Review Reports - Eight New Records of Siphonophores (Cnidaria: Hydrozoa) in Korean Waters

Round 1

Reviewer 1 Report

Overview

The aim of this paper is to examine the siphonophore species richness in neritic Korean waters and the extension of previously published regional knowledge on this cnidarian group. The work is original and deserves publication after consideration of the comments supplied below. Getting a handle on true species occurrences in coastal and open ocean regions is still today vastly hampered for this and other gelatinous zooplankton groups given the small number of taxonomic experts and still partly lacking molecular reference gene banks. The topic is interesting and highly relevant, particularly in the light of regional ‘jellyfication’ and ocean warming. However, the paper suffers from several flaws in structuring and a lack of oceanographic setting consideration. Diversity perspectives such as richness, evenness, and diversity measures are not included at all, leaving the meaning and spatial comparison of the numerous stations blank. The presented data certainly warrant publication, but need some better contextualisation and extended analysis. My concerns are elaborated further below. After careful revision, I look forward to see the manuscript again. Thus, my decision is major revisions.

Major comments

Abstract: The structure of the abstract should mirror the structure of the paper in mini format. Start with one or two sentences of introduction, then switch to your methods and only then describe the results, which are ultimately discussed in one or two more sentences. Right now, the structure is too Results-focused and can be shortened as much of it is descriptive and redundant.

Introduction: The introduction is generally clearly written, contains the most relevant information to understand the objective of the study, frames the project sufficiently, and leads logically to the study aims. As outlined below, there are several minor changes needed to increase reading flow and correct minor errors. Generally, it’s a fair introduction.

Materials and Methods: Similar to the introduction, the methods section is well written and requires only minor adjustments following my suggestions outlined in detail below. Generally, the authors do a fine job here.

Results: The results are unconventionally structured and deserve some reworking. Why aren’t the molecular results not part of the Results and only mentioned in the Discussion? That clearly warrants some restructuring. Also, the Results contain a high number of references, which is usually not allowed in peer-reviewed papers. As I am not working with taxonomic data myself regularly, this format may be usual and accepted. However, there are some errors in the geographic localisations, e.g., sometimes the city is listed before the country or the other way around; the usage of brackets is not consistent and needs careful screening in the revision. Generally, I feel the results are fair, but molecular work needs to be included before the Discussion. Some of the minor errors, I have outlined below.

Discussion: The discussion is partly mixed with the Results and needs delineating. For this purpose, I supplied detailed feedback in the minor comments below. What I miss for the most part is a consideration and discussion of the local oceanography, how water properties change with depth and what this may imply for species occurrences. Of course, I am aware that this can easily lead to a concept outside of the scope of this study, however, the discussion and general importance of this morphological and molecular regional work would greatly benefit from this, which will make the work more relevant for other studies on siphonophore species occurrences elsewhere. More biodiversity and biogeography perspectives, such as simple alpha diversity measurements contrasting the various station assemblages would be useful to… e.g., richness, evenness, diversity. Generally, species names should be abbreviated after the first time mentioned in this section. Currently, this is not yet the case,

Minor comments

Line 12: Change suborder to “Calycophorae”.

Line 13: Change to “Korean waters”.

Line 32: It is also a result of the very low number of morphological experts on siphonophores worldwide. Recently, P. R. Pugh died and besides losing a remarkable human, the jelly world lost one of its biggest siphonophore experts. Including this limiting factor besides fragility and polymorphism would be good before switching to molecular tools.

Line 36: Change to “The order…”.

Lines 39-41: This is clearly a result and brought in much too early in the introduction (if brought in at all). Remove and smoothen the transition to the family discussion below.

Line 61 (and in the abstract): “Jeju” is mentioned but the reader not too familiar with the region will not know where or what Jeju is. Please add information, in brackets or separated by commas, about it.

Line 62: Change to “southern” as done in the abstract.

Line 65: At this point (and also in the abstract) you haven’t written out that mt refers to mitochondrial and what the marker COI. Please add that information.

Line 70: Explain also here where and what “Jeju” is.

Lines 72-74: You lowered the net, not dropped it (did you lose it?) How deep was the ocean floor at these locations? Add information here. It would be interesting for the reader to add one sentence of net volume filtered ranges (in cubic meters).

Line 77: Why did you choose either 5 or 10% formalin? It is not clear to me when you fixed the sample in either of the solutions.

Line 78: You sorted siphonophore specimens, fair, but what happened to the rest of the zooplankton sample? Was it touch for some other analysis? Is it untouched and awaiting further analysis in the collection archive?

Line 90: The digital camera makes digital photos, great, so drop the digital before photo as this information is redundant.

Figure 1: This map should contain also a mention of “Jeju” and please add axes labels such as Longitude and Latitude to the overview part.

Table 1: As all your latitudes were °N and your longitudes °E, I suggest adding that information to the table heading and deleting it from the actual table. Save space this way. The date format needs to be changed to “Day Month Year” and the number of decimals for temperature reduced to one. No need for two decimals here. Salinity has no unit, so delete it. What kind of temperature and salinity data do we look at? Is that surface data, mean data, or do we have errors as they are from multiple collection events? This kind of information belongs in the table caption and is currently entirely missing.

Lines 101+104+116+117+118+120: Korea should be corrected to South Korea here.

Lines 110-111: “Ending with a final 5 min…”. That is redundant. Delete the “final”.

Line 133: “Version” should not be capitalised here and elsewhere in the manuscript. Currently, this is mixed throughout the text and needs to be correct to be consistent.

Line 138: Capitalise “I” and “C” to meet the acronym “AIC”.

Line 148: Before jumping into the morphology and taxonomy, it would be very useful to describe the oceanography of that area based on your CTD casts. This kind of information will be vital for your discussion of environmental envelopes for each species and the known tolerance windows globally.

Figures 2–4 look great and I appreciate the author’s efforts in detail!

Line 187: The two genus names require italic writing.

Line 201: Change to “North Pacific”.

Line 202: Change to “Southwest Atlantic”.

Lines 247-251: Some of the round brackets are off, please correct them. Also, there is no epiplanktonic, the term you want to use is epipelagic.

Line 383: Change to “Bellingshausen Sea”.

Line 440: Closed round bracket after “41” missing.

Line 637: Change to “Korean waters”.

Line 648: There is no such thing as “cold winter temperature”. The temperature is either low or the water is cold.

Line 651: You mentioned it earlier, but it does not become clear to me what is meant by “richer”. Please elaborate.

Lines 654 and before: You only presented surface temperatures, which I believe to have seen in Table 1. What about vertical profiles of temperature and salinity? How do they change with depth and are there regional differences… coast versus open sea? As you did integrative tows, it is not correct to imply that high surface temperatures are representative of the entire water column and the specimens you collected may originate from deeper colder, and saltier layers. Who knows. I would like to see some vertical plots and a discussion about this source of error.

Line 657: What are “actual” Korean waters?

The whole section 4.22 belongs to the Results. Only leave those parts in the Discussion that actually refer to previously published work and how these compare to your results. Also, all tables and figures (including the ones in the supplement) need to be referred to in the Results, not in the Discussion. I could not open Tables S2 and S4. Please check and resubmit those.

Lines 677+688: Leave the hands out. Also, you did not start with “on the one hand”.

Lines 686+709: Change to “intraspecific”.

Line 710: Species names must be written in italics.

Figure 5 caption should be self-explanatory. Thus, an abbreviation such as mtCOI, BI, and ML should be avoided and full-written terms used instead.

Table 2 caption and in the text should not use the vaguely defined term “checklist” but the more biologically correct term “species list”. Please change throughout such as in Line 726. Also, it is not necessary to highlight the “This study” species in grey, which is, BTW, not explained too.

The references vary in style, e.g., Reference 27 has a publication year not yet printed in bold. For the revised version, all these style errors should be corrected to mirror the generally very good thoroughness of this work.

Author Response

Dear Reviewer,

Thank you so much for your kind comments on the manuscript. We have prepared our responses as follows:

Overview

Thank you for your careful review. We will revise the manuscript by referring to the advice.

Major comments

Thank you for your good opinion! We added one line of introduction to Abstract and rearranged some sentences.

Thank you for the good evaluation. We revised it as mentioned below.

Thank you for the good evaluation.

It seems to be a very important point. We restructured the results and discussions as you said. References of synonym part cannot be excluded because it is essential in taxonomic research. The distribution's brackets and order have been reviewed overall.

Thank you very much for pointing out the structural problem. We modified it by referring to your comment. The addition to 'oceanography' would be very good, but the main purpose of this manuscript is to morphological record. We are planning an ecological paper of the entire Korean siphonophore (both in this paper and the previous known siphonophores) in the further study. And your proposal will have to be addressed in that study...! It was an inevitable choice not to abbreviate the species name. This is because the species covered in this paper may be confused because of the same alphabet (for example, Dimophyes and Diphyes should both begin with ~).

Minor comments

Line 12: Change suborder to “Calycophorae”.

We modified it.

Line 13: Change to “Korean waters”.

We modified it.

We agree with you. We added the sentence "In addition, the situation is even worse because there is a lack of morphological experts in siphonophores worldwide."

Line 36: Change to “The order…”.

We modified it.

Lines 39-41: This is clearly a result and brought in much too early in the introduction (if brought in at all). Remove and smoothen the transition to the family discussion below.

Thank you for a good idea. That sentence was moved to Line 60.

We added additional information.

Line 62: Change to “southern” as done in the abstract.

We modified it.

Line 65: At this point (and also in the abstract) you haven’t written out that mt refers to mitochondrial and what the marker COI. Please add that information.

We added an information.

Line 70: Explain also here where and what “Jeju” is.

The information was added to Line 60-61.

The expression 'drop' has been modified to 'towed'. The depth of station is shown in Table 1. And we don't think filtered volume has much to do with this study.

Line 77: Why did you choose either 5 or 10% formalin? It is not clear to me when you fixed the sample in either of the solutions.

We modified it.

Rest of the zooplankton sample is untouched and awaiting further analysis in the collection archive

Line 90: The digital camera makes digital photos, great, so drop the digital before photo as this information is redundant.

We modified it.

Figure 1: This map should contain also a mention of “Jeju” and please add axes labels such as Longitude and Latitude to the overview part.

You have added some labels.

All the suggestions were reflected. Temperature and Salinity are the data of the surface.

Lines 101+104+116+117+118+120: Korea should be corrected to South Korea here.

We modified it.

Lines 110-111: “Ending with a final 5 min…”. That is redundant. Delete the “final”.

We modified it.

Line 133: “Version” should not be capitalised here and elsewhere in the manuscript. Currently, this is mixed throughout the text and needs to be correct to be consistent.

We changed 'version' in manuscripts.

Line 138: Capitalise “I” and “C” to meet the acronym “AIC”.

We modified it.

Thank you for a good idea. However, this manuscript focuses on taxonomic research that describes unrecorded species. The mention of oceanography changes the direction of the paper.

Figures 2–4 look great and I appreciate the author’s efforts in detail!

Thank you for the good evaluation!

Line 187: The two genus names require italic writing.

In this sentence, Ceratocymba and Trigona were not a genus name, but generic group name. Therefore, it was changed to 'Ceratocymba' and 'Trigona' without italics.

Line 201: Change to “North Pacific”.

We modified it.

Line 202: Change to “Southwest Atlantic”.

We modified it.

Lines 247-251: Some of the round brackets are off, please correct them. Also, there is no epiplanktonic, the term you want to use is epipelagic.

We modified it.

Line 383: Change to “Bellingshausen Sea”.

We modified it.

Line 440: Closed round bracket after “41” missing.

We added it.

Line 637: Change to “Korean waters”.

We modified it.

Line 648: There is no such thing as “cold winter temperature”. The temperature is either low or the water is cold.

For clarify, the sentence was changed to 'Bassia bassensis was more abundant in winter than summer'.

Line 651: You mentioned it earlier, but it does not become clear to me what is meant by “richer”. Please elaborate.

It meant high abundance. We changed the sentence to '~were more abundant and larger' (also changed in earlier parts).

Unfortunately, we have not secured a vertical profile. We agree with you about the limitations you said. Therefore, a related discussion was added. 'However, the temperature presented in this research are limited to surface layer, and should be noted as it is different from the depth of water that collected our specimens. Nevertheless, since the temperature of the surface layer is an important indicator of the characteristics of the sea, these relationship needs to be considered.'

Line 657: What are “actual” Korean waters?

We remove 'actual' because it seemed like an ambiguous expression.

As you advised, we separated the result and discussion. Tables S2 and S4 also reconfirmed the status of the files.

Lines 677+688: Leave the hands out. Also, you did not start with “on the one hand”.

We modified it to 'While ~'.

Lines 686+709: Change to “intraspecific”.

We modified it.

Line 710: Species names must be written in italics.

We modified it.

Figure 5 caption should be self-explanatory. Thus, an abbreviation such as mtCOI, BI, and ML should be avoided and full-written terms used instead.

We mentioned full-written terms earlier, so using abbreviation would be good to avoid redundancy.

We modified it.

Reference part has been reviewed and modified as a whole. In this journal, books should not be bold to 'year'.

Reviewer 2 Report

The manuscript is clearly written, and results are also clearly presented, focusing on detailed description of newly found specimens. Obtained results will definably be very useful for future studies of siphonophores in the northwestern pacific.

specific remarks:

Introduction

It would be nice if Authors provide some additional background information’s, mainly how many species of siphonophores are recorded in Korean waters, and maybe one or two sentences about their abundance and significance.

Line 37 I assume there should be semicolon after “…nectophores”.

Materials and Methods

Sample collection

Line 71: how were the sampling locations chosen? Where they part of some other research?

Line 71-73: this sentence should be expanded, because at this point, I’m not sure how the hauls were performed. Were those vertical hauls from bottom to surface? Authors should specify this more clearly.

Line 73: how was the flowmeter installed? In the mouth of the net? Please specify.

Wat was the point of using flowmeter if those data are not used anywhere further in the manuscript? Similarly, temperature and salinity were only measured for surface layer while some hauls reached over 130 meters. Can they be used for indicating water masses? How is the water column stratified?

Table 1. Again, I don’t see much point in showing CTD data without at least some basic interpretation further in the manuscript. Also, the way PSS is used suggests it is a unit, which is not, I would suggest removing it.

Results

I think it would be beneficial for readability of the manuscript if some information’s, like name of the station were shown in table form, also there is no point in writing coordinate if they were already shown in previous table.

Discussion

Line 710: Agalma elegans should be in cursive.

Table 2. Park & Song 2004 should be removed.

In the subsection 4.1 Authors tried to use environmental data to explain differences in size of collected specimens, which doesn’t seem to be very repayable concerning CTD data only covering surface layer, and there is no way to tell at wat depth specimens were actually collected.

It would be also nice if Authors try to provide some insight to why those species weren’t found by previous surveys. Were they just omitted or are they changing their geographical distribution?

References

In some of the entrances year of the publication is not bolded, eq 6 and 8, I would suggest Authors to recheck if the whole literature is cited correctly.

The referee

Author Response

Dear Reviewer,

Thank you very much for your kind comments on the manuscript. We have prepared our responses as follows:

Authors found eight previously unrecorded siphonophores in the waters near Jeju and southern coast of Korea. Manuscript includes very detailed description of those specimens, as well as summarization of their distribution and habitats. Authors also conducted phylogenetic analysis based on mtCOI for each family and additionally confirmed phylogenies and genetic distances in each family based on acquired sequences and GenBank data. Sequences obtained in the study were also deposited in the GenBank database. The manuscript is clearly written, and results are also clearly presented, focusing on detailed description of newly found specimens. Obtained results will definably be very useful for future studies of siphonophores in the northwestern pacific.

Thank you for the good evaluation. We will revise the manuscript by referring to your advice.

specific remarks:

Introduction

Thank you for the good advice. We added additional information about Korean research to this paper. However, we added it to Discussion 4.3 to keep the topic. 'Park & Song described first siphonophores ~ less than 10% of the entire siphonophore.'

Line 37 I assume there should be semicolon after “…nectophores”.

We modified it

Materials and Methods

Sample collection

Line 71: how were the sampling locations chosen? Where they part of some other research?

R/V Dongbaek is a research vessel owned by Chonnam National University, Korea. It has periodically cruised the Jeju and sourthen Coast of Korean waters, and has been determined accordingly. We participated in 2018 and secured samples. The sampling site of R/V Eardo was determined by other research projects (KIOST, PE9998C, In Funding section).

We changed the ambiguous expression: 'We used a plankton net (mesh size: 200 µm, Ø: 60 cm) towed vertically from the bottom to the surface at each station'

Line 73: how was the flowmeter installed? In the mouth of the net? Please specify.

That's all that's in the sentence. Literally, it was installed at the entrance of Net according to the manufacturer's guide.

The use of flowmeter is a device for future ecological analysis, and is a basic task when using Net. We thought it would be better to write down the methods in detail, even if it is not much related to this study. The actual collection took place at various depths, but it is difficult to confirm exactly at what depth our Siphonophore was caught without using MOCNESS. Therefore, the water temperature and salinity data of the surface layer, which is an important and universal data representing the characteristics of the sea, were presented. Discussions on this have also been added.

We mentioned the CTD data in the discussion (Line 653). And removed the 'PSS'.

Results

We agree with you. We removed that redundancy GPS.

Discussion

Line 710: Agalma elegans should be in cursive.

We modified it

Table 2. Park & Song 2004 should be removed.

We modified it

We agree on your advice. Therefore, the discussion was added. 'However, the temperature presented in this research are limited to surface layer, and should be noted as it is different from the depth of water that collected our specimens. Nevertheless, since the temperature of the surface layer is an important indicator of the characteristics of the sea, these relationship needs to be considered.'

It would be also nice if Authors try to provide some insight to why those species weren’t found by previous surveys. Were they just omitted or are they changing their geographical distribution?

It seems to be a very important point. We added an insight related to it at discussion 4.3. ‘The reason for this is not just a small number of siphonophores ~ it might be that they have been continuously introduced in Korean waters from the past through ~ difficulty of taxonomical research and the lack of experts, many of them may have been omitted.’

References

In some of the entrances year of the publication is not bolded, eq 6 and 8, I would suggest Authors to recheck if the whole literature is cited correctly.

We revised the references overall. In this journal, books should not be bold to 'year'.

Reviewer 3 Report

The manuscript on "Eight new records of siphonophores (Cnidaria: Hydrozoa) in Korean waters" has well written with taxonomical features and molecular analysis. I have given some comments for the authors to follow.

Abstract line 12: (Calycophore and Physonecatae) - typo

Intro: line 27-29 : since no citation is given, cite some references in addition to the given link citation https://doi.org/10.3390/d13090420

Descriptions look like remarks, not in a taxonomic (telegraphic style) way of writing, Is this the format?

Since this is the new record in Korean waters, I suggest for providing arrow key in the figures to mark : hydroecial wing; pedicular canal and apex of nectosac; ostium; etc. for all figures. It will be beneficial for future researchers.

Lines 561, 562: remove italics for authority name and year. Check throughout the MS.

Molecular work is interesting and phylogenetic analysis based on mtCOI was conducted for each family. It will be helpful for the readers.

Author Response

Dear Reviewer,

Thank you so much for your kind comments on the manuscript. We have prepared our responses as follows:

Thank you for the review and advice! We will revise the manuscript by referring to your comments.

Abstract line 12: (Calycophore and Physonecatae) – typo

We modified it to ‘Calycophorae and Physonecatae’.

Intro: line 27-29 : since no citation is given, cite some references in addition to the given link citation https://doi.org/10.3390/d13090420

We added some references.

Descriptions look like remarks, not in a taxonomic (telegraphic style) way of writing, Is this the format?

It is different by authors choose different description methods. And we know that there is no problem if there is consistency. There are characteristics that can't be explained by the telegraphic style. So we use this format.

Thank you for your good opinion! We added arrows to Figure 2-4!

Lines 561, 562: remove italics for authority name and year. Check throughout the MS.

Line 561 has been modified. In the case of Line 562, it according to the subtitle form (Italic) required by the journal.

Molecular work is interesting and phylogenetic analysis based on mtCOI was conducted for each family. It will be helpful for the readers.

Thank you for the good evaluation!

Round 2

Reviewer 1 Report

The response to the review seems appropriate and I justt want to make a few suggestions before the manuscript is in shape to be accepted:

1) Still, I cannot open Tables S2 and S4. Please check once again.

2) Please add a sentence in the acknowledgements thanking the referee(s) for their contribution to improve the manuscript. This is an important part of the peer-review system.

3) Your suggested sentence "In addition, the situation is even worse because there is a lack of morphological experts in siphonophores worldwide" sounds off. Please change "experts in siphonophores worldwide" to "experts of this taxonomic group".

4) As your oceanographic sampling and representation in this manuscript are superficial and inadequate for any more meaningful analysis, I would recommend adding one sentence in the Discussion (at an appropriate place) saying that in future studies, oceanogrphic settings and siphonophore assemblage composition and abundance need to be investigated, but this was beyond the scope of the present study. Something like that.

Author Response

The response to the review seems appropriate and I justt want to make a few suggestions before the manuscript is in shape to be accepted:

Your advice was beneficial to our manuscript. Thank you.

1) Still, I cannot open Tables S2 and S4. Please check once again.

That's very strange. We open the files with no problems. We created a new file just in case.

2) Please add a sentence in the acknowledgements thanking the referee(s) for their contribution to improve the manuscript. This is an important part of the peer-review system.

Thank you for the good point! We added that sentence to the Acknowledgements session.

We modified it.

We added the sentences. ‘In addition, although not covered in this study, oceanographic settings and siphonophore assemblage composition and abundance need to be investigated in further studies. These approaches will lead to a broad understanding of Siphonophores.’

Reviewer 3 Report

The authors have done well in improvising the manuscript. Some grammar mistakes are found in the abstract and other areas and the reference format needs to be checked before the acceptance.

Author Response

The authors have done well in improvising the manuscript. Some grammar mistakes are found in the abstract and other areas and the reference format needs to be checked before the acceptance.

Your advice was beneficial to our manuscript. Thank you! We have reviewed grammar as a whole.