A. I think the effect of alkalinity on surface sediment Na/Ca ratio is quite apparent in case of Caribbean samples. In fact the change in Na/Ca is almost of the same magnitude as in figure-4. This issue may be little bit more clarified.

B. The dispersion (error bar) in the Na/Ca data from surface sediments are quite large (Fig. 6A). Authors may suggest how much error in paleosalinity measurement is expected using T.succulifer based Na/Ca ratio measurements? and how this will be advantageous to Mg/Ca based measurement currently used since the author has suggested multi-proxy approach at the end.

C. In a routine measurement, an aliquot of multiple well preserved shells are expected to be used for Na/Ca measurement, which i believe represent an homogenized number than the point specific measurements using EPMA which is bound to show a lot of dispersion. Author may kindly clarify how an EPMA based calibration line would work for aliquot based measurement?

Thanks for the point to point responses. I happy to accept the manuscript for publication in Biogeosciences.