Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa: insights from a stable isotope study covering an annual cycle

Morana, C.; Darchambeau, F.; Roland, F. A. E.; Borges, A. V.; Muvundja, F.; Kelemen, Z.; Masilya, P.; Descy, J.-P.; Bouillon, S.

doi:https://doi.org/10.5194/bg-12-4953-2015

Articles | Volume 12, issue 16

Biogeosciences, 12, 4953–4963, 2015

https://doi.org/10.5194/bg-12-4953-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Biogeosciences, 12, 4953–4963, 2015

https://doi.org/10.5194/bg-12-4953-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 12, issue 16

Research article 19 Aug 2015

Research article | 19 Aug 2015

Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa: insights from a stable isotope study covering an annual cycle

C. Morana et al.

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Final revised paper (published on 19 Aug 2015)
Preprint (discussion started on 11 Dec 2014)

Interactive discussion

Status: closed

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

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RC C9013: 'Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa): insights from a stable isotope study covering an annual cycle', Anonymous Referee #1, 09 Mar 2015
- AC C9193: 'Reply to the referee 1', Cedric Morana, 27 Mar 2015
RC C9032: 'Review of Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa): Insights from a stable isotope study covering an annual cycle.', Anonymous Referee #2, 10 Mar 2015
- AC C9198: 'Reply to the referee 2', Cedric Morana, 27 Mar 2015

Peer-review completion

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

AR by Cedric Morana on behalf of the Authors (27 Mar 2015) Author's response Manuscript

ED: Reconsider after major revisions (08 Apr 2015) by S. Wajih A. Naqvi

AR by Cedric Morana on behalf of the Authors (13 Apr 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Apr 2015) by S. Wajih A. Naqvi

RR by Anonymous Referee #2 (04 May 2015)

Suggestions for revision or reasons for rejection

Final review on manuscript BG-2014-511: “Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa): insights from a stable isotope study covering an annual cycle” by Morana et al.

I would like to first thank the authors for their responses to the other reviewer and my own initial comments. Both reviews had similar concerns regarding the main conclusion of the study i.e., that the lake is net autotrophic in light of the evidence provided in this study. Unfortunately, I was not convinced by the authors’ response. In their response, the authors cited many evidence from other studies to support their point (P9L7-20), not many of which were based on the novel data presented in this study. In fact, I found it a bit odd that the authors strongly based their arguments and calculations on Borges et al. (2014) (P9L7-16), and later stated that this conclusion (i.e., net autotrophy) is supported by the same study. How couldn’t it be? And how exactly the novel material presented in this study allows one to perform the calculations required to conclude on the metabolic status of the lake? Their main new argument for the support of net autotrophy probably comes from the very small change in d13C-DIC noted seasonally (Fig. 2b), but I still do not think that a change smaller than 1 per mill is enough to safely conclude that the lake is indeed autotrophic. I still believe that the study would have strongly beneficiate from other metabolic measurements or from a more detailed mass balance. I am sorry for not being more positive at this point, but I believe that even after reading authors’ clarifications, the isotopic evidence provided still fall short in convincingly addressing the question of the trophic status of Lake Kivu.

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ED: Reconsider after major revisions (24 Jun 2015) by S. Wajih A. Naqvi

AR by Anna Wenzel on behalf of the Authors (27 Jul 2015) Author's response Manuscript

ED: Publish subject to technical corrections (09 Aug 2015) by S. Wajih A. Naqvi