November 4, 2015
Dear Author,
Thanks for replying to reviewers. Please consider the following issues:

1. I agree with reviewer 1 (#10) that N:P as written (6.35/1.10, etc.) is confusing. If you are terribly compelled to do it that way (for some reason that I do not clearly see) then use both with # in parenthesis

“10. The authors report the N:P but not with P relative to one. I think this is confusing.
For example, page 10002, lines 14- 16. N:P 6.35/1.10, 12.00:1.25. It would be better if this was written as: 5.77 and 9.6 respectively and details of the concentration be inserted into a table, for example.
We prefer to report the N:P ratios as they are. That way, mesocosms with the same initial concentrations of N or P (center points) are easier to distinguish for the reader.”

2. Could we see an attempt of mass balance? This is a crucial issue in any m-cosm experiment.

“Given the extensive measurements of the P pools (see e.g. Figure 10), it would have been useful to see an attempt at mass balance.
We addressed this issue by data presented in Fig 10. Mass balances were not subject of this manuscript but will be addressed in a follow up study. More extensive presentation of mass balances would be beyond the scope of this study.”

3. In Abstract, L14: replace “excess P” with excess “phosphate”. Is that what you mean, Do you?


4. Throughout all text
Si is symbol for element Silicon, silicate is a mineral, silicic acid is nutrient for diatoms (or dissolved silicon, DSi).

Best regards

Silvio Pantoja
Associate Editor

Review bg-2015-236
January 9, 2016
Dear Dr. Meyer,
Thanks for submitting version 2 of bg-2015-236. Although most comments and questions of Reviewers have been taken care of, there a few that merits your further consideration:

1) Reviewer 1. “The authors report the N:P but not with P relative to one. I think this is confusing.. For example, page 10002, lines 14- 16. N:P 6.35/1.10, 12.00:1.25. It would be better if this was written as: 5.77 and 9.6 respectively and details of the concentration be inserted into a table, for example.”

Response. “We prefer to report the N:P ratios as they are. That way, mesocosms with the same initial concentrations of N or P (center points) are easier to distinguish for the reader.”

I agree with reviewer. We are not interested in a mesoscosm result by itself but inferences about ocean´s response, and for that it is easier for readers to have ratios relative to one since this article is based on deviations of canonical N:P. Please change accordingly.


2) “9. The authors switch between N and P and NO30 and PO43-. This needs to be fixed and made consistent throughout.”

Response: We made this consistent throughout the manuscript.”

I need to ask you to use proper nomenclature throughout the text. For general statements such as the ones in lines 47-52 of v2, it could be fine to use N or P, but regarding your results, you must refer to what you are experimenting with (nitrate or NO3-), but not N since nitrogen (N) involves a variety of chemical species you have not studied. One example is shown in conclusions in lines 328-329 of version 2 (“…ability of the plankton community to rapidly and intensively react to N availability. These results indicate that the ultimate limiting nutrient for phytoplankton production in our experiment was N.”).


3) Line 402 v2. Replace “measured” with “detected”. It makes a more clear argument.

4) Reviewer 2. “Given the extensive measurements of the P pools (see e.g. Figure 10), it would have been useful to see an attempt at mass balance.

We addressed this issue by data presented in Fig 10. Mass balances were not subject of this manuscript but will be addressed in a follow up study. More extensive presentation of mass balances would be beyond the scope of this study.”

Reviewer is referring to mass balance as part of the method. It cannot be “beyond the scope of this study” rather, how balance or lack of balance affects your interpretation.

5) Why nitrate plus nitrite increase during the first day?

6) Please write nitrate or NO3- (using subscripts and superscripts) throughout text and figures. Same format for nitrite, silicic acid.


Sincerely your


Dr. Silvio Pantoja
Associate Editor