Environmental factors influencing benthic communities in the oxygen minimum zones on the Angolan and Namibian margins

Hanz, Ulrike; Wienberg, Claudia; Hebbeln, Dierk; Duineveld, Gerard; Lavaleye, Marc; Juva, Katriina; Dullo, Wolf-Christian; Freiwald, André; Tamborrino, Leonardo; Reichart, Gert-Jan; Flögel, Sascha; Mienis, Furu

doi:https://doi.org/10.5194/bg-16-4337-2019

Articles | Volume 16, issue 22

https://doi.org/10.5194/bg-16-4337-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-16-4337-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 22

Research article

|

15 Nov 2019

Research article |

| 15 Nov 2019

Environmental factors influencing benthic communities in the oxygen minimum zones on the Angolan and Namibian margins

Ulrike Hanz, Claudia Wienberg, Dierk Hebbeln, Gerard Duineveld, Marc Lavaleye, Katriina Juva, Wolf-Christian Dullo, André Freiwald, Leonardo Tamborrino, Gert-Jan Reichart, Sascha Flögel, and Furu Mienis

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Final revised paper (published on 15 Nov 2019)
Preprint (discussion started on 25 Feb 2019)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Referee Comments for Manuscript bg-2019-52', Anonymous Referee #1, 15 May 2019
- AC1: 'Response to the interactive comment of referee #1', Ulrike Hanz, 21 Aug 2019
RC2: 'Referee's comments on bg-2019-52', Anonymous Referee #2, 24 Jul 2019
- AC2: 'Response to the interactive comment of referee #2', Ulrike Hanz, 22 Aug 2019

Peer-review completion

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

ED: Reconsider after major revisions (30 Aug 2019) by Ciavatta Stefano

AR by Ulrike Hanz on behalf of the Authors (30 Aug 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Sep 2019) by Ciavatta Stefano

RR by Anonymous Referee #2 (25 Sep 2019)

Suggestions for revision or reasons for rejection

This is a greatly improved manuscript, and the authors appear to have addressed most of the concerns raised in this reviewer’s previous assessment. The manuscript would be further improved by addressing some minor issues, as follows:
L26 The study does not really ‘explain’ why benthic communities differ, so perhaps ‘explore’ would be a better word to use.
L81 replace ( with ; before Fink
L107 insert hyphen between reef and covered
L109 The study does not really ‘identify’ why CWCs thrive, so perhaps ‘explore’ would be a better word to use.
L112 The data are not really ‘used to provide new insights in susceptibility’. Replace last sentence with ‘The data are used to improve understanding of the potential fate of CWC mounds in a changing ocean’.
L124 OMZ should be singular in this sentence (delete s)
L141 replace last part of sentence to read ‘expanding from the oceanic zone 350 km offshore towards the coast’
L143 insert hyphen between sun and warmed
L150 The TROL lander was not used in this study, so remove from the figure (and text)
L166 change ‘underneath’ to ‘in’
L170 move ‘also’ to between ‘were’ and ‘present’ on L171
L172 insert ‘along with some’ before M. oculata.
L174 replace ‘an even’ with ‘a’
L185 change to ‘hide in hollows in the coral framework’
L199 delete sentence about TROL
L218 Change to ‘Owing to technical problems turbidity data were only collected’
L226 Question: what is the rationale for using Spearman rank correlations, and how do you deal with non-independence among the observations? [This is not a show stopper, but I am still wondering].
L236 commas after filters and analysis are unnecessary – delete
L240 the ‘used’ is unnecessary – delete
L241 ‘standards’ not ‘a standard’, and ‘were’ not ‘was’
L242 ‘exercised’ is not the right word – use ‘used’
L244 ‘comparison with’ not ‘comparing’
L254 replace ‘about’ with ‘of’
L281 et seq. There is a real problem with using DOconc to mean DO concentration. Why can you not use simply DO, or better, DO concentration? If you use the latter you can simply distinguish between DO concentration (singular) and DO concentrations (plural). As DOconc is used it is often impossible to determine which is meant. Maybe use DOconc and DOconcs?
L284 replace ‘was stretching’ with ‘stretched’
L285 replace ‘towards’ with ‘to’
L291 delete ‘up to’
L293 the meaning of ‘towards 50 km from the coastline’ is very unclear. Why is the ‘section distance’ increasing from left to right, assuming that the coast is towards the right of the plots? Why not replace the x axis with ‘distance to the coast’?
L308 should read ‘decreased further to a minimum of’ … ‘and then increased to’
L311-2 is overall DOconc singular or plural in this sentence? I think singular, in which case it should be ‘was’ on L312
L317 again the x axes are confusing. Replace with ‘distance to the coast’?
L329 not clear what ‘especially’ is meant to mean – replace with ‘markedly’?
L340 change to ‘changed to a dominantly northerly direction’
L356 temperatures were (not was)
L358 DOconc here is plural, so change it (see note above)
L362 delete ‘overall’
L366 delete comma after ‘showed’
L396 change to ‘Carotenoids (0.08-0.12 μg l-1) and fucoxanthin (0.22 μg l-1), which are common in diatoms, were major components of the pigment fraction.’
L400 insert ‘were’ after SPOM
L408 delete ‘an’, change ‘ratio’ to ‘ratios’ and replace ‘on’ with ‘at’
L426 et seq. ‘likely’ on its own as an adverb is not good English. Use alternatives such as ‘probably’, ‘are likely to’, ‘may’, ‘might’ and so on. The sentence could read ‘It is probably that differences in present-day environmental conditions between the areas influence the faunal assemblages inhabiting them’.
L432 lowest DOconc is singular so ‘is’ not ‘are’
L434 replace ‘most likely’ with ‘probably’
L440 replace ‘was leading’ with ‘led’
L446 replace ‘likely’ with ‘possibly’
L468 DOconc is plural, so change to reflect this
L494 delete ‘low’ at the end of the line
L520 ‘stresses’ not ‘stress’
L524 insert comma after CWCs
L545 ‘coupled to periods of other environmental stressors’ makes no sense. Do you mean ‘Variations in food quality…, which were relatively small during this study, did not seem to be related to the presence of other environmental stressors’?
L549 replace ‘likely’ with ‘probably’
L552 replace ‘likely’ with ‘probably’
L555 replace ‘likely’ with ‘possibly’
L562 change to ‘may be unsuitable for CWCs’
L580 replace ‘likely defines the presence of CWCs’ with ‘probably defines the limits of suitable habitat for CWCs’
L581 ‘stress’ not ‘stressor’
L594 replace ‘is accumulated’ with ‘accumulates’

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ED: Publish subject to minor revisions (review by editor) (26 Sep 2019) by Ciavatta Stefano

AR by Ulrike Hanz on behalf of the Authors (03 Oct 2019) Author's response Manuscript

ED: Publish as is (10 Oct 2019) by Ciavatta Stefano

Short summary

Along the Namibian and Angolan margins, low oxygen conditions do not meet environmental ranges for cold–water corals and hence are expected to be unsuitable habitats. Environmental conditions show that tidal movements deliver water with more oxygen and high–quality organic matter, suggesting that corals compensate unfavorable conditions with availability of food. With the expected expansion of oxygen minimum zones in the future, this study provides an example how ecosystems cope with extremes.