The author have taken most critical points of the reviewers into account, but several points mainly raised by reviewer#3 should be addressed in more detail.

Reviewer#3 was asking for absolute FA data, however, the authors stated: "We did not use absolute FA amounts because our data set did not allow us to do so..." It would be good to state in the Mat&Met section why these data could not be measured.

I am not fully convinced by the authors response to the reviewer#3's statement: "As the authors admit, the absence of strong OA effects on the FA composition of phyto- and zooplankton reported here is not particularly surprising for a low salinity and high variability system such as the Baltic Sea. Hence, although this study is conducted properly, it has limited appeal and a presumably low impact."
In my opinion it would be good to increase the appeal of the present study by highlighting its specific new findings.

Thus, I would like to also have the reviewers opinion on a carefully revised manuscript.

Dear Dr. Bermudez,

the revised version fulfils all requirements of the reviewers and hence I am happy to let you know that we now can accept your manuscript as it is.

Sincerely yours Hans-Peter Grossart