Peer Review #1 of "Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea (v0.1)"

fall.The seasonality of heterotrophic prokaryotes (2.29 -4.21× 10 5 cell mL -1) was less noticeable than autotrophic picoplankton.The contribution of HNA cells was generally low in the upper layers, ranging from 36% in late spring and early summer to ca.48 -51% in winter and fall.Autotrophs dominated integrated picoplankton biomass in the upper 100 m, with 1.4-fold higher values in summer than in winter (mean 387 and 272 mg C m -2 , respectively).However, when the whole water column was considered, the biomass of heterotrophic prokaryotes exceeded that of autotrophic picoplankton with an average of 411 mg C m -2. Despite being located in tropical waters, our results show that the picoplankton community seasonal differences in the central Red Sea are not fundamentally different from higher latitude regions.