Dear Dr. Zilius
Thank you for your response (and dialogue) with the reviewers. I can see you have comprehensively addressed both reviewers comments. Please upload the final version of the manuscript and a copy of the responses as prompted by the system for me to do one final check over before acceptance.
Regards
Perran Cook

Dear Dr. Zilius
Thank you for your comprehensive response to the reviewers. Your manuscript makes an important contribution to improving our understanding of the spatial dynamics of N2 fixation and its role in coastal nitrogen budgets.

In my final reading of the manuscript and discussion, I picked up an important subtlety in your discussion regard P release from the sediment. As you note, water column anoxia is one factor, but sediment respiration is another important factor.

Cook, P.L.M., D.P. Holland, and A.R. Longmore, Effect of a flood event on the dynamics of phytoplankton and biogeochemistry in a large temperate Australian lagoon. Limnology & Oceanography, 2010. 55: p. 1123-1133.

The reason for this is most likely increased rates of increased rates of sulfate reduction and binding of Fe as FeS, which prevents the formation of FeOOH that would otherwise trap P.

Jensen, H.S., et al., Phosphorus cycling in a coastal marine sediment, Aarhus Bay, Denmark. Limnology and Oceanography, 1995. 40(5): p. 908-917.

Given the shallow nature of the lagoon, do you think higher respiration might be another mechanism driving P release rather than just anoxia?

Line 391-392 please check ref dates.

Regards
Perran Cook

Thanks for your response, you interpreted my question correctly.

Based on your response, I think your own data shows that increased respiration in summer also contributes to P release. Higher O2 fluxes probably mean both higher iron and sulfate reduction which drive P release. I think a sentence in the discussion to note this as a factor is warranted, but I leave that to your discretion.
Perran