Dear Drs. Call and Maher:

Thank you for submitting this paper to Biogeosciences. Two referees have evaluated your paper and believe it should be publishable after revision. I agree with their assessment. I therefore invite you to submit a revised version, modified according to your rebuttal. Your revised version will be inspected by me before a final decision will be made.

With best regards, Jack Middelburg, Associate Editor

Dear Dr. Call:

Thank you for submitting this paper to Biogeosciences. I have read the revised paper and I am happy to inform you that your paper is now accepted for publication.

However, while reading I identified a few minor corrections:
p.1, abstract. Accuracy is reported in permille, indicate that this refers to del13C to avoid confusion with accuracy of DIC.
p.7, last line section 3.3: mesocosm
p. 8, line 3, paragraph 3: before increasing during
p. 3, one but last line, paragraph 3: allochthonous

I am looking forward seeing your article in print.

With best regards, Jack Middelburg, Associate Editor