Dynamics of Vibrio cholerae in a Typical Tropical Lake and Estuarine System: Potential of Remote Sensing for Risk Mapping

Round 1

Reviewer 1 Report

 

I’m happy to see that ocean color remote sensing has the potentiality for monitoring the dynamics of Vibrio cholerae. This manuscript provided us some evidence for this topic by discussing the association between V. cholerae with temperature, salinity, phytoplankton, as well as zooplankton. Even though the relationships are not so strict as that in bio-optical algorithm developments, I think it’s worth to do this work. It’s not easy for me to understand the V. cholerae itself. However, I do some comments about the associations between V. cholerae and environmental factors.

I suggest authors to do moderate revision.

My comments are as follows:

1. The quantitative relationship between Chl-a and environmental V. cholerae risk is a critical part, which displays opposite patterns in brackish-water region with that in fresh-water. More explanations are expected for this result. How could we use it for further application? I also suggest authors to do similar analysis about the relationships between V. cholerae risk and temperature (and salinity, or other parameters), since the V. cholerae risk is related with many complex environmental factors.
2. After reading I know that the water salinity and temperature do have some effect on the occurrence of V. cholerae, could we use the remote sensing data about temperature and salinity to do assessment work of risk mapping, except for chlorophyll a data from ocean color?
3. Statistical parameters for the relationship in Equation (1) and (2) are necessary.
4. I suggest to modify the colorbar used in Figure 5 and 6 to make them clearly read.

Author Response

Thank you very much for your critical reading of our ms. Your comments helped us to improve the quality of or ms. We have taken maximum efforts to address all your comments.

Author Response File: Author Response.docx

Reviewer 2 Report

The author preliminarily explored the possibility to develop remotesensing-based risk maps of environmental V. cholerae, by putting in relation chlorophyll concentration and the occurrence of environmental V. cholerae. The Vemabanad Lake, the largest lake in Kerala (India), where cholera is endemic, was used as a case study. The authors quantified V. cholerae in biotic (phyto-and zooplankton, macrobenthos) and abiotic (sediment) matrices, finding out the V. cholerae was mainly associated with phytoplankton. Thus, they linked chlorophyll concentration, as determined by satellite obstervations, to the molecular detection of V. cholerae.

Data were reinforced by temperature and salinity monitoring ove a year. Laboratory experiments were carried out on previously isolated V. cholerae, screened for chitinase and laminarase.

We can consider the manuscript as a first attempt to use remote-sensing as a tool for preventng pandemics of cholera, by a continuos monitoring of water resources.

The manuscript should be revised for typesetting errors (mainly double spaces).

The results section contains a lot of comments whci must be moved to the discussion section.

Both discussions and conclusions need to be shortened.

Specific comments

• line 29, Skeletonema
• line 77, V. cholerae strains are...
• 289-294, it is a comment. Move to discussions.
• line 300, add a point at the sentence end.
• Figure 4, change name in "Sampling Station" and "Detection of V. cholerae (%)". 
• line 305, "...were also found to be favoured hosts", please avoid such kind of comments in the results section.
• lines 323-325, it is a comment. Please, avoid citations in the results section.
• lines 327-330, it is a comment
• line 377, Figure
• lines 384-386, it is a comment
• lines 395-398, it is a comment

Author Response

Thank you very much for your positive comments on our manuscript. Your comments helped us to improve the quality of or ms. We have taken maximum efforts to address all your comments.

Author Response File: Author Response.docx

Reviewer 3 Report

Well written paper presenting important and significant results. 

Minor suggestions given below:

Line 271 “micro?-“

Figure 1 could be improved by indicating the location of cities/urban centers referenced in the main text

Authors’ treatment of the data in order to generate a Vibrio probability map creates an arbitrary discontinuity in the middle of their probability map (See in Figure 6D) – a direct result of the apparent opposite trend for the brackish (figure 6A) and freshwater (Figure 6B) relationships between chlorophyll concentration and Vibrio presence. Of these, Figure 6A makes sense based upon the hypothesis that surface water eutrophic conditions results from runoff of large urban centers and rivers (again, the location of these should be added to the map in figure 1). Figure 6B shows a completely different trend --- why? And how can this be accommodated in a probability map without making unusual discontinuities in the probability spatial distribution?

Authors do not address this problem in the discussion until line 548 (the discussion begins on line 402). That is, many words are written before the authors bother to address the most puzzling aspect of their study and analysis. I suggest authors handle this problem at the beginning of their discussion.

 

Author Response

Thank you very much for your positive comments on our manuscript. Your comments helped us to improve the quality of or ms. We have taken maximum efforts to address all your comments.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I agree with the acceptance of this article. I do hope to see more further research about this subject from the authors.