The influence of episodic flooding on a pelagic ecosystem in the East China Sea

Chen, Chung-Chi; Gong, Gwo-Ching; Chou, Wen-Chen; Chung, Chih-Ching; Hsieh, Chih-Hao; Shiah, Fuh-Kwo; Chiang, Kuo-Ping

doi:https://doi.org/10.5194/bg-14-2597-2017

Articles | Volume 14, issue 10

https://doi.org/10.5194/bg-14-2597-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-14-2597-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 10

Research article

|

22 May 2017

Research article |

| 22 May 2017

The influence of episodic flooding on a pelagic ecosystem in the East China Sea

Chung-Chi Chen, Gwo-Ching Gong, Wen-Chen Chou, Chih-Ching Chung, Chih-Hao Hsieh, Fuh-Kwo Shiah, and Kuo-Ping Chiang

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Final revised paper (published on 22 May 2017)
Preprint (discussion started on 27 Jun 2016)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Reviewer's comments on bg-2016-246 Chen et al.', Anonymous Referee #1, 06 Aug 2016
RC2: 'Review of Chung-Chi Chen et al submitted to Biogeosciences', Anonymous Referee #2, 04 Sep 2016
AC1: 'Responses to reviewers’ comments on ms no: bg-2016-246 “The influence of episodic flooding on pelagic ecosystem in the East China Sea”', Chung-Chi Chen, 28 Sep 2016

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (09 Nov 2016) by Carol Robinson

AR by Chung-Chi Chen on behalf of the Authors (28 Nov 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Jan 2017) by Carol Robinson

RR by Anonymous Referee #1 (05 Jan 2017)

RR by Anonymous Referee #3 (21 Feb 2017)

Suggestions for revision or reasons for rejection

As noted by two previous referees, this manuscript provides a useful account of the distribution of several physico-chemical and biological variables in the East China Sea during contrasting situations of discharge of the Changjian (Yangtze) River. The authors have made a reasonable effort to address the suggestions of the referees. However, I have some additional comments that I would recommend to take into account before publication.
Microzooplankton is an important contributor to plankton community respiration, but this component of the food web was not measured in the study. In addition, the 330 µm mesh net used for zooplankton sampling (line 144) is likely to have failed to capture small components of the mesozooplankton. Curiously, the authors cite Calbet and Landry (2004) to support their sentence that “Zooplankton are the most important contributors to plankton CR” (line 307). However, Calbet and Landry (2004), as the title of their paper indicates, refer basically to microzooplankton, not to mesozooplankton, and state in their abstract that “The estimated contributions of microbial grazers to total community respiration are of the same magnitude as bacterial respiration”. The authors refer to this problem in only two lines (378-379) at the end of the more than three pages of section 3.3 (“Effects of . . . flooding on plankton community respiration”. I understand that at this point, it is impossible to obtain the missing microzooplankton data, but this drawback should be acknowledged from the beginning of the CR results and all the discussion should be framed accordingly, taking also into account that correlation is not causation. (e. g., sentences like these in lines 365-366 “phytoplankton and bacterioplankton might be the most important components contributing to CR”, and many others should be reconsidered and improved).
The abstract states (lines 33-34) that the study had a focus on community respiration (CR). However, in the Results and Discussion section, this question appears only after 8-9 pages of dealing with other topics. I would recommend to explain more specifically what will be the topics dealt with in the manuscript (lines 84-93) and to modify the abstract accordingly. In this way, the reader will know what to expect when looking at the results.
Other comments
Indicate somewhere in the Methods (rather than in line 360) that total plankton biomass is the “summed biomass of phytoplankton, bacterioplankton, and zooplankton”.
Line 376. Explain what is the “threshold discharge rate”.
Lines 193-194. It should be “Regarding the Ze”, I presume.
Lines 196 and following. It would be better to use “transmittance” rather than “transparency”.
Lines 237-239. Clarify if the N/P ratio of 22.3 +- 20.9 applies to all the “ECS”. (this seems the case, since the EDW is mentioned next).
Lines 413-414. fCO2 varied from 375.4 to 439.8 as SSS varied from 20.38 to 33.96 or in the opposite sense?
Line 459 “taken up” instead of “uptaken”.

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RR by Anonymous Referee #2 (27 Mar 2017)

ED: Publish subject to minor revisions (Editor review) (05 Apr 2017) by Carol Robinson

AR by Chung-Chi Chen on behalf of the Authors (11 Apr 2017) Author's response Manuscript

ED: Publish as is (27 Apr 2017) by Carol Robinson

AR by Chung-Chi Chen on behalf of the Authors (28 Apr 2017)

Short summary

To understand the flooding effects on a pelagic ecosystem in the East China Sea (ECS), a variety of variables were measured in 2009 (non-flood) and 2010 (flood). In 2010, the organic carbon consumption was higher than in 2009; this could be attributed to the vigorous plankton activities observed in low-salinity areas. A huge amount of f CO₂ was also drawn down in the flood. This flood effect might become more pronounced as extreme rainfall events increase dramatically throughout the world.