Dear authors,
Thank you for your responses to the reviewers' comments. I invite you now to upload a revised version of your manuscript that should take into account those comments, as outlined in your response.
Thank you for submitting your work to Biogeosciences.
Best regards,
Emilio Marañón

Dear authors,

Thank you for submitting the revised version of your manuscript, which is now acceptable for publication in Biogeosciences. Before you prepare the final version of your article, I would like to suggest that you consider an additional explanation for the relationship between degree of calcification and environmental drivers (pages 24-25). It is important to bear in mind that (as noted by Smith et al. 2012) a larger amount of calcite per cell does not necessarily indicate a higher rate of calcification (e.g. a faster turnover of PIC), but can result from a reduced rate of cell division. As noted by Paasche (Phycologia 33:324), 'calcification is less strongly curtailed than photosynthesis under adverse growth conditions'. This means that when C fixation is reduced (due to lack of light and/or nutrients) cells will become more heavily calcified (will have more liths per cell, and liths will be larger). This can explain your observation that liths are smaller in summer (the productive season), as well as the observations of Smith et al. in the Bay of Biscay (a higher % of overcalcified cells in winter).

Thank you for submitting your work to Biogeosciences.

Best regards,

Emilio Marañón