Dear Dr Morana, Dear authors,

Thank you for the insightfull revisions that you made in your paper quoted above. The revisions greatly increased the precision and clarity of your paper. To my opinion, all points were successfully adressed.

However, there are four minor points that were not fully satisfying to me:
- the introduction is long and could be made shorter and more appealing (as suggested by reviewer 2). Please shorten and add the newest reference (Zigah et al., 2015; L&O).

- The method section is not precised enough and the level of precision is not indicated for some of the analysis. Some effort was made for POC measurement in the revised version, but not for CH4 concentration. The section on CH4-13C measurement, which introduces mostly custom made measurements should be modified to include measurement precision, reproducibility and overall error on the measurements (based on certified standards as said in text). Adding a reference of your group on CH4-13C measurement (if there is one) could be useful.

- Add error bars on results graphs (fig. 2-7) as required by reviewer 2, comment 17, if larger than the data point size. If not, quote that in figure caption.

- Concerning Figure 4&5, I wonder how you calculated the CH4:02 ratio when O2<3µmol/l. Do you keep O2 as 3 µmol/l and recalculate the ratio with increasing CH4 concentration? This should be stated in the method section.

Thank you in advance for adressing these points,which are minor but important. If successfully adressed, your paper should be accepted.

Best regards,

C. Rabouille, guest editor