Characterising primary productivity measurements across a dynamic western boundary current region

Everett, JD; Doblin, MA

Characterising primary productivity measurements across a dynamic western boundary current region

Everett, JD

Doblin, MA

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Publication Type:: Journal Article
Citation:: Deep-Sea Research Part I: Oceanographic Research Papers, 2015, 100 pp. 105 - 116
Issue Date:: 2015-06-01

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Field	Value	Language
dc.contributor.author	Everett, JD https://orcid.org/0000-0002-6681-8054	en_US
dc.contributor.author	Doblin, MA https://orcid.org/0000-0001-8750-3433	en_US
dc.date.available	2020-05-25T19:22:21Z
dc.date.issued	2015-06-01	en_US
dc.identifier.citation	Deep-Sea Research Part I: Oceanographic Research Papers, 2015, 100 pp. 105 - 116	en_US
dc.identifier.issn	0967-0637	en_US
dc.identifier.uri	http://hdl.handle.net/10453/35876
dc.description.abstract	© 2015 Elsevier Ltd. Determining the magnitude of primary production (PP) in a changing ocean is a major research challenge. Thousands of estimates of marine PP exist globally, but there remain significant gaps in data availability, particularly in the Southern Hemisphere. In situ PP estimates are generally single-point measurements and therefore we rely on satellite models of PP in order to scale up over time and space. To reduce the uncertainty around the model output, these models need to be assessed against in situ measurements before use. This study examined the vertically-integrated productivity in four water-masses associated with the East Australian Current (EAC), the major western boundary current (WBC) of the South Pacific. We calculated vertically integrated PP from shipboard <sup>14</sup>C PP estimates and then compared them to estimates from four commonly used satellite models (ESQRT, VGPM, VGPM-Eppley, VGPM-Kameda) to assess their utility for this region. Vertical profiles of the water-column show each water-mass had distinct temperature-salinity signatures. The depth of the fluorescence-maximum (f<inf>max</inf>) increased from onshore (river plume) to offshore (EAC) as light penetration increased. Depth integrated PP was highest in river plumes (792±181mgCm<sup>-2</sup>d<sup>-1</sup>) followed by the EAC (534±116mgCm<sup>-2</sup>d<sup>-1</sup>), continental shelf (140±47mgCm<sup>-2</sup>d<sup>-1</sup>) and cyclonic eddy waters (121±4mgCm<sup>-2</sup>d<sup>-1</sup>). Surface carbon assimilation efficiency was greatest in the EAC (301±145mgC (mgChl-a)<sup>-1</sup>d<sup>-1</sup>) compared to other water masses. All satellite primary production models tested underestimated EAC PP and overestimated continental shelf PP. The ESQRT model had the highest skill and lowest bias of the tested models, providing the best first-order estimates of PP on the continental shelf, including at a coastal time-series station, Port Hacking, which showed considerable inter-annual variability (155-2957mgCm<sup>-2</sup>d<sup>-1</sup>). This work provides the first estimates of depth integrated PP associated with the East Australian Current in temperate Australia. The ongoing intensification of all WBCs makes it critical to understand the variability in PP at the regional scale. More accurate predictions in the EAC region will require vertically-resolved in situ productivity and bio-optical measurements across multiple time scales to allow development of other models which simulate dynamic ocean conditions.	en_US
dc.relation	http://purl.org/au-research/grants/arc/DP140101340
dc.relation	http://purl.org/au-research/grants/arc/DP1092892
dc.relation.ispartof	Deep-Sea Research Part I: Oceanographic Research Papers	en_US
dc.relation.isbasedon	10.1016/j.dsr.2015.02.010	en_US
dc.subject.classification	Oceanography	en_US
dc.title	Characterising primary productivity measurements across a dynamic western boundary current region	en_US
dc.type	Journal Article
utslib.citation.volume	100	en_US
utslib.for	0405 Oceanography	en_US
utslib.for	0402 Geochemistry	en_US
utslib.for	0403 Geology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	open_access
pubs.publication-status	Published	en_US
pubs.volume	100	en_US

Abstract:

© 2015 Elsevier Ltd. Determining the magnitude of primary production (PP) in a changing ocean is a major research challenge. Thousands of estimates of marine PP exist globally, but there remain significant gaps in data availability, particularly in the Southern Hemisphere. In situ PP estimates are generally single-point measurements and therefore we rely on satellite models of PP in order to scale up over time and space. To reduce the uncertainty around the model output, these models need to be assessed against in situ measurements before use. This study examined the vertically-integrated productivity in four water-masses associated with the East Australian Current (EAC), the major western boundary current (WBC) of the South Pacific. We calculated vertically integrated PP from shipboard ¹⁴C PP estimates and then compared them to estimates from four commonly used satellite models (ESQRT, VGPM, VGPM-Eppley, VGPM-Kameda) to assess their utility for this region. Vertical profiles of the water-column show each water-mass had distinct temperature-salinity signatures. The depth of the fluorescence-maximum (fmax) increased from onshore (river plume) to offshore (EAC) as light penetration increased. Depth integrated PP was highest in river plumes (792±181mgCm^-2d^-1) followed by the EAC (534±116mgCm^-2d^-1), continental shelf (140±47mgCm^-2d^-1) and cyclonic eddy waters (121±4mgCm^-2d^-1). Surface carbon assimilation efficiency was greatest in the EAC (301±145mgC (mgChl-a)^-1d^-1) compared to other water masses. All satellite primary production models tested underestimated EAC PP and overestimated continental shelf PP. The ESQRT model had the highest skill and lowest bias of the tested models, providing the best first-order estimates of PP on the continental shelf, including at a coastal time-series station, Port Hacking, which showed considerable inter-annual variability (155-2957mgCm^-2d^-1). This work provides the first estimates of depth integrated PP associated with the East Australian Current in temperate Australia. The ongoing intensification of all WBCs makes it critical to understand the variability in PP at the regional scale. More accurate predictions in the EAC region will require vertically-resolved in situ productivity and bio-optical measurements across multiple time scales to allow development of other models which simulate dynamic ocean conditions.

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http://hdl.handle.net/10453/35876