Quantifying Escherichia coli and Suspended Particulate Matter Concentrations in a Mixed-Land Use Appalachian Watershed
Round 1
Reviewer 1 Report
The authors quantitatively characterized E. coli concentration relative to SPM size distribution from four sites (#1 to #4) in a mixed-land use watershed of Appalachia. The study is interesting, however, it should be significantly improved. Introduction and material and methods are long and contains well-know information. Results and discussion include a simple description of their findings. The authors acknowledge multiple limitations associated to the study, without addressing them. The authors should have diluted their samples to overcome the IDEEX upper limit. Ideally, the authors should overcome these limitation and resubmit their manuscript. Figures, tables, references (and overall formatting) should be improved. Detailed comments are included.
Line 19: specify the watershed
Line 32: provide additional references
Line 33: remove WHO – it has been used once throughout the manuscript
Line 36: do not capitalize Alone
Line 37: 2+ examples are anticipated. Please edit this sentence accordingly
Line 39: provide a link between the first two paragraphs
Line 56: replace “suspended particulate matter” with SPM
Lines 60-73: do not repeatedly the same concept
Line 75: be more specific
Lines 90-104: reduce the length of this paragraph
Lines 106-111: it fits well after Line 73.
Line 114: provide additional maps of the investigated watershed in SI
Lines 115-152: the authors should consider move some of these info to SI
Line 148 and Table 1: Clarify the four sites. Use the same number of decimals (e.g., 54 vs. 27.6; 0.8 vs. 19, etc.). Spell-out “Ag”
Line 159: be specific and provide the details related to the instrumentation. Also, add details to Campbell Scientific (e.g., city, state)
Line 164: remove “for the current work”
Line 167: be specific and quantify “low, medium, and high(er) stages
Line 179; provide specs related to the filters used
Lines 195-197: remove this sentence.
Lines 195-210: please remove most of the text. It contains well-known concepts related to IDEXX.
Line 197: water should be collected aseptically.
Lines 203-205: this statement is wrong. The authors should have diluted the samples.
Line 205-210: This problem should have easily overtaken by diluting the samples!
Lines 212-231: please reduce this paragraph. Well-known concepts are included.
Lines 235-237: re-write this sentence
Lines 245-315: edit these sections. They contains a simple description of the data available (Tables 2 and 3, Figure2).
Line 266 and Table 2: provide the different units. Also, E. coli should be italic. Clarify the four sites. Do not use #1, #2, #3, and #4.
Lines 288-290: this is a self-imposed limitation of the study. The authors should have diluted their samples.
Lines 314-315 and table 3: replace shaded cells with “bold” numbers. Also, add a space between “<” and “5” (after Smallest Interval)
Lines 319-329: combine this paragraph with “3.1 Climate during Study”
Line 332: specify the GPS coordinate of the sampling location. Also, provide the atmospheric data source(s).
Line 334: replace Escherichia coli with E. coli
Lines 335-366: do not compare your findings with results obtained at the same locations.
Line 338 and Figure 5:E. coli should be italic. Also, replace um with mm. Please, improve the quality of this figure. Please use the same number of decimals (54% vs. 49.1% vs. 1.03)
Lines 341-346: redundant.
Line 367 and Figure 4: Use the same number of decimals (54 vs. 40.6).
Lines 371-372: remove ** and ***. No additional details are given. In alternative, please edit them.
Line 373: add a space between < and 5
Line 418 and Figure 6: Spell-out SPM in your legend, and add SPM after “matter” in your caption. There should be a space between “m” and “< interval”. Add filtration size in your legend. The four Y-axis should have the same range (0-800). Also, do not add “$” after each value on the Y-axis since the Y-axis name (Percentage Difference (%) is present).
Line 445 and Figure 7: E. coli should be italic (Y-axis). Show the actual values on the Y-axis (instead of + 1). Also, remove “Legend” from your legend. Be consistent throughout the manuscript. Add “filtration size” in your legend
Line 447: add space between m<interval<60. Be consistent
Line 470 and Figure 8:E. coli should be italic. Also, be consistent “<5” vs. “< 5”. Use the same decimal in your legend (54% vs. 406.6%)
Line 477-478: redundant
Lines 502-521: re-write this paragraph.
Lines 487-490: the authors should have implemented these suggestions instead of acknowledge them
Lines 502-509: remove these sentences. No intro or goals should be included here (conclusions!)
Line 516: remove PCA
Line 545: title shouldn’t be “italic”
Line 546: 2017 should be “bold”
Line 551: please edit this reference according to the journal’s guidelines
Lines 564-565: do not capitalize each word. Please be consistent throughout the manuscript
Lines 566-567: do not capitalize each word. Please be consistent throughout the manuscript
Lines 575; 579-580: do not capitalize each word. Please be consistent throughout the manuscript
Lines 606, 714: E. coli should be italic.
Line 610. Add “.” between “Mountains” and “Available”.
Lines 622-623: do not capitalize each word. “2008” should be “bold”. Also, add page number(s)
Line 650; 673-674: do not capitalize each word
Lines 704-705: please edit this reference. Authors à title à journal/book à year à issue à pages
Line 706: do not capitalize each word. Also, Remove “Environmental Science & Technology”
Author Response
The authors quantitatively characterized E. coli concentration relative to SPM size distribution from four sites (#1 to #4) in a mixed-land use watershed of Appalachia. The study is interesting, however, it should be significantly improved. Introduction and material and methods are long and contains well-know information. Results and discussion include a simple description of their findings. The authors acknowledge multiple limitations associated to the study, without addressing them. The authors should have diluted their samples to overcome the IDEEX upper limit. Ideally, the authors should overcome these limitation and resubmit their manuscript. Figures, tables, references (and overall formatting) should be improved. Detailed comments are included.
Author Response: We appreciate the constructive comments of this reviewer. We have substantially revised the manuscript based on the reviewers feedback and hope the reviewer will agree the article is now much improved. We understand the comment “well-known information”, and while we have removed some text that may be considered well-known by the reviewer, we respectfully submit that not all of the interdisciplinary pathogen community (this work is most certainly interdisciplinary) are as familiar as the reviewer may be with some of the material (context), so we have also left some of the informative/background text in place. We also appreciate the comment about limitations, and we have tried to better communicate limitations, and how they could be addressed in future work. We have also been clearer that many of the limitations could not be dealt with in the current work due to those additional studies being beyond the scope, fiscal and labor limitations of the current baseline work. The dilution approach that is aptly recommended by the reviewer is appropriate. However, the objectives (testing undiluted potential of the method) and fiscal limitations of the work precluded the dilution of samples. For example, in the current work each water sample resulted in three separate incubations. However, if each sample had to be, for example, serially diluted 3-5 times each (conservative estimate) every extracted water sample would require 9-15 incubations. Thus, if we wanted to maintain the number of samples collected during the study from each site (32), the total number of incubations would have risen from 384 to 1152-1920. This would result in a drastic increase in the cost (~$10k) associated with the work, which could not be absorbed by available funds. Therefore, we focused our approach on yielding valuable baseline information which can serve as a steppingstone for future work. We feel that despite this limitation, the work does supply new information, and is therefore publishable. Completing a similar study utilizing serial dilutions would make for an interesting follow-up to the current work. We have worked hard in the revision to be sure to articulate our approach (reasoning, etc.) more completely. We hope the reviewer agrees we have taken criticisms very seriously and that we have addressed all comments substantially and substantively. Thank you.
Line 19: specify the watershed
Author Response: Thank you for this observation, we have specified the watershed where noted.
Line 32: provide additional references
Author Response: We added the requested additional references.
Line 33: remove WHO – it has been used once throughout the manuscript
Author Response: We have removed the abbreviation.
Line 36: do not capitalize Alone
Author Response: We have corrected this typo.
Line 37: 2+ examples are anticipated. Please edit this sentence accordingly
Author Response: We have added additional examples, and changed the text from: “(e.g. E. coli)” to “(e.g. E. coli, enterococci or fecal coliform)”.
Line 39: provide a link between the first two paragraphs
Author Response: We appreciate the reviewer pointing out this flow problem, we have revised the final sentence of paragraph one to improve the link between the first two paragraphs, through the addition of the text “including the association of bacteria to suspended particulate matter (SPM)”.
Line 56: replace “suspended particulate matter” with SPM
Author Response: We have made the requested replacement.
Lines 60-73: do not repeatedly the same concept
Author Response: Thank you, we admit this section of text was rife with redundancies. We have simplified and clarified the text accordingly.
Line 75: be more specific
Author Response: We have added the required specificity by clarifying that the following sentence consists of specific examples. Thus, the text was altered from “Previous investigations have been …” to “For example, previous investigations have been…”.
Lines 90-104: reduce the length of this paragraph
Author Response: We appreciate this feedback and have reduced the length of the paragraph.
Lines 106-111: it fits well after Line 73.
Author Response: We appreciate the comment by the reviewer, however after the alterations to both these paragraphs based on the other comments by the reviewer we respectfully submit that the text fits best as it is now written.
Line 114: provide additional maps of the investigated watershed in SI
Author Response: The authors respectfully submit that the current land-use table and figure shows all study sites in the current work. It is unclear a) what additional maps would be useful (and not superfluous), and b) how if included they would add to the story. We appreciate any additional feedback the reviewer would be willing to supply, but have left the figure as-is at this time.
Lines 115-152: the authors should consider move some of these info to SI
Author Response: We thank the reviewer for this recommendation, however we maintain that this text is needed in order to inform readers of the characteristics of the location where the work took place, specifically readers who are not familiar with the area. Therefore, we feel the removal of this text from the main body of the article would result in the loss of important context that supports reader comprehension about the area(s) where the work took place.
Line 148 and Table 1: Clarify the four sites. Use the same number of decimals (e.g., 54 vs. 27.6; 0.8 vs. 19, etc.). Spell-out “Ag”
Author Response: We clarified the sites by adding information regarding their predominant land use types and we made the requested improvements to the table.
Line 159: be specific and provide the details related to the instrumentation. Also, add details to Campbell Scientific (e.g., city, state)
Author Response: The details have been added and the paragraph was altered. The text now reads as follows: “During the study period (7/20/18 – 10/27/18) climate data were recorded using research-grade climate instrumentation located within approximately 100 m of site #1 (Figure 1). Climatic variables (recorded at a height of 3m) included precipitation (TE525 Tipping Bucket Rain Gage), average air temperature and relative humidity (Campbell Scientific HC2S3 Temperature and Relative Humidity Probe), and average wind speed (Met One 034B Wind Set instrument).”
Line 164: remove “for the current work”
Author Response: We removed the phrase as requested.
Line 167: be specific and quantify “low, medium, and high(er) stages
Author Response: We have now quantified the different stages in the manuscript as follows: The sampling regime was determined by stream stage (based on the streamflow descriptions by Zeiger and Hubbart [42]) at the sites to ensure sample extraction occurred during low (approximately 25% bankfull), medium (approximately 40% - 60% bankfull) and high(er) (approximately >60% bankfull) stages
Line 179; provide specs related to the filters used
Author Response: Specs relating to filters were added in text. The following text was added “Hydrophilic, nylon net, Merck Millipore filters were used during filtration”
Lines 195-197: remove this sentence.
Author Response: The sentence was removed as requested
Lines 195-210: please remove most of the text. It contains well-known concepts related to IDEXX.
Author Response: The text in this paragraph was shortened as per the reviewer’s request, however as this work is targeting a multidisciplinary audience, who might not be as knowledgeable about the IDEXX process as the reviewer is and who will thus need the information of this paragraph, the text was not completely removed.
Line 197: water should be collected aseptically.
Author Response: Water samples were collected as per the USGS accepted grab sampling method described in the National Field Manual for the Collection of Water-Quality Data. Sampling bottles were cleaned between sample collections as per the requirements of the aforementioned field manual. We hope this clarification satisfies the reviewer and we have updated the data collection section to include this pertinent information.
Lines 203-205: this statement is wrong. The authors should have diluted the samples.
Author Response: We appreciate the concern expressed by the reviewer, however as the study was aimed at providing baseline information that can be used as a stepping stone in future work and given the fiscal limitations sample dilution was deemed infeasible (as noted in opening paragraph of this response).
Line 205-210: This problem should have easily overtaken by diluting the samples!
Author Response: We agree with the statement of the reviewer and have added text in the discussion section stating that future work could expand on our work by diluting samples. However, as stated in the opening paragraph of this response, the fiscal limitations of the work could not accommodate additional samples during the current work.
Lines 212-231: please reduce this paragraph. Well-known concepts are included.
Author Response: The paragraph was shortened as per the reviewer’s request. However as the paper is targeting a multi-disciplinary/interdisciplinary audience much of the current text in the paragraph is required to provide context to readers who may be less well-versed in these concepts.
Lines 235-237: re-write this sentence
Author Response: The sentence was re-written per the reviewer’s request. The text was altered from “According to historic records since 2007 [53], the period received 99 mm more precipitation than average (350 mm) while the temperature was normal for the period (19 °C).” to “Historic records since 2007 [55] indicated that the period comprised normal temperatures (average 19°C), but received 99 mm more precipitation than average (350 mm). ”
Lines 245-315: edit these sections. They contains a simple description of the data available (Tables 2 and 3, Figure2).
Author Response: Due to the redundancy of the text and Table 2 the table was removed from the manuscript.
Line 266 and Table 2: provide the different units. Also, E. coli should be italic. Clarify the four sites. Do not use #1, #2, #3, and #4.
Author Response: Due to a redundancy between table 2 and the preceding text this table has been removed from the manuscript.
Lines 288-290: this is a self-imposed limitation of the study. The authors should have diluted their samples.
Author Response: We agree with the reviewer that this is a limitation to the work brought about by the fiscal limitations of the current work (as described earlier).
Lines 314-315 and table 3: replace shaded cells with “bold” numbers. Also, add a space between “<” and “5” (after Smallest Interval)
Author Response: The recommended changes were made.
Lines 319-329: combine this paragraph with “3.1 Climate during Study”
Author Response: The paragraph was moved and combined with the “3.1 Climate during Study” section as per the reviewer’s request.
Line 332: specify the GPS coordinate of the sampling location. Also, provide the atmospheric data source(s).
Author Response: The GPS location was added and the atmospheric data source has been noted.
Line 334: replace Escherichia coli with E. coli
Author Response: The change was made as per the reviewer’s comment.
Lines 335-366: do not compare your findings with results obtained at the same locations.
Author Response: The comparisons have been removed as per the reviewer’s comments
Line 338 and Figure 5:E. coli should be italic. Also, replace um with mm. Please, improve the quality of this figure. Please use the same number of decimals (54% vs. 49.1% vs. 1.03)
Author Response: The reviewer’s corrections were implemented. Except um was replaced with µm instead of mm.
Lines 341-346: redundant.
Author Response: The reminder portion of this paragraph was removed as per the reviewer’s request.
Line 367 and Figure 4: Use the same number of decimals (54 vs. 40.6).
Author Response: The number of decimals in the figure are now the same
Lines 371-372: remove ** and ***. No additional details are given. In alternative, please edit them.
Author Response: The removal was made as per the reviewer’s comment
Line 373: add a space between < and 5
Author Response: The space has been added.
Line 418 and Figure 6: Spell-out SPM in your legend, and add SPM after “matter” in your caption. There should be a space between “m” and “< interval”. Add filtration size in your legend. The four Y-axis should have the same range (0-800). Also, do not add “$” after each value on the Y-axis since the Y-axis name (Percentage Difference (%) is present).
Author Response: We appreciate these reviewer recommendations. SPM was added in the caption and the space between “m” and “< interval” was added. The Y-axis ranges were changed as recommended. SPM was not spelled out in the legend as this created formatting issues and made the figure seem overly cluttered. That definition is included in the Figure heading. Finally, the percentage (%) after each Y-axis value was removed as recommended.
Line 445 and Figure 7: E. coli should be italic (Y-axis). Show the actual values on the Y-axis (instead of + 1). Also, remove “Legend” from your legend. Be consistent throughout the manuscript. Add “filtration size” in your legend
Author Response: “Legend” has been removed from our legend and the reasoning behind the +1 was clearly explained to avoid further confusion. This was achieved by adding the following note to the figure caption “Note all the E. coli concentration value had one added to them to avoid ln values being undefined were E. coli concentrations were zero”. An additionally note was added regarding the filtration size namely: ”Additionally, interval size was dictated by the filer sizes (5μm and 60μm) that we used during the filtration of the extracted water samples”, which will aid in claring up any misconceptions by the readers of the manuscript.
Line 447: add space between m<interval<60. Be consistent
Author Response: The spaces were added as requested.
Line 470 and Figure 8: E. coli should be italic. Also, be consistent “<5” vs. “< 5”. Use the same decimal in your legend (54% vs. 406.6%)
Author Response: E. coli was italicized and the spacing and decimal inconsistencies were removed.
Line 477-478: redundant
Author Response: The sentence has been removed.
Lines 502-521: re-write this paragraph.
Author Response: The paragraph has been altered to more effectively highlight study results. Study results were highlighted by altering the text to the following: “Key results showed the statistically significant correlation of SPM (α = 0.05 with E. coli concentration. Moreover, the importance of SPM in the < 5μm interval was also highlighted as 1) more than 90% of E. coli data was found in this smallest interval at all four sampling locations, 2) the interval also featured the strongest correlation with E. coli concentration data (α < 0.0001), and 3) increasing SPM concentrations in the ≤ 5µm interval showed corresponding increases in relative E. coli concentration”.
Lines 487-490: the authors should have implemented these suggestions instead of acknowledge them
Author Response: We appreciate the position of the reviewer in this matter, and hope that the revisions and responses to this point help to address the concerns.
Lines 502-509: remove these sentences. No intro or goals should be included here (conclusions!)
Author Response: We understand the style difference as noted here by the reviewer. However,
the convention in the hydrologic/geochemistry literature includes the option of providing a brief overview of the context of the work and as such we did not remove this text.
Line 516: remove PCA
Author Response: PCA was removed as requested.
Line 545: title shouldn’t be “italic”
Author Response: Italicized title was corrected.
Line 546: 2017 should be “bold”
Author Response: The requested change was made.
Line 551: please edit this reference according to the journal’s guidelines
Author Response: The reference was edited according to the journal’s guidelines.
Lines 564-565: do not capitalize each word. Please be consistent throughout the manuscript
Author Response: Formatting was corrected.
Lines 566-567: do not capitalize each word. Please be consistent throughout the manuscript
Author Response: Formatting was corrected.
Lines 575; 579-580: do not capitalize each word. Please be consistent throughout the manuscript
Author Response: Formatting was corrected.
Lines 606, 714: E. coli should be italic.
Author Response: E. coli was italicized.
Line 610. Add “.” between “Mountains” and “Available”.
Author Response: This reference is no longer included in the manuscript as it was removed when shortening the paragraph describing the suitability of the work in Appalachia.
Lines 622-623: do not capitalize each word. “2008” should be “bold”. Also, add page number(s)
Author Response: The requested changes were made.
Line 650; 673-674: do not capitalize each word
Author Response: Formatting was corrected.
Lines 704-705: please edit this reference. Authors à title à journal/book à year à issue à pages
Author Response: The reference was corrected as per the reviewer’s comment.
Line 706: do not capitalize each word. Also, Remove “Environmental Science & Technology”
Author Response: The reference was corrected as per the reviewer’s comment.
Reviewer 2 Report
The authors did not provide sufficient clarity on details relating to the sampling regime of the study, the number of samples collected per land-use site, and the frequency of sampling.
Details on how E.coli biomass was recovered for the 5um<interval<60um and measured using the Colilert are also not clear.
It would be difficult to assess findings and conclusion of the manuscript and hence i urge the authors to include these details before a proper review can be made.
Author Response
The authors did not provide sufficient clarity on details relating to the sampling regime of the study, the number of samples collected per land-use site, and the frequency of sampling.
Author Response: We thank the reviewer for this constructive observation. We have taken the reviewer’s comments seriously and greatly improved the manuscript. We have revised the data collection section of the manuscript to clarify the sampling procedure used during the current work including clearly stating the number of samples (n =32) collected from each sampling location.
Details on how E. coli biomass was recovered for the 5um<interval<60um and measured using the Colilert are also not clear.
Author Response: Thank you for pointing out this shortcoming in the manuscript. We have updated our data collection section to explain how E. coli biomass was recovered for the 5um < interval < 60um.
It would be difficult to assess findings and conclusion of the manuscript and hence i urge the authors to include these details before a proper review can be made.
Author Response: We appreciate this insightful comment by the reviewer. We have revised the concluding paragraph and more clearly highlighted key results. Study findings were highlighted by altering text in the conclusion from “Key results showed the predominance of E. coli concentrations correlated to the <5 μm interval, with more than 90% of the total average E. coli concentration being found in this interval at all four sampling locations. Further analysis emphasized that size interval (α < 0.0001) and SPM (α =0.05) showed statistically significant relationships with E. coli concentration. Furthermore, increasing SPM concentrations ≤ 5µm showed corresponding increases in relative E. coli concentration. Results generally indicate that E. coli in receiving water is found primarily in conjunction with SPM particles < 5µm in size, thus implying that E. coli principally remains free floating or attaches to particles <5µm in size in receiving waters” to “Key results showed the statistically significant correlation of SPM (α = 0.05 with E. coli concentration. Moreover, the importance of SPM in the < 5μm interval was also highlighted as 1) more than 90% of E. coli data was found in this smallest interval at all four sampling locations, 2) the interval also featured the strongest correlation with E. coli concentration data (α < 0.0001), and 3) increasing SPM concentrations in the ≤ 5µm interval showed corresponding increases in relative E. coli concentration. These results generally imply that E. coli principally remains free floating or attaches to particles <5µm in size in receiving waters”.
Reviewer 3 Report
This manuscript presents a needed study on quantifying the relationship between Escherichia (E) coli concentration, and suspended particulate matter (SPM) particle size class, and land use practices. I think the authors have done a great job in research design, data collection, data interpretation, as well as writing. I think it is relevant to the interests of the journal Water and should be published after some minor revisions are incorporated.
Line 36: Alone -> alone.
Table 1: Ag (%) -> Agricultural (%)
Figure 1: Label the white-color map, which I think is WV.
Line 220: Give a brief explanation on Anderson Darling Test and Ordinal logistic regression.
Line 245: Recommend abbreviating Suspended Particulate Matter to SPM here and many other occurrences in the manuscript (after line 40).
Table 2: Can be removed since the same information is also contained in Figure 2.
Figure 4: Describe why the CFU curves are more parallel with each other than the SPM curves are.
Figure 6: This figure can be more clearly presented. Suggest separate the SPM and E. coli information. Make a 4x2 plot with left 4 rows showing SPM information and right four shows showing E. coli information.
Line 465: Correlated not only (with) the ….
Author Response
This manuscript presents a needed study on quantifying the relationship between Escherichia (E) coli concentration, and suspended particulate matter (SPM) particle size class, and land use practices. I think the authors have done a great job in research design, data collection, data interpretation, as well as writing. I think it is relevant to the interests of the journal Water and should be published after some minor revisions are incorporated.
Author Response: We wish to thank the reviewer for this very supportive statement. We appreciate the time and energy spent by the reviewer to review the manuscript.
Line 36: Alone -> alone.
Author Response: The typo has been fixed, we thank the reviewer for bringing it to our attention.
Table 1: Ag (%) -> Agricultural (%)
Author Response: The requested changes were implemented.
Figure 1: Label the white-color map, which I think is WV.
Author Response: We respectfully submit that as the figure caption already contains information regarding the location of the watershed in WV labelling the insert map would be redundant and would result in the figure being more cluttered.
Line 220: Give a brief explanation on Anderson Darling Test and Ordinal logistic regression.
Author Response: The brief explanations were added as requested by the reviewer.
Line 245: Recommend abbreviating Suspended Particulate Matter to SPM here and many other occurrences in the manuscript (after line 40).
Author Response: The requested changes were implemented.
Table 2: Can be removed since the same information is also contained in Figure 2.
Author Response: The table has been removed due to the redundancy, as per the reviewer’s suggestion.
Figure 4: Describe why the CFU curves are more parallel with each other than the SPM curves are.
Author Response: We thank the reviewer for this observation. The objective of the current investigation was not establishing the relationships between different land use practices and SPM or E. coli concentrations in receiving waters, but rather investigate the relationship (correlation) between SPM (size class) and E. coli concentrations and the combined influence of land use practices on this relationship. Therefore, results pertaining to site differences between E. coli and SPM concentrations must be interpreted with caution (as noted in text). Additionally, the parallel shape of the curves (specifically during the final samples) are influenced by the irregular sampling regime, which had temporarily ceased while we were waiting for an appreciable precipitation event to increase stream stage at our sampling locations (as noted in text). Furthermore, the upper limit of the IDEXX method as applied could potentially be suppressing the shape of the CFU curves, thereby making comparison with the SPM curves difficult. We have clarified the shortcoming of the IDEXX method as applied and recommended future work include serial dilution, which were omitted from the current work due to the fiscal limitations of the investigation. We hope the reviewer finds the steps taken adequate to address this comment.
Figure 6: This figure can be more clearly presented. Suggest separate the SPM and E. coli information. Make a 4x2 plot with left 4 rows showing SPM information and right four shows showing E. coli information.
Author Response: We appreciate the recommendation by the reviewer, however as we wish to directly illustrate the percentage differences of both SPM and E. coli simultaneously between sites we feel the original formatting of four nested figures accomplishes this the best. There were other recommendations from other reviewers pertaining to this figure and we made a number of those changes. This includes revision of the Y-axis of the nested graphs to be consistent etc. We hope the reviewer will agree that the figure is now clear enough to warrant publication.
Line 465: Correlated not only (with) the ….
Author Response: The recommended correction was made.
Thank you again for your constructive and instructive comments that have substantively improved the manuscript.
Round 2
Reviewer 1 Report
The authors have addressed some of the previous concerns. However, due to the limitations of the experimental design and consequently of the results, this manuscript should be submitted as a Short Communication/Case Study.
