Spatiotemporal Distribution Pattern of Phytoplankton Community and Its Main Driving Factors in Dongting Lake, China—A Seasonal Study from 2017 to 2019

Round 1

Reviewer 1 Report

I went through the manuscript and found it could be published in Water after a full revision based on the comments given below:

Lines 17-20: I couldn’t understand this statement. Please revise.

Line 22: Please give full name for DO.

Line 22: The five-day biochemical oxygen demand. Please revise.

Line 23: Ammonia or ammonium? Please revise.

Line 30: CODmn and CODcr? They seem to be same.

Lines 32-35: I couldn’t understand this statement. Please revise.

Keywords: Can you please select better words than “positive” and “negative”?

Lines 41 and 42: “used indicators” of what?

Lines 48-60: What do you think about the impact of residence time of water on the eutrophication? Water residence time is one of the most drivers of eutrophication in lakes/reservoirs (see “Complex dynamics of water quality mixing in a warm mono-mictic reservoir” and “Hyper-nutrient enrichment status in the Sabalan Lake, Iran”). I would like to see a brief description about this main driver of eutrophication as well (at least a short statement supported with the introduced papers).

Line 66: I suggest to use “fed” instead of “injected”.

Section 2.1: Can you please give more information about the lake? Thermal regime? Trophic state? Maximum and average depths?

Section 2.2: No information given about QA/QC (quality control/assurance).

Line 137: More description is needed on linear regression and curve estimation used.

Figure 2: What is the unit used in vertical axis?

Figure 4: No title given for the vertical axis.

Discussion: Nice. But, this section needs a better support with the relevant published papers such as “Caspian Sea is eutrophying: The alarming message of satellite data”.

Conclusion: Please revise the last statement. I couldn’t understand it.

Author Response

Thanks very much for your valuable comments. The modifications response to your comments have been refined respectively as below.

1. Lines 17-20: I couldn’t understand this statement. Please revise.

   Response: We have revised the statement by revised model in the revised manuscript.

2. Line 22: Please give full name for DO.

Response: We have given “dissolved oxygen” as the full name for DO by revised model in the revised manuscript.

3. Line 22: The five-day biochemical oxygen demand. Please revise.

Response: Thanks very much for the Reviewer’s valuable comments. We have used “the five-day biochemical oxygen demand” rather than “biochemical oxygen demand” by revised model in the revised manuscript.

4. Line 23: Ammonia or ammonium? Please revise.

Response: We used ammonia nitrogen as the chemical factor in this paper.

5. Line 30: COD_Mn and COD_Cr? They seem to be same.

Response: The determination of chemical oxygen demand (COD) includes manganese method (COD_Mn) and chromium method(COD_Cr). COD_Mn is mainly used to measure low concentration of COD (< 5mg / L). However, high concentration of COD is mostly measured by COD_Cr. We used the two chemical factors as the independent indicators, inorder to give a more comprehensive analysis of the correlation between water quality factors and phytoplankton communities.

6. Lines 32-35: I couldn’t understand this statement. Please revise.

Response: Thanks very much for the Reviewer’s valuable comments. We have revised the statement by revised model in lines 38-41 of the revised manuscript.

7. Keywords: Can you please select better words than “positive” and “negative”?

Response: We have replaced “positive” and “negative” with “biodiversity” and “driving factors” respectively by revised model in the revised manuscript.

8. Lines 41 and 42: “used indicators” of what?

Response: We have replaced “used indicators” with “used indicators of water environment quality” by revised model in the revised manuscript.

9. Lines 48-60: What do you think about the impact of residence time of water on the eutrophication? Water residence time is one of the most drivers of eutrophication in lakes/reservoirs (see “Complex dynamics of water quality mixing in a warm mono-mictic reservoir” and “Hyper-nutrient enrichment status in the Sabalan Lake, Iran”). I would like to see a brief description about this main driver of eutrophication as well (at least a short statement supported with the introduced papers).

Response: Thanks very much for the Reviewer’s valuable comments. In our opinion, water residence time can act as the primary contributor of eutrophication in the lake and reservoir. So we have added a short statement about the influence of water residence time on eutrophication of lake or reservoir and “Complex dynamics of water quality mixing in a warm mono-mictic reservoir”, “Hyper-nutrient enrichment status in the Sabalan Lake, Iran” as two references [24,25] by revised model in the lines 67-70 of the revised manuscript.

10. Line 66: I suggest to use “fed” instead of “injected”.

Response: Thanks very much for the Reviewer’s valuable comments. We have use “fed” instead of “injected” in Line 80 by revised model in the revised manuscript.

11. Section 2.1: Can you please give more information about the lake? Thermal regime? Trophic state? Maximum and average depths?

    Response: Thanks very much for the Reviewer’s valuable comments. We have added an independent introduction for Dongting Lake in Lines 102-112 by revised model in the revised manuscript, just like the elevation, water level, water depth, temperature, trophic state, and so on.

12. Section 2.2: No information given about QA/QC (quality control/assurance).

    Response: Thanks very much for the Reviewer’s valuable comments. We added the information for QA/QC (quality control/assurance) in lines 137-139 and lines 162-163 by revised model in the revised manuscript.

13. Line 137: More description is needed on linear regression and curve estimation used.

Response: Thanks very much for the Reviewer’s valuable comments. We added the description for linear regression and curve estimation in lines 177-180 by revised model in the revised manuscript.

14. Figure 2: What is the unit used in vertical axis?

Response: We used (cells·L^-1) as the unit of phytoplankton density in the Figure 2.

15. Figure 4: No title given for the vertical axis.

Response: Thanks very much for the Reviewer’s valuable comments. We have added “Value of dominance” as the title of the vertical axis for Figure 4.

16. Discussion: Nice. But, this section needs a better support with the relevant published papers such as “Caspian Sea is eutrophying: The alarming message of satellite data”.

    Response: Thanks very much for the Reviewer’s valuable comments. We have added “Caspian Sea is eutrophying: The alarming message of satellite data” as reference [47] and “A comparison of factors influencing the summer phytoplankton biomass in China’s three largest freshwater lakes: Po-yang, Dongting, and Taihu”, “Phytoplankton dynamics and cyanobacterial dominance in Murchison Bay of Lake Victoria (Uganda) in relation to envi-ronmental conditions”, “Succession of phytoplankton functional groups and their driving factors in a subtropical plateau lake” as references [70-72].

17. Conclusion: Please revise the last statement. I couldn’t understand it.

    Response: Thanks very much for the Reviewer’s valuable comments. We have revised the statement in lines 429-433 by revised model in the revised manuscript.

Reviewer 2 Report

The manuscript entitled "Spatiotemporal distribution pattern of phytoplankton community and their main driving factors in Dongting Lake, China – A seasonal study from year 2017 to 2019" refers to interesting aspects concerning the changes of water quality, evolution rules and dominant phytoplankton groups, and major affecting factors taking into account the recent three years. However, the major revision should be done, especially to clarify the methodological aspect, precise species indications, and lack of Supplementary data, i.e. “Data supported this article were named Table S1, S2; Fig. 1 to 10”. They were not included for reviewing.

Detailed main comments

1. The Latin names of phyla should be revised according to Algaebase (www.alagebase.org) to be currently accepted taxonomically.

For example in lines 26-28: “Cyanophyta, Chlorophyta, Bacillariophyta, Cryptophyta and Dinophyta, and Synedra sp. and Melosira sp. were the dominant population in all seasons.”

Currently accepted taxonomically names of Cyanophyta is Cyanobacteria, instead of Dinophyta should be Miozoa. The same comment in the lines: 157, 232-233, 247.

Concerning Synedra sp. and Melosira sp. the full names of species should be given due to the dominant species.

The same comments concern all taxonomic names in lines: 158-160, 235-237, in Figure 4.

2. Please clarify the methodological aspect of microscopic analyses “Shaked the concentrated plankton sample fully and evenly, took 0.1L and put it in the plankton counting box for identification and counting, and then × 300 cells were counted under a 40x microscope and identified to the lowest taxonomic level (genus or species), taxonomic identification was performed according to [37].”

Please revise the sentence and indicate if used magnification was 40x or 400x. Were there the magnification: 40x on the lens and 10x on eyepiece?

3. It is strongly recommended to improve English grammar and style throughout the whole text.

For example: lines 141-142: “The results of this study found 67 genera of phytoplankton belonging to 6 phyla in Dongting Lake (Table S1)”.

4. In Figure 3 –please indicate the names of all taxonomic groups in the legend of figure.

Please give the explanation of codes used in Figure 5.

5. Please explain the sentence in lines: 195-196: “The dotted line indicated the correlation coefficient between 1 and 4 (p<0.05); the dashed line indicated the correlation coefficient between 4 and 7 (p<0.05) ; the solid line indicated the correlation coefficient above 7 (p < 0.01)”.
6.  Please add the lacking Supplementary material.

Author Response

Thanks very much for your valuable comments. The modifications response to your comments have been refined respectively as below.

1. The Latin names of phyla should be revised according to Algaebase (www.alagebase.org) to be currently accepted taxonomically.

   Response: Thanks very much for the Reviewer’s valuable comments. We have revised the Latin names of phyla according to Algaebase (www.alagebase.org) by revised model in the revised manuscript and Supplementary data (Table S1).

（1）For example in lines 26-28: “Cyanophyta, Chlorophyta, Bacillariophyta, Cryptophyta and Dinophyta, and Synedra sp. and Melosira sp. were the dominant population in all seasons.” Currently accepted taxonomically names of Cyanophyta is Cyanobacteria, instead of Dinophyta should be Miozoa. The same comment in the lines: 157, 232-233, 247. Concerning Synedra sp. and Melosira sp. the full names of species should be given due to the dominant species. The same comments concern all taxonomic names in lines: 158-160, 235-237, in Figure 4.

Response: We have used Cyanobacteria, Euglenozoa, Miozoa as the currently accepted taxonomically names instead of Cyanophyta, Euglenophyta, Dinophyta, respectively in line 205 by revised model in the revised manuscript. We have given Synedra acus Kützing, Melosira granulata (Ehrenberg) Ralfs, Oscillatoria acuminata Gomont, Anabaena azotica Ley, Pseudanabaena catenata Lauterborn as the full name for Synedra sp., Melosira sp., Oscillatoria sp., Anabeana sp., Pseudanabaena sp. respectively in lines 205-210 by revised model in the revised manuscript. And the same comment had been revised in lines 295-304 and Figure 4 by revised model in the revised manuscript.

2. Please clarify the methodological aspect of microscopic analyses “Shaked the concentrated plankton sample fully and evenly, took 0.1L and put it in the plankton counting box for identification and counting, and then × 300 cells were counted under a 40x microscope and identified to the lowest taxonomic level (genus or species), taxonomic identification was performed according to [37].”

Please revise the sentence and indicate if used magnification was 40x or 400x. Were there the magnification: 40x on the lens and 10x on eyepiece?

Response: Thanks very much for the Reviewer’s valuable comments. We have used “The concentrated plankton sample was shaken evenly, 0.1 L sample was placed in the plankton counting box for identification and counting, and then × 300 cells were counted using a microscope under the magnification of 400× (40× on the lens and 10× on eyepiece) and identified to the lowest taxonomic level (genus or species). Taxonomic identification was performed according to a previously described method [39] and AlgaeBase (www.alagebase.org). Meanwhile, the experts were invited to verify identification results” instead of “Shaked the concentrated plankton sample fully and evenly, took 0.1L and put it in the plankton counting box for identification and counting, and then × 300 cells were counted under a 40x microscope and identified to the lowest taxonomic level (genus or species), taxonomic identification was performed according to [37].” by revised model in the revised manuscript.

3. It is strongly recommended to improve English grammar and style throughout the whole text. For example: lines 141-142: “The results of this study found 67 genera of phytoplankton belonging to 6 phyla in Dongting Lake (Table S1)”.

Response: Thanks very much for the Reviewer’s valuable comments. We have invited native English speaking experts to improve English grammar and style throughout the whole text. The modifications had been done by revised model in the revised manuscript.

4. In Figure 3 –please indicate the names of all taxonomic groups in the legend of figure.

Response: Thanks very much for the Reviewer’s valuable comments. We have carried out the modifications of Figure 3 by revised model in the revised manuscript.

5. Please give the explanation of codes used in Figure 5. Please explain the sentence in lines: 195-196: “The dotted line indicated the correlation coefficient between 1 and 4 (p<0.05); the dashed line indicated the correlation coefficient between 4 and 7 (p<0.05); the solid line indicated the correlation coefficient above 7 (p < 0.01)”.

Response: Thanks very much for the Reviewer’s valuable comments. We have used ” The correlation between the physicochemical indicators and the phytoplankton indicators. Density, species, Shannon Wiener index, Margalef index and Pieloud index were abbreviated as Dens., Spe, Sha., Mar. and Pie., respectively. The blue line indicates a significant negative correlation, and the red line indicates a significant positive correlation. The dotted line “- - - - -” indicates the correlation coefficient (1<R<4) and significance (p<0.05); the dashed line ”– –– –” indicates  the correlation coefficient (4<R<7)  and significance (p<0.05) ; and the solid line “——” indicates  the correlation coefficient (R>7) and significance (p < 0.01)” as the explanation of codes used in Figure 5. The modifications had been done by revised model in lines 249-255 of the revised manuscript.

6. Please add the lacking Supplementary material.

Response: Thanks very much for the Reviewer’s valuable comments. We have added the Supplementary material as attachment for supporting the manuscript.

 

Round 2

Reviewer 1 Report

My suggestion is acceptance. Congratulations to the authors.

Author Response

Thanks very much for your valuable comments. We hope to get your guidance and help again in future research.

Reviewer 2 Report

The most of corrections were made, but still the manuscript was not corrected strictly according to pevious comments about taxonomically accepted names of species. 

The taxonomical names should be still corrected according to Algaebase (www.algaebase.org), especially Synedra acus Kützing and Melosira granulata (Ehrenberg) Ralfs and others are not currently accepted taxonomically. 

Author Response

Thanks very much for your valuable comments. We have corrected the names of species according to Algaebase (www.algaebase.org). of In the newly revised manuscript, Cyanophyta has been corrected to Cyanobacteria in line 31, Synedra acus Kützing and Melosira granulata (Ehrenberg) Ralfs have been corrected to Fragilaria radians (Kützing) D.M.Williams & Round and Aulacoseira granulata (Ehrenberg) Simonsen in line 32-33, line 205-208, line 298-299, Figure 4 and Supplement data; Oscillatoria acuminata Gomont has been corrected to Oxynema acuminatum (Gomont) Chatchawan, Komárek, Strunecky, Smarda & Peerapornpisal in line 209-210, line 304-305, Figure 4 and Supplement data; Cryptomonas acuta Butcher has been corrected to Teleaulax acuta (Butcher) D.R.A.Hill in line 303, Figure 4 and Supplement data; Scenedesmus naegelii Breb has been corrected to Scenedesmus naegelii Brébisson in Figure 4 and Supplement data. All the related modifications have been done and highlighted in yellow in the newly revised manuscript. Moreover, the other corrections have been done as revised model in the Supplement data. 

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.