Dear Dr Rebotim and co-authors,

Thank you very much for uploading your answers to the reviews by Drs Bijma and Mortyn. I think you have satisfyingly replied to their comments and improved your manuscript accordingly. Therefore, it is fit for publication in Biogeosciences after incorporating some minor issues I came across when reading the second version of your manuscript. Please incorporate them along with the changes you suggested yourself before uploading your final version.

I think it is good to incorporate (briefly) the reply to Dr Bijma’s first comment (i.e. the use of a size fraction for which the mortality is in the manuscript. For example, in the beginning of the discussion (page 11, somewhere between lines 15 and 25).
Page 2, line 18: this sentence “...in the plankton (Berger, 1969.....” seems incomplete.
Page 2, line 26: consider changing “...mechanism, with buoyancy being regulated by...” into “...mechanism, which is primarily regulated by...”
Page 2, line 28: “not sufficiently known” reads better as “not fully understood”
Page 3, line 5: the word “simulating” is slightly confusing here. Consider changing into: “...internal waves, leading to apparent vertical migration...”
Page 3, line 22: “...in many species...” should be “...among species...”
Page 5, line 27: I guess in some cases it was a midi- and in others a maxi-version of the Hydrobios net. Then it would be better to state “...either a Midi- or Maxi multiple closing net...”
Page 6, line 25: please specify “satellite values”. Values for what?
Page 6, line 31: please specify “the vertical profile for each species”. Their abundance?
Page 7, line 14: replace “ones” with “variables”.
Page 9, line 9: what does “seem to vary in proportion to their ALD” mean?
Page 9, line 21: replace “to a certain degree due to the” by: “caused by an”
Page 12, line 15: “...it could also represent...” should be a separate sentence.
Page 12, line 17: delete “had”
Page 13, line 14: insert “thereby” after the second “and”.
Page 13, line 28: insert a dot after “al”
Throughout the discussion: ALDs “below” or “above” a certain value can be confusing. Please refer to ALDs that are shallower or deeper than x meters.
Page 18, line 25: replace “above” by “more than”
Page 22, lines 11-13: this sentence is unclear. Equilibrium with respect to what? I guess this mainly refers to oxygen isotopes, because e.g. Mg/Ca is never said to be “in equilibrium” with that of seawater (although the reference to Nürnberg suggests that this sentence also refers to e.g. Mg-incorporation).
Page 22, line 26: complexity in what?
Page 22, line 29-30: what is the consequence of the (potentially) variable concentrations of pigments?

Dear Dr Rebotim and co-authors,

I think the last changes have resulted in a fine paper that I suggest to publish as it is now.

all the best,

Lennart