Effects of Water Temperature on the Growth, Antioxidant Capacity, and Gut Microbiota of Percocypris pingi Juveniles

Round 1

Reviewer 1 Report

Line 18: The authors report “Results showed that the body weights (from 20-60 d)”. What does "d" mean? Are you referring to days? Since it's placed after "weights", I think it's confusing. Please rephrase the sentence.

 

Lines 47-49: what is the thermal range of the natural environment in which this species lives?

 

Lines 55-56: why is 13 °C considered the "control level"?

 

Lines 94-95: Is the abbreviation of "day" used in the work "D" or "d"?

 

Table 1: does the significance indicated by the "different shoulder letters" refer to the values reported on a single (horizontal) row or within columns? Please specify in the caption.

 

Line 139: How was the weight gain rates calculated? Please specify in the text.

 

Figure 1: “The difference in the lower-case letters above the boxes indicates that there was a significant difference between the two groups”. It is not clear to me the representation of significance in the figure. For example in panel A, SOD, Sample time: 60 d, what does "ab" mean? It means that the “14C” datum is statistically significant both with respect to the “22C” datum indicated with “a” and the “26C” datum indicated with “b”? Or that "ab" is different from "a" and "b"?. Maybe “ab” should be referred to as "a,b"? Please specify better in the caption.

 

Line 179 and Supplementary Materials: the quality of the figures is very poor and difficult to read. Please improve the quality by making it equal to the figures in the manuscript.

 

Line 180: “1763.83” should be “1,763.83”

 

Line 211. Please check “microboita”

 

Line 252-253. The meaning of "although the optimum temperature was 8 — 27 °C [5]" is not very clear to me. Why "although"? The authors want to say that “do their results show that, within the interval 8-27 °C identified as optimum, the greatest weight gain range is observed at temperatures 18 °C and 22 °C? Although the data "optimum growth temperature was between 8 and 27 °C" is reported in the work [5], I personally believe it is a very wide range to be defined as optimum.

 

I believe that the work lacks information that would allow us to evaluate the meaning and correctness of the temperatures tested by the authors. The authors test the effect of temperatures of 14, 18, 22 and 26 °C declaring that optimum growth temperature of the studied species was between 8 and 27 °C. Why then do they limit the study to the four temperatures of 14, 18, 22 and 26 °C and not test even the lowest temperatures such as 8 °C or 10 °C?

 

Furthermore, the authors report that Percocypris pingi is an endemic species in upstream regions of the Yangtze River; what are the thermal ranges recorded during the year in these regions? What temperatures is fish exposed to during the year? What is the rationale behind the choice to test the thermal variation for periods of 20, 40, 60 days? Does it perhaps derive from the fact that in the natural environment fish can be exposed to those temperatures for that length of time?

 

Furthermore, the authors report that “Artificial reproduction and breeding are crucial to meet consumer demand and prevent the ongoing depletion of natural P. pingi resources”. At what temperature are these fish raised in breeding centres? Do the temperatures tested have any relation to those used on farms?

 

I believe the authors need to better justify the rationale behind the choice of thermal conditions tested.

 

I think the discussion can be expanded and integrated also in consideration of the above comments.

Author Response

Comments

Line 18: The authors report “Results showed that the body weights (from 20-60 d)”. What does "d" mean? Are you referring to days? Since it's placed after "weights", I think it's confusing. Please rephrase the sentence.

Response

The “d” refers to days. We have revised the sentence. Thank you very much for your comments.

 

Comment

Lines 47-49: what is the thermal range of the natural environment in which this species lives?

Response

The tolerance range of larval P. pingi retrodorslis to temperature is 0 - 32°C.

 

Comment

Lines 55-56: why is 13 °C considered the "control level"?

Response

We don’t know why Ghosh et al. considered 13 °C as the "control level". We speculate that the temperature may be the optimal temperature for chum salmon.

 

Comment

Lines 94-95: Is the abbreviation of "day" used in the work "D" or "d"?

Response

“d” is the unit of day, while D0, D20, D40, and D60 are part of the sample name to indicate sampling time.

 

Comment

Table 1: does the significance indicated by the "different shoulder letters" refer to the values reported on a single (horizontal) row or within columns? Please specify in the caption.

Response

Thank you for your comment. Significant differences in means between different culture temperature groups are indicated by different shoulder letters in the same row (p < 0.05). We have revised the caption according to your comment.

 

Comment

Line 139: How was the weight gain rates calculated? Please specify in the text.

Response

Thank you for your comment. All fish were individually weighted at 0, 20, 40, and 60 d after the start of experiment to calculate the weight gain rate and SGR. We have added the description of the calculated methods of weight gain rate and SRG into the Materials and Methods section of our revised manuscript.

 

Comments

Figure 1: “The difference in the lower-case letters above the boxes indicates that there was a significant difference between the two groups”. It is not clear to me the representation of significance in the figure. For example in panel A, SOD, Sample time: 60 d, what does "ab" mean? It means that the “14C” datum is statistically significant both with respect to the “22C” datum indicated with “a” and the “26C” datum indicated with “b”? Or that "ab" is different from "a" and "b"?. Maybe “ab” should be referred to as "a,b"? Please specify better in the caption.

Response

Thank you very much for your comments. The showing method is very commonly used to indicate whether there are significant differences between groups of data (e.g. Liu et al., 2021. Protein Cell, 12(5): 315-330.; Zhang et al., 2019. Nature Biotechnology, 37: 676-684). "ab" means that there is no significant difference between the groups marked with “a” and “b”. Although it is easier understanding and more reasonable to use “a,b”, it is customary to use “ab” instead of “a,b”. As this method is widely used, we do not think it is necessary to make special instructions.

 

Comment

Line 179 and Supplementary Materials: the quality of the figures is very poor and difficult to read. Please improve the quality by making it equal to the figures in the manuscript.

Response

Thank you for your comment. We have improved the quality of the figures according to your comment.

 

Comment

Line 180: “1763.83” should be “1,763.83”

Response

Thank you for your comment. We have revised the number according to your comment.

 

Comment

Line 211. Please check “microboita”

Response

It should be “microbiota”. We have revised the word. Thank you.

 

Comment

Line 252-253. The meaning of "although the optimum temperature was 8 — 27 °C [5]" is not very clear to me. Why "although"? The authors want to say that “do their results show that, within the interval 8-27 °C identified as optimum, the greatest weight gain range is observed at temperatures 18 °C and 22 °C? Although the data "optimum growth temperature was between 8 and 27 °C" is reported in the work [5], I personally believe it is a very wide range to be defined as optimum.

Response

Thank you for your comment. Although the optimum temperature of P. pingi was reported range from 8 to 27°C, our results showed that the growth rates of P. pingi at 18 and 22°C were significantly higher than those at 14 and 26°C. These results implied that the temperatures range from 8 to 14°C and range from 26 to 27°C probably were not the optimum temperature of P. pingi.

 

Comment

I believe that the work lacks information that would allow us to evaluate the meaning and correctness of the temperatures tested by the authors. The authors test the effect of temperatures of 14, 18, 22 and 26 °C declaring that optimum growth temperature of the studied species was between 8 and 27 °C. Why then do they limit the study to the four temperatures of 14, 18, 22 and 26 °C and not test even the lowest temperatures such as 8 °C or 10 °C?

Response

Thank you for your comments. The Percocypris pingi retrodorslis in reference [5] should be Percocypris retrodorslis, and it is considered as another species different from P. pingi in our manuscript. We have added another reference that reports the tolerance range of adult P. pingi to teimperature is 2 - 28°C, and the optimal growth temperature is 20 - 25°C.

 

Comment

Furthermore, the authors report that Percocypris pingi is an endemic species in upstream regions of the Yangtze River; what are the thermal ranges recorded during the year in these regions? What temperatures is fish exposed to during the year? What is the rationale behind the choice to test the thermal variation for periods of 20, 40, 60 days? Does it perhaps derive from the fact that in the natural environment fish can be exposed to those temperatures for that length of time?

Response

According to the existing data, the water temperature range of the upstream of the Yangtze River is between 6-25°C. In the wild, Percocypris pingi can live in 2-28°C, and they can be exposed to the temperatures for 60 days or even longer. In this study, we set 20, 40, 60 days as a cycle to observe the growth of P. pingi at different water temperatures to find the optimal growth temperature.

 

Comment

Furthermore, the authors report that “Artificial reproduction and breeding are crucial to meet consumer demand and prevent the ongoing depletion of natural P. pingi resources”. At what temperature are these fish raised in breeding centres? Do the temperatures tested have any relation to those used on farms?

Response

Currently, the culture method of P. pingi is mainly to use natural mountain spring water for culture, and the culture temperature in the culture is generally 13 - 22 °C. The temperature settings in our study referred to the current breeding temperature and its outdoor living temperature.

 

Comment

I believe the authors need to better justify the rationale behind the choice of thermal conditions tested.

Response

Thank you for your comment. Currently, the culture method of P. pingi is mainly to use natural mountain spring water for culture, and the culture temperature in the culture is generally 13 - 22 °C. The temperature settings in our study referred to the current breeding temperature and its outdoor living temperature.

 

Comment

I think the discussion can be expanded and integrated also in consideration of the above comments.

Response

Thank you very much for your above comments. We have revised our manuscript according to your comments and added some discussions in our revised manuscript.

Reviewer 2 Report

The manuscript with ID (fishes-2042698) by Wu and coauthors has evaluated the effects of water temperature on the growth, antioxidant capacity and gut microbiota of P. pingi juveniles. The manuscript is interesting; however, several major revisions are present in the manuscript. Authors have to prepare a point-by-point response to the points raised by the anonymous reviewer.

1. I made several track changes and highlights present in the PDF file. Authors have to revise them very carefully.

2. I suggest changing the title to be

“Effects of Water Temperature on the Growth, Antioxidant Capacity and Gut Microbiota of Percocypris pingi Juveniles”

3. Line 24: “temperature had a cumulative impact on the proliferation of” – I cannot understand these words

4. You should include "Water temperature" in the keywords

5. Line 26: A concise brief conclusion should be included at the end of the abstract

6. Line 35: Authors have to include an appropriate suitable reference here in this position

7. Line 89: add appropriate reference

8. Line 94: add number of fish samples

9. Line 95: Authors have to add the calculations used to assess growth rates such as final weight, weight gain, weight gain %, FCR and SGR

10. Table 1: Authors should add the results of final weight, FCR, and SGR. Survival rate % should be also included

11. Line 179: (Fig. S1 and S2) should be presented in the text and not included as supplementary files.

12. Line 204: (Fig. S3 and S4) should be presented in the text and not included as supplementary files.

13. Line 240: Authors did not discuss their results of antioxidant and biochemical parameters. This is a weaking point in the manuscript.

14. Line 276: I do not agree with the lines present in Conclusion section. Authors have to add new points on how the results of their study benefit the researchers and aquaculturists who work in the field of aquaculture.

Comments for author File: Comments.pdf

Author Response

Comments

The manuscript with ID (fishes-2042698) by Wu and coauthors has evaluated the effects of water temperature on the growth, antioxidant capacity and gut microbiota of P. pingi juveniles. The manuscript is interesting; however, several major revisions are present in the manuscript. Authors have to prepare a point-by-point response to the points raised by the anonymous reviewer.

Responses

Thank you very much for your comments. We are very grateful to you for providing such detailed and useful comments, which are of great value for us to revise and improve our manuscript. We have revised our manuscript according to your comments in most cases, and responded the comments as follows.

 

Comment

1. I made several track changes and highlights present in the PDF file. Authors have to revise them very carefully.

Responses

Thank you very much for your comments. We have revised our manuscript according to your comments in most cases. However, according to the self-explanatory principle, we did not modify the Latin-scientific name that first appeared in the figure legends. Meanwhile, according to the specification of academic papers, we did not modify the Latin scientific name of E. coli when it first appeared in the text of our manuscript. The culture water parameters were not adjusted. They were the results of actual measurements. Therefore, we have moved these results to the Results section of our revised manuscript.

 

Comment

2. I suggest changing the title to be

“Effects of Water Temperature on the Growth, Antioxidant Capacity and Gut Microbiota of Percocypris pingi Juveniles”

Response

Thank you very much for your comments. We have changed the title according to your comment.

 

Comment

3. Line 24: “temperature had a cumulative impact on the proliferation of” – I cannot understand these words

Response

It should be “temperature significantly impact on the growth of P. pingi”. We have revised the sentence. Thank you for your comment.

 

Comment

4. You should include "Water temperature" in the keywords

Response

Thank you for your comment. We have added “Water temperature” as keywords.

 

Comment

5. Line 26: A concise brief conclusion should be included at the end of the abstract

Response

Thank you for your comment. We have revised the abstract according to your comment.

 

Comment

6. Line 35: Authors have to include an appropriate suitable reference here in this position

Response

Thank you for your comment. We have added the reference according to your comment.

 

Comment

7. Line 89: add appropriate reference

Response

Thank you for your comment. We have added the reference according to your comment.

 

Comment

8. Line 94: add number of fish samples

Response

Thank you for your comment. Three samples were collected at each sampling time. We have added the number according to your comment.

 

Comment

9. Line 95: Authors have to add the calculations used to assess growth rates such as final weight, weight gain, weight gain %, FCR and SGR

Response

Thank you for your comment. All fish were individually weighted at 0, 20, 40, and 60 d after the start of experiment to calculate the weight gain rate and SGR. However, excessive satiety feeding was adopted in this experiment, and the surplus feed was discharged into the treatment system of the recirculating aquaculture system. The FCR was not accurately calculated. Therefore, we did not use the indicator. We have added the description of the calculated methods of weight gain rate and SRG into the Materials and Methods section of our revised manuscript.

 

Comment

10. Table 1: Authors should add the results of final weight, FCR, and SGR. Survival rate % should be also included

Response

The final weights were showed in the Table 1. We have added the specific growth rates into the table. No fish died abnormally during the experiment. Therefore, we don’t add the survival rate in the table, while we added the result in the Result section of our revised manuscript. As mentioned above, excessive satiety feeding was adopted in this experiment, and the surplus feed was discharged into the treatment system of the recirculating aquaculture system. The FCR was not accurately calculated. Therefore, we don’t add the FCRs into the table.

 

Comment

11. Line 179: (Fig. S1 and S2) should be presented in the text and not included as supplementary files.

Response

Thank you for your comment. We have removed the Figure S1 and S2 to the text from the supplementary files according to your comment.

 

Comment

12. Line 204: (Fig. S3 and S4) should be presented in the text and not included as supplementary files.

Response

Thank you for your comment. We have removed the Figure S3 and S4 to the text from the supplementary files according to your comment.

 

Comment

13. Line 240: Authors did not discuss their results of antioxidant and biochemical parameters. This is a weaking point in the manuscript.

Response

Thank you for your comment. We have added the discussion of the results of antioxidant and biochemical parameters.

 

Comment

14. Line 276: I do not agree with the lines present in Conclusion section. Authors have to add new points on how the results of their study benefit the researchers and aquaculturists who work in the field of aquaculture.

Response

Thank you for your comment. We have revised the Conclusion section according to your comment.

Round 2

Reviewer 1 Report

The manuscript was implemented following the comments of the reviewers and I believe it may be suitable for publication.

Reviewer 2 Report

Authors have properly addressed my comments in the modified version of the manuscript.