Phytoplankton Community Dynamics in Ponds with Diverse Biomanipulation Approaches

Round 1

Reviewer 1 Report

The study analyzes the composition and biomass of the phytoplankton community in three lakes. Two lakes were stocked with different species with regard to nutrition, while one lake was not stocked to serve as a reference value. The experiment was conducted to test the effectiveness of biomanipulation in improving water quality in terms of eutrophication. The results are consistent with previous research and have shown that this method is effective when stocking is done in such a way that there is a reduction at both higher and lower trophic levels, including carnivorous fish, filter-feeding and detritus-feeding fish.

The results of this experiment are a valuable contribution to deepening our knowledge of biomanipulation and its application to improve water quality.

Author Response

We are grateful for your time and the acknowledgment of our research. Following the constructive feedback from all reviewers, we have carefully made further additions and adjustments to the manuscript content. These changes have been tracked using the revision mode for clarity and ease of review.

Author Response File: Author Response.pdf

Reviewer 2 Report

The results of this study validate that using top predators such as fish can effectively control algae, serving as one of the methods to manage freshwater eutrophication. However, ecologically, it is considered that there could be some overinterpretation. Nevertheless, the authors have summarized the research results well, providing a detailed explanation of phytoplankton biomass and community composition (diversity) for each period. Therefore, it seems acceptable to mention some methodologies and make minor revisions before publication.

Overall, my comments is below;

This study was conducted from June 2022 to July 2023 in the ponds of Yuqiao Reservoir in China with the objective of ameliorating eutrophied ponds using fish and higher trophic-level predators to examine total phytoplankton quantity and nutrient dynamics. Specifically, the study underscores the efficacy of diverse fish stocking in the CFD pond for reducing phytoplankton density, especially in controlling cyanobacteria. The limited impact observed in ponds stocked only with carnivorous and herbivorous fish suggests that a more integrated approach is indispensable for effective eutrophication management. This finding underscores the potential of tailored biomanipulation strategies for aquatic ecosystem restoration, particularly in shallow water bodies, underscoring the significance of ongoing research for achieving sustainable ecological balance and improving water quality.

The methodology section requires more detailed information regarding the identification of phytoplankton and the enumeration of extremely small cyanobacteria such as Microcystis. Incorporating references and additional explanations related to the methods used would enhance the reliability of the study.

It is crucial to comprehensively address these aspects in the paper to ensure a thorough understanding of the research. Unfortunately, the paper does not specifically mention representing phytoplankton cluster biomass based on cell volume or the conversion method from cell volume to biomass. If there are no details provided in the paper regarding these aspects, it is recommended to make appropriate revisions to include the necessary information.

Additionally, incorporating references or citing relevant literature that outlines the conversion of cell volume to biomass and how it was interpreted as biomass would be beneficial for readers.

-Species names must be written in italics in the text. Please reflect where this is not the case.

-The request is related to a specific methodology, "Comparison of comprehensive trophic status indices," and providing details on how it was calculated and relevant references. However, the provided text doesn't contain information about this methodology. "Comparison of comprehensive trophic status indices," based on the other papers, please provide that additional information between this study and previous stuties in discussion.

Author Response

The results of this study validate that using top predators such as fish can effectively control algae, serving as one of the methods to manage freshwater eutrophication. However, ecologically, it is considered that there could be some overinterpretation. Nevertheless, the authors have summarized the research results well, providing a detailed explanation of phytoplankton biomass and community composition (diversity) for each period. Therefore, it seems acceptable to mention some methodologies and make minor revisions before publication. Overall, my comments is below; This study was conducted from June 2022 to July 2023 in the ponds of Yuqiao Reservoir in China with the objective of ameliorating eutrophied ponds using fish and higher trophic-level predators to examine total phytoplankton quantity and nutrient dynamics. Specifically, the study underscores the efficacy of diverse fish stocking in the CFD pond for reducing phytoplankton density, especially in controlling cyanobacteria. The limited impact observed in ponds stocked only with carnivorous and herbivorous fish suggests that a more integrated approach is indispensable for effective eutrophication management. This finding underscores the potential of tailored biomanipulation strategies for aquatic ecosystem restoration, particularly in shallow water bodies, underscoring the significance of ongoing research for achieving sustainable ecological balance and improving water quality.

Response: We greatly appreciate your insightful feedback and the time you've invested in reviewing our work. In light of your observations, we have refined the manuscript to temper any overinterpretation of ecological outcomes. Additionally, we've clarified our methodologies and made minor revisions as you recommended. The nuances of diverse fish stocking and its implications for eutrophication control have been articulated more precisely, acknowledging the need for integrated approaches in biomanipulation. Your suggestions have been instrumental in enhancing the manuscript's overall quality.

1. The methodology section requires more detailed information regarding the identification of phytoplankton and the enumeration of extremely small cyanobacteria such as Microcystis. Incorporating references and additional explanations related to the methods used would enhance the reliability of the study. It is crucial to comprehensively address these aspects in the paper to ensure a thorough understanding of the research.

Response: Thank you for your constructive suggestion. We have expanded the methodology section to include detailed procedures for the identification and enumeration of phytoplankton, with particular emphasis on small cyanobacteria like Microcystis spp. These enhancements can be found in the revised manuscript (L109-122).

2. Unfortunately, the paper does not specifically mention representing phytoplankton cluster biomass based on cell volume or the conversion method from cell volume to biomass. If there are no details provided in the paper regarding these aspects, it is recommended to make appropriate revisions to include the necessary information. Additionally, incorporating references or citing relevant literature that outlines the conversion of cell volume to biomass and how it was interpreted as biomass would be beneficial for readers.

Response: We appreciate your valuable suggestion regarding the representation of phytoplankton biomass. Acknowledging this gap, we have now included a detailed description of the method for converting phytoplankton cell volume into biomass in the manuscript (L122-128). Additionally, we have incorporated reference[16] (Huang, X.F. Survey, Observation and Analysis of Lake Ecology, 1st ed; Standards Press of China: Beijing, China, 2000; pp.72-77) to provide a comprehensive understanding of the methodology employed.

3. Species names must be written in italics in the text. Please reflect where this is not the case.

Response: Thank you for highlighting the formatting issue regarding the italicization of species names. We have thoroughly reviewed the manuscript and corrected all instances where species names were not properly italicized.

4. The request is related to a specific methodology, "Comparison of comprehensive trophic status indices," and providing details on how it was calculated and relevant references. However, the provided text doesn't contain information about this methodology. "Comparison of comprehensive trophic status indices," based on the other papers, please provide that additional information between this study and previous stuties in discussion.

Respose: We appreciate your observation regarding the omission of details on the "Comparison of comprehensive trophic status indices." Following your advice, we have included a succinct introduction and the calculation formula for the Comprehensive Nutrient Status Index in the manuscript (L226-239). Additionally, we have incorporated relevant references - Jin, X.C.; Tu, Q.Y. Specification For Lake Eutrophication Survey, 2nd edition (China Environmental Science Press: Beijing, China, 1990, pp. 286-291) and Wang, M.C.; Liu, X.Q.; Zhang, J.H. Evaluate method and classification standard on lake eutrophication (Environmental Monitoring in China, 2002, 18(5), 47-49) to provide a more comprehensive understanding. Corresponding adjustments have also been made in the discussion section (L516-527) to reflect these inclusions.

Author Response File: Author Response.pdf