Invasive Water Hyacinth (Eichhornia crassipes) Increases Methane Emissions from a Subtropical Lake in the Yangtze River in China
, Shanshan Xiang 1,2, Yuhu Shi 1,2,*, Xiuhuan Xu 1,2, Huicui Lu 3, Wenhui Ou 1,2 and Jiawei Yang 1Round 1
Reviewer 1 Report
Dear Authors,
I revised the manuscript “Invasive water hyacinth (Eichhornia crassipes) increase in methane emission from a subtropical lake in the Yangtze River, China” submitted to the Diversity Journal. The paper is interesting. In the article, the authors raise very important issues related to the emissions of the ceipolar gas which is methane from shallow lakes. This is a very important study that brings new knowledge to the field of methane emissions from lakes overgrown with plants imported by humans.
I have a few comments that should be taken into account.
Please put tables and graphs directly in the text where we refer to them.
2.1. Study area description
Please start your title with a capital letter.
2.2. CH4 measurements
Line 106. Why were measurements taken from April to December.
Line 107-110. Please add a diagram or a photo of the measuring chambers.
2.3. Measurements of environmental factors
Line 133. Please provide the thermometer model.
Line 136. Why were the samples taken in September (due to the growth phase of the plants?)
Author Response
Response to Reviewer 1 Comments
Reviewer 1
I revised the manuscript “Invasive water hyacinth (Eichhornia crassipes) increase in methane emission from a subtropical lake in the Yangtze River, China” submitted to the Diversity Journal. The paper is interesting. In the article, the authors raise very important issues related to the emissions of the ceipolar gas which is methane from shallow lakes. This is a very important study that brings new knowledge to the field of methane emissions from lakes overgrown with plants imported by humans.
I have a few comments that should be taken into account.
Point 1: Please put tables and graphs directly in the text where we refer to them.
Response 1: We thank you very much for your comments and suggests, the tables and graphs have been putted in the text where refer to them (see the revised version ).
Point 2: 2.1. Study area description
Please start your title with a capital letter.
Response 2: the “study area description” in the 2.1 title was changed with the a capital letter. (See the revisied version).
Point 3: 2.2. CH4 measurements
Line 106. Why were measurements taken from April to December.
Response 3: The growing season of the vegetation in the subtropical region were usually between april to November, to accurately estimate methane emissions, the data in December were also measured in the study, furthermore, the values was also referred to as referenced vslued in the Winter.
Point 4: Line 107-110. Please add a diagram or a photo of the measuring chambers.
Response 4: the photo of the mesuring chambers in the text have been added. (see the figure 2 in the revisied version)
Point 5: 2.3. Measurements of environmental factors
Line 133. Please provide the thermometer model.
Response 5: The thermometer model has been provied in the revisied version.
Point 6: Line 136. Why were the samples taken in September (due to the growth phase of the plants?)
Response 6: The growth phase of the plants also highly occurred in September, but more impormently in July and August, maily due to the impactes of the COVID-19 disease, so it is preventing us from doing field tests.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Invasive aquatic plants significantly destroy the ecology balance and affect the greenhouse gases emission. The authors investigated the effect of invasive water hyacinth (Eichhornia crassipes) on methane emission from a subtropical lake in the Yangtze River, China. They found that the fluxes of CH4 emission in the invasive plant zone were significantly higher than those of the floating-plant and the open water zones. Moreover, the CH4 emission had weaker correlations with the water temperature, water depth, and dissolved oxygen concentration. The author has obtained some valuable data. The results are valuable for the ecology protection in the basin of the Yangtze River. However, the authors should highlight the innovative, ecological environmental value of their research work. Some other comments are as follows:
Please add the hypothesis at the end of the introduction section and discuss in the discussion section.
Line 84, 2.1. study area description, study should be revised as Study.
Line 129, and 130, V and A should be used in italic.
Line 144, was measured using by?
Line 148 and line 150, gas fluxes should be revised as methane fluxes.
Line 168, CH4 emission flux, line 169, CH4 emission fluxes, flux or fluxes?
Line 182-185, p value should be given in this paragraph.
Line 205, 206, total phosphorus (TP) and total nitrogen (TN), the abbreviate should be given when they first appeared.
Line 277, Water depth is as one of main factors, is as?
In the conclusion section, based on the data in the paper the authors could not obtain the conclusion that CH4 emission fluxes in the Hong Lake were much higher than those of boreal lakes and reservoirs , which could be attributed to the eutrophication.
Author Response
Response to Reviewer 2 Comments
Invasive aquatic plants significantly destroy the ecology balance and affect the greenhouse gases emission. The authors investigated the effect of invasive water hyacinth (Eichhornia crassipes) on methane emission from a subtropical lake in the Yangtze River, China. They found that the fluxes of CH4 emission in the invasive plant zone were significantly higher than those of the floating-plant and the open water zones. Moreover, the CH4 emission had weaker correlations with the water temperature, water depth, and dissolved oxygen concentration. The author has obtained some valuable data. The results are valuable for the ecology protection in the basin of the Yangtze River. However, the authors should highlight the innovative, ecological environmental value of their research work. Some other comments are as follows:
Point 1: Please add the hypothesis at the end of the introduction section and discuss in the discussion section.
Response 1: We thank you very much for your comments and suggests. The influence of invasive plants water hyacinth on methane emission from lake wetland has been elaborated in the introduction section, while we added a suggest in the discussion section that the wetland restoration project to remove invasive plants, so as to reduce methane emission. (See the red word in the revisied version).
Point 2: Line 84, 2.1. study area description, study should be revised as Study.
Response 2: The “study area description” in the 2.1 title has been changed with the a capital letter. (See the revisied version).
Point 3: Line 129, and 130, V and A should be used in italic.
Response 3: The V and A in the text have been used in italic.
Point 4: Line 144, was measured using by?
Response 4: The total nitrogen concentration (g•kg-1) was measured using by the Kjeldahl method with the acid digestion of H2SO4 in the text.
Point 5: Line 148 and line 150, gas fluxes should be revised as methane fluxes.
Response 5: The gas fluxes have been revised as methane fluxes.
Point 6: Line 168, CH4 emission flux, line 169, CH4 emission fluxes, flux or fluxes?
Response 6: The CH4 emission flux in the Line 168 has been revised as CH4 emission fluxes.
Point 7: Line 182-185, p value should be given in this paragraph.
Response 7: The Line 182-185, p value have been given in this paragraph.
Point 8: Line 205, 206, total phosphorus (TP) and total nitrogen (TN), the abbreviate should be given when they first appeared.
Response 8: The abbreviate of the total phosphorus (TP) and total nitrogen (TN) in the 2.3 partes have been amended when they first appeared, and the Line 205, 206, the total phosphorus and total nitrogen had been also abbreviated.
Point 9: Line 277, Water depth is as one of main factors, is as?
Response 9: Due to the CH4 is produced in sediment under anoxic condition by methanogens and is released to the atmosphere, therefore, water depth or water table level in wetlands is usually a major factor affecting the spatial and temporal variation of CH4 emission flux.
Point 10: In the conclusion section, based on the data in the paper the authors could not obtain the conclusion that CH4 emission fluxes in the Hong Lake were much higher than those of boreal lakes and reservoirs , which could be attributed to the eutrophication.
Response 10: We thank you very much for your suggests, and we have revised in the text, please see the revised version.
Author Response File: Author Response.docx
Reviewer 3 Report
Water hyacinth (Eichhornia crassipes) is one of the most important invasive plants in the world, especially in central and southern China. Many people have paid attention to the invasion mechanism and prevention methods of water hyacinth, but few studies have paid attention to the impact of water hyacinth invasion on the greenhouse gas emissions of lakes. This well-written paper examines the effects of invasive water hyacinth on CH4 emissions from subtropical lake in the Yangtze River, China. In particular, the results show that invasive water hyacinth increased CH4 emissions from lakes. This is a good study which provides a reference for fine quantification of the greenhouse gas balance of the lake. But there are some problems must be solved before it is considered for publication. If the following problems are well-addressed, I believe that the essential contribution of this paper is important for the region lake carbon budget affected by invasive plants.
1. In the abstract section, no matter whether the difference is significant or not, the p value should be given at the same time. Same problem also appears on the results section.
2. Page 2, line 29-30, "greenhouse effect" appeared two times in this sentence, I suggest the authors change the second "greenhouse effect" to "global warming.
3. Page 2, line 50, Change "it" to "water hyacinth".
4. Page 3, line 121, The correlation coefficient R2 greater than 0.7 were accepted in this study, which were lower than we usually do of 0.9, Please explain.
5. Page 3, line 132-135, How deep were these environmental parameters measured below the water surface?
6. Page 3, line 136-138: Was you measure the aboveground biomass or the whole plant biomass? I think the "soil " means "sediment" here, and includes those in Table 1.
7. In the "3.1. The environmental factors", the author should analyze whether there are significant differences in environmental factors between different sampling points.
8. Page 4, line 173: Are " CH4 emissions " here average values?
9. Page 5, line 198-201: What is the connection between the studies of Wang and Pickard et al. and the present study?
10. In the "Table 1", please ensure that numbers and text are centered and aligned.
11. In the "Figure 1", the figures in your paper are a bit blurry. Please consider replacing them with clearer ones.
Author Response
Response to Reviewer 3 Comments
Water hyacinth (Eichhornia crassipes) is one of the most important invasive plants in the world, especially in central and southern China. Many people have paid attention to the invasion mechanism and prevention methods of water hyacinth, but few studies have paid attention to the impact of water hyacinth invasion on the greenhouse gas emissions of lakes. This well-written paper examines the effects of invasive water hyacinth on CH4 emissions from subtropical lake in the Yangtze River, China. In particular, the results show that invasive water hyacinth increased CH4 emissions from lakes. This is a good study which provides a reference for fine quantification of the greenhouse gas balance of the lake. But there are some problems must be solved before it is considered for publication. If the following problems are well-addressed, I believe that the essential contribution of this paper is important for the region lake carbon budget affected by invasive plants.
Point 1: In the abstract section, no matter whether the difference is significant or not, the p value should be given at the same time. Same problem also appears on the results section.
Response 1: We thank you very much for your suggests, we have added the p value in the” Results” in the text, while not in the “Abstract” section, because of the ” Results” have added.
Point 2: Page 2, line 29-30, "greenhouse effect" appeared two times in this sentence, I suggest the authors change the second "greenhouse effect" to "global warming.
Response 2: We have changed the second “greehouse effect” in the text.
Point 3: Page 2, line 50, Change "it" to "water hyacinth".
Response 3: we have changed the "it" to "water hyacinth" in the text.
Point 4: Page 3, line 121, The correlation coefficient R2 greater than 0.7 were accepted in this study, which were lower than we usually do of 0.9, Please explain.
Response 3: We have revised it, and we explained that it was as result of the explosive release on the CH4 at some point.
Point 5: Page 3, line 132-135, How deep were these environmental parameters measured below the water surface?
Response 5: These environmental parameters on the water temperature, pH, DO, and conductivity were measured with a water depth of 10cm, and its has been revised in the text.
Point 6: Page 3, line 136-138: Was you measure the aboveground biomass or the whole plant biomass? I think the "soil " means "sediment" here, and includes those in Table 1.
Response 6: Yes, the bimmass of plants included the whole plants.
Point 7: In the "3.1. The environmental factors", the author should analyze whether there are significant differences in environmental factors between different sampling points.
Response 7: The differences in the environmental factors among sampling points has been analyzed in the revised version.
Point 8: Page 4, line 173: Are " CH4 emissions " here average values?
Response 8: Yes, and we have added the “Mean” word in the revised version.
Point 9: Page 5, line 198-201: What is the connection between the studies of Wang and Pickard et al. and the present study?
Response 9: We thank you very much for your suggests, and we acceped your suggests and deleted in the manuscript, but we revised it in the revised version.
Point 10: In the "Table 1", please ensure that numbers and text are centered and aligned.
Response 10: we have checked and revised it.
Point 11: In the "Figure 1", the figures in your paper are a bit blurry. Please consider replacing them with clearer ones.
Response 11: we have added a clearer Figure 1 in the revised version.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear Authors,
I have revisited the manuscript “Invasive water hyacinth (Eichhornia crassipes) increase in methane emission from a subtropical lake in the Yangtze River, China” submitted to the Diversity Journal. The work has been improved according to my recommendations. The article is fully suitable for publication in to the Diversity Journal.
Author Response
Point 1: I have revisited the manuscript “Invasive water hyacinth (Eichhornia crassipes) increase in methane emission from a subtropical lake in the Yangtze River, China” submitted to the Diversity Journal. The work has been improved according to my recommendations. The article is fully suitable for publication in to the Diversity Journal.
Response 1: Thank you very much for your time and efforts on reviewing this manuscript.
Reviewer 2 Report
The authors have improved the manuscript and have responded appropriately to the reviewers’ concerns. However, some issues are remaining and should be fixed.
1. Line 53-54, the sentence “the large mats can decrease the dissolved oxygen concentration in surface water due to the mats” doesn't seem to conform to the syntax, please check.
2. Line 151, it is confused whether the soil sample is air-dried, dried at 70°C, or first air-dried then dried at 70°C
3. Line 181, the conductivity of TNs doesn’t have unit, but others have units, and it is better to add the unit as the others.
4. Line 198, it is suggested to mark the significant differences of each indicator in Table 1 in different locations with letters (such as a, b, c, and d) to make it clearer.
5. Figure 5, Is the significance level changed to P=0.10, which conflicts with the description in Section 2.4. If significance level was accepted at P=0.05 as the description in Section 2.4, it seems inappropriate to mark P=0.08 and P=0.03 with * and **.
Author Response
The authors have improved the manuscript and have responded appropriately to the reviewers’ concerns. However, some issues are remaining and should be fixed.
Point 1: Line 53-54, the sentence “the large mats can decrease the dissolved oxygen concentration in surface water due to the mats” doesn't seem to conform to the syntax, please check.
Response 1: We thank you very much for your comments and suggests. Compared to the original text, we have checked it in our manuscripts and corrected properly (See the revised version) .
Point 2: Line 151, it is confused whether the soil sample is air-dried, dried at 70°C, or first air-dried then dried at 70°C
Response 2: We thank you very much for your suggests. We have revised in the text, please see the revised version.
Point 3: Line 181, the conductivity of TNs doesn’t have unit, but others have units, and it is better to add the unit as the others.
Response 3: We thank you very much for your suggests. We have added in the text.
Point 4: Line 198, it is suggested to mark the significant differences of each indicator in Table 1 in different locations with letters (such as a, b, c, and d) to make it clearer.
Response 4: We thank you very much for your suggests. We have maked in the Table 1 in the text.
Point 5: Figure 5, Is the significance level changed to P=0.10, which conflicts with the description in Section 2.4. If significance level was accepted at P=0.05 as the description in Section 2.4, it seems inappropriate to mark P=0.08 and P=0.03 with * and **.
Response 5: We thank you very much for your suggests. We have revisied it and marked only the P = 0.03 with * in the Figure 5.
Author Response File: Author Response.docx
Reviewer 3 Report
THe authos have revised the manuscript well.
Author Response
Point 1: The authos have revised the manuscript well.
Response 1: Thank you very much for your time and efforts on reviewing this manuscript.
