April 6, 2015
Review of bg-2014-406

Dear Dr. Reisdorph,

I agree with reviewers that major changes need to be done before considering publishing in the journal. I find that your responses to them are not very well supported. I am elaborating further on this as follows.

Sincerely yours

Silvio Pantoja
Associate Editor
…

1. Abstract. Please rewrite sentence starting Line 2, page 4: “Seasonally averaged data were analyzed on a regional basis to account for distinct biogeochemical differences within the bay due to spatial variation in rates of primary production and the influence of glacial-fed stratification, particularly in the northern regions”

Explain what you mean with regional basis, or delete. In any case the sentence does not say much “Respiration and air-sea gas exchange were the dominated drivers of carbon biogeochemistry between the fall and winter of 2012.” This is the abstract of your results: Which aspect of “carbon biogeochemistry” are you referring to?

Line 10, page 4 in abstract and rest of text:

“The highest carbon production occurred within the lower bay between the summer and fall of 2011 with 11 ~1.3x10^10 g C season-1. Bay-wide, there was carbon production of ~2.6x10^10 g C season-1 between the summer and fall”

It is not clear when the highest production occurred since “between season” could be 1 day, or 3 months. In agreement with one of the reviewer, please change the unit of time to day or other, but not season.

2. Abstract. Page 4, line 13. It is “dominant” driver, Isn´t?

3. Text. I agree with reviewers regarding acronyms. They are not necessary and make reading more difficult, which is certainly a goal of the journal. Please remove them, including CRM, BOD

4. Response: “AR: We discuss the influence of wind mixing, as well as glacial flour, on our NCP estimates throughout the ms and within the new Discussion section. Influences on stratification are discussed near the beginning of the Background section. Internal waves and constrictions are discussed near the beginning of the new Discussion section. Stratification (primarily salinity-driven) is also discussed in this new section. The influence of winds, turbulent and tidal mixing are also mentioned throughout the Discussion in places where these mechanisms are identified to impact DIC, TA, NCP and nutrient concentrations. We have also added additional text to address other caveats and assumptions to consider in regards to our NCP estimates. These additions are throughout the text and can be viewed via the tracked changes.“

The referee points to the effect of those “important limitations and caveats that need to be considered “on your interpretation”, i.e. your error bars in the conclusion. Please address this issue

5. Consider this comment by Referee 3 “The introduction and background need to be shorten and it should focus on more relevant aspects that i) influence NPP fluxes within Glaciar Bay and ii) that better explain the caveats that underlay the methodological approach used (see the general comments above)
6. Referee 3 “ The justification of the work is (STILL) poorly presented …”
Editor: Is there a scientific question?

7. Referee 1. “ Figure 4 needs to be redrawn. No scientific information can be extracted this way numbers on the map without error bars.”

Editor: Consider this comment in the new version

8. Discussion should be shortened and may be separate into sections for clarity. There is a mix of literature data and your results that it is difficult to follow. Discuss your data referring to your figures and values.

9. Response to Referee 1. “We understand that these global comparisons are important. However, we do not feel it is within the primary focus of this ms. We touch on similar fjords from around the world, but the focus of this ms is to provide a first time estimate of NCP in GLBA. Including GLBA in a more detailed global comparison is out of the scope of this ms and 40 may be more appropriate for a future publication.”

For the journal the issues brought up by Referee1 are important; a local process of broader significance

10. “The description of the study area lacks numerical information on bathymetry, areas and salinity distribution. The presentation of the results has to be raised to a level of overview and synthesis from the tedious rounds of descriptive text. Graphics and tables might improve the presentation in this respect. The primary subject of the manuscript, net community production, is assessed on the basis of salinity normalized DIC data. The details of the calculations are not sufficiently described but this reviewer recalls the paper by Friis et al, (1999) on the errors which may be introduced by conventional salinity normalization when the low salinity end-members have significant inorganic carbon concentrations (Friis et al., 2003).”

The article needs error estimates, with propagation. Please address this issue properly

11. “RC: Glacial flour is one of the characteristics of glacial waters. Are there any carbonate minerals in the glacial flour that could affect the DIC determinations?”

“AR: Added text to the Methods section to address this comment: “While glacial flour may supply some carbonate minerals to the marine system, influencing DIC and CaCO2 concentrations, we were not able to quantify the amount of glacial flour deposited in the Bay or analyze its composition for this study.”

Editor: This could be an important caveat that needs to be properly addressed, ¿how this could affect your interpretation?

12. “RC: Seasonal water column DIC concentration changes can be a good approximation to determine seasonal NPP (especially in open ocean). This methodological approach has however important limitations mainly because it is difficult to constrain several processes that can add or take out inorganic carbon from the water column (besides the air-sea exchange of CO2 that has been properly ad-dressed in this paper). Boundary conditions in a highly dynamic environment such a fjord are difficult to constrain. The respiration of allochthonous organic carbon from terrestrial (and maybe to a lesser extent oceanic) origin can severely distort in situ NPP estimations hence its implications need to be better addressed (at least the caveats that need to be considered). “

How could it affect your measurements and interpretation?

“Another important flaw of the paper is the poor consideration of physical processes that drive NPP within Glacier Bay. The interplay between seasonal freshwater fluxes, influence of nutrient laden more oceanic waters and wind, tidal and other type of water column mixing/stratification processes (including internal waves, the impact of constrictions etc.) have been poorly treated”

This aspect needs to be considered

13. In Fig. 1 what is summer-fall? Is it summer and fall? Explain
14. Figure 5 is of poor quality
15. Use “NO3-“ or “nitrate”, not “NO3” throughout the text
16. In 2.0 Background. Section 2.0 has to be re-written with relevant referenced information, and shorten. The text is too general to be useful at providing background information about your study site.
17. Replace “Figure 1” with “Fig. 1” throughout the text
18. Replace “Conductivity-temperature-depth (CTD) data were collected on downcasts with a Seabird 19-plus system” with “Conductivity, temperatura and pressure were collected on downcasts with a Seabird 19-plus CTD”
19. Please revise general writing such as in “1 μmoles kg-1” instead of “1 μmol kg-1”, etc.
20. Page 10, line 18: samples were calibrated? Explain or rewrite lines 18 -21
21. Page 11, “Macronutrient samples”, these are seawater samples for…
22. Combine in one sentence lines 18-23 in page 11: “Seasonally averaged atmospheric pCO2 values (μatm) were used (388.4, 388.9, 393.4, 393.8 and 391.8 for summer 2011 through summer 2012, respectively). Seasonally atmospheric pCO2 values were averaged from the monthly averaged Mauna Loa archive found at www.esrl.noaa.gov. Seasonally atmospheric pCO2 values were averaged from the monthly averaged Mauna Loa archive found at www.esrl.noaa.gov.”
23. Page 14 , line 2: Salinity was “the” lowest
24. Page 14, line 18: “Again” the isohalines remained. Remove or replace “again”.
25. Page 13, section 4.1. Add a figure and reduce at least one page.
26. Section 4.2- Show your data in a figure, and reduce text by app. 50%
27. Section 4.3. Show figure(s) and reduce text by half at least. Same for Section 4.4
28. Figure 4. Replace by one that shows spatial variability in NCP
29. Page 22, lines 15-16. This is not a place to repeat a figure caption. Change or remove. Same for Page 24, lines 1-2.
30. Page 24. Lines 4-7 do not add anything. Remove. Same with lines 8-15. What is the relationship with this study? If it has, it should go in a proper place. This is the result section
31. Please summarize Section 4.6
32. Re-organize the Discussion section, and shorten
33. Conclusion should be about your work (this work). Rewrite and shorten

4 June 2015

Dear Dr. Reisdorph

Thanks for submitting a revised version of ms bg-2014-406. There are a few issues that need to be taken care of, related to comments expressed in my previous communication (Line # refers to file “bg-2014-406-manuscript-version3.pdf”).

1. Abstract, Lines 7-9 Production per season. Use per day
2. Abstract, Page 1, Line 18. Find a synonym for impact: “The impact of deglaciation in Glacier Bay has been observed to seasonally impact”
3. Abstract, page 1, Line 23. Add comma: “dissolved inorganic carbon inorganic macronutrients”
4. Abstract, page 2, Line 11. Show your data of “substantial spatial and temporal variability” to be able to conclude that “largely reflect glacial influences within the bay”.
5. Introduction, Page 4, line 22 “Our goal for this study was to better understand carbon cycling in Glacier Bay and how it is impacted by glacial runoff. Additionally, we wish to fill in some gaps in how these processes may influence net community production within a glaciated fjord ecosystem and better understand how continued glacial melt will impact productivity in Glacier Bay, as well as in similar glaciated fjord ecosystems worldwide.”

*Referee 3 “ The justification of the work is (STILL) poorly presented …”
Editor: Is there a scientific question?

“Justification of the work” is still “poorly presented”, as previously mentioned by Editor and Referee 3. In addition, “better understand” (which is not a strong argument to sustain a study) appears twice here. Please rewrite considering those comments (*)


6. Page 7 and the whole text. Abbreviation DO for dissolved oxygen is not needed. Use oxygen. Same with TA

7. Page 8 and the whole text. Silicate is a mineral. You mean silicic acid, Don´t you?

8. “AR: We have added a “Caveats” section (Section 4.0) that discusses these aspects and how they impact our DIC and NCP values.”

The reviewer mentioned “important limitations” that are not reflected neither in the abstract nor in the conclusion sections. I would suggest estimating numerically their impact on your overall conclusions. This has to be reflected in your conclusions.

9. Conclusions: First two paragraphs do not belong here as written. Please summarize of delete. This is conclusion of your work, based on the scientific question that needs to be clearly expressed at the end of introduction (see #5 above).


I encourage reviewing those aspects. Thanks again for your interest in Biogeosciences.


Best regards

Silvio Pantoja
Associate Editor