Status and Perspectives of the Ichthyofauna of the Labudovo okno Ramsar Site: An Analysis of 14 Years of Data

Round 1

Reviewer 1 Report

The study of Nikolić et al. concerns long-term changes in the composition of the ichthyofauna of the Labudovo Okno Ramsar Site, an important site for  regional biodiversity and water supply to the Danube basin. Therefore, the research is of great importance both in terms of knowledge and application, especially since it concerns a long period of 14 years. Currently, however, they raise serious doubts as to the correctness of the analysis. First of all, the authors base their conclusions on the “linear regressive analysis of the tendencies of relative biomass and relative annual production”, the results of which they did not show (it probably was not done). Based on Figures 3C and 3D, it would probably not be significant (there are too few points). However, the effect of time in the MANOVA model (lines 169-171) is significant. Differences in time could therefore be demonstrated using one of the post-hoc tests available in the Statistica package. This will probably allow to prove the differences in time and enable the conclusions contained in the manuscript.

The second general remark concerns systematics. It's not entirely up to date. For example, in most current databases, e.g.

https://www.gbif.org/species/10307246

https://www.fishbase.se/summary/FamilySummary.php?ID=756

https://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp

some cyprinids are classified as Leuciscidae. This applies also to those mentioned in the manuscript, for example: Alburnus alburnus, Abramis brama or Ballerus sapa (Abramis sapa is not currently correct).

 

Detailed notes:

Table 1 – What do the shaded places in the table mean?

 “The test shows no significance between the studied localities, but it is obvious that the highest values of relative biomass were measured at the Đurica and Vič localities” lines 166-167 - Significance of what? Significance of differences. It needs to be improved everywhere.

Figures 3C and 3D – What do the points on the graph mean?

„Figure 3. ANOVA/MANOVA test conducted to identified the distribution of the relative 174 biomass and relative annual production in investigated localities (A) and period of 175 investigation (B). Linear regressive analysis of the tendencies of relative biomass (C) and 176 relative annual production (D)” - Figures 3A and 3B do not present a statistical test, only relative biomass and production in individual sites. There are no descriptions of the Y axis. Besides, the drawings are illegible, they have to be made anew and not imported from Statistica. You have to put real error bars (Statistica doesn't do that) and define them in the figure caption.

The same applies to Figure 4.

“The linear regression analysis clearly shows the declining trend of the two parameters of fisheries biology - relative biomass and relative annual production” lines 190-191 Linear regression analysis was not performed!!!

The theses contained in the Conclusions are too little discussed in the Discussion.

Author Response

Thank you for your comments and suggestions.

They were helpful. in improving the text of MS.

Author Response File: Author Response.pdf

Reviewer 2 Report

Line 41.  34.829,32 ha or 34,829.32 ha?

Lines 71-78. Aims of the manuscript should be present in its introduction.

Line 83-84. I recommend the relevant Handbook of European Freshwater Fishes (M.Kottelat and J.Freyhof, 2007) for the fish taxonomical identification that should provide reproducibility of results.

Lines 113-147. Sampling localities description should be placed in 2.1. All the localities should be clearly presented in the figure 1.

Lines 154-155 and the Table 1. Authors should check all fish names and families by the Eschmeyer’s Catalog of Fishes. E.g. Alburnus alburnus belongs now to the family Leuciscidae, Pseudorasbora parva belongs to the family Gobionidae. Abramis sapa now is valid as Ballerus sapa, Aspius aspius now is valid as Leuciscus aspius.

Figure 2 will be changed after the Authors make taxonomical amendments. Generally, I guess the sharing all the observed fish by ecological guilds (piscivorous, planktivorous etc.) should be more comprehensive for the understanding processes in the ecosystem

Line 163. Authors should add the biodiversity indexes for each year after line “Total” or provide it some separate table.

Figure 3 was given in poor quality

Lines 272-278. The Conclusions is written in the most general nature and is not related to the data obtained and their discussion.

 Lines 337-342. Several sources were put over the No19 in References

Author Response

Thank you for your comments and suggestions.

They were helpful. in improving the text of MS.

Author Response File: Author Response.pdf

Reviewer 3 Report

1- No mention of Figure 2 in the context of the article.

2- The image in Figure 5 is very small.

3- The aim of the study must be written at the end of the introduction.

 

Comments for author File: Comments.pdf

Author Response

Thank you for your comments and suggestions.

They were helpful. in improving the text of MS.

Author Response File: Author Response.pdf

Reviewer 4 Report

Dear Authors

Minor corrections that I consider necessary in the manuscript are indicated as sticky notes within the text (pdf version). Especially in Table 1 Should be written common names of all species. Because in the discussion part, these species  by common names cause confusion. In addition, the resolutions of the graphics given in Figure 3 should be better. 

Best wishes

 

Comments for author File: Comments.pdf

Author Response

Thank you for your comments and suggestions.

They were helpful. in improving the text of MS.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Graphs imported from Statistica are still wrong. Error bars show neither the standard deviation nor another measure of variation. Descriptions in figures should be in larger font.

Author Response

We greatly appreciate your suggestions and comments.

Author Response File: Author Response.docx

Reviewer 2 Report

It is not necessary to give formulas for calculating diversity indices (lines 155-173) as they are well known. It would be enough to give a link to the source, for example

Biological Diversity Frontiers in Measurement and Assessment (Eds. A.E. Magurran and B.J. McGill)

 

Authors should recheck the status of species by https://www.iucnredlist.org/

as there are many errors in Table 1, e.g.:

 

Carassius carassius was evaluated as “LC” by Freyhof, J. & Kottelat, M. 2008. Carassius carassius. The IUCN Red List of Threatened Species 2008: e.T3849A10117321. https://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T3849A10117321.en. Accessed on 26 May 2023.

Barbus barbus was evaluated as “LC” by Freyhof, J. 2011. Barbus barbus (errata version published in 2016). The IUCN Red List of Threatened Species 2011: e.T2561A97789324. https://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T2561A9454585.en. Accessed on 26 May 2023.

Perccottus gleni was evaluated as “LC” by Bogutskaya, N. 2022. Perccottus glenii. The IUCN Red List of Threatened Species 2022: e.T159715238A159715260. https://dx.doi.org/10.2305/IUCN.UK.2022-1.RLTS.T159715238A159715260.en. Accessed on 26 May 2023.

 

I strongly recommend that the authors divide the observed fish species into at least two ecological guilds as predators and non-predators and then discuss the relationship between predator abundance/biomass and the diversity indices.

Author Response

We greatly appreciate your suggestions and comments.

Author Response File: Author Response.docx