Fish Diversity in Relation to Littoral Habitats in Three Basins of Lake Kivu (East Africa)

Round 1

Reviewer 1 Report

This work presents information on fish assemblages and their diversity from a poorly studied area, and the results are interesting and worth publishing. However, several issues preclude me from recommending this work to be published in its present form.

For starters, the title does not adequately represent the contents of the work. The Authors sampled only a minor part of the total lake and based on this small percentage; they are extrapolating the results for the whole lake. The habitats and fish species they refer to in the text, include only the sampling stations, and, as previously said, these included only a small percentage. The authors should clearly specify the scope and limitations of this work.

Introduction

The introduction is too long and not clearly focused. What is the relevancy of all the paragraphs included? There are many scattered ideas, but it is difficult to follow what was the main idea behind this work. There is no working hypothesis, and the question driving this work is not clear.

M&M

Authors should clearly specify why the sampling stations were selected, and if these are representative of the whole lake and why. Also, it is necessary to explain on what basis the sampling stations were selected.  

Sampling procedures need to be also further explained. For example, the gillnet was a single net with different mesh sizes? and if so, what was the extension of every mesh size and what was the selectivity of this fishing gear?

In terms of statistical analyses, authors should justify the use of a non-parametric test instead of ANOVA. Also, why did the authors use the Shannon index instead of others such as Simpson? Or others? I recommend the use of hill numbers instead.

For the multivariate analyses, they could have used Distance-based linear models (DISTLM) and distance-based redundancy analysis (dbRDA) in order to link the environmental and biological variables, and then draw conclusions on which environmental variables are more responsible for the differences in fish assemblages.

Results

I found this section very long and difficult to follow. The results of the environmental and other biological parameters are not reported. Neither the ANOVA of the physicochemical parameters.

In contrast, the results of the multivariate analysis are redundant and with many unnecessary graphs. The use of DISTLM and dbRDA, would allow the use of only one graph.

Table 2 has unexplained letters, and the sites they are referring to are not present.

Discussion

The lack of a working hypothesis makes the discussion a suite of different ideas with no clear direction. What does exactly this paper want to demonstrate or answer? Differences in fish assemblage composition according to habitat? The reason for the disappearance of certain species? Authors should clearly define the goal, the hypothesis, and the scope of this work giving the limitations of their sampling design.

Conclusion

There are no conclusions, but a mere repetition of the results. To draw a strong conclusion, you need a clear working hypothesis

The English is not incorrect, but still, the manuscript is tough to follow. There are many scattered ideas within a paragraph. Also, some paragraphs are too long. 

Authors should clearly state the subject for every paragraph and stick to it. Also, paragraphs should be clear and concise, using simple words.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

- The introduction takes up a significant amount of space in the manuscript. It is necessary to shorten this section.

- Line 69-73. It is indicated that five anthropogenic factors. But the authors list six factors. Specify the data.

- Line 92-96. Write more clearly the aim and objectives of the study.

- Section 2.1 contains similar information that the authors indicated in the introduction. Duplication of text is unacceptable.

- Why is Table 1 needed in the manuscript? These are diary entries, research protocol. I think this table is not needed here.

- In the title of Table 1, the authors describe the sites where samples were taken. I propose to make a description of these sites in the manuscript (it is better to do it in the form of a table with a specific description of vegetation, soil, etc.).

- Line 325. Are you sure there are 18 species living in the lake? Or are these 18 species only caught by you, and there are actually more of them? Clarify the phrase.

- Figure 1 is poorly executed. It is divided into several pages. The drawing should be redone.

- Line 549. See Line 325.

- It is necessary to redo the conclusion.

- The manuscript was not prepared according to the rules of the journal.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I thank the authors for responding to my comments and making corrections to the manuscript.

Author Response

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Author Response File: Author Response.docx