Impact of Water Fluctuation from a Dam on the Mekong River on the Hatching Success of Two Sandbar-Nesting Birds: A Case Study from Bueng Kan Province, Thailand
Round 1
Reviewer 1 Report
The manuscript investigated the hatching success of two birds in the Mekong River shore, and analyze the impact of the upstream dam. The authors have carried out carefully field sampling and numerical simulation, the conclusion is interesting. I think the manuscript can be published after the following problems are addressed.
(1) It is better to label the study area in Figure 1 so that the readers can learn about the relation of study area and the dams.
(2) Figure3: what is the meaning of vertical axis of the top picture.
(3) From Figure 2, it is observed that the study area has two sides adjacent to the water and it may more easy to be flooded than the area in ref [21]. The authors should mention this difference in analysis.
(4) In Figure 4, the manuscript presents the water stages from January to May. I thought the authors should present the highest water stage from 1980 to 2009 (when the Jinhong Dam was constructed), so that we can compare the dam release against the natural water stage.
(5) The hatch periods of the two bird are about 20 days, and they are much larger than the water stage fluctuation period. So I believe that the reason for nest flooding is the high water stage, rather than the rising rate of the water stage.
Author Response
Comment (1) It is better to label the study area in Figure 1 so that the readers can learn about the relation of study area and the dams.
Answer: Thanks for the suggestion, we totally agree with it. We added the star symbol («) to the Figure 1 and label as a study area location. The Figure 1 caption now read “Dams and proposed dams at the Mekong River mainstream in 2010, Star symbol («) represents the location of the study area located at Bueng Kan provincial town, Thailand. This map was adapted from the MRC Strategic Environment Assessment map [8]”
Comment (2) Figure3: what is the meaning of vertical axis of the top picture.
Answer: We label the vertical axis of each graph separately to clarify this point (updated version attached below).
Comment (3): From Figure 2, it is observed that the study area has two sides adjacent to the water and it may be more easy to be flooded than the area in ref [21]. The authors should mention this difference in analysis.
Answer: Our study area covered an area of ~75 ha (~0.75 km2) and only was present during dry season, but in ref [21] their study area covered more extensive sandbars present along 60-km stretch from Stung Treng to Kratie, Cambodia. We are aware that their study area was much larger and differed in being located on both sides of Mekong River, so we did not proceed on direct comparative analysis between nest survival rates of our study site and theirs.
Comment: (4) In Figure 4, the manuscript presents the water stages from January to May. I thought the authors should present the highest water stage from 1992 to 2009 (when the Jinhong hydroelectric Dam was constructed), so that we can compare the dam release against the natural water stage.
Answer: We could not present the highest water stage from 1992 to 2009 in the figure because the only available data (in MRC database) before the Jinhong hydroelectric Dam was constructed were from year 1992 and 2003, and after constructed between year 2016 to 2022. We therefore present water stage of year 1992 (water level was lower than 2003) to represent the lowest water level before the dam was constructed and year 2018 (study year) and the average line was not information in MRC database but the MRC database presented average water level.). To clarify that issue the figure caption is now read “Water levels between January to May in the years 1992, 2003 and 2016–2022 (only available data in MRC database) at Paksane hydrological station, Lao PDR. Maroon line represents the daily average water level in the years 1992, 2003 and 2016–2021 (only available data). Purple line represents the daily average water level in 1992 (the first year of MRC report). Yellow line the daily average water level in 2018 (Study year).
Source: http://ffw.mrcmekong.org/stations.php?StCode=PAK&StName=Paksane”.
Comment (5) The hatch periods of the two birds are about 20 days, and they are much larger than the water stage fluctuation period. So, I believe that the reason for nest flooding is the high-water stage, rather than the rising rate of the water stage.
Answer: It appears that water levels in our study area were highly fluctuating during March and April when supposed to be dry season which water level increase down to the lowest level (see patterns of the year 1992 in Figure 4).
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript attempts to highlight an important issue related with the impact of dam on the nesting success of birds. However, apart from the English language, the entire manuscript needs to be revised in order to help the reader to perceive the information in its true sense and without ambiguity. For example, the title itself is not clear. It could begin like: 'Impact of dam/ water flow/ fluctuation on the hatching success................'
General statements including description of dam and other issues need to be significantly reduced. Likewise, the discussion section also needs to contain only relevant comparisons of the results of this manuscript with the previous studies.
In short, the manuscript requires major revision throughout.
Author Response
Answer:
1) We edited the new title as “Impact of water fluctuation by dam in the Mekong River on the hatching success of two sandbar-nesting birds: a case study from Bueng Kan Province, Thailand”.
2) We edited the new version of the manuscript and reduced text from 5,091 word to 4,545 word.
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No. 1712191 (word) |
New edition (word) |
|
|
Introduction |
808 |
561 |
|
Method |
1099 |
1100 |
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Results |
1578 |
1570 |
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Discussion |
1463 |
1109 |
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Conclusion |
143 |
205 |
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Total |
5091 |
4545 |
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
1. The language need to be improved. The text may be checked by a native English speaking scientist/author/member editorial board of the journal.
2. If possible,Fig.6 may be deleted. It is of little importance
3. Page 17: Line 486 to 496 may be deleted as the contents of these lines are not main part of the study
4. Conclusion : delete line 509 to 514. These lines do not reflect the findings of main study
Author Response
1. The language need to be improved. The text may be checked by a native English speaking scientist/author/member editorial board of the journal.
Ans: We will send the manuscripts to MDPI Language Editing Services.
- If possible, Fig.6 may be deleted. It is of little importance
Answer: We edited as reviewer suggestion deleted Figure 6.
- Page 17: Line 486 to 496 may be deleted as the contents of these lines are not main part of the study
Answer: Page 17: Line 486 to 496 changed to Page 13: Line 390-400. Therefore, we edited as reviewer suggestion and deleted at line 390-400.
- Conclusion : delete line 509 to 514. These lines do not reflect the findings of main study
Answer: Page 17: Line 509 to 514 changed to Page 13: Line 413-418. Therefore, we edited as reviewer suggestion and deleted at line 413-418.
Author Response File: 
Author Response.docx
