Ecosystem regimes and responses in a coupled ancient lake system from MIS 5b to present: the diatom record of lakes Ohrid and Prespa

Cvetkoska, Aleksandra; Jovanovska, Elena; Francke, Alexander; Tofilovska, Slavica; Vogel, Hendrik; Levkov, Zlatko; Donders, Timme H.; Wagner, Bernd; Wagner-Cremer, Friederike

doi:https://doi.org/10.5194/bg-13-3147-2016

Articles | Volume 13, issue 10

https://doi.org/10.5194/bg-13-3147-2016

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

Special issue:

Integrated perspectives on biological and geological dynamics...

https://doi.org/10.5194/bg-13-3147-2016

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

Articles | Volume 13, issue 10

Research article

|

31 May 2016

Research article |

| 31 May 2016

Ecosystem regimes and responses in a coupled ancient lake system from MIS 5b to present: the diatom record of lakes Ohrid and Prespa

Aleksandra Cvetkoska, Elena Jovanovska, Alexander Francke, Slavica Tofilovska, Hendrik Vogel, Zlatko Levkov, Timme H. Donders, Bernd Wagner, and Friederike Wagner-Cremer

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Preprint (discussion started on 11 Sep 2015)
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Interactive discussion

Status: closed

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

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RC C6498: 'Cvetkoska et al 2015', Jane Reed, 14 Oct 2015
RC C6885: 'Review of Cvetkoska et al. Ecosystem regimes and responses in a coupled ancient lake system from MIS 5b to present: the diatom record of lakes Ohrid and Prespa.', Anonymous Referee #2, 22 Oct 2015
AC C8570: 'Author comment on the reviews of Cvetkoska et al. 2015', Aleksandra Cvetkoska, 19 Dec 2015

Peer-review completion

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

ED: Reconsider after major revisions (22 Dec 2015) by Jack Middelburg

AR by Aleksandra Cvetkoska on behalf of the Authors (08 Mar 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Mar 2016) by Jack Middelburg

RR by Jane Reed (29 Mar 2016)

RR by Anonymous Referee #2 (01 Apr 2016)

Suggestions for revision or reasons for rejection

Review of Cvetkoska et al (REVISED). Ecosystem regimes and responses in a coupled ancient lake system from MIS 5b to present: the diatom record of lakes Ohrid and Prespa.

Cvetkoska et al. present a diatom record of high quality, alongside various geochemical proxies, from a c. 92ka lake sediment sequence retrieved from Lake Ohrid (part of the SCOPSCO project). The main purpose of the research is to compare this record to a previously published diatom record from the adjacent Lake Prespa (to which Ohrid is hydrologically connected) in order to compare system resistance and resilience to past climate change and to investigate the potential for Prespa to influence change in Ohrid.
In a review of an earlier draft manuscript, four substantive issues were identified relating to the interpretation of the data: (i) diatom response to variables in Ohrid; (ii) diatom concentration; (iii) lake interconnectivity (including sequence correlation); (iv) focus of the paper (see details contained in the earlier review). In addition, some minor queries / suggestions were made, including a further round of proof reading to improve the clarity of prose.
The revised manuscript has directly addressed all of the issues raised (which were helpfully highlighted and this was much appreciated). In the revised version, more detail is provided with regards to diatom responses and concentrations, as well as lake interconnectivity and the paper seems more focussed. Some minor queries remain (see below) and, although the manuscript is well structured and generally well written, a further round of proof reading will iron out the few remaining instances in which clarity slips.

SPECIFIC QUERIES / EDITS

ABSTRACT

Line 17: suggest specify aquatic ecosystem interactions

Line 21: suggest modify to ‘’interglacial and interstadial’’ and ‘’glacial’’

Line 22: ‘appear synchronous in both lakes’ Given the uncertainties in correlating these two sequences, could you qualify this statement?

Line 25: Suggest also specify lake level changes alongside trophic status changes in Prespa.

Line 26: ‘Lake Ohrid appears relatively resistant’ Could you specify what aspect of Lake Ohrid is resistant (e.g. changes in trophic state etc)?

Line 26: Climate change is the only apparent external forcing mechanism investigated, so is it reasonable to claim that Ohrid will behave in the same way to other external forcings?

INTRODUCTION

Line 11: would it be more appropriate to specify which continental ecosystems (terrestrial, aquatic) or is statement intentionally broad?

Page 3, Line 20: Suggest change the word ‘interdependence’ to better reflect the one-way influence of Prespa on Ohrid.

ENVIRONMENTAL SETTING

Page 4, Line 27: specify which summer and winter months (JJA, DJF?)

Page 4, Line 28: mean annual precipitation? Based on how many years / which publication?

Page 5, Lines 13-15 (as above)

Page 5, Line 17-18: specify cause of 10m lake level decline (abstraction, lower P/E?)

ECOSYSTEM DYNAMICS

Page 11, Line 1: It would be informative to quantify the dating errors within / between the sequences.

Page 11, Line 5-6: I’m not sure I follow the logic of this. Please explain / justify.

Page 12, Line 12: I would still urge some caution with using diatom concentrations to infer productivity changes. In this case, a change in diatom concentrations during a period of constant SAR is identified. However, if there are long sediment intervals between tie points / tephra layers, then constant SARs are a large assumption – this calculation will be insensitive to shorter term variability in sedimentation rates, which can potentially account for changes in diatom concentrations. It may be worth considering the environmental context to further support productivity-driven changes in diatom concentrations (e.g. although other variables are considered, what is the nature of the catchment at this time (densely vegetated?), are there any changes in proxies of sediment in-wash etc?

Page 12, Line 16-17: what is the regional nature of climate change during this interval? Providing this information will add context.

ECOSYSTEM INTERNAL INTERACTIONS AND DYNAMICS

Page 20, Line 2: Mention is made here and elsewhere that there is no diatom-based evidence for a change in lake level of Ohrid. Perhaps this claim can be made based on isotope evidence, but given that the core site is at >240m water depth, surely any change in lake level would have to be pretty major before the diatoms would respond (via benthic expansion for example)? If the other Ohrid diatom-based records are from shallower core sites then please state (with depth) to make the case that there is no diatom-inferred lake level change.

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ED: Publish subject to minor revisions (Editor review) (17 Apr 2016) by Jack Middelburg

AR by Aleksandra Cvetkoska on behalf of the Authors (30 Apr 2016) Author's response Manuscript

ED: Publish subject to technical corrections (12 May 2016) by Jack Middelburg

AR by Aleksandra Cvetkoska on behalf of the Authors (14 May 2016) Manuscript

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