Vertical Distribution, Community and Population Structures of the Planktonic Chaetognatha in the Western Subarctic Pacific: Insights on the Eukrohnia Species Group

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Review for the paper "Vertical Distribution, Community and Population Structures of the Planktonic Chaetognatha in the Western Subarctic Pacific: Insights on the Eukrohnia Species Group" by Haochen Zhang, Yuya Nakamura, and Atsushi Yamaguchi submitted to "Oceans".

 

General comment:

 

The Chaetognatha represents a relatively small zoological group comprising only a few genera; however, they play a vital role in pelagic food webs. As voracious carnivores, chaetognaths can feed on copepods and other mesozooplankton, thereby regulating plankton biomass in the oceans. The authors investigated the vertical distribution, population structure, and size structure of three common taxa inhabiting the Western Subarctic Pacific Ocean. This research is based on a comprehensive dataset covering all seasons and main depth layers, with the methods used to collect and analyze data being relevant. The key results are clearly visualized and partially discussed. Nevertheless, there are two main concerns that prevent me from recommending the article's acceptance in its current form. Specifically, there is an absence of relevant statistical treatment of the data, and the discussion needs to be expanded by considering the potential role of environmental factors in driving population and size structures of the chaetognaths populations. Additionally, I have several minor suggestions to improve the manuscript.

 

Major concerns:

 

1) I recommend conducting relevant statistical analyses. Comparisons of different variables (hydrological conditions, abundance of Chaetognatha) across seasons must be performed based on common criteria (ANOVA, PERMANOVA, or others). Furthermore, inter-species and depth-related differences should also be tested.

 

2) Section 4.3: The authors ought to consider the possible influence of environmental variables (temperature, water masses, and currents) in determining the population structures of the chaetognaths populations in their study. This would provide a more comprehensive understanding of the factors affecting these populations.

 

Specific remarks.

 

L11-12, 41-42. Unclear sentence, copepods and chaetognathats are different groups and the sentence sounds that chaetognathats is a group in the Copepoda. Additionally, in many oceans copepods and euphausiids are the most important taxa in terms of the total biomass. Consider replacing "For the various oceans, Chaetognatha dominates in the zooplanktonic biomass, accounting for 10–30% of the copepod biomass" with "In the oceans, Chaetognatha can contribute significantly in the total zooplankton biomass (up to 10–30%)".

 

L58. Consider replacing "all zooplankton biomass" with "total zooplankton biomass".

 

L68-73: The sentence is awkwardly phrased and could benefit from being split into two sentences to improve clarity.

 

L76: It may be better to rephrase "depth was varied with species" as "depth varied for the species" for clearer understanding.

 

Materials and methods: I suggest including a brief section to describe the general environmental conditions in the region, such as climate, circulation, bathymetry, and currents. This information would enhance the reader's understanding of the context in which the research was conducted.

 

Table 3: It would be beneficial to round off the core depths in Table 3 (e.g., 100 instead of 100.4, etc.) for simplicity and easier comprehension.

 

Fig. 4–7: The font size of the scale bars and text in all the plots (Figures 4–7) should be increased to improve readability as they are currently not visible.

 

L380: The unit in line 380 should be double-checked. It may be better phrased as "6–100 μm" instead of "6–100 micromoles."

 

L385–387. Consider replacing "The most prominent finding of this study is that both Eukrohnia species in this study: E. hamata and E. bathypelagica, had no massive mature specimens reported for E. hamata in the Arctic Ocean (Figures 5–7)" with "The most prominent finding of this study is that both Eukrohnia species (E. hamata and E. bathypelagica) had no large mature specimens reported for E. hamata in the Arctic Ocean (Figures 5–7)".

 

A brief conclusion summarizing the main findings should be included in the ms.

Comments on the Quality of English Language

The text should be revised.

Author Response

Thank you for providing a comprehensive review of our manuscript. Our answers to comments and corrections in the revised manuscript were marked with red. For details, see the attached file. 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please see the attach file

Comments for author File: Comments.pdf

Author Response

Thank you for providing a comprehensive review of our manuscript. Our answers to comments and corrections in the revised manuscript were marked with red. For details, see the attached file. 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

No further comments.

Comments on the Quality of English Language

Minor

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have taken into account all my reccommendations.