Ecological River Water Quality Based on Macroinvertebrates Present in the Ecuadorian Amazon

Round 1

Reviewer 1 Report

Such an interesting topic, insightful and requirement minor improvement.

Comments for author File: Comments.pdf

Author Response

Abstract

Comment: Abstract must consist of Introduction, Problem Statement, Methodology, Result & Discussion and Conclusion/ Final Findings.

Reply: The abstract was modified.

Introduction

Comment: Line 67-69. The author is suggested to add this statement in the text. “The Biological Monitoring Working Party (BMWP) index is a water quality index used to assess the overall health of a water body based on the presence and abundance of aquatic macroinvertebrates, such as insects, mollusks, and crustaceans. These organisms are used as indicators of water quality because they are sensitive to changes in the physical and chemical conditions of the water, as well as to pollution”.

Reply: The statement was included as suggested the reviewer.

Materials and Methods

Comment: Line 99-101. I noticed the statement the author copied from google, not self-sentenced. This is the statement I found in the google, “It is recommended to avoid sampling macroinvertebrates during winter in order to avoid extreme conditions, both of hydrological regime and temperature, to ensure a reliable water quality assessment.” Please check. Should there be a similarity thus it subjects to plagiarism.

Reply: The statement was rewritten.

 

Data collection

Comment: The author to state how long the covering period the sampling works was conducted; one year, two years, etc. Line 122-123. The statement “Samples were collected in three zones of the river section (left, right, and central banks)”. The collection of samples has to deliberately explained. It is a norm to proceed with sampling catering for temporal; dry and wet seasons spatially.

Reply: The sampling methodology has been modified including the information asked by the reviewer. Sampling was carried out in the period of least precipitation.

2.2.1. Physicochemical analysis – Please check is it true to analyze inorganic and organic compounds, and stored at 8°C until analysis. Normal practice is 4oC.

Reply: the mistake was corrected.

2.2.3.   Determination of the BMWP-Col index and grouping by Functional Feeding Group

Comment: The index development can be categorized into three regions of observation.; upstream, middle and downstream.

Reply: The River Continuum Concept (RCC) was included in the introduction. A graph where FFG is grouped in the three section (upstream, center and downstream) was included. The behavior of FFG related to RCC was also discussed.

2.2.4.   Data Analysis

Comment: Line 169. The cluster analysis based on the similarity (Euclidean distances) substantially grouping the homogenous invertebrates’ communities (common characteristics) within the same group but dissimilar or non-homogenous with other invertebrates’ communities in terms composition, etc. Spatiotemporal analysis as it involves with space and time is imperatively to be carried out in this study. The accumulation of allochthonous materials such as leaves and twigs. The accumulation of these materials in riverbeds provides shelters, or habitats, and food sources for macroinvertebrates. The prediction of trend on the invertebrates’ communities during dry and rainy season should have been carried out. Bear in mind, one sampling station within each region

Reply: The spatiotemporal analysis and the prediction of the trend of the communities could be considered for further research because variables such as ecological traits, environmental data, soil cover, etc were not recorded in this study. This has been mentioned as a recommendation in the conclusion. 

 

Result

Comment: It is noticeable the result from the cluster analysis is not discussed in the result & discussion. Please explain.

Reply: The cluster analysis was removed because it did not contribute with essential information about the water quality categorization.

Comment: Line 264-265: At the beginning of 264 the river, there was a greater diversity of families and downstream the number decreased, thus this statement is a quite doubtful as my statement in Line 315-316 (Discussion).

Reply: This information was reviewed and corrected.

Comment: The author confuses with the abbreviation CP and PC. Which one the exact abbreviation the author use.

Reply: This mistake was corrected in the whole document.

Comment: The author needs to state the confidence level of the analysis as well; descriptive analysis.

Reply: confidence levels have been included in the Table 1 for each variable.

 

Discussion

Comment: The author did not discuss on the cluster analysis based on the similarity (Euclidean distances) in the result and discussion. In the data analysis it stated. The clustering to describe and to make spatial and temporal comparisons of communities (assemblages) of macrointerbrates in heterogeneous environments.

Reply: The cluster analysis was removed because it did not contribute with essential information about the water quality categorization.

Comment: Line 293-296: I refer to the statement “The values of turbidity in this study are lower than those reported by [18] (10.59 295 UFT)”. Please state the value of turbidity in this study and explain on why the industrialized area influence the turbidity value. What is the correlation of wastewater and       turbidity. Need to be well explained.

Reply: The value of turbidity was included and the explanation was written in the discussion.

Comment: Line 304-306: When applying the BMWP-Col index, it was determined that the water quality index 304 is better when there is more diversity of macroinvertebrates regardless of the number of 305 individuals; thus, the water quality improves as more families increase. This statement is correct, but somehow the author needs to put the citation for supportive purpose.

Reply: The citation was added.

Comment: Line 315-316: “downstream river water has 315 a diffusion effect (self-cleaning)”. Technically, I have a bit argument with this. The downstream river is the receiving point of pollutants from multisources points, therefore the self-cleansing or self-purification in the downstream area is quite vague and doubtful.

Reply: Citation has been included and it is discussed with other studies.

Comment: Line 318-321: I do have doubtful with the statement.

Reply: The information was reviewed and confirmed.

Comment: Line 370-371: The presence of this family is possibly due to the fact that downstream the river undergoes a purification process, thus the water is moderately polluted. What is the evidence that the downstream undergone for self-purification reflectance to any indicator.

Reply: This result has been discussed with other studies.

 

References

Comment: I noticed that none of the references cite the article journals of MDPI.

Reply: There are various references form MDPI journals in the reference list.

Reviewer 2 Report

In this study, the authors evaluated the water quality of five sites along the Yanaquincha River, located in the Ecuadorian Amazon, by measuring physicochemical parameters and macroinvertebrate community structure. They calculated the Biological Monitoring Working Group Colombia (BMWP-Col) biotic index and also classified individuals into functional feeding groups. The authors state that there is a lack of information from this region. 

 

This is a descriptive study that reads more like a technical report than a scientific paper. It does not discuss any ecological theories. The authors should discuss their data considering at least the River Continuum Theory. Does their data follow this theory?

The number of sites sampled is low, and they sampled each site four times. However, instead of analyzing each sample separately, showing the variability at the same site, they grouped the four samples into just one per site, thus reducing the sample size, and making the results of the statistical analysis quite problematic. 

I suggest that the authors look for a statistician specialized in biological data to check their analysis since I believe the authors lack experience in this regard. There is a lot of important information missing (distances used, stress values, etc). For example, the authors used Euclidean distance to analyze the presence and abundance of biological data, whereas the most appropriate metrics are the Hellinger distance or the Bray-Curtis distance (Sorensen distance for presence and absence data), according to Legendre & Gallagher (2001). This must be changed.

The analysis in Table 3 is completely wrong. The abundance numbers do not match those described in the text.

The discussion is not well organized, with the authors starting by discussing the abiotic variables, then discussing the biological community results, then going back to talk about the abiotic variables, and then again about the biotic data. Their conclusions are just repetitions of the results, without incorporating any information about conservation or environmental management. What have we learned from the study? What possible proposals for improving local environmental quality? Are any of these proposals already being put into practice? What is the key information for decision-makers?

Please, find specific comments in the attached document.

Comments for author File: Comments.pdf

Author Response

Comment: This is a descriptive study that reads more like a technical report than a scientific paper. It does not discuss any ecological theories. The authors should discuss their data considering at least the River Continuum Theory. Does their data follow this theory?

Reply: The River Continuum Concept (RCC) has been included in the introduction. A graph where FFG is grouped in the three section (upstream, center and downstream) was included. The behavior of FFG related to RCC was also discussed.

The number of sites sampled is low, and they sampled each site four times. However, instead of analyzing each sample separately, showing the variability at the same site, they grouped the four samples into just one per site, thus reducing the sample size, and making the results of the statistical analysis quite problematic. 

Reply: Each time only one sample was taken (four times per site). The standard deviation and the interval of confidence has been included in Table 1. In the PCA analysis has been modified taken into consideration all samples every time for each site and it can be seen in the Figure 3. In addition, data of hydromorphological and chemical variables from the four sampling times each site has been placed as Supplementary Material.

Comment: I suggest that the authors look for a statistician specialized in biological data to check their analysis since I believe the authors lack experience in this regard. There is a lot of important information missing (distances used, stress values, etc). For example, the authors used Euclidean distance to analyze the presence and abundance of biological data, whereas the most appropriate metrics are the Hellinger distance or the Bray-Curtis distance (Sorensen distance for presence and absence data), according to Legendre & Gallagher (2001). This must be changed.

Reply: The cluster analysis was removed because it did not contribute with essential information about the water quality categorization.

The analysis in Table 3 is completely wrong. The abundance numbers do not match those described in the text.

Reply: Table 3 was checked and the values were corrected in the text.

Comment: The discussion is not well organized, with the authors starting by discussing the abiotic variables, then discussing the biological community results, then going back to talk about the abiotic variables, and then again about the biotic data. Their conclusions are just repetitions of the results, without incorporating any information about conservation or environmental management. What have we learned from the study? What possible proposals for improving local environmental quality? Are any of these proposals already being put into practice? What is the key information for decision-makers?

Reply: The discussion section has been re-structured, grouping the information according to the variables as suggest the reviewer. In addition, a paragraph indicating the importance of the study and the importance of applying the sustainable development objectives in the locality was added.

The importance of these kind of studies was mentioned in the conclusions, due to these water sources are used for the irrigation of agricultural crops and recreational activities; therefore, to know the water quality is important.

Comment: Please, find specific comments in the attached document.

Reply: All specific comments have been corrected in the manuscript.

Reviewer 3 Report

COMMENTS TO THE AUTHOR(S)

This study examined the “Ecological River Water Quality Based on Macroinvertebrates Present in the Ecuadorian Amazon”. Given that water quality is a global concern, this paper is timely and could offer new insights water quality based on macroinvertebrates. The manuscript is generally well written and easy to understand. I suggest that the authors revise the manuscript incorporating the following comments and suggestions into an updated version.

Major changes:

·         On what basis the authors selected physico-chemical water quality parameters for the current study?

·         The authors did not mention that how many water quality parameters samples were collected for the current study.

·         Did the authors normalize the data before statistical analysis?

·         The authors miss interpreted the cluster analysis results. It’s better to interpret the results as per the dendrogram of the cluster analysis mainly focusing on grouping.

·         The authors should incorporate a subsection “implications for management and sustainable development “clearly depicting that how their results can be used for water quality management.  

·         It’s better to show Table 1 and 2 graphically.

Minor changes:

·         Its BOD₅ not BO₅D. Make corrections accordingly.

·         Its Turbidity (FTU) not Turbidity (UFT). Make corrections accordingly.

·         Improve the quality of figures

Author Response

Major changes:

Comment: On what basis the authors selected physico-chemical water quality parameters for the current study?

Reply: The references were added to indicate in which studies the physico-chemical water quality parameters were selected.

Comment: The authors did not mention that how many water quality parameters samples were collected for the current study.

Reply: This information has been included in the methodology section.

Comment: Did the authors normalize the data before statistical analysis?

Reply: The data was normalized by subtracting the average from the variable value and dividing by the standard deviation.

Comment: The authors miss interpreted the cluster analysis results. It’s better to interpret the results as per the dendrogram of the cluster analysis mainly focusing on grouping.

Reply: The cluster analysis was removed because it did not contribute with essential information about the water quality categorization.

Comment: The authors should incorporate a subsection “implications for management and sustainable development “clearly depicting that how their results can be used for water quality management. 

Reply: The importance of the study and the importance of applying the sustainable development objectives in the locality was added in the discussion.

Comment: It’s better to show Table 1 and 2 graphically.

Reply: In this case, the authors have chosen to remain the data in the tables because additional information have been added.

Minor changes:

Its BOD₅ not BO₅D. Make corrections accordingly.

Reply: The corrections were done.

Comment: Its Turbidity (FTU) not Turbidity (UFT). Make corrections accordingly.

Reply: All the corrections were done.

Comment: Improve the quality of figures.

Reply: The quality of the figures was improved.

 

Round 2

Reviewer 2 Report

The authors have made some improvements in the treatment of the data, but there is still a lot of work to be done in this document. I made some suggestions in the attached file. Authors need to ask a statistician how t interpret PCA plots. I also believe that the document needs a thorough  English revision. The authors were not careful enough to remove Spanish expressions like "y" instead of "and". There are even phrases repeated in the text. 

Comments for author File: Comments.pdf

Author Response

Comment: This is not a good adjective. Better options are: Unreliable, Dubious, Uncertain

Reply: the word uncertain was used.

Comment: My suggestion

Reply: The reviewer´s suggestion has been used in the text of the introduction.

Comment: Previously

Reply: The word previously has been used.

Comment: and

Reply: the word “and” has replaced “y” (Spanish) in the whole document.

Comment: Please, explain that the number represents the sampling campaign.

Reply: This has been explained in the text and mentioned in the title of Figure 3.

Comment: This is not how you should interpret the PCA plot.

Reply: The reviewer´s suggestion has been used in the text of the introduction.

Comment: Explain why this point were the exception.

Reply: the possible reason for the exception has been mentioned in the text.

Comment: This phrase must be joined with the previously, because both are dealing with DO levels.

Reply: This issue was done last time, but like the changes were with track of changes, looks like the system when transform the word document to pdf remain some of the text that was deleted (this because of the track changes option). This issue was reported to the assistant editor who verified it, that is why this time the corrections are not with track of changes, they are highlighted. This problem occurred in some parts of the text.

Comment: And how this relate to your results?

Reply: It has been explained that the results of the study agree the RCC hypothesis.

Comment: This is a discussion about the abiotic variables and should be moved up. Here you are discussion the Biotic variables.

Reply: This was done in the last correction of the manuscript, but like the changes were with track of changes, looks like the system when transform the word document to pdf remain some of the text that was deleted (this because of the track changes option). This issue was reported to the assistant editor who verified it, that is why this time the corrections are not with track of changes, they are highlighted. This problem occurred in some parts of the text.

Comment: This sentence repeats the sentence above highlighted in pink. This is unacceptable!!! Authors are not in control of their own text. Please review your manuscript carefully. It is your name that is at stake

Reply: This text was deleted in the last version of the manuscript, but like the changes were with track of changes, looks like the system when transform the word document to pdf remain some of the text that was deleted (this because of the track changes option). This issue was reported to the assistant editor who verified it, that is why this time the corrections are not with track of changes, they are highlighted. This problem occurred in some parts of the text.

Authors thank to the reviewer for his/her valuable comments that allowed to improve the manuscript.

Round 3

Reviewer 2 Report

None.