Biomanipulation of Periphytic Algae in the Middle Route of South–North Water Diversion Project Canal: An In Situ Study in the Lushan Section

Round 1

Reviewer 1 Report (Previous Reviewer 3)

 

The manuscript discusses the Middle Route of South-to-North Water Diversion Project (MSNWDP), which is the world's largest inter-basin water diversion project. The project faces a unique problem of algal pollutants that threaten water quality due to the natural growth and shedding of periphytic algae. While mechanical means can remove algal pollutants, introducing algae-eating fish and improving the rate at which fish utilize the system's primary productivity is the best way to address the issue. The paper focuses on carrying out an in-situ biomanipulation experiment of different fish groups to identify fishes that adapt well to the water environment of the main canal and have a good feeding effect on the algae. The study provides a reference and scientific basis for similar work in the MSNWDP and other large-scale water conservancy projects.

 

The manuscript substantially improved comparing with the previous version specially, the statistical analysis and including marking systems to monitor the growth of different fish.

However, the manuscript still has several corrections must be considered before acceptance.

In line 92 it is mentioned that the experiment lasted two months “The in-situ experiment was originally planned to last for two months from December 15, 2019.” However in the results section it is indicated that the experiment started at 15 Dec to 30 April. Could you revised which is correct.

The Latin names must be italicized along the manuscript.

Table 2 is missing the tubular format, could you revise it to be readable.

Figure 3, the letters of significancy must be written above the box to be clearer for the readers.

 

 Also, the manuscript need extensive impoving  in to increase the readability of the MS.

Author Response

1. In line 92 it is mentioned that the experiment lasted two months “The in-situ experiment was originally planned to last for two months from December 15, 2019.” However, in the results section it is indicated that the experiment started at 15 Dec to 30 April. Could you revised which is correct.

Reply: We have revised these contents, please see line 93, and line 150-151.

 

2. The Latin names must be italicized along the manuscript.

Reply: We have revised these contents, please see the new manuscript.

 

3. Table 2 is missing the tubular format, could you revise it to be readable.

Reply: The format of the table may have changed after uploading to the manuscript system, please see the table below.

Table 2 The changes in periphytic algae density at the bottom of the cage for each fish group

Date	Group 1	Group 2	Group 3	Group 4	Control group
	104 cells·cm-2
2019-12-15	534.24±12.43	486.62±31.29	677.41±26.70	713.08±22.10	561.12±30.69
2019-12-27	231.71±30.75	237.17±15.97	288.18±43.61	255.28±22.62	572.41±25.49
2020-1-4	222.15±11.00	224.93±12.84	253.29±19.92	261.85±27.23	543.68±20.57
2020-1-15	227.03±8.57	213.45±30.27	262.18±11.27	213.86±13.99	543.38±28.27
2020-1-21	237.25±18.46	223.59±11.77	224.09±35.56	186.61±15.77	554.18±38.45
2020-4-30	238.09±10.68	137.42±10.96	206.86±8.81	154.23±6.23	624.80±18.47

 

4. Figure 3, the letters of significancy must be written above the box to be clearer for the readers.

Reply: We have revised these contents.

 

5. the manuscript need extensive improving in to increase the readability of the MS.

Reply: We have revised the previous manuscript, please see the new manuscript.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report (Previous Reviewer 2)

The authors have addressed the previous comments, making the manuscript better and easier to understand. However, the scientific names of the studied fish species have to be italicized. Also, the presentation of data in Table 2 should be organized. 

Author Response

1. The authors have addressed the previous comments, making the manuscript better and easier to understand. However, the scientific names of the studied fish species have to be italicized. Also, the presentation of data in Table 2 should be organized.

Reply: We have revised these contents, please see the new manuscript.

Author Response File: Author Response.docx

Reviewer 3 Report (New Reviewer)

Please see my comments attached.

Comments for author File: Comments.pdf

Author Response

1. Line 14: “X. davidi were introduced from Liling National Catfish Breeding Farm, Hunan province.” Are there any associated biological invasion risks since the fish was introduced from other river systems?

Reply: there are not exist biological invasion risks, because the X. davidi is a native fish species in the Danjiangkou Reservoir.

 

2. Table 2 reads a mess. Please redo that…

Reply: The format of the table may have changed after uploading to the manuscript system, please see the table below.

Table 2 The changes in periphytic algae density at the bottom of the cage for each fish group

Date	Group 1	Group 2	Group 3	Group 4	Control group
	104 cells·cm-2
2019-12-15	534.24±12.43	486.62±31.29	677.41±26.70	713.08±22.10	561.12±30.69
2019-12-27	231.71±30.75	237.17±15.97	288.18±43.61	255.28±22.62	572.41±25.49
2020-1-4	222.15±11.00	224.93±12.84	253.29±19.92	261.85±27.23	543.68±20.57
2020-1-15	227.03±8.57	213.45±30.27	262.18±11.27	213.86±13.99	543.38±28.27
2020-1-21	237.25±18.46	223.59±11.77	224.09±35.56	186.61±15.77	554.18±38.45
2020-4-30	238.09±10.68	137.42±10.96	206.86±8.81	154.23±6.23	624.80±18.47

 

3. I am a marine ecologist and I have some concerns over the variability of biomanipulation effects due to scales. In the ocean (particularly in China’s inshore Yellow), the algae bloom has taken tolls on local ecosystem well-being with increased fish mortality (https://doi.org/10.3389/fmars.2022.813024). There is a possibility that the massive algae bloom outbreak can render the proposed biomanipulation useless. I would like to see the authors discussing this issue related to either scale or ecosystem characteristics. Obviously, you cannot have a silver bullet in biomanipulation for all algae treatment.

Reply: Thanks a lot for your valuable advice, we added these contents, please see line 199-213.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report (Previous Reviewer 3)

The manuscript improved substantially.

 

 

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.

Round 1

Reviewer 1 Report

The work presented to me for review aroused mixed feelings in me. On the one hand, an interesting, practical and, what is important, a useful environment for research, on the other hand, the text is often incomprehensible, absolutely necessary for a thorough correction before possible publication. Detailed comments are attached.

Comments for author File: Comments.pdf

Reviewer 2 Report

Please see attached review comments

Comments for author File: Comments.pdf

Reviewer 3 Report

 

There are 15 in-situ cages were used and four treatments so how many replicates per each treatment (as the author mention there are 2 replicates this is confusing).

In addition, the number of fish in each replicate is very few (3) to perform statistical analysis (3 fish per replicate). In this case, the data in not homogenic or not in normal distribution. Therefore, the used one way analysis of variance is not the best way, it must be treated with non-parametric tests.

Figure 4 and 5 (Boxblot) showed the presence of odd numbers which need special statistical treatment.

How did the authors determine growth of each fish without tagging system.

The full profile of water quality must be included along the study periods.

Why the sampling time did not have a periodic sequence, where there are 3 months lost from Jun 21 to April 30.

Moreover the final version was made in a rush, were long section of the tempelte still with the main text lines 78-93.