Dear Dr. Ghadouani

Thank you for uploading your suggestions how to revise the manuscript in response to the comments by the reviewers.
Based on the reviews and your answers I suggest that you revise the manuscript as you have outlined before. Depending on the revised version I may consider getting a feedback by the reviewers whether they consider the revision appropriate or not.
In addition to the comments by the reviewers I suggest that you pay attention to the following issues that I add as editor (some being related to points mentioned in the reviews as well, others are in addition):
p. 11111, L. 1: Which are the global communities you have in mind?
p. 11111, L. 4: … one of the biggest challenges…: based on what can you make this statement?
p. 11114, L. 21/22: Reichwaldt, unpublished data: The assumption of complete mixing is essential for the interpretation of the results. Therefore you have to show some of the unpublished data in the SI such that one can see that your statement on the complete mixing is actually supported by the data.
p. 11115, L. 11: … an algorithm…: please specify.
p. 11118: L. 7 – 18: I am not fully convinced by your answer to the comment by Reviewer 2. You agree that his suggestion of including the sites as an additional variable was an easier option. But you do not provide an argument why not to adopt this proposition. It seems not to be a tremendous hurdle regarding time and effort but could improve readability of the manuscript. Therefore, I suggest that you carry out the proposed analysis or provide a clear argument why not to do so. Whether the analysis is carried out in R or not is not an issue here.
p. 11120/11121, sections 3.3 and 3.4: For these two sections, I share similar concerns as expressed in Review 2. One concern is the writing/presentation. For example, you state that the lakes differ regarding the correlations that are observed and refer to Table 2 (p. 11120, L. 24). This table however, does not report the site-specific correlations. Therefore, it is not appropriate. A table showing the site-specific results is missing.
You also hardly present data that allow for a better understanding why the correlation structures obtained differ depending on whether one looks at the lakes individually or if pooled together. In order to improve this part of the manuscript I suggest three things:
i) Complement Table 2 with the results for the single lakes
ii) Include additional scatter plots that depict all data from all lakes in a single chart for each single explaining variable (e.g., cyanobacterial fraction as a function of TP). Include the correlations of the single lakes and the correlation for the pooled data set.
iii) Discuss these scatter plots.
The table and figures will allow for a much better understanding of what is going on. The scatter plots for example will allow for a better understanding to which degree the partially conflicting results between single-lake and pooled lake data sets can be explained by the different ranges of the explaining variables among lakes.

p. 11122, L. 1 (and elsewhere): The expression of site-specific and unique environmental triggers may be somewhat misleading. Perhaps it would be more appropriate to talk of context-dependency: one probably does not need a unique explanation at each site, but within a general explanatory concept for cyanobacterial blooms the relevance of a single environmental factor may depend on the site-specific combination of other factors. Reading your manuscript I have the impression that this corresponds to what you have in mind. Hence, I think it is more of a linguistic issue you may think about.
p. 11124, L. 15 – 19: This statement seems to contradict the statement on p.11123, L. 25 – 27. Please clarify.
A further comment regarding your replies to the reviews:
Response 3 to Review 2: You argue that you have not included temperature and pH into the statistical analysis because these variables did not differ among the lakes. This argument is not convincing for two reasons:
i) It contradicts your own approach: Table 1 shows that TFe did not differ among the lakes. Nevertheless, you have included TFe into the analysis.
ii) The fact there is no significant difference between lakes does not imply that there is no influence.
I strongly suggest that you include the two variables into the analysis.

Sincerely

Dr. Christian Stamm
Editor HESS
Environmental Chemistry
Eawag
Ueberlandstr. 133
CH-8600 Dübendorf, Switzerland

Dear Dr. Ghadouani

thank you for the thorough revision of the manuscript. I consider the open issues as well addressed and think the manuscript is ready for publication after some minor technical corrections. I list these points right below.

Sincerely

Christian Stamm

Points for technical corrections:

L. 44: Please explain TFe because it is the first use in the text.
L. 249: Should it not be "99.9% methanol and 0.1% trifluoroacetic acid"?
L. 297: You say that the temperature ranged between 27 and 43°C during the study period. However, this is just based on the measurements during the sampling days. Please reword accordingly or depict the full range in Fig. 3B of data from the meteorological station.
L. 323: "air temperature" instead of "Air temperature"
Fig. 2: Only the upper part of the SD are visible. Please correct.