Comment on Lesser et al. Using Stable Isotope Analyses to Assess the Trophic Ecology of Scleractinian Corals. Oceans 2022, 3, 527–546
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsMy apologies for taking some time, despite which I have not been able to judge the validity of all the competing arguments!
The ms is interesting and in general pretty well-written, although in places it is a little challenging to follow. I have no major criticisms, but there are scattered minor typos that need correcting, and, in as many other places, the text could be made easier to follow by minor amendments or added punctuation, as listed below.
I addition, would it be worth addressing within the last paragraph or two the question of whether across species, species more typical of greater depths tend to rely more on heterotrophy? That I believe is the general paradigm assumed by most reef researchers, one that is probably distinct from the issue being argued in this paper, as to whether within a species corals become more heterotrophic with increasing depth.
29 trophic (not tropic)
35 concludes (not conclude)
37 suggest “their declining photosynthetic…
43 analyses (not analysis)
55 delete “the” before Lesser et al.
58 suggest delet “the foundation of” (not necessary and confusing)
66 spell out POM on first use
66 insert “in” before a greater
88 suggest “and thus affect the ability… (for clarity)
92 suggest “highlighting, sufficient to reveal….
97 suggest insert commas after “depth,” and after “values,
101 suggest comma after “heterotrophy,
104 suggest “while” instead of “but” after depth,
115 suggest “metric that cannot be explained…(rather than which)
121 suggest comma after “contradictory,
134 hyphen in “non-bleached
137 insert “for” after “evidence
166 insert comma after “[37-39],
166 close up between see and [40,41]
168 insert comma after “three key assumptions,
169 delete “be” before “caused by..
177 insert “the” before “symbiont type remains..
177 lower case t in “these conditions…
186 insert “the” before “large-scale seasonal…
188 insert comma after “study,
192 suggest insert “Thus” before “the isotope-based P/R ratios…
211 suggest comma after “symbiont,
218 suggest comma after “depth,
246 growth not grow
248 suggest “in their lower depth range” (not at)
252 close up before citations 2 -61
261 suggest rephrase as: “both for actual photosynthetic performance and for any changes in metabolic demand…” (easier to follow)
292 suggest comma after “depth,
297 suggest comma after “can,” and “but depth …(not and depth)
347 delete “s” in authors – if only one author.
359 delete stray semi-colon before “1987”
Please check for any typos in other references.
Author Response
My sincere apologies for the typos in the manuscript. I appreciate the time and effort invested in providing the recommended edits. All recommended edits were implemented with the exception of line 35. The subject (Lesser et al.) is plural (multiple authors) so the verb remains in plural form.
Given the multitude of issues with bulk tissue stable isotopic data, higher resolution techniques are required to clarify the questions surrounding the trophic ecology of photosymbiotic corals at depth. To date, there is no reliable data available on the trophic ecology of photosymbiotic corals >60 m. While there is indirect evidence which is suggestive, the lower half of the photic zone remains essentially unexplored for trophic ecology including the photosymbiotic taxa which dominate the deepest depths (i.e., Leptoseris spp. in the Indo-Pacific). A couple lines were added in the final paragraph to clarify the current status.
Given the 15 months that has passed since original manuscript submission (Feb 3, 2023), a few additional edits were incorporated:
(1) Line 167. The general scientific consensus is that McConnaughey's kinetic model has been superseded by Adkin's pH model with respect to coral skeletal d18O. Confirmed via personal communication with Peter Swart.
(2) Line 231: The specific caveats for the d15N AA-CSIA trophic position metric were added for clarity
(3) Line 263: An additional citation (Cooper et al. 2011) regarding P/R ratio was added to demonstrate the potential role of respiration in driving P/R ratio with depth
(4) Line 328: An additional citation (Carmignani et al. 2023) which was published after the original manuscript submission was added.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe comment on Lesser et al. 2020 presents a detailed overview of the complexities of using stable isotopes to assess trophic status of corals and highlights how some of these complexities can lead to different conclusions. Overall, the article raises valid points that are well supported by the referenced literature. However, the comment is unnecessarily hostile and disrespectful towards the original article and authors. This is clearly an active research topic without a clear consensus across the field, and as the comment says, "there is evidence to suggest that some depth-generalist coral species increase their reliance on heterotrophy with increasing depth". I recommend the author significantly change the tone of the comment, to more diplomatically address their concerns with the original article.
Author Response
In an effort to avoid any hostile and undiplomatic tone, minor diction and edits were incorporated. The goal of this response manuscript is to objectively share the available science holistically and correct the egregious misrepresentations in Lesser et a. 2022. If there are specific lines/words that appear to be unwarranted, I welcome feedback to make additional edits.
Given the 15 months that has passed since original manuscript submission (Feb 3, 2023), a few additional edits were incorporated:
(1) Line 167. The general scientific consensus is that McConnaughey's kinetic model has been superseded by Adkin's pH model with respect to coral skeletal d18O (confirmed via personal communication with Peter Swart).
(2) Line 231: The specific caveats for the d15N AA-CSIA trophic position metric were added for clarity
(3) Line 263: An additional citation (Cooper et al. 2011) regarding P/R ratio was added to demonstrate the potential role of respiration in driving P/R ratio with depth
(4) Line 328: An additional citation (Carmignani et al. 2023) which was published after the original manuscript submission was added.
