Evaluation of the Influence of Habitat Heterogeneity and Human Activities on the Distribution of Microbial Diversity in a High Elevation Drop River

Round 1

Reviewer 1 Report

Major comments

There are methods included in the results and discussion sections that are not described or not properly described in the methods. All methods must be included and adequately described.

The methods and techniques are suitable for the detection of microbial diversity, not for the characterization of harmful bacteria. Some generations described as potential pathogens may also be neutral or beneficial bacteria. No genomes or metagenomes were sequenced; there is no description of genetic potentials. Also, isolates were not retrieved or tested in the laboratory. Support for some of the results is lacking.

The methods should describe in detail all data processing and diversity analysis. There is no information about the total number of reads, how reads were selected for quality, about parameters and software for quality processing, about diversity analyzes (QIIME? or other software), about KEGG, etc.

There are basic sections in the manuscript that can be deleted, for example, the section on sequencing technologies, including the basics. The manuscript must be revised so that it is balanced; there are sections with basic information that are not useful for understanding the manuscript and the lack of relevant information, for example methods, that were omitted.

 

Author Response

Dear reviewer, thank you very much for your review and guidance of our manuscripts. Thank you for your valuable suggestions. We have revised the paper according to your suggestions. Please refer to it and give us guidance.

Author Response File: Author Response.docx

Reviewer 2 Report

Please see attached the comments.

Comments for author File: Comments.pdf

Author Response

Dear reviewer, thank you very much for your review and guidance of our manuscripts. Thank you for your valuable suggestions. We have revised the paper according to your suggestions. Please refer to it and give us guidance.

Author Response File: Author Response.docx

Reviewer 3 Report

Manuscript ID: diversity-2257309

The authors studied bacterial community composition (BCC) in 13 sampling locations of the Huotong River. The main results showed significant variation in taxonomic composition along the river and that this changes are driven by turbidity and salinity. In addition, the effect of nutrient concentration as a proxy of human impact was also tested. 

Although the work seems interesting I have many concerns about the study.

Major concerns: 

Title:

Evaluation of the habitat heterogeneity and human activities on the distribution of microbial diversity in a great drop river

This title does not reflect the study: Habitat heterogeneity and diversity were not calculated.  Thus, habitat heterogeneity and distribution of bacterial diversity were not analysed.

Introduction

The introduction needs to be focused on the main objective of the paper. In the present form, the introduction is very poor, it begins with a methodological discussion on molecular methods used in microbiology (two paragraphs) that should be completely deleted. In the two following paragraphs, the authors intended to focus the research, but they need to clarify the novelty of the paper. Finally, there are contradictions between the two paragraphs, Has the river higher or less human activities?, and these considerations should agree with the description of the study area.  In addition, there are some confusing terms such as great / large drop

Material and Methods

Line 82. The subtitle: General situation of the research area is confusing, change it to:   Study area description.

Line 83. Rephrase the first sentence.  

Line 88 and Line 95. The authors need to explain what they consider as a “short” river, otherwise it seems rather contradictory: The river is short (line 88) and Huotong River has a total length of 56.8km (Line 95). Why a river of such length is a short river?

Line 99 the subtitle 2.2. Experiment design should be deleted, because no experiment was carried out.

Line 105, what is considered as human interference?  Do you mean human activities? If so, please refer along the manuscript as human activities.

The sampling point description is too long and with some sentences that are the objective the work (line 108-114) that should be moved to other parts of the paper (i.e. introduction).

Line 151-153. Chlorophyll a determination needs to be described, volume? Extraction methods and reading methodology.

The data analysis is very confusing. The KEGG analysis and PICRUSt are not included in the section and they were applied and appeared for the first time in the results (line 322).

Results

The physico-chemical parameters section is very confusing, because the authors refer first to differences along the rivers but then refer to an average. Please apply statistical tests to determine the existence (or not) of significant differences.

KEGG analysis and PICRUSt analysis carried out were presented in a very short paragraph with low scientific support for the diseases involves (cancer, neurodegenerative pathologies). Can you increase the information to support these assumptions?

Discussion

This section is again very confusing. In the first paragraph, the authors compare the studied river with the Mississippi River,  why?  The Mississippi river is very long (more than 3,000 km), while the Huotong River has around 60 km long.  Finally, the last sentence of the first paragraph stated that the authors found “that environmental stress could drive a greater β diversity”. However, the authors did not analyse β diversity (that would be very interesting to test).  In adition, it is unclear what the authors mean by “environmental stress”. Based on this the entire paragraphs should be rewritten.

In the second paragraph, Line 376. “ not conducive to Cyanobacteria to degrade nutrients” Did Cyanobacteria degrade nutrients? Please explain.

Lines 395-410. There is some contradiction in the statements of this paragraph of “water quality” resulting from the measurements of TN and TP concentration. Please revise the entire paragraph, give the statistical significance of the changes in the concentration, and give details of the water (salinity, pH, etc) in the estuary and what you are expecting on the effect on nutrients.

Lines 411-438. This paragraph should be rewritten. First, the effect of temperature did not accomplish for any important result because the sampling was carried out in only one season (summer). The other study the authors mentioned considers two seasons, thus, two different temperatures, but it doesn’t correspond to this study.  The second part of the paragraph is important because you stated that the differences were due to turbidity and salinity. I consider that this part can be discussed more deeply based on the literature and the main obtained results.

The other three paragraphs are highly speculative and should be rewritten on the basis of the obtained results (in particular those of KEGG analysis). I consider that this last part of the manuscript (KEGG analysis) can be deleted from the results and the discussion because it does not affect the conclusion of the study.

References

Please revise the citation, some of the references were not cited in the text (i.e. Huber et al 2020).

Author Response

Dear reviewer, thank you very much for your review and guidance of our manuscripts. Thank you for your valuable suggestions. We have revised the paper according to your suggestions. Please refer to it and give us guidance.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors followed my recommendations and corrected the different sections. However, I consider that the English grammar and style should be improved.

Author Response

Many thanks to reviewers for the review and suggestions. According to the  suggestion, we have asked MDPI to edit our manuscript in English.

Author Response File: Author Response.pdf