Dear author,
The manuscript presents data complementary to that presented in Gazeau. Unfortunately the presentation of the data seems somewhat arbitrary: It is unclear when the different parameters were estimated and why, in particular when BP and specific growth rates and "net growth rates" were estimated. Viral losses were estimated at t0, t24 and T48, but only values at t0 and t24 are shown in Fig. 1 why? Growth rates in Table 2 and Fig 1 (first row) gives values of BP or bacterial accumulation rates? Please define what µapp is in the methods. Figure 1: How are cell specific growth rates determined, are those based on 3H-Leu incorporation or on bacterial accumulation rates? How are VLP (virus production) and bacterial mortality rates estimated? (none of these are mentioned in the materials and methods). In short, please describe all parameters (how they are estimated) and corresponding acronyms used in the materials and methods, and keep those in the result presentation. It is also difficult to follow when each parameter was measured and why the full dataset is not presented here: it seems that parameters are presented selectively and over different time periods (i.e. Table 2 and Fig. 1), there is, however, no justification for this. Please provide a table with all measurements and their uncertinties carried out here in the manuscript or supplements. Provide rates at comparable time intervals as well as temporal evolution of relevant abundances (i.e. HB, Synechococcus, picoeukaryotes and heterotrohic nanoflagellates (HNF)).

Further, the discussion seems based more on the evolution of abundances in the treatments (lines 423-459) presented in Gazeau (same issue) without the robust analysis that the parameters presented here deserve; with the available data one would expect robust interpretation of bacterial temporal abundance changes based on growth rates, mortality rates and the contribution of viruses and HNF grazing to mortality (see also reviewers'1 comments).

Additional comments:
Line 104: samples for what? BP?
line 111: add "Heterotrophic procaryotes (HB), synechococcus...."
Lines 113-116: I imagine here you refer to 2 different parameters? Specific growth rates based on 3H-Leu and accumulation rates ("net growth rates"?) based on evolution of abundances in each treatment at the beginning of the experiments? Does the net accumulation rate correspond to µapp in table 2? Why are the time intervals in Table 2 different?
line 143:"Briefly, increase in virus abundance in the control tubes represents lytic viral production (VPL), and an increase in mitomycin C treatments represents total (VPT)". Do you mean "Briefly, increase in virus abundance in the control tubes represents lytic viral production (VPL), and in mitomycin C treatments represents total (VPT)". That is for the mitomycin C treatment you also record changes in viral abundances?
Fig.1 Legend: replace "raw" with "row".
Fig.1: the data in row 1 (specific growth rates) correspond to what sampling time?
Lines 196-199: how do the regressions in Figure 2 inform on bottom up controls? What is the actual point here? If resources were not limiting no response in dust amended tanks would be expected isn't it?
Line 201-203: how is top down controls on HNF abundance relevant in the context of this manuscript?
Lines 208-209, Table 1:"The abundance and production of virus-like particles (VLP) increased following an east to west gradient (Table 1).". It would make sense to organise stations in the table also from east to west." Also please indicate in the text: "The initial abundances and production of virus-like...".
Lines 209-212: FLC and FLIC show actually opposite trends which are unrelated to VLP and Virus production rates.
Line 213-222: In terms of understanding processes Figure S3 would be more relevant. I would suggest providing Fig. S3 with the main text, and explain changes in proportion based on the evolution of abundances.
Lines 318-314: The manuscript discusses top-down and bottom-up controls using indexes without referring to the rates presented i.e. differences between bacterial production and accumulation rates, or simply the evolution of bacterial abundances in dust amended vs. control are the best indicators of top-down/bottom-up control.
Lines 496-498:"Overall, the impact of such simulated pulsed nutrient deposition will depend on the initialbiogeochemical conditions of the ecosystem, with likely possible large impact on microbial trophic interactions and community structure." It is not clear how the data presented here supports this conclusion.

Sincerely,
Christine Klaas

Dear author,
The manuscript presents data complementary to that presented in Gazeau. Unfortunately the presentation of the data seems somewhat arbitrary: It is unclear when the different parameters were estimated and why, in particular when BP and specific growth rates and "net growth rates" were estimated. Viral losses were estimated at t0, t24 and T48, but only values at t0 and t24 are shown in Fig. 1 why? Growth rates in Table 2 and Fig 1 (first row) gives values of BP or bacterial accumulation rates? Please define what µapp is in the methods. Figure 1: How are cell specific growth rates determined, are those based on 3H-Leu incorporation or on bacterial accumulation rates? How are VLP (virus production) and bacterial mortality rates estimated? (none of these are mentioned in the materials and methods). In short, please describe all parameters (how they are estimated) and corresponding acronyms used in the materials and methods, and keep those in the result presentation. It is also difficult to follow when each parameter was measured and why the full dataset is not presented here: it seems that parameters are presented selectively and over different time periods (i.e. Table 2 and Fig. 1), there is, however, no justification for this. Please provide a table with all measurements and their uncertinties carried out here in the manuscript or supplements. Provide rates at comparable time intervals as well as temporal evolution of relevant abundances (i.e. HB, Synechococcus, picoeukaryotes and heterotrohic nanoflagellates (HNF)).

Further, the discussion seems based more on the evolution of abundances in the treatments (lines 423-459) presented in Gazeau (same issue) without the robust analysis that the parameters presented here deserve; with the available data one would expect robust interpretation of bacterial temporal abundance changes based on growth rates, mortality rates and the contribution of viruses and HNF grazing to mortality (see also reviewers'1 comments).

Additional comments:
Line 104: samples for what? BP?
line 111: add "Heterotrophic procaryotes (HB), synechococcus...."
Lines 113-116: I imagine here you refer to 2 different parameters? Specific growth rates based on 3H-Leu and accumulation rates ("net growth rates"?) based on evolution of abundances in each treatment at the beginning of the experiments? Does the net accumulation rate correspond to µapp in table 2? Why are the time intervals in Table 2 different?
line 143:"Briefly, increase in virus abundance in the control tubes represents lytic viral production (VPL), and an increase in mitomycin C treatments represents total (VPT)". Do you mean "Briefly, increase in virus abundance in the control tubes represents lytic viral production (VPL), and in mitomycin C treatments represents total (VPT)". That is for the mitomycin C treatment you also record changes in viral abundances?
Fig.1 Legend: replace "raw" with "row".
Fig.1: the data in row 1 (specific growth rates) correspond to what sampling time?
Lines 196-199: how do the regressions in Figure 2 inform on bottom up controls? What is the actual point here? If resources were not limiting no response in dust amended tanks would be expected isn't it?
Line 201-203: how is top down controls on HNF abundance relevant in the context of this manuscript?
Lines 208-209, Table 1:"The abundance and production of virus-like particles (VLP) increased following an east to west gradient (Table 1).". It would make sense to organise stations in the table also from east to west." Also please indicate in the text: "The initial abundances and production of virus-like...".
Lines 209-212: FLC and FLIC show actually opposite trends which are unrelated to VLP and Virus production rates.
Line 213-222: In terms of understanding processes Figure S3 would be more relevant. I would suggest providing Fig. S3 with the main text, and explain changes in proportion based on the evolution of abundances.
Lines 318-314: The manuscript discusses top-down and bottom-up controls using indexes without referring to the rates presented i.e. differences between bacterial production and accumulation rates, or simply the evolution of bacterial abundances in dust amended vs. control are the best indicators of top-down/bottom-up control.
Lines 496-498:"Overall, the impact of such simulated pulsed nutrient deposition will depend on the initialbiogeochemical conditions of the ecosystem, with likely possible large impact on microbial trophic interactions and community structure." It is not clear how the data presented here supports this conclusion.

Sincerely,
Christine Klaas