Effects of hypoxia and non-lethal shell damage on shell mechanical and geochemical properties of a calcifying polychaete

Leung, Jonathan Y. S.; Cheung, Napo K. M.

doi:https://doi.org/10.5194/bg-15-3267-2018

Articles | Volume 15, issue 10

https://doi.org/10.5194/bg-15-3267-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-15-3267-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 10

Research article

|

01 Jun 2018

Research article |

| 01 Jun 2018

Effects of hypoxia and non-lethal shell damage on shell mechanical and geochemical properties of a calcifying polychaete

Jonathan Y. S. Leung and Napo K. M. Cheung

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Final revised paper (published on 01 Jun 2018)
Supplement to the final revised paper
Preprint (discussion started on 04 Oct 2017)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of the ms by Leung and Cheung', Anonymous Referee #1, 12 Oct 2017
- AC2: 'Response to Reviewer 1', Jonathan Leung, 15 Dec 2017
RC2: 'Review of Leung and Cheung', Anonymous Referee #2, 18 Oct 2017
- AC1: 'Response to Reviewer 2', Jonathan Leung, 15 Dec 2017
RC3: 'Leung & Cheung- Review', Anonymous Referee #3, 20 Oct 2017
- AC3: 'Response to Reviewer 3', Jonathan Leung, 15 Dec 2017

Peer-review completion

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

ED: Reconsider after major revisions (23 Feb 2018) by Tina Treude

AR by Jonathan Leung on behalf of the Authors (22 Mar 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Apr 2018) by Tina Treude

RR by Anonymous Referee #4 (07 Apr 2018)

Suggestions for revision or reasons for rejection

This manuscript presents clear results from an interesting experiment investigating he impacts of hypoxia and shell damage on a species of calcifying polychaete. The results suggest calcification can be maintained after shell damage and during exposure to 3 weeks of hypoxia, however mechanical and physical properties change with exposure to shell damage and hypoxia.

Introduction

This was generally well written with a clear scientific question and means to answer it. I feel the concept of changing shell mineralogy should be introduced in more detail with clearer rational behind the expected outcomes in the experiment. Introducing the different energetic costs of aragonite/calcite production in polychaetes would make the scientific significance more robust.

Methods

I have a few minor problems with the methodology section. Oxygen consumption measurements were generally well explained however I do not understand the sentence "the final dissolved oxygen concentration of FSW was recorded when it becomes steady by gently stirring the FSW inside the syringe" (L142). Additionally, a clear justification regarding the exclusive use of non-parametric tests for all the data should be provided.

Results

Slightly more detail could be given in the written description of the results however the figures and tables are excellent and all relevant data is presented.

Discussion

This section was generally excellent however there are some patterns in the results which should be better discussed. The authors state the energy demand for calcification is enormous (L227). In relative terms compared to organic tissue production, calcification is a minute cost being ~ 15 x lower than the cost of organic tissue synthesis (Palmer 1983, Marine Biology). This idea should also be discussed further as in the non-lethal shell damage treatment, calcified structures contained more organic material than in the non damage treatment. This would suggest and even higher cost of shell production. I also feel that the changes in clearance rates are extremely important as the energy income dictates the magnitude of energy partitioning to different growth and metabolic processes. It is interesting that in the normoxic treatment, calcification rate was ~ 4 x higher in the shell damage treatment than control despite a ~ 3 x decrease in food cosumption compared to the control! This is quite contradictory and should be discussed with relation also to somatic tissue growth and maybe reproduction. Lastly I think the discussion would benefit from a slight expansion of the section discussing changes in shell mineralogy. The authors correctly state that producing calcite shells is more energetically favourable than aragonite shells, however what is the magnitude of this change? If it is in the region of half the cost then it is indeed a significant change, however I don't believe that changing shell mineralogy will have that much of a significant effect on the energetic cost of shell production. Rather changing mineralogy will have more of an impact on dissolution capacity and shell strength.

Additionally, there are also some grammatical mistakes at several occurrences in the manuscript which need correcting (L96, L244, L276, L294 among others.)

References

Palmer, A. (1983). Relative cost of producing skeletal organic matrix versus calcification: evidence from marine gastropods. Marine Biology, 75, 287–292. Retrieved from http://link.springer.com/article/10.1007/BF00406014

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RR by Anonymous Referee #3 (09 Apr 2018)

ED: Publish subject to minor revisions (review by editor) (09 Apr 2018) by Tina Treude

AR by Jonathan Leung on behalf of the Authors (21 Apr 2018) Author's response Manuscript

ED: Publish subject to technical corrections (10 May 2018) by Tina Treude

AR by Jonathan Leung on behalf of the Authors (13 May 2018) Author's response Manuscript

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Short summary

Some calcifiers can sustain normal shell growth under hypoxia, which may involve trade-offs against shell quality. This hypothesis was tested by measuring the shell growth and shell properties of a calcifying polychaete. Despite the adverse effect on metabolism, we found that hypoxia had limited impact on shell growth probably due to the changes in shell properties as trade-offs. This suggests that such plastic response could be fundamental for calcifiers to maintain calcification under hypoxia.