PCLM-D-24-00078

Exploring novel North Water Polynya ecosystems under climate change

PLOS Climate

Dear Dr. Gillie,

Thank you for submitting your manuscript to PLOS Climate. After careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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PLOS Climate

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does this manuscript meet PLOS Climate’s publication criteria? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

Reviewer #2: Yes

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Reviewer #1: No

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I congratulate the authors for developing and applying a novel approach to delineate the impacts of climate change in marine ecosystems by combining two modelling approaches, SDMs and EwE. It is a well-written study, but overall there are certain methodological aspects that need to be clarified and elaborated in the manuscript.

Lines 185-199: A number of statistical approaches are used here (GAM, BRT, RF), but these are not fully evaluated in the manuscript. I believe that the results of these analyses should be included in a supplementary file, given that the methodologies are discussed in detail in "S1_Text". In addition, I believe that this is necessary to comply with the PLOS Data Policy.

Line 179: Brief information on these scenarios would be a welcome addition.

Line 235: "23" or "24", is one group multi-stanza or separately defined?

Line 384: Have all Ecosim simulations reached equilibrium? Were the final biomasses reported when the model simulations reached equilibrium? If not, the averages for the decade would be more statistically sound.

Line 410: It is not clear which scenario this is. This is difficult to follow and I suggest that emission scenarios be specified when they are first mentioned, possibly in brackets.

Lines 426-433: The pedigree index scales between 0 and 1, so it is not clear how the authors calculated index values above 1. Also, the pedigree index value for the whole Ecopath model should be also given.

Line 486: This notation for the number "9.11e-07" is not reader friendly and I suggest adopting a more humanised notation.

Line 561: Is the mean transfer efficiency considered to be really low? It is close to the theoretical value of 10%.

Reviewer #2: This paper aims to study the potential future marine ecosystem structures of the North Water Polynya by using SDMs and Ecopath with Ecosim modelling. It is clearly presented, and well-justified in both methods used and scenarios followed. Attention should be given to unreferenced and sometimes slightly contradictory statements that are sometimes somewhat in opposition to the scientific literature, particularly on trophic links. Overall, an excellent paper that would benefit from some minor revisions to the text, and perhaps consideration of shortening. Consider also whether all the supplementary materials are necessary. This paper is a valuable contribution to the advancement of the state of scientific knowledge.

Detailed comments:

Abstract and introduction both very clearly written and logically structured, with nice framing of the issues and potential changes to the NOW in a changing environment.

L116 Assuming an increasing abundance of competing species before any results (or clear justifications) does not fit in the introduction.

M&M

L124 I'm not sure that breeding seasons fit with the other listed descriptors of seasonal variation.

L132 Arctic cod tend to be towards the middle of the trophic chain.

L140 Rephrase, as an ocean is not formed but rather joined.

L142 dissolution, not dissolvelment.

Section 2.2.1 Why were orca selected?

Was there a relevant temporal range for the species occurrence data?

L169 Gridding alone does not generally rarefy, unless only single records per gridsquare existed. Was further rarefaction by other methods necessary?

Section 2.2.2 Was stratification considered?

Was the current period relevant to the species occurrence data period?

L203 All data?

L220-222 Description of AUC should be at first mention (L216).

L225 What thresholds?

L233 Are killer whales truly novel in this ecosystem? If so, why is it thought that they may become ecosystem components? They inhabit many other Arctic regions, so why aren't they already in the NOW?

L333 Also due to likely increased mixing from storminess.

Table 1 Would you define the large and small pelagic producers please?

Results

L416-418 Given that there are thriving populations of orca in the temperate and tropical zones, and populations that migrate from the tropics to the Arctic, are the inputs to these models robust? Temperature-based declines of this magnitude seem unlikely, and some sub-populations eat both fish and mammals.

Sections 3.2.1, 3.2.2 seem more suited to the methods section.

L472-473 How do obligate benthic inverts feed on pelagic FGs? Through scavenging?

L470-471 Consider making the link between the coupler species here and those in the preceding section to avoid repetition.

L479-480 Note that zooplankton etc. are all consumers, and that B. saida (adult) largely consumes zooplankton, with likely very little direct phytoplankton consumption (validated by numerous diet and isotope studies).

Fig 3 Why is only 1 scenario shown?

Table 3 Note that blue is increase and red is decrease in the caption.

Fig 4 The shading is a bit unclear, it would be better to use cross-hatching, and to remove mention of TL>4 from the legend.

Discussion

L566-586 But there is also possible decrease in future stratification due to increased storminess and mixing.

L590 Less so for whales.

L593 I am not sure that this is absolutely the case for these copepods, it is more about food availability and temperature refugia - please reference these types of statements.

L597 Larger, fatter copepods are also often Calanus spp.

L621 Arctic cod diet inconsistent with L479-480, plus they feed on a range of small pelagic inverts.

L632-634 Not highly likely as most are already quite mobile across a broad range of latitudes.

L679 though, not through.

Please read carefully throughout, there are some (very minor) grammatical errors, e.g. singular/plural forms of verbs, oddly placed commas.

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Reviewer #1: Yes: Ekin Akoglu

Reviewer #2: Yes: Kirsteen MacKenzie

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Exploring novel North Water Polynya ecosystems under climate change

PCLM-D-24-00078R1

Dear Miss Gillie,

We are pleased to inform you that your manuscript 'Exploring novel North Water Polynya ecosystems under climate change' has been provisionally accepted for publication in PLOS Climate.

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Thank you again for supporting Open Access publishing; we are looking forward to publishing your work in PLOS Climate.

Best regards,

Vijai Dharmamony

Academic Editor

PLOS Climate

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Reviewer Comments (if any, and for reference):