Faunistic and Structural Changes in Shallow Coastal Benthic Communities of the Ebre Delta (NW Mediterranean Sea)

Round 1

Reviewer 1 Report

The manuscript diversity-2313372 entitled “Faunistic and structure changes in shallow coastal benthic communities of the Ebre Delta (NW Mediterranean Sea)” by Ramón et al., is an interesting study exploring changes on the megabenthic assemblages of the Ebre delta. This study must be of interest for the readers of Diversity journal. However, the methods and data analyses have severe faults and needs a major revision to be publish in this journal.

MAIN PROBLEMS

The objective of the study is to explore changes on the diversity structure and biomass of megabenthos between two dates. The time replication is very small, comparing two distant periods of time without information about years between the studied periods. Despite this problem the study can have interest. The main problem is that the analyses described on the methods and the presented results are very different. In the results the authors show values of diversity indexes, ANOVA analyses and ANOSIM analysis that were not mentioned or described on the methods. Authors explored differences among the groups defined in the MDS using ANOSIM. This is a huge mistake, groups should be defined a priory, in their case they must compare the two time periods and the different depths in a single analysis. MDS is graphical representation and no conclusion should be retires from them. Another uncommon situation is the use of PERMANOVA to explore differences in depth and ANOSIM to explore differences among groups. They are similar analyses, however PERMANOVA is more flexible for complex design with several factor. Therefore authors should consider only one analysis (PERMANOVA) to explore differences between dates (fixed factor) and depths (Fixed factor).

On line 117 authors remove “rare”species. This is a mistake as rare species sometimes are the best indicators of the effects of disturbance. However, authors transform data to reduce the effect of dominant species. This is contradictory with the removal of rare species.

The discussion of the results should be changed in function of the results of the new analyses. However, this is a observational study and it is not able to establish any cause effect relationship.

I am not a native English speaker but I think that English can be improved and I am sure that the objectives and structure of manuscript must be revised.

Univariate analyses of biodiversity index (ANOVA)

Multivatiate analyses (PERMANOVA, PERMDISP, ANOSIM)

Univariate analyses of biomass (ANOVA)

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The paper based its results on an extensive study carried out along two periods apart, which make them really valuable for monitoring studies aiming to analyse the state and evolution of the ecosystem. The sampling and taxonomical methodology used by the authors within the research is clearly explained and scientific-sound and the statistical interpretation is appropriate and fit to purpose.
However, we recommend an English proofreading (see for example, the highlighted text in the attached MS). Also, some phrases or paragraphs could be considered too lengthy and a better synthesis of the results and discussions would increase their scientific value. The discussions seems a little bit elusive and not pointed to explain well why, for example, the biomass of megafauna has decreased so drastically, while an apparent improvement of abundance and diversity have occurred in case of some taxa.  
After these minor improvements of the manuscript, we recommend the paper be published.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Authors have improved the manuscript. I only have some comments about issues that must be fixed before publication.

Line 92. Delete “void” and add “lack of information”

Line 287. 9999 instead 9,999

Line 289. “…test was done to explore the differences…”

Line 297. Authors have to do a two-way ANOVA. You cannot merge the two different factors in one

Line 431. Decrease of number of species?

You did a very detailed discussion therefore I think that you must remove the parts where you repeat the results again. If not the discussion is very long and repetitive with results section.

Author Response

Please see the attachment

Author Response File: Author Response.docx