Small phytoplankton contribution to the standing stocks and the total primary production in the Amundsen Sea

Lee, Sang H.; Kim, Bo Kyung; Lim, Yu Jeong; Joo, HuiTae; Kang, Jae Joong; Lee, Dabin; Park, Jisoo; Ha, Sun-Yong; Lee, Sang Hoon

doi:https://doi.org/10.5194/bg-14-3705-2017

Articles | Volume 14, issue 15

https://doi.org/10.5194/bg-14-3705-2017

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

https://doi.org/10.5194/bg-14-3705-2017

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

Articles | Volume 14, issue 15

Research article

|

10 Aug 2017

Research article |

| 10 Aug 2017

Small phytoplankton contribution to the standing stocks and the total primary production in the Amundsen Sea

Sang H. Lee, Bo Kyung Kim, Yu Jeong Lim, HuiTae Joo, Jae Joong Kang, Dabin Lee, Jisoo Park, Sun-Yong Ha, and Sang Hoon Lee

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Final revised paper (published on 10 Aug 2017)
Preprint (discussion started on 24 Oct 2016)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'comments', Anonymous Referee #1, 17 Nov 2016
- AC1: 'Author response to # 1 reviwer's comments', Sang Lee, 14 Jan 2017
RC2: 'comments', Anonymous Referee #2, 12 Dec 2016
- AC2: 'Author response to # 2 reviwer's comments', Sang Lee, 14 Jan 2017

Peer-review completion

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

ED: Reconsider after major revisions (22 Jan 2017) by Gerhard Herndl

AR by Sang Lee on behalf of the Authors (01 Mar 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (01 Mar 2017) by Gerhard Herndl

RR by Anonymous Referee #1 (13 Mar 2017)

RR by Anonymous Referee #2 (14 Apr 2017)

RR by Andrew Davidson (19 Apr 2017)

Suggestions for revision or reasons for rejection

Major comments
The paper presents another in their series of papers by these authors looking at the phytoplankton community in the Amundsen Sea. This is a little-known region of high productivity and the contributions of small phytoplankton to overall biomass, productivity and elemental cycling is timely, especially given the prediction that this fraction of the community is predicted to become increasingly important with changing climate. Furthermore, the increasing interest in the decline of glaciers in the region due to basal melt, this region could be an interesting site to track the effect of declining salinity on the phytoplankton community. Thus I deem this paper timely and topical.

Title Does not sufficiently cover the content of the paper which deals with standing stocks (Chl a & POC), productivity and nutrient draw down.

The manuscript is currently formulaic in its presentation. With each parameter measured being subjected to the same comparisons between small and large phytoplankton, inside and outside the Amundsen Bay polynya. Much of this presentation of data would be usefully presented in a table, freeing the authors up to consider the similarities and differences among sites and sizes In addition, the authors consider few other environmental factors, including currents/gyres in the region, effects of the time of year, and successional maturity over the summer and where their study fits in this seasonal progression.

The statistical analysis is rudimentary, consisting of t-test among pairs of variables and I wonder if this has led to “over-analysis” of their data and they provide no indication of the statistic methods they employed in their methods section. I am no authority on this topic and I suggest they should seek some advice on the best statistical approach for their study. It may be better to perform a one-way ANOVA to compare sites inside and outside the polynya using the concentrations and rates they have measured (this will give overall significance of difference). They could then use post-hoc Tukey tests to determine which specific variables are significantly different.

I am also a little uncertain why the authors consider site 3 (and 3.1) to be outside the polynya given that it consistently shows biological characteristics characteristic of polynya sites. This site is on the fringe of the polynya, experiencing approximately 30% ice cover, which is not high. At best it is in the transition zone between the two distinctly different environments. The authors might also wish to consider the currents /gyres in the region and the potential for carriage polynya-like phytoplankton communities to this site.

Minor comments
It is unclear when the ice cover image refers to - the time of the survey?, the preceding winter? Please clarify.
There are instances repeating the results (e.g. lines 208, 224, 241).
Lines 271-3. I think the argument should be reversed, namely that the proportion of the production contributed by the mall cells increases as the overall productivity declines. It has long been known that there is a fairly consistent background of nano- and pico-plankton upon which is superimposed the bloom of large cells, especially diatoms. Thus my suggestion that you reverse your argument.
Captions overall need to be more fulsome e.g. caption to Table 1 should perhaps be "Percent contributions of small cells to depth-integrated total concentrations of chlorophyll a, POC, PON and uptake of carbon and nitrogen".
Fig 1. Marine Byrd Land should be Marie Byrd Land - as above please specify the time of the ice concentration.
Fig 7. The points on your regression are not normally distributed on the X-axis, rendering your regression invalid. You need to log the % productivity vales as well or find another way to compare the productivity contributed by small cells with changing uptake rate.

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ED: Publish subject to minor revisions (Editor review) (22 May 2017) by Gerhard Herndl

AR by Sang Lee on behalf of the Authors (05 Jun 2017) Author's response Manuscript

ED: Publish as is (28 Jun 2017) by Gerhard Herndl

AR by Sang Lee on behalf of the Authors (06 Jul 2017)

Short summary

Little information on the contribution of small-sized phytoplankton is currently available in the Amundsen Sea. Based on a strong negative correlation between the contributions of small phytoplankton and the total daily primary production of phytoplankton found in this study, we concluded that a potential decrease in total primary production would be led by increasing contribution of small phytoplankton in the Amundsen Sea under rapidly warming environmental conditions.