The Assessment of Phytoplankton Dynamics in Two Reservoirs in Southern Africa with Special Reference to Water Abstraction for Inter-Basin Transfers and Potable Water Production

Round 1

Reviewer 1 Report

Dear Authors:

I carefully went through your manuscript and found it could be published in Water after following major revisions.

 

ABSTRACT

Second statement: Which reservoirs?? Please introduce.

Please indicate the dry and wet seasons? Do you mean summer and winter, respectively?

INTRODUCTION

By look at through Introduction, readers may conclude that the impact of climate change is more than anthropogenic activities in bloom of Cyanobacteria in reservoir. But, this is not a true conclusion since Cyanobacteria in lakes and especially in reservoirs (as man-made lakes) are more affected by anthropogenic factors. Please revise the manuscript to avoid such conclusion for readers.

Lines 64-79: What do you think about “The deep chlorophyll maximum (DCM)”?

Lines 107-115: Please give proper references.

Exactly, what is the main novelty of this manuscript? Could you please expanded the last statement in Introduction to provide your perspectives on the implications of the finding to the broader community?

Materials and Methods

Lines 135-138: please revise. The mixing should be due to cold conditions in winter.

Please add “mean depth” to Table 1.

Why did you select one sampling station? Why close to the dam structure?

Please give the accuracy of the sampling devices.

Lines 205-209: Please give more details of QA/QC. How much were the recovery rates?

Lines 221-230: No citation exists to justify this section. What is Fisher LSD? What are the Repeated Measures Mixed Models?

Line 233: Do you mean TN:TP molar ratio?

Did you use TN:TP for trophic state classification? Or, determination of limiting factor? Did you use Carlson trophic state index? Please see and cite” Caspian Sea is eutrophying: the alarming message of satellite data” for further clarification.

Lines 237-242: What do you mean by PCA? Please give the full name and a brief description by using “Multivariate statistical analysis of surface water quality based on correlations and variations in the data set”.

Results and Discussion

Did you look at through “Complex dynamics of water quality mixing in a warm mono-mictic reservoir” and “Temporal and depth variation of water quality due to thermal stratification in Karkheh Reservoir, Iran”? These papers can help you to better support your conclusions made in different parts of the manuscript.

PCA results are not clear to me. Please add more descriptions.

We agree with the authors conclusion that consuming the water withdrawn from different depth in reservoir may result in different human health impacts. But, the authors need to justify your conclusion by citing the same results by others for water quality parameters such as the study conducted by Aradpour et al. titled: Alarming carcinogenic and non-carcinogenic risk of heavy metals in Sabalan dam reservoir, Northwest of Iran.

Conclusions

Would you please add more suggestions for future improvement of the water quality in both reservoir?

 

 

 

 

Author Response

Comments and Suggestions for Authors
Dear Authors:
I carefully went through your manuscript and found it could be published in Water 
after following major revisions.
ABSTRACT
Second statement: Which reservoirs?? Please introduce.
Line 21: The name of the two reservoirs (Swakoppoort and Von Bach dams) were 
included in the abstract.
Please indicate the dry and wet seasons? Do you mean summer and winter, respectively?
Line 24 : The dry seasons are autumn, winter and spring and wet season is summer. 
All included in the abstract.
INTRODUCTION
By look at through Introduction, readers may conclude that the impact of climate change is 
more than anthropogenic activities in bloom of Cyanobacteria in reservoir. But, this is not a 
true conclusion since Cyanobacteria in lakes and especially in reservoirs (as man-made lakes) 
are more affected by anthropogenic factors. Please revise the manuscript to avoid such 
conclusion for readers.
Line 24, 53, 55, 63-64: This was included in the introduction entire introduction.
Lines 64-79: What do you think about “The deep chlorophyll maximum (DCM)”?
Line 81-84, and 96-98: This was addressed in introduction
Lines 107-115: Please give proper references.
Line 111-119: This was addressed in the introduction
Exactly, what is the main novelty of this manuscript? Could you please expanded the last 
statement in Introduction to provide your perspectives on the implications of the finding to 
the broader community?
Line 122-125: This was addressed in the introduction
Materials and Methods
Lines 135-138: please revise. The mixing should be due to cold conditions in winter.
Line 147-148: This was addressed
Please add “mean depth” to Table 1.
This was addressed and added to Table 1
Why did you select one sampling station? Why close to the dam structure?
This was addressed in Line 169-177
Please give the accuracy of the sampling devices.
This was addressed in Line 182-183
Lines 205-209: Please give more details of QA/QC. How much were the recovery rates?
This was addressed in Line 220-225
Lines 221-230: No citation exists to justify this section. What is Fisher LSD? What are the 
Repeated Measures Mixed Models?
The following references were added to the text Line 240:
1) Wu, L., 2009. Mixed effects models for complex data. CRC press.
2) Richardson, J., Feuchtmayr, H., Miller, C., Hunter, P.D., Maberly, S.C. and 
Carvalho, L., 2019. Response of cyanobacteria and phytoplankton abundance to 
warming, extreme rainfall events and nutrient enrichment. Global Change 
Biology, 25(10), pp.3365-3380.
Wu (2009) explains the theory regarding Mixed Model analysis, whereas, Richardson et al. 
(2019) is an example where Mixed Model analysis is applied in water quality/limnology 
research. 
Line 233: Do you mean TN:TP molar ratio?
Yes, is it TN:TP molar ratio in Line 250
Did you use TN:TP for trophic state classification? Or, determination of limiting factor? Did 
you use Carlson trophic state index? Please see and cite” Caspian Sea is eutrophying: the 
alarming message of satellite data” for further clarification.
TN:TP was used for classification of trophic stated. This citation was addressed in 
Line 252 
Lines 237-242: What do you mean by PCA? Please give the full name and a brief description 
by using “Multivariate statistical analysis of surface water quality based on correlations and 
variations in the data set”.
Line 254-256: The text was changed by writing the abbreviation PCA in full. The 
suggested “Multivariate statistical analysis of surface water quality based on 
correlations and variations in the data set” was also added.
Results and Discussion
Did you look at through “Complex dynamics of water quality mixing in a warm mono-mictic 
reservoir” and “Temporal and depth variation of water quality due to thermal stratification in 
Karkheh Reservoir, Iran”? These papers can help you to better support your conclusions 
made in different parts of the manuscript.
This was addressed in Line 490-495 and 504-509
PCA results are not clear to me. Please add more descriptions.
Line 438-445: The text in the Results section describing the PCA was improved.
We agree with the authors conclusion that consuming the water withdrawn from different 
depth in reservoir may result in different human health impacts. But, the authors need to 
justify your conclusion by citing the same results by others for water quality parameters such 
as the study conducted by Aradpour et al. titled: Alarming carcinogenic and non-carcinogenic 
risk of heavy metals in Sabalan dam reservoir, Northwest of Iran.
This was addressed in Line 557-564
Conclusions
Would you please add more suggestions for future improvement of the water quality in both 
reservoir?
This was addressed in Line 611-621

Reviewer 2 Report

The MS submitted by Sirunda and coworkers analyses phytoplankton dynamics in two reservoirs in southern africa. Environmental parameters like temperature, pH changes as well as biochemical parameters of water have been monitored during 16 years (2003-2019). Biotic parameters as well as characerization of phytoplankton communities constitute the main core of this work. The topic is of interest, sheds light on environmental microbiolgy, but partially fits to the scope of the journal. Considering that toxicity due to toxic species has not been explored into detail, this work is more related to journals focused on microbiology.

Discussion is dificult to follow in the way that it is written. Conclussion are not concise enough. Severeal sentences are not understandable (due to English or because it seems that few words are missing). Error bars are missing in most of the graphs. Numbers in tables do not included their standard deviation values. All these issues must be addressed by the authors in order to improve this version.

More comments have been embebdded through the MS in order to help the authors to improve this version.

Comments for author File: Comments.pdf

Author Response

Comments and Suggestions for Authors
The MS submitted by Sirunda and coworkers analyses phytoplankton dynamics in two 
reservoirs in southern africa. Environmental parameters like temperature, pH changes as well 
as biochemical parameters of water have been monitored during 16 years (2003-2019). Biotic 
parameters as well as characerization of phytoplankton communities constitute the main core 
of this work. The topic is of interest, sheds light on environmental microbiolgy, but partially 
fits to the scope of the journal. Considering that toxicity due to toxic species has not been 
explored into detail, this work is more related to journals focused on microbiology.
Discussion is dificult to follow in the way that it is written. Conclussion are not concise 
enough. Severeal sentences are not understandable (due to English or because it seems that 
few words are missing). Error bars are missing in most of the graphs. Numbers in tables do 
not included their standard deviation values. All these issues must be addressed by the 
authors in order to improve this version.
Errors bars were included in all the graphs. Standard deviation included in all tables. 
The discussion was edited, and the conclusion was enhanced to read better.
More comments have been embebdded through the MS in order to help the authors to 
improve this version.
The comments in the PDF documents were addressed and incorporated in the MS 

Round 2

Reviewer 1 Report

Thanks to the authors, almost all of my comments have been responded properly. Still, I have some minor suggestions that can improve the readability of the manuscript for readers

L20: Please add the location of dams.

Table 1: Do you mean potential or real evaporation? They are completely different. I think it should be potential. Please clarify.

Tables 2 to 5: Please change “Depths ranges” to “Depth ranges”.

Good luck

 

 

Author Response

L20: Please add the location of dams.

Location of the two dams was included in L20-L22

Table 1: Do you mean potential or real evaporation? They are completely different. I think it should be potential. Please clarify.

It is potential evaporation and this was included in Table 1

Tables 2 to 5: Please change “Depths ranges” to “Depth ranges”.

This was changed in all the table from 2-5 of the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thanks for your time and effort addressing the suggestions I made. Please, check the format of the references according to authors' guidelines.

Author Response

Thanks for your time and effort addressing the suggestions I made. Please, check the format of the references according to authors' guidelines.

The references format was checked and updated using the authors’ guidelines

Author Response File: Author Response.pdf