)meas (O2/Ar)sat16Slide17
Spatial
maps of 17Ddiss
and biological O2 saturation (from O2/Ar)
Samples collected at up to 50 of 66 standard
CalCOFI
stations compared to 16 productivity (
14
C-PP) stations
August
August
17Slide18
Variability of 17D-GOP and O
2:Ar-NCPAnnual NCP and GOP in mmol O2 m-2 d-118Slide19
17D-GOP : 14C-PP
19From Juranek and Quay (2013)
MBARI (Munro and Quay, unpublished data)Slide20
Comparison of NCP/GOP
Study LocationAuthors
NCP/GOPO2 terms
NCP/NPP
C terms
NCP/NPP
Laws et al (2000)
CalCOFI
– Entire Grid
CalCOFI
– N. Inshore
CalCOFI
– Offshore
Munro et al. 2012
0.16±.06
0.20±.06
0.15±.06
0.31±.12
0.39±.12
0.29±.12
0.26
0.38
0.18
HOT
BATS
Subarctic N. Pacific
Equatorial Pacific
Southern Ocean
North Atlantic – bloom
– annual
Quay et al. 2010
Barkan
et al. 2009
Juranek
et al. 2012
Hendricks et al. 2005
Stanley et al. 2010
Reuer
et al. 2007
Hamme
et al. 2010
Quay et al. 2012
0.19±.08
0.13±.05
0.08 - 0.13
0.06±.05
0.08 - 0.13
0.35±.13
0.07±.06
0.38±.15
0.25±.10
0.15 - 0.25
0.12±.10
0.15 - 0.25
0.68±.25 0.14±.12
0.15
0.14
0.35
0.12
0.70
0.50
0.50
Coastal Ocean
NCP/GOP
ratio similar to open
ocean
(
unexpected)
20Slide21
Particle Export Ratio21
As predicted by the Dunne et al. 2007 algorithm which is a function of chl a and SST From Sarmiento and GruberSlide22
POC Export Production22
From Sarmiento and GruberSlide23
Conclusions I17
D-GOP shows seasonality nearshore17D-GOP consistently 5-7x 14C-PP and 4x VGPM17D-GOP/14C-PP = 2-3x at MBARISuggests that CalCOFI 14C-PP underestimates NPP due to methodological effects in 14C-PPCannot rule out variability in O2/CNCP:GOP ratios close to ratios observed in the open ocean (0.1 to 0.2)Higher ratios than predicted by export models offshore23Slide24
Variability in NCP at CalCOFI over the last three decades
24Slide25
Trends in O2 in the S. Cal. Current
%change in O2 1984-2006
O2 trends at ~250 m depthFrom McClatchie et al. 2010
Bograd
et al. 2008 Slide26
Methods: Estimating Biological O2 saturation using O2 saturation
Consistent relationship between biological O2 saturation and O2 saturationEstimated for each region/seasonO2 and nitrate budgets constructed: upwelling terms; horizontal advection; time rate of change; NCP26Slide27
NCP anomaly calculated by differencing quarterly NCP with long-term mean for month of cruise
27Slide28
Longterm NCP trends in the South CCS
28
MEI: Multivariate ENSO Index (
Wolter
and
Timlin
1998)PDO: Pacific Decadal Oscillation (Mantua et al. 1997)NPGO: North Pacific Gyre Oscillation (Di Lorenzo et al. 2008) Slide29
Conclusions IINegative NCP anomalies in response to strong El Niño events (e.g.,
1987, 1991-92, 1998) Less signficant NCP response to weak El Niño and La Niña events.Since 2007, positive NCP anomalies based on all NCP estimates (i.e., O2:Ar, nitrate budget, 15N incubations and satellite NPP)NCP trends over the past three decades suggest that export of organic material to depth within the CalCOFI grid not responsible for lower O2 concentrations at depth observed by Bograd et al. (2008) and McClatchie et al. (2010)29Slide30
Questions?30