Review Reports - Effects of Arctic Warming on Microbes and Methane in Different Land Types in Svalbard

Round 1

Reviewer 1 Report

In the paper by Zhang et al. “Study on microbes and methane in different landforms of the high Arctic Svalbard”, the study status of microorganisms and CH₄ in the high Arctic Svalbard are stated. The problems that needs to be addressed in future were also proposed. The relevance of the paper is related to the rapid warming in the Arctic, in which large quantities of CH₄ can be released, and various microorganisms play a major role in both the production and consumption of methane. Microorganisms are sensitive to environmental changes and can reflect environmental changes with changes in community composition, biomass and function.

Svalbard is one of the most significant warming areas in the Arctic: in 14 years, the average annual temperature has in-creased by nearly 5 °C. The authors describe a general microbial and environmental study in Kongsfjorden, New Ålesund. Kongsfjorden is influenced by both North Atlantic Current and glacial melt water. In recent years, there has been a significant increase in the input of the warm Atlantic current. The sensitivity of Kongsfjorden to changes makes it an ideal place to study the effects of climate change on Arctic costal ecosystems.

The dta of various researchers, including the authors' data, on obvious seasonal and long-term variations in the distribution of various dominant microplankton species are presented. The influence of the collapse and melting of terrestrial glaciers on the biological community in the soil is considered. An assessment of general studies of CH4-correlated microbes in Ny-Alesund is given with recommendations for the use of metagenomic and metarscriptome analysis to study both community structure and functions in glacial ice cores and their melting streams, soils, lakes and seawater, and sediments.

In general, the article is informative and of scientific interest to readers.

Minor

Some negligence is noted in the design of the article: in some places letters in words are missing, words are distorted; some references are missing; some references distorted.

Examples include the following:

Abstract

Replace "However, we still do not know seasonal and inter-annual variations of these microbes and their regulation mechanisms in glacers, galcer melting, snow lakes and coastal maine water" with "However, we still do not know seasonal and inter-annual variations of these microbes and their regulation mechanisms in glaciers, glacier melting, snow lakes and coastal marine water "

Zhang et al. 2019; Cao et al. 2019 - not in References

Blok et al, 2017 (link),

Blok D (2017) Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra. Global Change Bio 23 (1): 406-420 (Reference) - does not exist

Exist:

Casper T Christiansen et al., 2017. Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra. Global Change Bio 23 (1): 406-420

Author Response

The data of various researchers, including the authors' data, on obvious seasonal and long-term variations in the distribution of various dominant microplankton species are presented. The influence of the collapse and melting of terrestrial glaciers on the biological community in the soil is considered. An assessment of general studies of CH4-correlated microbes in Ny-Alesund is given with recommendations for the use of metagenomic and metarscriptome analysis to study both community structure and functions in glacial ice cores and their melting streams, soils, lakes and seawater, and sediments.

In general, the article is informative and of scientific interest to readers.

Reply: Thanks for your kindly comments. And we have corrected the minor errors APAS.

Minor

Some negligence is noted in the design of the article: in some places letters in words are missing, words are distorted; some references are missing; some references distorted.

Examples include the following:

Abstract

Replace "However, we still do not know seasonal and inter-annual variations of these microbes and their regulation mechanisms in glacers, galcer melting, snow lakes and coastal mainewater" with "However, we still do not know seasonal and inter-annual variations of these microbes and their regulation mechanisms in glaciers, glacier melting, snow lakes and coastal marine water "

Reply: We have corrected the glaciers, glacier and marine in the Abstract.

Zhang et al. 2019; Cao et al. 2019 - not in References

Reply: Both references have been in References now. And Cao et al. 2019 is corrected to Cao et al. 2020.

Blok et al, 2017 (link),

Blok D (2017) Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra. Global Change Bio 23 (1): 406-420 (Reference) - does not exist

Exist: Casper T Christiansen et al., 2017. Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra. Global Change Bio 23 (1): 406-420

Reply: The reference is corrected to Christiansen CT, Haugwitz MS, Priemé A, Nielsen CS, Elberling B, Michelsen A, Grogan P, Blok D (2016) Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra. Global Change Bio 23(1): 406-420. Thanks for telling.

Author Response File: Author Response.docx

Reviewer 2 Report

The present review should analyze the linkages between microbes and methane in arctic environments, a topic that currently has an increasing importance due to the climate changes occurring in high latitude regions.

However, the manuscript is quite vague, being it basically an assemblage of information and figures from other publications, rather than a systematic inventory and analysis of the literature focused on the linkages between microbes and methane. The main critical points in the manuscript are:

The manuscript does not adopt a standard structure used in scientific publications, divided in sections (introduction, discussion, conclusions) that would facilitate the comprehension by the readers. For example, the main topic of the study is discussed only briefly at the end of the manuscript (Section 5).
It does not present a detailed description of the global biogeochemical cycle of methane and of its abiotic and biotic transformations in aquatic and land environments, as well as in the atmosphere.
It cover a large variety of topics, which range from microbial community structure in soils, freshwater and seawater, to water mass circulation in Svalbard region, to climate changes and glacier melting. However, several sections of the text discuss aspects of the trophic network in aquatic environments without to relate them to the dynamics of methane.
It shows generic figures that are not specifically related to this topic (Figure 1, 5), figures that are not informative (Figures 3, 4, 11) and figures that refer to studies on methane in other non polar regions (Figure 2).
An editing of the manuscript might also improve the text, in particular as concerned the Abstract (see the following specific comments).

For this reasons, I think that this manuscript is not acceptable in this form for the publication on WATER, but I suggest its resubmission to the journal after rejection.

The authors should reorganize the whole content of the manuscript in a more systematic way, selecting only the literature specifically addressed to the study of the dynamics of methane in arctic regions and discussing it in distinct sub-sections focused on land, freshwater and marine environments.

The authors might also consider to widen this analysis including the literature published in the whole Arctic and not only in the Svalbard region.

Specific comments:

Page 1, The Abstract should be improved, avoiding repetitions of the concepts and reporting the most important results of this study. Here there are some suggestions:

“The Arctic is the fastest warming region …”
The sentence: “All these have restricted the cognition of feedback of climate and environmental change.” is not very clear. Perhaps its meaning is: “This gap of knowledge limits the understanding of the linkages between climate and environmental changes.”
The sentences “Methane is sensitive to temperature changes. High Arctic are huge reservoirs of methane.” might be modified as follows: “In the Arctic, there are large reservoirs of methane, which are sensitive to temperature changes.”
The sentence “These CH4 are usually produced by microbes.” should be modified as follows: “CH4 is usually produced by microbes.”
The following sentence is a repetition: “we still don't know much about the change of microcommunities and methane producing and consumption in different water types of high Arctic.” It should be deleted and substituted with the results of the study.

Page 8: …. ancient microbes buried in frozen soils, ….

If the authors wish to describe the climate changes in the Svalbard region (Section 2), they might show an analysis of the time series of meteorological parameters in the region (air temperature, snow cover, etc.) that are available, for example, at eKlima portal of the Norwegian Meteorological Institute (URL: http://www.met.no/).

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Line numbers are missing; it is very difficult to make comments without those.

In general, figures should be placed after introduction in the text

The goals need to be introduced properly in the main text. It is only briefly mentioned in the abstract

Fig. 1 does not have a closing loop

All content described in section ‘1. General Description of Microorganisms’ is basic knowledge. Focus more on psychrophiles (microorganisms adapted to cold conditions are called psycrophiles)

DMSP can reduce the warming climate? This and several other statements do not make much sense and are misleading

Source for figure 3 and 4 is missing.

Why does figure 5 have two images depicting the same fjords?

What is the purpose of focusing on Kongsfjorden?

Italicize genus and species-e.g., Poterioochromonas malhamensis

Fig. 9-why is comparing between microbial population between 2012 and 2013 important? Also the legends and axes in the upper two images are too small. What do the arrows in the bottom figure indicate?

Glaical Dust pits needs its own heading

There is no word called Preukaryotes? You mean prokaryotes?

Prokaryotes more affected by phosphate and nitrogen than by temperature-not always true. What is the source for this statement?

Author Response

Comments and Suggestions for Authors

The manuscript requires a lot of major revision, especially in organization and language. In the present format, I recommend 'reject' for publication in MDPI Water. Also, it is not a good fit for the scope of MDPI Water. A revised version of this review article might be a better fit in a different journal like MDPI Microorganisms. Line numbers are missing; it is very difficult to make comments without those. In general, figures should be placed after introduction in the text. The goals need to be introduced properly in the main text. It is only briefly mentioned in the abstract.

Repy: Thanks for your comments. Although it is negtive, however, we still make a better revision as possble as we can, from structure to language. And line numbers are added this time. Hopefully it can help. We have tried our best to put the figures after introduction in the text. We put the figures in front of the text just want to make the ms in order. This time we also state the goals at the six part as “To sum up, despite the importance of microbes in producing/consumption methane, we still don't know much about the methanogens composition and their contribusion changes in methane cycling at different land types of the high Arctic Svalbard. Consequently, the following scientific problems that neads to be solved are as follows:” Hopefully, this time it is much better. Thanks again.

Fig. 1 does not have a closing loop

Reply: Sorry, We don’t understand what do you mean. But what we draw are microbial food loop and classic food chain. Would you please point the error out?

All content described in section ‘1. General Description of Microorganisms’ is basic knowledge. Focus more on psychrophiles (microorganisms adapted to cold conditions are called psycrophiles). DMSP can reduce the warming climate? This and several other statements do not make much sense and are misleading

Reply: this time we state that “Microorganisms adapt to cold conditions are called psycrophiles. Most microofanisms in the high Arctic are psychrophiles. For examples, ice algae and phytoplankton, such as some Phaeo-cystis, produce Dimethylsulfoniopropionate (DMSP) that have negtive effect on the warming climate (He et al 2012; Zeng et al 2013, 2021).” In line 30-33. We hope the sentences is much clear this time.

Source for figure 3 and 4 is missing.

Reply: Figure 3 is from Kings Bay AS; Figure 4 is from the net” https://image.so.com/i?src=360pic_strong&z=1&i=0&cmg=154”. Now they are added behind the former legends.

Why does figure 5 have two images depicting the same fjords?

Reply: The left with labled information of fjords is the main part of the right.

What is the purpose of focusing on Kongsfjorden?

Reply: Because it is the fjord with most studies in Svalbard. Now the statement is added in line 119.

Italicize genus and species-e.g., Poterioochromonas malhamensis

Reply: Yes. Thanks for telling.

Reply: Because the physiochemical factors changed little between the two years, but the microbial community has distinct community structures. Now the figures are replotted. And the arrows at bottom figure indicate the dates (months) the abundance data gotten. This sentence is added this time. They are as:

Figure 9. Distribution map of main microplankton communities in Kongsjroden in 2012:.Upper left - prokaryotes; Upper right - eukaryotes; Bottom – ciliates, The arrows at bottom figure indicate the dates (months) the abundance data gotten (Zhang et al. 2019; Cao et al. 2019; Feng et al. 2014 )

Glaical Dust pits needs its own heading

Reply: Sorry, We do not understand what do you mean.

There is no word called Preukaryotes? You mean prokaryotes?

Reply: Yes. The spelling error is corrected this time.

Prokaryotes more affected by phosphate and nitrogen than by temperature-not always true. What is the source for this statement?

Repy: Now it is corrected to “Prokaryoes could be more affected by phosphate and nitrogen than by temperature (Cao et al. 2020).” Thanks for telling.

Author Response File: Author Response.docx

Reviewer 4 Report

Theme of this paper is of international interest, well representing recent research trend in this field. But this paper is not that much well written. In general the title of the presented article does not correspond to its content. First, it is not clear from the text what studies the authors have conducted. Probably the authors assume studies by Zhang et al., 2021, published in another journal and cited in the text as well as Zhang et al., 2019, which is not in the list of references of the article. Second, the object of the research (Svalbard) itself is huge and multifactorial. That is why it was expected that the authors had factual material on microbes and the methane content and its genesis. Actually the research methodology is not given in the article, there is no data in the form of tables, and the discussion is based on the literary analysis of other sources or references to articles published about 10 years ago, in 2012. The only one figure carrying information about the ratio of methane and microbes (Fig. 2) is taken from another work and is not discussed in the artical as well as not linked to its content. On the page 5, it is mentioned that the authors used the fieldwork results received 7 years ago (the data are not given because they were published in another article by Zhang et al., 2021). The most recent (2018) data of the authors are presented on the page 7 and consist of 2 sentences and one picture (Fig. 10). At the same time the rest of the presented figures are taken from previous works without any changes, analysis and data reinterpretation. On the page 8, the authors write: "Our study shows that the impact of the Atlantic warm stream on the microbial community has been exacted since the year of 2017. Compared with the mixed water masses, effects of temperature, salty and macronutrient in Atlantic Current is more pronounced in 2019». However the data on temperature, salty, macronutrient are not provided in the article. It is obvious that without actual data, it is impossible to prove the influence of any factor on microorganisms. Also there is no data on methane, no isotope studies have been conducted, however it is claimed that methane has a microbial origin. Improved structure: once you've explicitly stated what your objective(s) is (are), then, assuming you have two objectives, then use them to structure your Methods section, Results section and Discussion sections.
Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 5 Report

This article reviews microbes and methane in different landforms of the high arctic Svalbard. It gives an overview of the food chain in the system and further gives the distribution of the different species. The following need to be addressed before I can recommend it for publication.

First, it is mostly well written but there are grammatical and typographical mistakes that need to be fixed before it should be published. For example,

Abstract has “changes.High”
Page two had a quote with “Everingthing is Everywhere”
Page 3 has “km3”, but this should be cubed.
Page 5 has “Microplankton is basis”.

There are others that need to be fixed but I leave it up to the authors to give it a through reading to find these mistakes.

Second, some of the text in the figures are difficult to read, for example Figure 7 and 9. For the latter, I could not make out any of the labels on the yaxis even after magnifying. Please make all text in figures easy to read without magnifying.

Third, section 6 looks like conclusions but the title is very long and something shorter and more to the point would be better. Also, please add more descriptions about the relevance of answering these questions in regards to us understanding our oceans and climate in general.

Author Response

Reply: Thanks for your coments.

First, it is mostly well written but there are grammatical and typographical mistakes that need to be fixed before it should be published. For example,

Abstract has “changes. High”

Reply: Yes. Now we correct this types errors as possible as we can.

Page two had a quote with “Everingthing is Everywhere”

Reply: Now the citation is changed to “Everingthing in Everywhere, but, the environment addresses”.

Page 3 has “km3”, but this should be cubed.

Reply: Yes, it is corrected now.

Page 5 has “Microplankton is basis”.

Reply: This time we change it to “Microplankton are basis”. But we are not very sure about that.

There are others that need to be fixed but I leave it up to the authors to give it a through reading to find these mistakes.

Reply: Yes, we know and have tired our best to correct them. But perhaps there is still some. We are very sorry about that. Thank you!

Reply: We replot some figures this time. Hopefully it is better now.

Figure 7. Contributions of Poterioochromonas malhamensis to microeukaryotic DNA library from different water masses and water-layers at different stations in the Kongsfjorden: SW-surface water; IW- intermediate mixed water; TAW- Variant Atlantic Water (Zhang et al. 2021).

Reply: this section is changed as:

Unanswered questions needs to be adressed between microbial correlations with CH₄ in Svalbard

To sum up, despite the importance of microbes in producing/consumption methane, we still don't know much about the methanogens composition and their contribusion changes in methane cycling at different land types of the high Arctic Svalbard. Consequently, the following scientific problems that neads to be solved are as follows:

(1) How will the microbial community in Svalbard change along with the rapid warming Arctic and the whole enviromental changes? How does the internal microbial relationship change alongside?

(2) How does internal microbial relationship affect the realization of ecological function of microbiome?

(3) Is Svalbard a source or sink to CH₄ in the future? What relative contributions of CH₄ in glacier/permafrost melting, meltwater, soil and by microbial mediated is to the whole concentration of CH₄ in Svalbard?

(4) What is the influence of microbiome changes in different media in CH₄ cycling?

(5) Does CH₄ cycling changes in Svalbard greatly influence the global CH₄ change?

Hopefully it is better now.

Regards!

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have provided a revision of the manuscript taking in consideration my specific comments, and the present version of the manuscript was improved compared to the first submission. However, the main problem of this manuscript is that it is neither a review (please, see the guidelines that should be adopted for scoping reviews PRISMA; URL: http://prisma-statement.org/Extensions/ScopingReviews) nor a research articles (i.e. a study based on new experimental data validated by certified scientific methods). It seems rather a “Communication”, being it a mix of both these two types of scientific publications. For this reason, the final decision on the acceptance of this manuscript should be made by the Editor, on the basis of the rules of classification of the manuscripts in this journal.

In the text, there are still a number of specific corrections that should be done:

Line 18: … reason….

Line 85: … environment….

Lines 85-86: The references (like Zhang et al. 2021) should not be included in the titles and subtitles of the manuscript, but in the body of the text.

Line 192: This title might be better as: “Effects of glacier collapse and melt on microbes”.

Line 196: … of frozen soil…

Line 198: … abundant microbes…

Lines 208-212: Please, add the relevant references to these sentences.

Lines 213-236: In this section, the source of the data shown in the Figure 12 should be repeated. Please, add the relevant references.

Lines 270: This also complicates …

Lines 295-297: The format of this paragraph is not correct. The Acknowledgments should be separated by the Conclusions.

Line 444-447: References 66 and 67 are repeated two times.

References: In the body text, the references are not provided as sequential numbers, as required by the format of WATER, but as surname of the authors and year.

Author Response

Comments and Suggestions for Authors

Reply: Yes. I think the editors may help us put it into an appropriate type. Thanks for your possitive comment. It really gives us strength.

In the text, there are still a number of specific corrections that should be done:

Line 18: … reason….

Reply: Yes. You are right. This time we have tried our best to modify the small spelling mistakes. Reason is corrected to reason in line 18.

Line 85: … environment….

Reply: It is corrected to environment in line 85

Lines 85-86: The references (like Zhang et al. 2021) should not be included in the titles and subtitles of the manuscript, but in the body of the text.

Reply: The references is deleted from the titles or subtitles. Now we put the reference of Zhang et al. 2021 into the body of the text. Thanks for telling.

Line 192: This title might be better as: “Effects of glacier collapse and melt on microbes”.

Reply: The title is changed to “Effects of glacier collapse and melt on microbes” according to your kindly reply. Thanks!

Line 196: … of frozen soil…

Reply: The soil is corrected in line 196.

Line 198: … abundant microbes…

Reply: It is corrected to “abundant microbes” in line 196.

Lines 208-212: Please, add the relevant references to these sentences.

Reply: The reference (Zhang et al. 2021) is added to the sentences.

Lines 213-236: In this section, the source of the data shown in the Figure 12 should be repeated. Please, add the relevant references.

Reply: The reference (Zhang et al. 2021) is added in line 236.

Lines 270: This also complicates …

Reply: The sentence is corrected to This also complicates community structure, function and interactions.

Lines 295-297: The format of this paragraph is not correct. The Acknowledgments should be separated by the Conclusions.

Reply: Yes. It is seperated now.

Line 444-447: References 66 and 67 are repeated two times.

Reply: The repeated reference is deleted. You are so careful. Thank you!

References: In the body text, the references are not provided as sequential numbers, as required by the format of WATER, but as surname of the authors and year.

Reply: Yes. We still want to wait for the comments of the edditors about the reference format.

We really learn a lot from you, dear Reviewer. Thanks again.

Submission Date

06 August 2021

Date of this review

12 Oct 2021 09:48:01

Author Response File: Author Response.docx

Reviewer 3 Report

The authors have addressed my previous comments sufficiently.

However, the article still has a lot of grammatical errors, spelling mistakes, and incomplete sentences that make it difficult to read. For example, the first sentence in the abstract starts as 'All these have restricted climate change..."-what are 'all these'? There are also different font sizes and types that need to be corrected. Such errors degrade the quality of an otherwise decent review article.

The authors should make use of MDPI language editing services and thoroughly edit their article to make it a higher quality review paper.

Author Response

Comments and Suggestions for Authors

The authors have addressed my previous comments sufficiently.

The authors should make use of MDPI language editing services and thoroughly edit their article to make it a higher quality review paper.

Reply: Thanks for your comments. This time we corrected the grammatical errors, spelling mistakes, and incomplete sentences as possible as we can. As to use the MDPI language editing sevices, we are sorry we don’t have enough funding to do that. So, sorry about that. Thanks again for your careful check of this paper.

Submission Date

06 August 2021

Date of this review

14 Oct 2021 16:19:10

Author Response File: Author Response.docx

Reviewer 4 Report

Dear authors,

After the changes your manuscript looks

much better from the scientific point of view

and logicaly structured. In my opinion it is acceptable

for publication, after minor language

(spelling/grammar) revision.

Author Response

Comments and Suggestions for Authors

Dear authors,

After the changes your manuscript looks much better from the scientific point of view

and logicaly structured. In my opinion it is acceptable for publication, after minor language (spelling/grammar) revision.

Reply: We have check this paper and corrected the language as possible as we can. Thanks again for your possitive comments and careful check.

Submission Date

06 August 2021

Date of this review

18 Oct 2021 11:52:19

Author Response File: Author Response.docx