Fish Diversity and Abundance Patterns in Small Watercourses of the Central European Plain Ecoregion in Relation to Environmental Factors

Round 1

Reviewer 1 Report (Previous Reviewer 1)

No comments.

Author Response

Thank you very much for your opinion. 

Reviewer 2 Report (Previous Reviewer 3)

Review

Paper title: Fish diversity and abundance patterns in small watercourses of the Central European Plain ecoregion in relation to different environmental factors

 

The authors conducted a field study to reveal species composition and diversity indices of fish communities in 10 rivers in Poland. They measured physico-chemical parameters. The authors and discussed their findings concerning the conservation status of the area and the role of environmental factors in driving fish communities. These new data may have important implications for the management of small watercourses in the Central European Plain ecoregion.

 

All these reasons explain the relevance of the paper by Adam Brysiewicz and co-authors submitted to "Water".

 

General scores.

 

The data presented by the authors are original and significant. The study is correctly designed and the authors used appropriate sampling methods. In general, statistical analyses are performed with good technical standards. The authors conducted careful work that may attract the attention of a wide range of specialists focused on fish biology and conservation.

 

Major concerns.

L 338-340. This section and Fig. 7 should be present in the Results.

The authors should include information about the most common fish species in each group: Rheophilous fish, Limnephilous fish, and Euryoecious fish. Ideally, they should include a list of species representing the number of specimens for each species. This information is partly presented in the Discussion but this is not enough.

 

L 22. Change “estimate of” to “estimate”

L 40. Change “which has” to “which have”

L 116. Change “astiamted” to “estimated”

L 129. Change “post-hoc test” to “a post-hoc test”

L 135. Change “analysis were” to “analysis was”

L 205. Change “affect” to “effect”

L 258. Change “variation” to “the total variation”

L 291. Change “a long-term” to “the long-term”

L 326. Change “the  total  variation” to “total  variation”

L 328. Change “under considerable effect of” to “affected by”

L 359. Change “threats” to “threat”

Author Response

Dear Reviewer,

Thank you very much for your valuable comments. They certainly improved the quality of our text. We have commented on the revisions in this version and we hope you will accept them.

We have marked the corrections in the text in green.

Major concerns.

L 338-340. This section and Fig. 7 should be present in the Results. - We improved and moved the text and figure to the Results

The authors should include information about the most common fish species in each group: Rheophilous fish, Limnephilous fish, and Euryoecious fish. Ideally, they should include a list of species representing the number of specimens for each species. This information is partly presented in the Discussion but this is not enough. - We supplemented the results with the most popular species of fish from each group.

 

L 22. Change “estimate of” to “estimate” - We improved

L 40. Change “which has” to “which have” - We improved

L 116. Change “astiamted” to “estimated” - We improved

L 129. Change “post-hoc test” to “a post-hoc test” - We improved

L 135. Change “analysis were” to “analysis was” - We improved

L 205. Change “affect” to “effect” - We improved

L 258. Change “variation” to “the total variation” - We improved

L 291. Change “a long-term” to “the long-term” - We improved

L 326. Change “the  total  variation” to “total  variation” - We improved

L 328. Change “under considerable effect of” to “affected by” - We improved

L 359. Change “threats” to “threat” - We improved

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

In my opinion, the manuscript entitled "Fish diversity and abundance patterns in small watercourses of the Central European Plain ecoregion in relation to environmental factors" is an example of an interesting and very well done research. The authors have done solid and diligent work, as I can tell from the high-quality manuscript. In my opinion, the article is valuable, the Introduction correctly guides the reader to the aim of the study and contains relevant literature citations. The Results section is detailed, the Discussion is clear and well written. I have only 3 minor suggestions that should be applied before publishing the article:

1) Please add the following sentence to "Statistical analysis" (line 129):

The significance level of each test was equal to 0.05

(of course 0.05 if that level of significance was applied)

2) Page 4, line 124

There is: "[,25,26]"

Probably missing number or not necessary comma. Please correct.

3) Page 7, line 181

There is: (0.487 (. **))

Probably not necessary dot (full stop). Please check.

 

Author Response

Dear Reviewer,

Thank you very much for your time and valuable comments. They certainly improved the quality of our text. We have commented on the revisions in this version and we hope you will accept them.

We have marked the corrections in the text in green.

1) Please add the following sentence to "Statistical analysis" (line 129):

We added to the text

2) Page 4, line 124

There is: "[,25,26]"

We corrected.

3) Page 7, line 181

There is: (0.487 (. **))

Is OK.

Once more thank you for your comments.

Authors.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Manuscript ID: water-1754707

 Title: Fish diversity and abundance patterns in the small watercourses of the Central European Plain ecoregion in relation to different environmental factors

 Although the manuscript could provide important information regarding to the trophic state of surveyed rivers based on the fish community, comparing them with other ecosystems (perhaps in the same region) that have different trophic status; the amount of mathematical analysis is such that the manuscript tempts into exaggeration.

It is necessary to edit a great deal of information to ensure that the manuscript contains clear and concise ideas.

Since Fig. 5 does not show clearly its information, the lines 119-138 does not make sense.

Unfortunately, there was no mention of how fish density was calculated at each site studied.

Table 2 header is wrong.

The line of the fish abundance in Fig. 3 does not make sense, unless there is interdependence between the analyzed rivers. Is that correct?

Why did you decide to perform a CCA for species of particular guilds (Table 4 and Fig. 4) after a stepwise regression (Table 3) considering all the environmental conditions in both analyses? Didn't it seem to you that after the analysis you obtained similar results?

Why was it necessary to use so many diversity indices and so many dominance indices?

Why was it necessary to use two Jaccard tests?

Comments for author File: Comments.docx

Author Response

Responses to the comments of the Reviewer No. 1

 Dear Reviewer,

thank you very much for your time and a thorough review of our manuscript. Below are the answers to your comments. We have included the corrections directly in the text of the manuscript.

We hope that we made all the comments in line with your expectations. If the manuscript is published, your review will significantly improve the quality of our article.

Thank you very much again!

Kind regards,

Authors.

 

Manuscript ID: water-1754707

 

Title: Fish diversity and abundance patterns in the small watercourses of the Central European Plain ecoregion in relation to different environmental factors

 

Although the manuscript could provide important information regarding to the trophic state of surveyed rivers based on the fish community, comparing them with other ecosystems (perhaps in the same region) that have different trophic status; the amount of mathematical analysis is such that the manuscript tempts into exaggeration.

It is necessary to edit a great deal of information to ensure that the manuscript contains clear and concise ideas.

We corrected and eliminated redundant data in the manuscript.

Since Fig. 5 does not show clearly its information, the lines 119-138 does not make sense.

Information has been removed from the manuscript text

Unfortunately, there was no mention of how fish density was calculated at each site studied.

The fish density was determined by calculating the number of fish per 1 m² of water surface area.

Table 2 header is wrong.

Corrected

The line of the fish abundance in Fig. 3 does not make sense, unless there is interdependence between the analyzed rivers. Is that correct?

Figure 3 shows the number of fish species in a given watercourse and their density. It was reasonable to establish auxiliary lines for each of the scales to make the drawing legible. We only left the auxiliary lines for the main scale.

Why did you decide to perform a CCA for species of particular guilds (Table 4 and Fig. 4) after a stepwise regression (Table 3) considering all the environmental conditions in both analyses? Didn't it seem to you that after the analysis you obtained similar results?

It is true that both CCA and stepwise regression lead to the same conclusions - they show which environmental variables influence fish stocking overall and by guild. However, we first decided to check what are the relationships between individual variables and which may influence each other, and by means of regression analysis we checked numerically the influence of individual physicochemical parameters of water and types of substrate on fish densities.

Why was it necessary to use so many diversity indices and so many dominance indices?

In our analyzes, we used the PaST program which enabled calculations for many biotic indicators. We assumed that these results could be of use to readers and researchers. However, since we do not compare them in our manuscript, we agree with the Reviewer's suggestion and reduce their number to the most important ones.

Why was it necessary to use two Jaccard tests?

The Jaccard test was performed only 1 time (Table 6), it was performed to compare ichthyofauna syndromes between watercourses.

 

Author Response File: Author Response.doc

Reviewer 2 Report

I congratulate the authors of the article for the work done, for the data obtained and for the bibliography compiled and used in the text. Although before publication, the following must be reviewed:

 

The environmental factors must be correctly classified and defined. This clarification is important to interpret the results. Some examples:

·      The authors use equally concepts as hydrological (lines 21, 157,166, tables 2 and 3) and hydromorphological or hydromorphometric (line 308, 356, 358), not meaning the same.

·      The authors include hydraulic concepts as speed or velocity (that’s the correct way to name it) and flow and there are some confusions, for example in table 3 the flow unit is cm/s being the correct a volume/time unit.

·      Physiological parameters are named in line 157 and none are used in the analysis. I supposed the authors referred to ecological guilds (rheophilic, limnophilic…),

 

There are some inconsistencies in the text that, if they remain, should at least be clarified, for example, in the discussion section.

·       An example, about small watercourses: “Though their ichthyofauna is usually poorer than that of large rivers, they may provide habitat for valuable protected species as well as for alien and invasive species” (lines 18-20). “In spite of this, studies on this group [about ichthyofauna] in small watercourses are often neglected though according to some authors [15] such waters may show an even higher biodiversity and species richness than large rivers” (lines 56-59).

·       And more important, related to the objective in the abstract it’s stated: “The objective of this study was to compare the ichthyofaunal diversity and to identify the effect of physico-chemical, hydrological and environmental factors on the fish diversity and density in 10 small watercourses located mainly in agricultural areas” (lines 20-23). But in the introduction section “(i) assessment of environmental conditions and (ii) determining of the number of fish species, their density and diversity in small watercourses of the European ecoregion 'Central Plains'” (lines 69-70”. First the authors pointed out diversity and after they add some explained variables more as richness (a component of biological diversity.

 

The authors must standardize criteria in the text, some examples:

·      The expressions “The Central European Plain ecoregion” and “The European ecoregion 'Central Plains'” are used throughout the manuscript. Please, check if both are correct.

·      Past 4.05 (line 149) and PAST 4.05 (164).

 

The abbreviations of the studied watercourses could appear on the maps of the Figure 1 to follow better the content of the paper.

 

A table with the ecological guild and the invasiveness feature for each of the species is missing. I also think that the authors should take advantage of the opportunity to include the study of the relationship between the invasiveness feature of the fish species the environmental factors.

 

QGIS 3.24 in line 89 must be cited and referenced in the bibliography.

 

The authors must justify the selection of the ecological indices. Why have been used so many? They don’t explain nothing about them in the discussion section. Could you obtain the same information with one or two to simplify?

 

Please, review the 2.3 Abbreviations used. There is at least one mistake, in line 126 (G.gob;L.cep).

 

Normalcy should be replaced by normality (line 153).

 

When abbreviating a term, use the full term the first time (i.e UPGMA and CCA) (lines 162-163).

 

All CCA assumptions must be examined and explicitly confirmed (i.e. multicollinearity).

 

The concept of “biogen” must be explained to understand better the sentence “The high content of biogenes (N-NO3, N-NH4 and P-PO4)” (lines 174-175). I propose to use “nutrients”.

 

The authors ought to explain the relationship between the presence of nutrients and the “high” trophic level of studies watercourses and the importance in the results (line 177).

 

The header of Table 2 is not correct (line 183).

 

The scientific name of Chinese sleeper ought to be used the same as for stone moroco (preferably topmouth gudgeon) and stone loach (line 234).

 

The implications of the high p values (p>0,5) in Tables 4, 5 an 8.

 

The results in the figures must be explained better and reviewed. For example, in figure 6:

“The CCA graph shows that the greatest number of biotic indices is affected by speed, N-NH4, P-PO4 and width. There is also a positive effect on particular biotic indices of N-NH4 and P-PO4, width and flow, oxygen and N-NO3 EC and pH, and a negative effect of macrophyte coverage and speed (Fig. 6)” (lines 261-264). The authors repeat N-NH4, P-PO4 and width and it’s no clear the relationships with the other variables. When the authors refer to macrophyte coverage, are they referring to number of plants? Or degree of growth? Or both?

 

Considering the above mentioned, the discussion section must be reviewed.

Author Response

Reviewer 2

Review Report (round1)

 

 

Dear Reviewer,

Thank you for your time and a thorough review of our manuscript. If it is published, all the Reviewer's comments certainly helped to improve its quality. Below (replies to comments in bold) we have included the corrections directly in the text of the manuscript.

Kind regards,

Authors.

 

 

The environmental factors must be correctly classified and defined. This clarification is important to interpret the results. Some examples:

• The authors use equally concepts as hydrological (lines 21, 157,166, tables 2 and 3) and hydromorphological or hydromorphometric (line 308, 356, 358), not meaning the same.

Thank you very much for the suggestion! As we sometimes refer to several parameters for standardization, we have included the term "hydrometric" in the text.

• The authors include hydraulic concepts as speed or velocity (that’s the correct way to name it) and flow and there are some confusions, for example in table 3 the flow unit is cm/s being the correct a volume/time unit.

Yes, we corrected and completed the correct entry in the table      

 

• Physiological parameters are named in line 157 and none are used in the analysis. I supposed the authors referred to ecological guilds (rheophilic, limnophilic…),

Yes, we referred to ecological guilds

 

There are some inconsistencies in the text that, if they remain, should at least be clarified, for example, in the discussion section.

• An example, about small watercourses: “Though their ichthyofauna is usually poorer than that of large rivers, they may provide habitat for valuable protected species as well as for alien and invasive species” (lines 18-20). “In spite of this, studies on this group [about ichthyofauna] in small watercourses are often neglected though according to some authors [15] such waters may show an even higher biodiversity and species richness than large rivers” (lines 56-59).
• And more important, related to the objective in the abstract it’s stated: “The objective of this study was to compare the ichthyofaunal diversity and to identify the effect of physico-chemical, hydrological and environmental factors on the fish diversity and density in 10 small watercourses located mainly in agricultural areas” (lines 20-23). But in the introduction section “(i) assessment of environmental conditions and (ii) determining of the number of fish species, their density and diversity in small watercourses of the European ecoregion 'Central Plains'” (lines 69-70”. First the authors pointed out diversity and after they add some explained variables more as richness (a component of biological diversity.

 We have made a correction in the abstract.

 

The authors must standardize criteria in the text, some examples:

• The expressions “The Central European Plain ecoregion” and “The European ecoregion 'Central Plains'” are used throughout the manuscript. Please, check if both are correct.

We have improved and unified one form: Central European Plain

 

• Past 4.05 (line 149) and PAST 4.05 (164).

We have improved and unified one form: PAST

 

The abbreviations of the studied watercourses could appear on the maps of the Figure 1 to follow better the content of the paper.

Fig 1 has been corrected by adding individual sites on the watercourses

 

A table with the ecological guild and the invasiveness feature for each of the species is missing. I also think that the authors should take advantage of the opportunity to include the study of the relationship between the invasiveness feature of the fish species the environmental factors.

This is a very interesting topic and we are currently working on another manuscript in which we want to compare in detail the environmental and hydrochemical conditions in watercourses for the presence of invasive species in the studied watercourses, especially on Pseudorasbora parva and Perccottus glenii. We want to present the topic broadly and precisely.

 

QGIS 3.24 in line 89 must be cited and referenced in the bibliography.

 

We added:

Menke, K.; Smith, R.; Pirelli, L.; Van Hoesen, J. Mastering QGIS. 1sted.; Pack Publishing: Birmingham UK, 2015; pp. 391

 

The authors must justify the selection of the ecological indices. Why have been used so many? They don’t explain nothing about them in the discussion section. Could you obtain the same information with one or two to simplify?

Yes, of course you can simplify the table and show the most standard biotic indexes.

 

Please, review the 2.3 Abbreviations used. There is at least one mistake, in line 126 (G.gob;L.cep).

We removed the entire section 2.3 due to suggestions from another Reviewer

 

Normalcy should be replaced by normality (line 153).

Corrected

 

When abbreviating a term, use the full term the first time (i.e UPGMA and CCA) (lines 162-163).

Added

All CCA assumptions must be examined and explicitly confirmed (i.e. multicollinearity).

The validation inflation factors were checked, assuming the value of 10 as the borderline factor for multicollinearity. The above-mentioned values were not found in any case, and the correlations between the variables were not high (only in a few cases statistically significant correlations were found).

 

The concept of “biogen” must be explained to understand better the sentence “The high content of biogenes (N-NO3, N-NH4 and P-PO4)” (lines 174-175). I propose to use “nutrients”.

 Corrected

 

The authors ought to explain the relationship between the presence of nutrients and the “high” trophic level of studies watercourses and the importance in the results (line 177).

 We explain this by describing the use of the river basins where Molnica, Kraska and Zielona are subject to high agricultural pressure. There are no buffer zones in the studied watercourses to protect against the run-off of nutrients, we have noticed the flowing substances into the water more than once, because farmers very close to the river conduct intensive farming.

 

The header of Table 2 is not correct (line 183).

Corrected

 

The scientific name of Chinese sleeper ought to be used the same as for stone moroco (preferably topmouth gudgeon) and stone loach (line 234).

Added

 

The implications of the high p values (p>0,5) in Tables 4, 5 an 8.

 The results in the figures must be explained better and reviewed. For example, in figure 6:

“The CCA graph shows that the greatest number of biotic indices is affected by speed, N-NH4, P-PO4 and width. There is also a positive effect on particular biotic indices of N-NH4 and P-PO4, width and flow, oxygen and N-NO3 EC and pH, and a negative effect of macrophyte coverage and speed (Fig. 6)” (lines 261-264). The authors repeat N-NH4, P-PO4 and width and it’s no clear the relationships with the other variables. When the authors refer to macrophyte coverage, are they referring to number of plants? Or degree of growth? Or both?

 We have changed Fig 6 and added a new description with an explanation.

 

Author Response File: Author Response.doc

Reviewer 3 Report

Review

Paper title: Fish diversity and abundance patterns in the small watercourses of the Central European Plain ecoregion in relation to different environmental factors

 

The authors conducted a field study to reveal species composition and diversity indices of fish communities in 10 rivers in Poland. They measured physico-chemical parameters. The authors and discussed their findings concerning the conservation status of the area and the role of environmental factors in driving fish communities. These new data may have important implications for the management of small watercourses in the Central European Plain ecoregion.

 

All these reasons explain the relevance of the paper by Adam Brysiewicz and co-authors submitted to "Water".

 

General scores.

 

The data presented by the authors are original and significant. The study is correctly designed and the authors used appropriate sampling methods. In general, statistical analyses are performed with good technical standards. The authors conducted careful work that may attract the attention of a wide range of specialists focused on fish biology and conservation.

 

Major concerns.

I suggest modifying the title as follows “Fish diversity and abundance patterns in small watercourses of the Central European Plain ecoregion in relation to environmental factors”

L 183. The authors should provide a relevant table caption.

Fig. 3. As fish density is not a continuous variable, the authors should use histograms instead of line for this parameter representation.

 

Specific comments.

L 69. Change “determining  of” to “determining”

L 70. Change “estimate of” to “to estimate”

L 76. Change “sudied” to “studied”

L 89. Change “database” to “the database”

L 96. Change “summer,” to “summer, and”

L 97. Change “in 2017-2020” to “over the period 2017-2020”

L 102. Change “using” to “using a”

L 107. Change “automatic” to “an automatic”

L 112. Change “during 24 h” to “for 24 h”

L 155. Change “Dunn” to “Dunn’s”

L 162. Change “UPGMA” to “the UPGMA”

L 163. Change “was performed” to “were performed”

L 184. Change “Dunn” to “Dunn’s”

L 191. Change “in  two sites” to “at  two sites”

L 218. Change “variation” to “the total variation”

L 219. Change “p value” to “p-value”

L 228. Change “variation” to “the total variation”

L 229. Change “p value” to “p-value”

L 235. Change “extent of” to “extent by”

L 243. Change “Jaccard index” to “the Jaccard index”

L 247. Change “Jaccard index” to “the Jaccard index”

L 253. Change “environment” to “the environment”

L 257. Change “variation” to “the total variation”

L 258. Change “p value” to “p-value”

L 263. Change “i pH” to “and pH”

L 268. Change “human  effect” to “the human  effect”

L 271. Change “direct  influence” to “a direct  influence”

L 283. Change “long-term” to “a long-term”

L 304. Change “environment” to “environmental”

L 307. Change “effect  of” to “effect  on”

L 346. Change “biological productivity” to “the biological productivity”

L 352. Change “high content” to “the high content”

L 368. Change “increase” to “an increase”

L 373. Change “but  also  of” to “but  also”

Author Response

Początek formularza

Dear Reviewer,

thank you very much for your time and a thorough review of our manuscript. Below are the answers to your comments. We have included the corrections directly in the text of the manuscript.

We hope that we made all the comments in line with your expectations. If the manuscript is published, your review will significantly improve the quality of our article.

Thank you very much again!

Kind regards,

Authors.

 

Paper title: Fish diversity and abundance patterns in the small watercourses of the Central European Plain ecoregion in relation to different environmental factors

 

The authors conducted a field study to reveal species composition and diversity indices of fish communities in 10 rivers in Poland. They measured physico-chemical parameters. The authors and discussed their findings concerning the conservation status of the area and the role of environmental factors in driving fish communities. These new data may have important implications for the management of small watercourses in the Central European Plain ecoregion.

 

All these reasons explain the relevance of the paper by Adam Brysiewicz and co-authors submitted to "Water".

 

General scores.

 

The data presented by the authors are original and significant. The study is correctly designed and the authors used appropriate sampling methods. In general, statistical analyses are performed with good technical standards. The authors conducted careful work that may attract the attention of a wide range of specialists focused on fish biology and conservation.

 

Major concerns.

I suggest modifying the title as follows “Fish diversity and abundance patterns in small watercourses of the Central European Plain ecoregion in relation to environmental factors” - corrected

L 183. The authors should provide a relevant table caption. - completed

Fig. 3. As fish density is not a continuous variable, the authors should use histograms instead of line for this parameter representation.

We improved the graph - we removed the extra lines for the auxiliary scale, we also changed both variables to histograms:

 Specific comments.

L 69. Change “determining  of” to “determining” - corrected

L 70. Change “estimate of” to “to estimate” - corrected

L 76. Change “sudied” to “studied” - corrected

L 89. Change “database” to “the database” - corrected

L 96. Change “summer,” to “summer, and” - corrected

L 97. Change “in 2017-2020” to “over the period 2017-2020” - corrected

L 102. Change “using” to “using a” - corrected

L 107. Change “automatic” to “an automatic” - corrected

L 112. Change “during 24 h” to “for 24 h” - corrected

L 155. Change “Dunn” to “Dunn’s” - corrected

L 162. Change “UPGMA” to “the UPGMA” - corrected

L 163. Change “was performed” to “were performed” - corrected

L 184. Change “Dunn” to “Dunn’s” - corrected

L 191. Change “in  two sites” to “at  two sites” - corrected

L 218. Change “variation” to “the total variation” - corrected

L 219. Change “p value” to “p-value” - corrected

L 228. Change “variation” to “the total variation” - corrected

L 229. Change “p value” to “p-value” - corrected

L 235. Change “extent of” to “extent by” - corrected

L 243. Change “Jaccard index” to “the Jaccard index” - corrected

L 247. Change “Jaccard index” to “the Jaccard index” - corrected

L 253. Change “environment” to “the environment” - corrected

L 257. Change “variation” to “the total variation” - corrected

L 258. Change “p value” to “p-value” - corrected

L 263. Change “i pH” to “and pH” - corrected

L 268. Change “human  effect” to “the human  effect” - corrected

L 271. Change “direct  influence” to “a direct  influence” - corrected

L 283. Change “long-term” to “a long-term” - corrected

L 304. Change “environment” to “environmental” - corrected

L 307. Change “effect  of” to “effect  on” - corrected

L 346. Change “biological productivity” to “the biological productivity” - corrected

L 352. Change “high content” to “the high content” - corrected

L 368. Change “increase” to “an increase” - corrected

L 373. Change “but  also  of” to “but  also” - corrected

Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

An editing detail: Please make sure lines 240 to 249 are not above Table 7.

Author Response

Dear Reviewer,

Thank you very much. We checked and it is correct.

Reviewer 2 Report

The current version has only considered a small part of the comments made in the previous revision. Contradictions noted (i.e. about the richness of fish in small streams, now in 59-62 lines and 325-326 lines), misconceptions (such as biogen or speed – velocity - flow continue to be used throughout the document, I insist, units of flow are volume/time, the authors continue using speed instead of velocity, it’s no clear when they refer to flow or flow velocity). These variables must be explained for a better understanding of the document. “Physiological parameter” is used in line 163 when I suppose you refer to “physico-chemical”. What are the unit of vegetation coverage?, etc… When the reviewer does a correction or proposal, it must be reviewed throughout the entire document.

 

Some of the discussed results are not supported by statistical analysis or they are difficult to check in figures and tables as they appear in the document (i.e. the content of “biogenic” substances and conductivity in forest-dominated catchment areas, low oxygen concentration in watercourses with high concentration in ammonia… why not a correlation?).

 

The authors must check the results contrasting the text with the interpretation of the corresponding figures, mainly those related to nutrients (i.e. the N-NO3 content). Why they chose some explanatory parameters and forget others than have a higher relationship with the response variables.

 

The document needs to be carefully reviewed.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

First, I would like to thank the authors for considering most of the comments and suggestions that I made in the previous review. The manuscript has improved remarkably. However, there are still some aspects to improve so that the manuscript can be published according to my criteria.

 

I have noticed that some of the errors noted in previous revisions have not been corrected throughout the manuscript. Please, I ask the authors that when I make a comment, I point it out in a line, paragraph, figure or table, take it into account and correct it throughout the manuscript. First, because this is not the task of the reviewer, and second, because coherence must be maintained in the text.

 

Thus, to continue with the review, I make the following comments:

 

- Lines 21-24. I suggest the following wording to be consistent with the text. The objectives of this study were the assessment of environmental conditions, the determination of the number of fish species, their density and diversity in 10 small water courses of the European ecoregion 'Central Plains', and to estimate of the effect of individual habitat parameters on the ichthyofauna.

 

- Lines 26-28. Reviewing the manuscript, I have verified that the concepts and the differences between velocity of water and flow are still not very clear. This mistake has not been fixed and it appears into text, tables and figures. Therefore, I suggest that throughout the manuscript the authors replace velocity of water and speed of water for “flow velocity” and flow by “discharge”. The unit of flow velocity is cm/s and the unit for discharge is cm3/s. Please, take your time and carefully read the entire manuscript. For example, in these lines: “Statistical analyses showed that the density of rheophilous fish was under the effect of flow velocity, discharge, width, depth, oxygen content and pH…”. 

 

- Line 29. Replace EC by “electric conductivity”

 

- Line 54. Change “velocity up” by “speed up”, here speed is part of a verb and doesn’t refer to “speed of water”. Please, carefully read the manuscript and keep an eye on the changes proposed by the reviewers. It is very tiring to repeat the same thing repeatedly. I think it’s not necessary to point out the same from now on.

 

- Line 65. Replace “kind of substratum” by “streambed substrate composition” from now on, e.g., in Table 3 and line 439. 

 

- Line 66. Replace “content of nutrients substances” by “contents of nutrients” since the nutrients can be substances or compounds, chemically speaking. Same in line 348. 

 

- Line 71. “The objectives of this study were (i) the assessment of environmental conditions and”.

 

- Line 105. Add after “species identification” the following “collected ichthyofauna were classified by three ecological guild groups: limnophilic, rheophilic and eurytopic. 

 

- Line 107. Add “EC” after “electric conductivity”. “catches, temperature, electric conductivity (EC) and oxygenation were measured directly in…”.

 

- Lines 122-123. Please rewrite: “Plants were identified to species. Number of species (psc.) and vegetation coverage (in %) 123 were astiamted”. It's not understood. What’s the meaning of psc.?

 

- Line 160. Has been done the Shapiro-Wilk test with the packet MASS for R? If so, eliminate ) was carried out using the R software 161 [2827], 

Line 162, Replace “physico-chemical characters” by “physico-chemical and hydrometrical parameters”. 

 

- Line 167 and 240.  Replace “step-wise” by “stepwise”

 

- Line 169: “These analyses were done with the packet MASS for R 4.0.5 GGally”. Are included the Kruskal-Wallis test and the Dunn`s test with Bonferroni correction in these analyses?

 

- Line 178. The order of presentation of the results should follow the order of presentation of the methodology

 

- Lines 195-196. “Table 2. Physico-chemical and hydrometrical conditions in the studied watercourses, with 196 results of Kruskal-Wallis and Dunn`s tests”. Replace “conditions” by “parameters”.

 

- Line 194. Figure 2. “Results of cluster analysis (UPGMA) for the studied watercourses”.

 

- Line 201. Replace CC (CzarnaCedron)  by CCd to be consistent throughout the manuscript. 

 

- Lines 202-203. Review the following sentence: “The Yellow color marks catchments with more than 50% of agricultural crops, and orange marks water 203 courses in catchments with more than 30% forests)”. The colors of the rows are not assigned correctly. It’s the opposite. Wardynka does not have the largest forest area?

 

-Lines 208-227 Please, rewrite again. Read carefully, there are some mistakes as widith and deep (width and depth are the correct), line 2015. On some occasions the authors add r values and p significance with asterisks, on others no (lines 223-227). Please, be consistent. Moreover, the authors point out correlations no significative, for example between EC and depth (0.334, .). Again, read carefully, these mistakes of interpretation of results mut be solved. Please, highlight the most interesting results.

Line 239. .Section 3.3 Not always is specified in what sense (positive or negative) does environmental parameters influence in fish.

 

- Line 242. “influenced by flow velocity, discharge, width, depth, oxygen content as well as pH. For limnophilous…”

 

- Line 250. Table 3. Results of stepwise regression and correlation of the effect of variables on the fish density of particular guilds

 

- Line 251. Table 3. Add (%) in “Vegetation coverage”. 

 

- Line 260 Table 4. Eigenvalues, % of explained variation and p- value estimates for three axes determined by CCA for the effect of conditions on the fish density of particular guilds

 

- Line 261. I would like to know how significance levels greater than 0.05 are interpreted in all the CCA analysis. This comment is valid for all the CCA analysis, although I only do it on this one. What statistic does the p-value refer to? I ask the same in the previous review, but I haven’t had any answer. if the p-value is less than 0,05, the null hypothesis is rejected.  If not, then we fail to reject the null hypothesis. But, what’s the null hypothesis?

 

- Line 264. flow in cm/s, which flow? Velocity flow? Or discharge? Please, follow the abovementioned comments related to flow velocity and discharge (volumetric flow rate).

 

- Line 273. The following comment is extensive to all the CCA analysis. The interpretation of some of the graphics is not complete. There are parameters exerting influences that are not explained in the text. E.g., in figure 5, P. glenii is positively influenced by depth, EC, flow velocity, etc,,, as well as nitrates, phosphates and discharge.  but in the text only the last ones are mentioned. Other example, in fig. 6, Shannon H index is related to flow velocity, O2, nitrates, temperature (see in graphic a mistake, temperatura), as well as phosphates.  

 

- Line 279. Fig. 5 attention to flow (cm/s) and speed (cm/s). Just a reminder. Please, review all the manuscript to be consistent.  

 

- Line 328. Figure 6 “CCA graph for the ecological indices on environmental conditions”. Please, replace environmental indices by ecological indices, as the authors refer in the text. 

 

- Line 355. What is indicated in the text cannot be seen in table 7. An asterisk could be added in agricultural localities, for example. 

 

- Line 378. Again, flow velocity and volume. Review, please.

 

- Lines 386-387. I don’t understand the sentence. “Especially assemblages of stream-dwelling fish are often associated with flow regimes and hydrometrical the total variation”. Could you explain or rewrite a more understandable way.

 

- Lines 389-391 Refer to figure 4. I see clearly that rheophiles are under considerable effect of discharge (cm3/s), but also of depth, width, temperature (Temp, in other graphs the authors use temperature, please be consistent). it is not like that in the case of limnophiles which are most influenced by nnh4 and degree of growth. 

 

- Lines 392.-432. I miss more references to the results in the studied watercourses to compare with the complete information presented by the authors in the discussion section. 

 

- Line 410. Why is not presented this graphic in the results section?

 

- Lines 412-414. I would place the following sentence before “excess of ammonia” in line 404. “Fish exposure to pollution by inorganic nitrogen compounds (NH4 + , NH3, NO2 - , HNO2, and NO3 - ) has effects on the reproduction, growth and survival of freshwater fish”

 

- Lines 426-432. Could you explain the following sentence? “The phenomenon may be responsible for the small number of fish species and decrease in density of all species in the studied watercourses with increasing concentration of P-PO4, as a result of the high content of P-PO4 in these watercourses (0.61-1.46 mg P-PO4)” But in Figure 4 there is a positive correlation between phosphates a rheophiles.