Next Article in Journal
Learning the Indicative Patterns of Simulated Force Changes in Soil Moisture by BP Neural Networks and Finding Differences with SMAP Observations
Next Article in Special Issue
Pollution Evaluation and Health Risk Assessment of Trace Metals in Eleven Tissues of Mylopharyngodon piceus Collected from an Aquaculture Pond in Huzhou, near Southern Taihu Lake
Previous Article in Journal
Can Carbon Neutrality Commitment Contribute to the Sustainable Development of China’s New Energy Companies?
Previous Article in Special Issue
Do Changes in Prey Community in the Environment Affect the Feeding Selectivity of Silver Carp (Hypophthalmichthys molitrix) in the Pearl River, China?
 
 
Article
Peer-Review Record

The Effects of Water Depth on the Growth of Two Emergent Plants in an In-Situ Experiment

Sustainability 2022, 14(18), 11309; https://doi.org/10.3390/su141811309
by Xiaowen Lin, Xiaodong Wu *, Zhenni Gao, Xuguang Ge, Jiale Xiong, Lingxiao Tan and Hongxu Wei
Reviewer 1: Anonymous
Reviewer 2: Anonymous
Sustainability 2022, 14(18), 11309; https://doi.org/10.3390/su141811309
Submission received: 5 August 2022 / Revised: 24 August 2022 / Accepted: 6 September 2022 / Published: 9 September 2022
(This article belongs to the Special Issue Wetlands: Conservation, Management, Restoration and Policy)

Round 1

Reviewer 1 Report

Degradation and restoration of shallow lakes are receiving wide attentions due to the global trends of eutrophication. Research have been carried out widely on the mechanisms underlying the loss of submersed and emergent macrophytes, particularly on submersed macrophytes. Knowledge with regards to effects of water depth on the establishment and maintenance of emergent macrophytes is relative limited. This study presented an in-situ experiment to explain the potential effects of water depth on the establishment and developments of two typical emergent macrophytes (Typha and Zizania) and their environments. The paper is generally acceptable after a major revision. The concerns are listed as follows:

1. Actually, some works have been published concerning the potential effects of water depth particularly their dynamics on growth of wet plants and also emergent plants. It would be better if you could include some of them in the introduction.

2. It would be nice if you could provide some pics to show the experiment systems and also the schedule, from which the readers could image how the author designed and performed the tests.

3. It is strongly recommended to include the analysis of various growing environments (if measured)their changes related to water depth and growth of plants.

4. Path analysis might help to explore how the water depth influence the macrophytes, their environments and their interactions.

5. You might be interested to read some published papers related to growth of submersed macrophytes which are as important as emergent plants in maintaining heathy ecosystems as follows:

5.1 Water depth and development of macrophytes: Total phosphorus thresholds for regime shifts are nearly equal in subtropical and temperate shallow lakes with moderate depths and areas. Freshwater Biology, 2014, 59: 1659-1671.

5.2 Macrophyte restoration related to water depth and underwater light: Submersed macrophyte restoration with artificial light-emitting diodes: a mesocosm experiment. Ecotoxicology and Environmental Safety, 2021.

5.3 Influence of lake basin in macrophyte development: Alternative stable states and controlling factors of submersed macrophytes in large shallow Lake Taihu, China. Journal of Oceanology and Limnology, doi.org/10.1007/s00343-022-1286-z

5.4 The limitation of short-term mesocosm test: Can short-term, small experiments reflect nutrient limitation on phytoplankton in natural lakes? Chinese Journal of Oceanology and Limnology, 2017, 35(3): 546-556.

6. Abstract: "The effects of water depths on the growth and photosynthetic fluorescence characteristics of two emergent plants (T. latifolia and Z. latifolia) were studied in eutrophic Lake Gehu by in-situ experiments. "T. latifolia and Z. latifolia should use their full names when they first appear.

7. Introduction: Lake Gehu (31°3′N, 119°49′E) is a typical shallow lake in the middle and lower reaches of the Yangtze River, China." Please add some background information such as nutrient level and ecosystem status.

8. Include a map showing the lake and also the experiment system.

9. It might help understand the process of changes if you could analyze the dynamics in macrophytes and their environments and also their interactions along the experiment.

10. What are the mechanism underlying the influence of water depth on establishment and growth of the two emergent plants.

11. Figure 2d: On the 20th and 40th days, there are no data of dead leaves when the water depth is 20cm. Is it because there is no number of dead leaves or the data is lost?

12. Figure 3f: On the 65th day, there are no data for leaf width when the water depth is 100 cm and 120cm.Is it because all the leaves have fallen off so you can't get the data?

Author Response

Dear expert, your comments on this paper are of great help to improve it. Thank you! Now we response to your questions and suggestions as follows:

 

  1. Actually, some works have been published concerning the potential effects of water depth particularly their dynamics on growth of wet plants and also emergent plants. It would be better if you could include some of them in the introduction.

Response:Thank you for your suggestion.We have added relevant references for elaboration in the introduction.

 

  1. It would be nice if you could provide some pics to show the experiment systems and also the schedule, from which the readers could image how the author designed and performed the tests.

Response:Thank you for your suggestion.We haved added the map of experimental design (Figure 2).

 

  1. It is strongly recommended to include the analysis of various growing environments (if measured),their changes related to water depth and growth of plants.

Response:Thank you for your suggestion.But it is sorry that we only monitored the changes of water depth and water level during the experiment, ,and we did not monitor other environmental factors, so we only added the data of water level in our article(Figure 8).

 

  1. Path analysis might help to explore how the water depth influence the macrophytes, their environments and their interactions.

Response:As you say, path analysis is an important method in ecology, which can be used to analyze the linear relationship between multiple independent variables and dependent variables.However, our paper only involved water depth as an environmental factor, and only discussed the influence of water depth on emergent germination and growth, rather than their interactions.So we did not use path analysis. But we will pay extra attention to this interaction in the subsequent research.

 

  1. You might be interested to read some published papers related to growth of submersed macrophytes which are as important as emergent plants in maintaining heathy ecosystems as follows:

5.1 Water depth and development of macrophytes: Total phosphorus thresholds for regime shifts are nearly equal in subtropical and temperate shallow lakes with moderate depths and areas. Freshwater Biology, 2014, 59: 1659-1671.

5.2 Macrophyte restoration related to water depth and underwater light: Submersed macrophyte restoration with artificial light-emitting diodes: a mesocosm experiment. Ecotoxicology and Environmental Safety, 2021.

5.3 Influence of lake basin in macrophyte development: Alternative stable states and controlling factors of submersed macrophytes in large shallow Lake Taihu, China. Journal of Oceanology and Limnology, doi.org/10.1007/s00343-022-1286-z

5.4 The limitation of short-term mesocosm test: Can short-term, small experiments reflect nutrient limitation on phytoplankton in natural lakes? Chinese Journal of Oceanology and Limnology, 2017, 35(3): 546-556.

Response:Thank you for your recommendation.We have read these articles in detail and they are really good and enlightening.

 

6.Abstract: "The effects of water depths on the growth and photosynthetic fluorescence characteristics of two emergent plants (T. latifolia and Z. latifolia) were studied in eutrophic Lake Gehu by in-situ experiments. "T. latifolia and Z. latifolia should use their full names when they first appear.

Response:Thank you for your reminder.We have changed the abbreviation to the full name.

 

7.Introduction: Lake Gehu (31°3′N, 119°49′E) is a typical shallow lake in the middle and lower reaches of the Yangtze River, China." Please add some background information such as nutrient level and ecosystem status.

Response:Thank you for your suggestion.We have added some background information such as physical and chemical properties of water and sediment in our article(Table 1).

 

8.Include a map showing the lake and also the experiment system.

Response:Thank you for your suggestion.We haved added the study area map (Figure 1) and experimental design map(Figure 2).

 

9.It might help understand the process of changes if you could analyze the dynamics in macrophytes and their environments and also their interactions along the experiment.

Response:Thank you for your suggestion.Indeed,our paper only involved water depth as an environmental factor, and only discussed the influence of water depth on emergent germination and growth, rather than their interactions,and we will pay extra attention to this interaction in the subsequent research .

 

10.What are the mechanism underlying the influence of water depth on establishment and growth of the two emergent plants.

Response: The influence mechanism of water depth on the establishment and growth of two emergent plants is mainly reflected in the following two aspects.First of all, water depth mainly affects plant growth by limiting resources,such as carbon dioxide, oxygen, underwater light.The slower underwater gas exchange with increasing water depth and the decrease in the redox potential and oxygen concentration.Secondly,because the photosynthetic organs are submerged in water, photosynthesis is blocked, and the supply of oxygen to the roots is insufficient. In severe cases, anaerobic respiration is forced to occur in the underground parts, thereby rapidly consuming carbohydrates, and inhibiting plant germination and growth.And under the stress of water depth ,emergent plants adapt to changes in water depth through morphological changes influenced by these two mechanisms.

 

11.Figure 2d: On the 20th and 40th days, there are no data of dead leaves when the water depth is 20cm. Is it because there is no number of dead leaves or the data is lost?

Response:It is because there is no dead leaves when the water depth is 20cm rather than data loss.

 

12.Figure 3f: On the 65th day, there are no data for leaf width when the water depth is 100 cm and 120cm.Is it because all the leaves have fallen off so you can't get the data?

Response:Yes,all the leaves have fallen off when the water depth is 100 cm and 120cm on the 65th day.

 

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

In the manuscript entitled “The effects of water depth on the growth of two emergent plants in an in-situ experiment”, the authors have conducted an in situ experiment in shallow Lake Gehu, located in central China, during which they tested the effect of water depth on the growth, survival, physiology and morphology of two main emergent plants, Typha orientalis and Zizania caduciflora. While increasing water depth has no significant effects on germination for both species, it decreased plant height, tiller number, leaf length, width and number, and shoot:root ratio. The authors also showed that the best photosynthetic yield was obtained in the depth range of 20 to 60 cm, suggesting that this range is best for both species growth. Overall, this study presents very interesting findings, and is of good quality. Results are presented in a clear manner, and well-related to other studies. However, important information about statistical tests are missing. Even if the results of this study are quite regional, and might not be applicable to other locations, environments or species, they are still useful for the scientific community in my opinion. I have some specific comments that are listed below.

L12: Species names must be spelled out completely when first occurring in the paper. Please replace T. orientalis and Z. caduciflora by Typha orientalis and Zizania caduciflora.

L43: “too high or too low of a water depth”. Weird wording, I would rewrite the sentence.

L70 to L80: I think some important information are missing in the Material and Method section. Maybe a map showing the study area (e.g. the lake area) and where the experiment was conducted in the lake could be great, as well as a picture or a schematic representation of the experiment maybe.

L83: For how long exactly has been running the experiment? Please clarify this.

L84: How did you measure the germination rate? Please indicate this.

L109: From which study does the equation used to calculate the ETR come from? Please add a reference.

L112-L119: Before performing a one-way ANOVA, some hypotheses must be checked. How did you check the residuals normality (Shapiro-Wilk test?) and homoscedasticity (Levene or Bartlett test?) before performing the ANOVAs? This information must be added to the text.

L134-L162: Exact p-values must be added instead of P<0.05 or P>0.05.

L145-L146: The word “significant” must always be used with a p-value. Please add the p-value testing the effect of water depth on tillers, and add the correlation parameters between tillers and water depth.  

L167-L169: Please indicate panels meaning in Figure 2 caption.

L176-L177: “The height of plants at water depths of 40–60 cm was much higher than that of the other treatment group”. 3much” should be replaced by the exact percentage of difference.

L201-L203: Please indicate panels meaning in Figure 3 caption.

L216. Indicate the p-value testing the effect of water depth on ETRmax.

L220-L221: Please indicate panels meaning in Figure 4 caption.

L223-L224: Please indicate panels meaning in Figure 5 caption.

L244-L250: This paragraph is interesting, but needs to be related more with your results. As for now, it appears only as a list of published results, but not connected with the results on germination rates that you obtained.

L283-L285: As you stated, the water level of lake Gehu greatly fluctuated during your study, potentially affecting the outcome of your experiment. I think that monitoring water level over the course of the experiment could have been interesting.

L315-L319: I do not understand this statement about the ‘opportunity window’. Please either delete it or make it clearer.

Author Response

 

Dear expert, your comments on this paper are of great help to improve it. Thank you! Now we response to your questions and suggestions as follows:

 

(1)L12: Species names must be spelled out completely when first occurring in the paper. Please replace T. orientalis and Z. caduciflora by Typha orientalis and Zizania caduciflora.

Response:Thank you for your reminder.We have replace T. orientalis and Z. caduciflora by Typha orientalis and Zizania caduciflora.

 

(2)L43: “too high or too low of a water depth”. Weird wording, I would rewrite the sentence.

Response:Thank you for your reminder.We have rewritten the sentence.

 

(3)L70 to L80: I think some important information are missing in the Material and Method section. Maybe a map showing the study area (e.g. the lake area) and where the experiment was conducted in the lake could be great, as well as a picture or a schematic representation of the experiment maybe.

Response:Thank you for your suggestion.We haved added the map of study area (Figure 1) and experimental design (Figure 2).

 

(4)L83: For how long exactly has been running the experiment? Please clarify this.

Response:Our experiment lasted 65 days from March 17, 2015 to May 20, 2015.We have noted in the article.

 

(5)L84: How did you measure the germination rate? Please indicate this.

Response:The germination rates of T. orientalis and Z. caduciflora rhizomes were calculated every 2 days after one week of the experiment by lifting the plastic buckets to the water surface gently.It is considered germinated when leaves grow out of rhizomes.The germination rate is equal to the number of rhizomes that have germinated divided by the total number of rhizomes.

 

(6)L109: From which study does the equation used to calculate the ETR come from? Please add a reference.

Response:Thank you for your reminder.We have added references to support it.

 

(7)L112-L119: Before performing a one-way ANOVA, some hypotheses must be checked. How did you check the residuals normality (Shapiro-Wilk test?) and homoscedasticity (Levene or Bartlett test?) before performing the ANOVAs? This information must be added to the text.

Response:Thank you for your reminder.We used one-way ANOVA to analyze the effect of water depth on germination and growth of emergent plants. Before ANOVA , data were tested for normality (shapiro-wilk) and Homogeneity of variance . Data that did not meet normality were log-transformed. We have added this information to the text.

 

(8)L134-L162: Exact p-values must be added instead of P<0.05 or P>0.05.

Response:Thank you.We have added exact p-values in the article.

 

(9)L145-L146: The word “significant” must always be used with a p-value. Please add the p-value testing the effect of water depth on tillers, and add the correlation parameters between tillers and water depth. 

Response:Thank you for your reminder.We have added the p-value in our article.

 

(10)L167-L169: Please indicate panels meaning in Figure 2 caption.

Response:Thank you for your suggestion.We have added the meaning of the panels in Figure 2 caption.

 

(11)L176-L177: “The height of plants at water depths of 40–60 cm was much higher than that of the other treatment group”. 3much” should be replaced by the exact percentage of difference.

Response:Thank you for your suggestion.We have We have used the exact percentage instead of "much" in the text.

 

(12)L201-L203: Please indicate panels meaning in Figure 3 caption.

Response:Thank you for your suggestion.We have added the meaning of the panels in Figure 3 caption.

 

(13)L216. Indicate the p-value testing the effect of water depth on ETRmax.

Response:The data we present in the figure are the mean values obtained from multiple measurements. However, it is a pity that only the mean values were recorded in our original data, which could not meet the data requirements of one-way ANOVA. Therefore, for the sake of rigor, we deleted the word “significant”.

 

(14)L220-L221: Please indicate panels meaning in Figure 4 caption.

Response:Thank you for your suggestion.We have added the meaning of the panels in Figure 4 caption.

 

(15)L223-L224: Please indicate panels meaning in Figure 5 caption.

Response:Thank you for your suggestion.We have added the meaning of the panels in Figure 5 caption.

 

(16)L244-L250: This paragraph is interesting, but needs to be related more with your results. As for now, it appears only as a list of published results, but not connected with the results on germination rates that you obtained.

Response:Thank you for your suggestion.It actually didn't have much relevance to our findings, so we have deleted it.

 

(17)L283-L285: As you stated, the water level of lake Gehu greatly fluctuated during your study, potentially affecting the outcome of your experiment. I think that monitoring water level over the course of the experiment could have been interesting.

Response:Yes, we did monitor the water level of Lake Gehu during the process of our experiment and have added data about water level in our article.

 

(18)L315-L319: I do not understand this statement about the ‘opportunity window’. Please either delete it or make it clearer.

Response:We have added a description of the ‘opportunity window’. The “opportunity window” means that within a range of water depth, plants can profit from the environment in which they grow and have maximum biomass.This range of water depth is the most suitable range for plant growth.

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Thanks for revision. My comments were mostly considered. Concerning the growing environmental condition, I would suggest to make some discussions. Although the authors have not measured much environmental variables, environments might actually influence the growth of plants and vice versa. I'd like to see some more discussion about the interaction between plant and environments. 

Author Response

Author Responses:

Dear expert, your comments on this paper are of great help to improve it. Thank you! Now we response to your questions and suggestions as follows:

 

Thanks for revision. My comments were mostly considered. Concerning the growing environmental condition, I would suggest to make some discussions. Although the authors have not measured much environmental variables, environments might actually influence the growth of plants and vice versa. I'd like to see some more discussion about the interaction between plant and environments.

Response:Thank you for your suggestion.We have added some discussion about interactions between light, oxygen, carbon dioxide and plant growth .

Author Response File: Author Response.docx

Back to TopTop