Using Single-Species and Whole Community Stream Mesocosm Exposures for Identifying Major Ion Effects in Doses Mimicking Resource Extraction Wastewaters

Round 1

Reviewer 1 Report

The paper is generally well done, the description of the different steps and phases of the research are well defined, discussion is perhaps too long.

Some figure are not so clear (i.e. Fig. 4, 5 and 7).

The authors should also to explain if the work can be extended to other situations and how.

Author Response

Responses to Review 1 comments:

Comment 1: We are glad to hear that the reviewer found the paper ‘well done’ and that the description of the effort was adequate. We made several attempts to shorten the discussion and understand that it is a relatively long read compared to other papers. However, we think the length is necessary to convey the relevance of the results to the problem of managing resource extraction wastewaters. We reviewed the discussion section again and made minor deletions, but it still runs a bit long. We think the length is warranted given the comprehensive nature of the study.

Comment 2: We have provided new PDF files for figures 4, 5, and 7.

Comment 3: We have noted at L137 to L141 how this study is generally applicable to areas where potential impacts from deep well resource extraction, as well as surface or near surface coal mining could be occurring simultaneously. Thank you for this suggestion.

Reviewer 2 Report

The article is well written. However, a couple of suggestions are mentioned below.

1) Please enhance the quality of Figures 5 and 7.

2) Please add concise conclusion for better and quick approach to the exact finding of this extensive work.

The article is acceptable after revisions.

Author Response

Responses to Review 2 comments:

Comment 1: New PDFs have been provided by Figures 5 and 7. The quality of these two figures have been enhanced.

Comment 2: A “Conclusion” section has been added. Thank you for the suggestion.

Reviewer 3 Report

The novelty of the study should be described at the end of the introduction section.

The conclusion section is missing.

Why had the highest dose of the DWB recipe negative impact on certain ecologies?

Figures 5 and 7 are not clearly visible.

What are the differences between Ex-situ Cincinnati culture and Duluth culture?

Author Response

Responses to Review 3 comments:

Comment 1: We have added two sentences (L141 to L145) in the last paragraph of the introduction describing the novelty of our study.

Comment 2: We considered the last paragraph of the discussion a ‘conclusion’ to the study. We have added a section titled “Conclusions” and revised the last paragraph to read more like a traditional conclusion section.

Comment 3: Regarding the question about the highest level of the DWB recipes. The question, as written does not make it clear what the reviewer is asking. We think the reviewer means to ask why did the highest dose of the DWB recipe impact certain ecologies negatively? We address this question with additional text L696 to L701.

Comment 4: We have included new PDF files of the figures 5 and 7. The text should be more legible in these new versions.

Comment 5: These ex-situ tests both involve larval fathead minnows (P. promelas). The Ex Situ test designated as the Cincinnati Culture uses fish cultured in Cincinnati, while the Duluth culture signify that the fish used in this test were cultured at our EPA lab in Duluth, Minnesota. The significance is that the cultured fish are reared in waters of different background TDS/Specific Conductivity. The larval fatheads from the Duluth culture were reared in lower TDS water coming from Lake Superior. The fish obtained from the Cincinnati Culture are reared in condition tap water whose source is the Ohio River, which has a higher TDS content. We were interested in determining if the differences between these background TDS’s of the cultures affected the way that the fish responded to the excess TDS of the different dosing recipes. This is explained in the Methods section: L357 to L3363. We’ve added a clarifying text in this section of the revised version of the MS to make this clearer as well as directing the reader to this text in the description of Figure 3.

Round 2

Reviewer 3 Report

References 10, 16, 62, 68, and 69 are not related to this work. Therefore, all these references should be removed.

 

Reference section is too long. It should be restricted to those references which are very relevant to this work.

Author Response

Regarding the comments about too many references and more improvement to the conclusions section.

We thank the reviewer for these comments. We have removed the 5 references suggested by the reviewer as unnecessary and reviewed the rest of the citations in the document. While we feel all of the remaining references were relevant, several were conceptually redundant. We have tried to reduce this redundancy by eliminating an additional 18 references. Therefore, we have reduced the number of references by 23. 

Finally, we added an additional sentence to the conclusion section to improve it further and be more consistent with the abstract. It highlights a major relevance of the results for the management of resource extraction wastewaters.

Author Response File: Author Response.docx