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Seasonal and inter-annual variability in nutrient supply in relation to mixing in the Bay of Biscay

Seasonal and inter-annual variability in nutrient supply in relation to mixing in the Bay of Biscay
Seasonal and inter-annual variability in nutrient supply in relation to mixing in the Bay of Biscay
A key challenge in oceanography is to capture and quantify processes that happen on short time scales, seasonal changes and inter-annual variations. To address this problem the P&O European Ferries Ltd. Ship MV Pride of Bilbao was fitted with a FerryBox from 2002 to 2010 and data returned to NOC in real time providing near continuous measurements between UK (Portsmouth) and Spain (Bilbao) of temperature, salinity, chlorophyll-fluorescence and oxygen. Additional monthly samples were collected on manned crossings. Over 6000 samples were analysed for nitrate (nitrate and nitrite) concentrations. The timing of nitrate concentration increases (with winter mixing) and decreases (with the spring bloom) are different on and off shelf and in autumn nitrate concentrations remain high on the shelf. Off shelf in the Bay of Biscay, the mixed layer depth assessed using Argo floats, was found to vary from 212 m in relatively mild winters (such as 2007/2008) to 476 m in cold winters (2009/2010). Years with deeper mixing were associated with an increase in nitrate concentrations in the surface waters (~3 ?mol l?1) and the increased vertical nutrient supply resulted in higher productivity the following spring. Bloom progression could be seen through the increase in oxygen anomaly and decrease in nitrate concentrations off shelf prior to changes further north on the shelf and phytoplankton growth was initiated as shoaling begins. The full dataset demonstrates that ships of opportunity, particularly ferries with consistently repeated routes, can deliver high quality in situ measurements over large time and space scales that currently cannot be delivered in any other way.
Nitrates, Time-series, Ship of opportunity, North East Atlantic, Bay of Biscay
0967-0645
68-75
Hartman, Susan E.
2f74a439-395a-4ee7-89a2-eff4cc8d9481
Hartman, Mark C.
cdd63b60-f89a-4ef8-842d-7803f8213c18
Hydes, David J.
ac7371d4-c2b9-4926-bb77-ce58480ecff7
Jiang, Zong-Pei
801435b8-c2e5-476e-84c0-b49ef65ad382
Smythe-Wright, Denise
18f22519-f0f3-4144-ad0d-051fd3374fe8
González-Pola, Cesar
bd181724-7b79-4e9e-a373-1a26180b1a4c
Hartman, Susan E.
2f74a439-395a-4ee7-89a2-eff4cc8d9481
Hartman, Mark C.
cdd63b60-f89a-4ef8-842d-7803f8213c18
Hydes, David J.
ac7371d4-c2b9-4926-bb77-ce58480ecff7
Jiang, Zong-Pei
801435b8-c2e5-476e-84c0-b49ef65ad382
Smythe-Wright, Denise
18f22519-f0f3-4144-ad0d-051fd3374fe8
González-Pola, Cesar
bd181724-7b79-4e9e-a373-1a26180b1a4c

Hartman, Susan E., Hartman, Mark C., Hydes, David J., Jiang, Zong-Pei, Smythe-Wright, Denise and González-Pola, Cesar (2014) Seasonal and inter-annual variability in nutrient supply in relation to mixing in the Bay of Biscay. Deep Sea Research Part II: Topical Studies in Oceanography, 106, 68-75. (doi:10.1016/j.dsr2.2013.09.032).

Record type: Article

Abstract

A key challenge in oceanography is to capture and quantify processes that happen on short time scales, seasonal changes and inter-annual variations. To address this problem the P&O European Ferries Ltd. Ship MV Pride of Bilbao was fitted with a FerryBox from 2002 to 2010 and data returned to NOC in real time providing near continuous measurements between UK (Portsmouth) and Spain (Bilbao) of temperature, salinity, chlorophyll-fluorescence and oxygen. Additional monthly samples were collected on manned crossings. Over 6000 samples were analysed for nitrate (nitrate and nitrite) concentrations. The timing of nitrate concentration increases (with winter mixing) and decreases (with the spring bloom) are different on and off shelf and in autumn nitrate concentrations remain high on the shelf. Off shelf in the Bay of Biscay, the mixed layer depth assessed using Argo floats, was found to vary from 212 m in relatively mild winters (such as 2007/2008) to 476 m in cold winters (2009/2010). Years with deeper mixing were associated with an increase in nitrate concentrations in the surface waters (~3 ?mol l?1) and the increased vertical nutrient supply resulted in higher productivity the following spring. Bloom progression could be seen through the increase in oxygen anomaly and decrease in nitrate concentrations off shelf prior to changes further north on the shelf and phytoplankton growth was initiated as shoaling begins. The full dataset demonstrates that ships of opportunity, particularly ferries with consistently repeated routes, can deliver high quality in situ measurements over large time and space scales that currently cannot be delivered in any other way.

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Hartman_revised manuscript_2.pdf - Accepted Manuscript
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More information

Accepted/In Press date: October 2013
Published date: August 2014
Keywords: Nitrates, Time-series, Ship of opportunity, North East Atlantic, Bay of Biscay
Organisations: Ocean and Earth Science, Marine Biogeochemistry

Identifiers

Local EPrints ID: 362610
URI: http://eprints.soton.ac.uk/id/eprint/362610
ISSN: 0967-0645
PURE UUID: 7047d4e7-bf53-4f43-97a0-81270cebc850

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Date deposited: 27 Feb 2014 14:10
Last modified: 28 Oct 2019 21:00

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