Resource Partitioning of Sympatric Lutjanids in the Northern Gulf of Mexico Using Stable Isotope Analysis
, Kevin M. Boswell 4 and James H. Cowan, Jr. 5,†Round 1
Reviewer 1 Report
Table1 Please add the TL range information for each species in four regions. Actually, TL information is helpful to understand the ontogenetic changes. In addition, for contextual consistency, the abbreviated names of species (GS, LS, RS, VS) need to be reflected in the table 1.
In 2.3 Statistical analysis, lack of the formula for calculating isotopic niche overlap proportion, please make it up.
Figure 3 and 4, suggest using MA instead of Macro.
Please, explain why not collected their own basal resources (MA/POM/BMA) in four regions. You know that there may be great differences in the stable isotope values of the basal resources in different regions, therefore, I think the percent contribution of the basal resources of 4 species may not be accurate. Please check it.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
I completed my evaluation of the manuscript fishes-2341746 “Resource partitioning of sympatric Lutjanids in the northern Gulf of Mexico using stable isotope analysis” submitted to Fishes. This study addresses an important topic evaluation of a trophic niche overall of four commercially and ecologically important closely relative species in four areas of northern Gulf of Mexico. The text structure is clear, informative and well written. The method section is described in detail, data analysed and interpreted in the clear discussion section (the best part of the manuscript).
I see only one problem in the study, not balanced samples in different parts of the Gulf. I fully understand it is not easy (often impossible) to collect perfectly balanced data. Except of this little concern, I have only a few very minor comments, which might improve the manuscript
Line 43: I prefer to replace “members” with “species”.
Line 57: More details about the C and S isotopes can be added. What isotopes are more common in nature and what is the interpretation of the deviance (e.g., C 13-14, S 32-34).
Line 62: I prefer to replace “fishes” with “species”.
Line 62: Are Lutjandids distributed in other parts of the sea or are they endemic in the Gulf (the actual meaning).
Line 66: What is the maximal size of the top predators?
Line 76: I miss the information about isotopic elements (i.e., C, N, S).
Line 129: Please, add the version of R software you used.
Line 137: Change (32) to [32].
Line 187: Please, add the species abbreviation in the brackets, e.g.: (gray, GS), (gold, LS),…
Line 518, 521: The species names in Latin should be in italics.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
About comment 2, you maybe mistook my meaning, I wanted to know how you calculated the isotopic niche overlap (‰2). Please check it.
Author Response
Reviewer 1 comments Round 2
1) About comment 2, you maybe mistook my meaning, I wanted to know how you calculated the isotopic niche overlap (‰2). Please check it.
We have added a verbal description of the method for estimating niche overlap. We did not feel a full formula was necessary due to its simplicity (i.e., simple proportions) and adding the space for another formula would have disrupted the spacing and formatting for the remainder of the document. Textual description has been added in lines 154-163 of the revised document.
Author Response File: 
Author Response.docx
