Drivers of summer oxygen depletion in the central North Sea

Queste, Bastien Y.; Fernand, Liam; Jickells, Timothy D.; Heywood, Karen J.; Hind, Andrew J.

doi:https://doi.org/10.5194/bg-13-1209-2016

Articles | Volume 13, issue 4

https://doi.org/10.5194/bg-13-1209-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

Low oxygen environments in marine, fresh and estuarine...

https://doi.org/10.5194/bg-13-1209-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 13, issue 4

Research article

|

29 Feb 2016

Research article |

| 29 Feb 2016

Drivers of summer oxygen depletion in the central North Sea

Bastien Y. Queste, Liam Fernand, Timothy D. Jickells, Karen J. Heywood, and Andrew J. Hind

Download

Final revised paper (published on 29 Feb 2016)
Preprint (discussion started on 12 Jun 2015)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

- Printer-friendly version

- Supplement

RC C3570: 'Review of "Drivers of summer oxygen depletion in the central North Sea, by B. Y. Queste, L. Fernand, T. D. Jickells, K. J. Heywood, and A. J. Hind"', Anonymous Referee #1, 15 Jul 2015
RC C3782: 'Review of “ Drivers of summer oxygen depletion in the Central North Sea” by B. Y. Queste et al.', Anonymous Referee #2, 24 Jul 2015
RC C4344: 'Review of manuscript “Drivers of summer oxygen depletion in the central North Sea” by Queste et al.', Anonymous Referee #3, 14 Aug 2015
AC C6983: 'Reply to reviewers' comments', Bastien Queste, 23 Oct 2015

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (30 Oct 2015) by Lothar Stramma

AR by Bastien Queste on behalf of the Authors (10 Nov 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (11 Nov 2015) by Lothar Stramma

RR by Anonymous Referee #1 (30 Nov 2015)

RR by Charlotte Williams (07 Dec 2015)

RR by Anonymous Referee #3 (14 Dec 2015)

Suggestions for revision or reasons for rejection

Re-review of “Drivers of summer oxygen depletion in the central North Sea” by Queste et al.

Although my review was fairly minor and I was happy to see this work published, the authors provided a generally poor response to my initial review. Almost every single major point was swatted away without any intent for meaningful attention. If you read the responses to my major points, you may see that they are effectively not addressed. In particular Point 3.

I do not recommend publication until Point 3 at the very least is properly addressed.

I have included a short review in response to some points that I still feel need addressing.

Point 3:

Firstly, It is surprising the T and S glider are calibrated against the CTD data. However, the chl-a fluorometry is not because of a storm. Surely the CTD fluorometer has been recently calibrated? The few casts available will be a better indicator of the chl-a than the manufacturer's count. I remind you that the manufacturers conversion from fluor to chl-a is estimated using a lab culture or chl-a standard. This is in no way representative of open ocean phytoplankton communities especially if they are mixed communities, which they generally are.

If you cannot convert to meaningful chl-a data using any of the ship based profiles, then you shouldn’t use the data and then I request you remove chl-a data from your paper entirely.

Secondly, it is simply bad practise to not correct your data as best possible for publication. Its unacceptable to publish uncorrected data, especially when undertaking a quenching correction to the fluorescence data is so straightforward (even more so when you have some backscatter data available). It is necessary to display correct data for all future readers and their interpretation of the data. I’m sure the journal will agree that this is imperative.

You talk about diurnal signals of the DCM but you have not corrected for quenching! Even if by eye you can see quenching to 25m or so, you still need to correct and make sure ‘diurnal’ variability is not being impacted by quenching. You have BB data, so correct it.

You have not addressed this part of Point 3 either:
“Lastly, Section 6.2 refers a lot of the chl-a data and DCM but all these references are to Fig 3d. One cannot clearly see the variations of this chl-a with the section alone – esp. when you start referring to diurnal variability and links with the winds enhancing chl-a through nutirent supply. . . these statements are too definitive given the way the data is currently displayed. In order to really see the variations a 1D time series of integrated chl-a through the water column should be displayed. If this doesn’t reveal any variability then the DCM should be somehow isolated and plotted as a 1D time series. Hence, coming back to the quenching – if you provide an integrated time series, then the data has to have the quenching addressed first as this will bias the time series.“
It is not clear to see diurnal chl-a variability in the section. A 1D integrated plot of the mean Chl-a should show this… especially if there is a way to isolate that chl-a that is termed part of the DCM.

Point 5:

The authors are resistant to simply indicate MLD on their plots and yet they state the need to “showing their relative contribution and the mixed layer depth in this two layer system”.
Its easy to put MLD on your plots, so do it. It will help all reading the paper. Do the same for BML (7deg isotherm) since there is so much emphasis on this. It will not clutter the plots what so ever and if the ‘black line would be lost in the rapid change from red to blue” then how about picking another color!? White? A single line on the plots will not be an issue and will definitely not hide your gradients.

Hide

ED: Reconsider after major revisions (17 Dec 2015) by Lothar Stramma

AR by Bastien Queste on behalf of the Authors (03 Feb 2016) Author's response Manuscript

ED: Publish as is (09 Feb 2016) by Lothar Stramma

AR by Bastien Queste on behalf of the Authors (09 Feb 2016)

Short summary

In stratified shelf seas, physical and biological conditions can lead to seasonal oxygen depletion when consumption exceeds supply. An ocean glider obtained a high-resolution 3-day data set of biochemical and physical properties in the central North Sea. The data revealed very high oxygen consumption rates, far exceeding previously reported rates. A consumption–supply oxygen budget indicates a localized or short-lived resuspension event causing rapid remineralization of benthic organic matter.