The Diversity of Phytoplankton in a Combined Rice-Shrimp Farming System in the Coastal Area of the Vietnamese Mekong Delta

Round 1

Reviewer 1 Report

The manuscript is relatively clear written, and results are also clearly presented, although statistical part of the work is somewhat lacking and could be improved. Authors should also verify taxonomy because some of it is out of date.

Specific remarks:

Abstract:

Line 17-18 I would strongly suggest Authors to verify if they are using currently accepted taxonomy. I’m quite sure that terms like Cyanophyta, Bacillariophyta, Euglenophyta and Pyrrophyta are not accepted. I know that general practice is to use lower taxonomic ranks instead of Phyla, Class should be sufficient. This remark applies to the whole article, as well as particular species identified by the Authors. Phytoplankton taxonomy can be quite dynamic, and it is a good practice to verify if the used names are still correct (E.g Anabaena circinalis should probably be Dolichospermum sigmoideum)

Introduction

Line 36 “General Statistics Office of Viet Nam (2019)” I assume that those data are available online? Then it should be included in the references list.

Line 39-42 Since its 2022 already, how those plans turned out?

Line 61-62 Was the planned target reached?

Materials and Methods

Line 108 Figure 2 is not referenced in text.

Line 116 There should be a space before meter (0.5m).

Line 136 Shannon-Wiener, 1949 – should be included in reference list.

Line 142 Henna and Rya, 1995 – same as above.

Statistical analyses and diversity indices

From the description it is unclear if authors transformed the raw data before statistical analyses.

While chosen methods are correct, I do feel that authors could put more effort into analyzing their data. Maybe by investigating the spatial distribution or using ANOSIM to check for similarities between group, performing MDS analysis could also be helpful. All those analyses could be performed with PRIMER, but I would strongly advise authors to look into R.

It is also unfortunate that authors did not measure any hydro physical or hadrochemical variables that would help in interpretation of phytoplankton data.

Results

Line 166-167 If authors are aware of that then why weren’t those variables measured?

Figure 5. Maybe instead of writing Group1, etc. authors could write their proper names (Start of crop cycle, etc.)

Discussion

Line 280-280 genera should be written in cursive.

Line 327 Wu, 1984 is not included in the reference list.

It would be interesting if authors provided more comparison with natural phytoplankton assemblages in this region, how different are the rice-shrimp systems, what makes them special?

References

23, 24 and 30 are not referenced in the manuscript

24 and 25 are not in alphabetical order

 

The referee

Author Response

Thank you for your valuable comments. Attached file is our reply to you in detail.

Author Response File: Author Response.docx

Reviewer 2 Report

Review for the paper "The diversity of phytoplankton in a combined rice-shrimp farming system in the coastal area of the Vietnamese Mekong delta" by Nguyen Dinh Giang Nam, Nguyen Thanh Giao, Nguyen Hieu Trung, Minh N. Nguyen, Nigel K. Downes, Nguyen Vo Chau Ngan submitted to "Water".

 

General comment.

 

The microscopic plants of the plankton, collectively called phytoplankton, harness sunlight to make organic matter, which then provides food for protozoans and grazing animals such as copepods. Phytoplankton act as a producer in the biological chain and have the most sensitive response to changes in the water environment, this group is also an important bioindicator. Biological criteria are widely used in ecological health assessments due to their ability to integrate the impacts of measured and unmeasured factors, providing a better evaluation of environmental conditions than water chemistry alone. Therefore, studying phytoplankton allows for assessing the status or health of the aquatic ecosystems and providing information on possible causes of change in its other components. The authors were focused on the phytoplankton assemblage inhabiting combined a rice-shrimp farming system in the coastal area of the Vietnamese Mekong delta. They revealed high phytoplankton diversity based on Shannon-Wiener index and delineated three distinct succession periods during the rice-shrimp crop cycle. New data expand our knowledge on phytoplankton in a typical rice-shrimp culture and may be useful for monitoring and environmental assessment in similar agricultural industries. The manuscript is generally well written (in terms of English and general presentation). It has a comprehensive data set and main findings are well supported with statistical analyses. Discussion is in an academic style and consistent with the authors' results. I have only minor suggestions to improve the article.

 

Specific remarks.

 

L160-167, 186-189, 193-194, 202-204, 235-236. I recommend moving these sections in the Discussion. The "Results", in my mind, must contain only the authors' findings. Any comparison with other reports should be done in the Discussion.

L171–172, 197-200, 211-214. These statements need to be supported with statistical analysis. Please, compare data for different periods using ANOVA or another test.

Fig. 4. Better to use Cells/L instead of individual/L for phytoplankton density (Axis Y).

L290, 291. Consider replacing "individuals per litter" with "cells per litter".

Author Response

We appreciate to your comments. Please see the attachment.

Author Response File: Author Response.docx