The ‘Perfect’ Conversion: Dramatic Increase in CO2 Efflux from Shellfish Ponds and Mangrove Conversion in China
Round 1
Reviewer 1 Report
Review
Paper title: The ‘Perfect’ Conversion: Dramatic Increase in CO2 Efflux from Shellfish Ponds and Mangrove Conversion in China.
The authors conducted a study to reveal the role of shellfish ponds in CO2 emissions in China. They found that the estimated effluxes were significantly higher than those reported for mangrove forests. An analysis of historical data indicated a significant increase in CO2 released. The authors concluded that the expansion of aquaculture ponds is a topic of rigorous management.
All these reasons explain the relevance of the paper by Xiaoguang Ouyang and co-authors submitted to "Sustainability".
General scores.
The data presented by the authors are original and significant. The study is correctly designed and the authors used appropriate methods. In general, the statistical analyses are performed with good technical standards. The authors conducted careful work that may attract the attention of a wide range of specialists focused on environmental sciences and ecosystem services.
Specific comments.
L 66. Change “avoid” to “avoids”
L 91. Change “is” to “was”
L 92. Change “is” to “was”
L 100. Change “accelerated” to “accelerating”
L 103. Change “remains as” to “remains”
L 116. Change “During August” to “From August”
L 124. Change “in consecutive” to “on consecutive”
L 126. Change “aluminium” to “aluminum”
L 131. Change “at 200” to “at a 200”
L 155. Change “based” to “based on the”
L 157. Change “1970s” to “the 1970s”
L 159. Change “1980s-2010” to “1980-2010”
L 159. Change “mangrove lost” to “mangrove loss”
L 164. Change “except” to “except for”
L 167. Change “Shapiro-Wilk test” to “the Shapiro-Wilk test”
L 169. Change “Paired-sample t test” to “A paired-sample t-test”
L 172. Change “Monte Carlo method” to “The Monte Carlo method”
L 181. Change “t test” to “t-test”
L 182. Change “efflux” to “effluxes”
L 201. Change “varies” to “varied”
L 205-211. “However, the overall area..”. This section is more suitable for "Discussion".
L 206. Change “1980s” to “the 1980s”
L 213-214. Change “yr-1” to “yr-1” (superscript)
L 216-217. The authors should use sub- and superscript where appropriate (CH4, yr-1…).
L 219, 220, 221, 222. Change “Area” to “The area”
L 224. Change “1980s” to “the 1980s”
L 225. Change “2010s” to “the 2010s”
L 243. Change “6.56% increase” to “the 6.56% increase”
L 245. Change “of temperature” to “in temperature”
L 251. Change “with light” to “to light”
L 253. Change “may be also” to “may also be”
L 273. Change “average” to “the average”
L 297. Change “farming” to “farming by”
L 297. Change “which suggested” to “who suggested”
L 298. Change “were almost five times” to “was almost five times higher than”
L 302. Change “effort” to “efforts”
L 312. Change “ponds are” to “ponds is”
L 320. Change “Fin fish” to “Finfish”
L 325. Change “comparison with” to “comparison to”
L 326. Change “influence of” to “influence”
L 327. Change “significant increase” to “a significant increase”
L 341. Change “Shellfish ponds invasion” to “Expansion of shellfish ponds”
L 348. Change “high” to “a high”
L 353. Change “to 6.56%” to “to the 6.56%”
L 358. Change “approaches to” to “approaches”
L 371-378. Please, complete these sections or delete.
L 448. Change “2018b” to “2018”
Author Response
General scores.
The data presented by the authors are original and significant. The study is correctly designed and the authors used appropriate methods. In general, the statistical analyses are performed with good technical standards. The authors conducted careful work that may attract the attention of a wide range of specialists focused on environmental sciences and ecosystem services.
Response: Thank the reviewer for acknowledging the contribution of our study.
Specific comments.
L 66. Change “avoid” to “avoids”
Response: Agreed. Line 72.
L 91. Change “is” to “was”
Response: Agreed. Line 99.
L 92. Change “is” to “was”
Response: Agreed. Line 100.
L 100. Change “accelerated” to “accelerating”
Response: Not agreed since this is coherent with the former part of the sentence. ‘…has caused a collapse…, thus accelerated…… ’.
L 103. Change “remains as” to “remains”
Response: Agreed. Line 111.
L 116. Change “During August” to “From August”
Response: Agreed. Line 124.
L 124. Change “in consecutive” to “on consecutive”
Response: Agreed. Line 132.
L 126. Change “aluminium” to “aluminum”
Response: Not agreed. Both are correct but aluminium is used for British English and aluminum is used for American English. Our manuscript uses the British English.
L 131. Change “at 200” to “at a 200”
Response: Agreed. Line 140.
L 155. Change “based” to “based on the”
Response: Agreed. Line 164.
L 157. Change “1970s” to “the 1970s”
Response: Agreed. Line 167.
L 159. Change “1980s-2010” to “1980-2010”
Response: Agreed. Line 168.
L 159. Change “mangrove lost” to “mangrove loss”
Response: Agreed. Line 169.
L 164. Change “except” to “except for”
Response: Agreed. Line 187.
L 167. Change “Shapiro-Wilk test” to “the Shapiro-Wilk test”
Response: Agreed. Line 189.
L 169. Change “Paired-sample t test” to “A paired-sample t-test”
Response: Agreed. Line 191.
L 172. Change “Monte Carlo method” to “The Monte Carlo method”
Response: Agreed. Line 194.
L 181. Change “t test” to “t-test”
Response: Agreed. Line 203.
L 182. Change “efflux” to “effluxes”
Response: Agreed. Line 204.
L 201. Change “varies” to “varied”
Response: Agreed. Line 242.
L 205-211. “However, the overall area..”. This section is more suitable for "Discussion".
Response: Agreed. Have moved the sentences to the Discussion section. Line 358-363.
L 206. Change “1980s” to “the 1980s”
Response: Agreed. Line 359.
L 213-214. Change “yr-1” to “yr-1” (superscript)
L 216-217. The authors should use sub- and superscript where appropriate (CH4, yr-1…).
Response: All these are unfixed changes when the manuscript was automatically transformed to the journal’s style. Have fixed the style problem. Line 236-7, 251.
L 219, 220, 221, 222. Change “Area” to “The area”
Response: Agreed. Line 253-6.
L 224. Change “1980s” to “the 1980s”
Response: Agreed. Line 258.
L 225. Change “2010s” to “the 2010s”
Response: Agreed. Line 259.
L 243. Change “6.56% increase” to “the 6.56% increase”
Response: Agreed. Line 278.
L 245. Change “of temperature” to “in temperature”
Response: Agreed. Line 280.
L 251. Change “with light” to “to light”
Response: Not agreed. There is no difference between ‘in comparison with’ and ‘in comparison to’.
L 253. Change “may be also” to “may also be”
Response: Agreed. Line 288.
L 273. Change “average” to “the average”
Response: Agreed. Line 316.
L 297. Change “farming” to “farming by”
Response: Have changed the style of reference. Line 340.
L 297. Change “which suggested” to “who suggested”
Response: Agreed. Line 340.
L 298. Change “were almost five times” to “was almost five times higher than”
Response: Agreed. Line 341.
L 302. Change “effort” to “efforts”
Response: Agreed. Line 345.
L 312. Change “ponds are” to “ponds is”
Response: Agreed. Line 355.
L 320. Change “Fin fish” to “Finfish”
Response: Agreed. Line 368.
L 325. Change “comparison with” to “comparison to”
Response: Not agreed. Have responded to this problem in response to the reviewer’s comment on Line 251.
L 326. Change “influence of” to “influence”
Response: Agreed. Line 374.
L 327. Change “significant increase” to “a significant increase”
Response: Agreed. Line 375.
L 341. Change “Shellfish ponds invasion” to “Expansion of shellfish ponds”
Response: Agreed. Line 389-90.
L 348. Change “high” to “a high”
Response: Not agreed. Don’t think ‘a’ is suitable before ‘high emission aquaculture ponds’.
L 353. Change “to 6.56%” to “to the 6.56%”
Response: Agreed. Line 401.
L 358. Change “approaches to” to “approaches”
Response: Agreed. Line 406.
L 371-378. Please, complete these sections or delete.
Response: This section was added during the journal’s editorial process. Have deleted it as it is not suitable for this study.
L 448. Change “2018b” to “2018”
Response: Agreed. Line 539.
Note: the line numbers in the responses correspond to the manuscript without markup.
Reviewer 2 Report
It is worth adding more information by the authors of the presented research problem. I took the liberty of describing the information that should be included in the manuscript. The authors should pay more attention to the characteristics of the research problem and the willingness to solve it. Therefore, an insightful description should interest many readers. And so: mangroves, also known as mangroves, are evergreen plant communities - trees and shrubs that grow densely on the sea coasts in the hot climate of the tropics. They grow on the border between land and water, in shallows, in bays, in estuaries. Usually found in the tidal area, they are regularly flooded by rising water levels. At high tide, only the crowns of the tree are visible, while at low tide the ground and the roots are exposed. Although mangrove forests are diverse in species, the common feature of the trees and shrubs growing here are stilted adventitious roots that stabilize plants during waves, respiratory roots, thanks to which plants breathe oxygen contained in the atmosphere (this type of roots occurs in plants that grow on boggy and anaerobic substrate) and resistance to high salinity of water.
Why did the authors not add information that mangroves are a source of livelihood for local communities that obtain fish and crustaceans from them, but also honey or silk (for example, Madagascar has an endemic species of silkworms living in the mangroves). All these aspects can affect CO2. Authors should take this into account when describing the discussion of the results.
The authors did not even mention that mangroves are not only natural sewage treatment plants but also natural anti-flood and anti-storm systems. Mangrove forests improve coastal water quality by retaining, removing and circulating nutrients, pollutants and particulates from land-based sources, filtering these materials out of the water before reaching coral reefs and seagrass habitats. Mangrove root systems slow down the flow of water, facilitating the deposition of sediment. At the same time, mangroves provide nutrients to neighboring coral reef and seagrass communities, contributing to the health of these ecosystems. After all, this is very important information !!!
Another problem that the authors do not solve is:
-uncontrolled urban development. The higher the population density on the coasts, the faster the decay of the mangroves;
-tourism, particularly adversely affects the areas where it is a pillar of the region's economy
- agriculture - after deforestation and the separation of marshy areas, rice fields are established;
- salt extraction - mangrove forests are replaced by salines, ie plants producing salt by evaporating seawater;
charcoal production - mangroves are cut down to turn the wood into charcoal for the local community to use for its own needs.
Author Response
It is worth adding more information by the authors of the presented research problem. I took the liberty of describing the information that should be included in the manuscript. The authors should pay more attention to the characteristics of the research problem and the willingness to solve it. Therefore, an insightful description should interest many readers.
Response: Thank the reviewer for the suggestion on this point. Have added description on mangroves and more information on the ecosystem services provided by mangroves. Line 34-7, 39-41.
Why did the authors not add information that mangroves are a source of livelihood for local communities that obtain fish and crustaceans from them, but also honey or silk (for example, Madagascar has an endemic species of silkworms living in the mangroves). All these aspects can affect CO2. Authors should take this into account when describing the discussion of the results.
Response: Have discussed changes in CO2 efflux related to the likelihood provision for local communities, including seafood and silviculture. Line 308-10, 312.
The authors did not even mention that mangroves are not only natural sewage treatment plants but also natural anti-flood and anti-storm systems. Mangrove forests improve coastal water quality by retaining, removing and circulating nutrients, pollutants and particulates from land-based sources, filtering these materials out of the water before reaching coral reefs and seagrass habitats. Mangrove root systems slow down the flow of water, facilitating the deposition of sediment. At the same time, mangroves provide nutrients to neighboring coral reef and seagrass communities, contributing to the health of these ecosystems. After all, this is very important information !!!
Response: Have provided more information on the ecosystem services provided by mangroves. Line 37-41.
Another problem that the authors do not solve is:-uncontrolled urban development. The higher the population density on the coasts, the faster the decay of the mangroves;-tourism, particularly adversely affects the areas where it is a pillar of the region's economy;- agriculture - after deforestation and the separation of marshy areas, rice fields are established;- salt extraction - mangrove forests are replaced by salines, ie plants producing salt by evaporating seawater; charcoal production. mangroves are cut down to turn the wood into charcoal for the local community to use for its own needs.
Response: While we acknowledge that other anthropogenic disturbances are importance sources of CO2 efflux, we focus on the impact of mangrove conversion to aquaculture ponds in this study. Putting everything in foci will make our study lose the focus. Therefore, we briefly discuss the impact of other anthropogenic disturbances. Line 310-2.
Note: the line numbers in the responses correspond to the manuscript without markup.
Reviewer 3 Report
I have read this manuscript with big interest. This seems to be really impressive study, and it is communicated very properly. I appreciate that such a highly-complex issue is explained very clearly and logically. The methodology is well explained, as well as the outcomes and their interpretations. This paper will be interesting to the broad circle of the readers from across the globe, and I tend to recommend it for publication after small improvements.
Line 24-25: Phrase unclear because shellfish ponds are also aquaculture ponds. Please, check for the same uncertainty in the other parts of the manuscript.
Subsection 2.2: can you give a simple scheme indicating the location of sampled points?
Lime 147: please, add a reference to this source.
Discussion: according to the methodological section, the field research was undertaken in 2015. May be something changed since then? Even if no, you need to add the related discussion of the validity of your research.
Figs. 2 and 4: please, think more about re-designing these drawings. These look a bit old-fashioned, and one may even have impression that they are taken from any old work (I guess this is not so in fact).
Author Response
I have read this manuscript with big interest. This seems to be really impressive study, and it is communicated very properly. I appreciate that such a highly-complex issue is explained very clearly and logically. The methodology is well explained, as well as the outcomes and their interpretations. This paper will be interesting to the broad circle of the readers from across the globe, and I tend to recommend it for publication after small improvements.
Response: Thank the reviewer for the appreciation of our manuscript.
Line 24-25: Phrase unclear because shellfish ponds are also aquaculture ponds. Please, check for the same uncertainty in the other parts of the manuscript.
Response: Have made it clear that aquaculture ponds include shellfish ponds. Line 25.
Subsection 2.2: can you give a simple scheme indicating the location of sampled points?
Response: Yes, we used a random sampling scheme to take samples from four shellfish ponds and six locations of mangroves adjacent to the ponds. The locations have been provided in Figure 1. Line 133-4.
Lime 147: please, add a reference to this source.
Response: Have added the reference here. Line 156.
Discussion: according to the methodological section, the field research was undertaken in 2015. May be something changed since then? Even if no, you need to add the related discussion of the validity of your research.
Response: There has been not much change in the sampling area since then. Have discussed the validity of our study. Line 295-8.
Figs. 2 and 4: please, think more about re-designing these drawings. These look a bit old-fashioned, and one may even have impression that they are taken from any old work (I guess this is not so in fact).
Response: We plot the figures with historical areal changes in aquaculture/shellfish ponds and our estimates on CO2 efflux from the ponds. Have replaced the figures with bar plots or whisker-box plots (Figure 2 and 4).
Note: the line numbers in the responses correspond to the manuscript without markup.
Reviewer 4 Report
Comments and Suggestions for Authors
The ‘Perfect’ Conversion: Dramatic Increase in CO2 Efflux from Shellfish Ponds and Mangrove Conversion in China
-The subject of this paper is suitable for publication profile of Sustainability.
- The article concerns a very important and current subject of Dramatic Increase in CO2 Efflux from Shellfish Ponds and Mangrove Conversion in China, which is known and is a big problem , therefore the article will surely find many readers.
- The paper is well written, the text is clear and easy to read by the reader. The figures are drawn correctly. Overall, the paper was written in fluency and clear organization. The conclusions presented by the authors are consistent with the evidence and arguments, the authors have shown that CO2 efflux from shellfish ponds converted from mangroves in China revealed high dark and light CO2 efflux from these ponds (0.61 and 0.90 kg CO2 m−2 yr−1, respectively; = 37.67 and 56.0 mmol m−2 d−1) compared with reported fluxes from land converted from tropical wetlands.
-I classify the paper as original scientific paper.
-I propose the adoption of the manuscript with minor revision.
- I would like to suggest to the authors to define better the aim and to point out the novelty of the work. The most important achievement result from the conducted research with regard to the previously published results should be emphasized.
Author Response
-The subject of this paper is suitable for publication profile of Sustainability.
- The article concerns a very important and current subject of Dramatic Increase in CO2 Efflux from Shellfish Ponds and Mangrove Conversion in China, which is known and is a big problem , therefore the article will surely find many readers.
- The paper is well written, the text is clear and easy to read by the reader. The figures are drawn correctly. Overall, the paper was written in fluency and clear organization. The conclusions presented by the authors are consistent with the evidence and arguments, the authors have shown that CO2 efflux from shellfish ponds converted from mangroves in China revealed high dark and light CO2 efflux from these ponds (0.61 and 0.90 kg CO2 m−2 yr−1, respectively; = 37.67 and 56.0 mmol m−2 d−1) compared with reported fluxes from land converted from tropical wetlands.
-I classify the paper as original scientific paper.
-I propose the adoption of the manuscript with minor revision.
Response: Thank the reviewer for acknowledging the importance and contribution of our study.
- I would like to suggest to the authors to define better the aim and to point out the novelty of the work. The most important achievement result from the conducted research with regard to the previously published results should be emphasized.
Response: Have made the aim sharp and underscored the novelty of our study. Have emphasized the most important results of our study and discussed the points with published results. Line 78, 81-86, 409-12.
Note: the line numbers in the responses correspond to the manuscript without markup.
Round 2
Reviewer 2 Report
There are no corrections in the manuscript that I requested to improve the manuscript. The authors did not respond to my comments. No professionalism. I do not accept this manuscript for publication.
Author Response
We have used tracked changes in the last revised version of our manuscript and indicated line numbers where we revised the manuscript. I think the reviewer may read the original submitted manuscript rather than the revised version. Now I have used tracked changes but also highlighted changes made to the manuscript.
Round 3
Reviewer 2 Report
The article is still not very well written for me and needs to be corrected according to my first review.
I leave the final decision to the Editor.
Author Response
In the first revised version, we have revised the manuscript based on your comments and provided point-by-point responses to your comments. I don’t know what you mean the manuscript needs to be corrected according to the first review. It is unclear which points have not been corrected. However, we have gone through the manuscript again and provided further details where necessary. The new changes are highlighted in green. The file name is ‘sustainability-1445548_version3’.
