A Three-Dimensional Coupled Hydrodynamic-Ecological Modeling to Assess the Planktonic Biomass in a Subalpine Lake
Round 1
Reviewer 1 Report
Review for the paper by Wen-Cheng Liu and Hong-Ming Liu submitted to "Sustainability".
Paper title: A Three-Dimensional Coupled Hydrodynamic-Ecological Modeling to Assess the Planktonic Biomass in a Subalpine Lake.
The authors applied a 3-D ecological model to reveal the main factors affecting plankton biomass in Tsuei-Feng Lake. They found clear relationships between some environmental factors and plankton biomass.
General scores.
The data presented by the authors are original and but their significance is not obvious. The modeling study is correctly designed and the authors used appropriate model methods but input parameters used in this study seem to be inappropriate. Also, there is no any description of methods to collect and treat biological data that make it difficult to assess the authors' results. Some results are doubtful probably due to inappropriate terms or input parameters. Discussion is poor and must be substantially improved.
Specific comments.
A clear and detailed description of methods to collect biological data (phytoplankton and zooplankton) must be included in the ms. Also, provide data on the processing and treatment of plankton samples. Please, indicate sampling devices, frequency of sampling, time of sampling, total number of samples, fixation and treatment of plankton samples separately for phyto- and zooplankton etc. Description of processing must include splitting of samples, identification of taxa, microscope description etc.
Equations 7-8. Units for all terms of the equations must be indicated. Provide references for constants from Table 3.
Page 5. First sentence. Why you used two groups of zooplankton? What were the main differences between copepods and others?
The model did not consider intraspecific and interspecific competition in plankton assemblages that might lead to inconsistent results. Moreover, seasonal differences in plankton communities must also be taken into account because trophic structure strongly affects the total biomass of a plankton group. Additionally, an important factor that may drive the total zooplankton biomass is fish predation. However, fish biomass was not included in the author's model.
All these limitations must be considered and discussed in the ms.
Table 3. Please, explain how values for parameters were obtained. For example, growth rates for
phytoplankton may vary from 0.5 to 5 day–1. Usually, the growth rate of phytoplankton is 0.3–1.7 day–1. Mortality rates for zooplankton may be 0.001–0.5 day–1 with a mean value of 0.05–0.01 day–1. It is more likely that the authors underestimate this parameter. Moreover, the growth rate for the majority of copepod taxa lies between 0.1–0.7 day–1 (Hirst and, 2003) and never exceeds 2.5 day–1. I feel that the growth rates for zooplankton seem to be strongly overestimated that might lead to inappropriate results. The same can be said for phytoplankton growth rate. The authors should refer to relevant literature sources to obtain realistic input parameters for their model.
Hirst, A.G., Bunker, A.J., 2003. Growth of marine planktonic copepods: Global rates and patterns in relation to chlorophyll a, temperature, and body weight. Limnology and Oceanography, 48, 1988–2010.
The authors stated that "The results of sensitivity analysis indicated that phytoplankton biomass was significantly influenced by the predation rate of phytoplankton (PRP), while zooplankton biomass was importantly influenced by the basal metabolic rate of zooplankton (BMZ)."
This is very confusing because it may be rephrased as "phytoplankton affect phytoplankton and zooplankton affect zooplankton". Corresponding results should be better explained or deleted.
Basal metabolism is an inalienable and stable parameter of an organism and it is difficult to imagine how it can be increased or decreased by 50%.
The authors use the term "Predation rate of phytoplankton". Please, define it. Phytoplankton are a group of photosynthetic organisms, not predators.
The authors also use the terms "Basal metabolism rate" and "basal metabolic rate". They should be consistent throughout the text.
The last paragraph in the Introduction "This article is organized as follows… Section 5 summarizes the conclusions" should be deleted.
Section "The water depth, water temperature, and meteorological data…" Please, indicate the frequency of sampling. The authors should describe the methods they used to sample phyto- and zooplankton, to process the samples in the laboratory and to calculate the biomass in detail.
The authors should explain why they considered only macrozooplankton (Fig. 2). They also should be consistent throughout the text and use "zooplankton" or "macrozooplankton"
In the text, the authors stated that "Phytoplankton can be divided into two state variables: periphyton and drifting phytoplankton, which include blue algae, diatoms, and others" while in Fig 2. they indicated "Diatom", "green algae" (not blue) and "others". Please, check.
Figure 2. Change “Copepod” to “Copepods”. The authors should define all abbreviations in the caption for this figure.
Table 3. There is no information about the basal metabolism of zooplankton.
Figure 3, caption. Please, use "Tsuei-Feng Lake" instead of TFL in this caption.
Figure 7. There are duplicated plates "d", "e" and "f" while plates "g" and h" are absent. Please, revise.
Equation 12 should be moved to the Materials and Methods.
There is a section entitled "Fish" in Fig. 2 whereas this factor is not considered in the paper. Moreover, the authors stated (P. 2) that "The objective of this study was to develop a three-dimensional hydrodynamic-ecological coupled model (SCHISM-Ecol) to simulate the hydrodynamics, water quality, and biomass of phytoplankton, zooplankton, and FISH in Tsuei-Feng Lake (TFL)…".
The authors stated that "We suppose that environmental variations, including water temperature and inflow, would be dominant factors affecting planktonic biomass". However, light regime and grazing impact are known to be important drivers of phytoplankton biomass. The same applied to fish predators in the case of zooplankton.
The authors did not discuss which underlying mechanisms explain their findings, i.e. the role of inflow discharge alterations in fluctuations of plankton biomass and roles of other factors. They should also discuss their own data concerning environmental variables in the lake as well as seasonal changes in plankton biomass. Finally, the authors should compare their results to findings of other authors who modeled plankton dynamics in other lakes.
In the current form, this paper can not be recommended for publication.
Author Response
Please see the attached file for response to Reviewer.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Review of a manuscript submitted to the Sustainability, entitled „A Three-Dimensional Coupled Hydrodynamic-Ecological Modeling to Assess the Planktonic Biomass in a Subalpine Lake” Manuscript ID: sustainability-1387518, by Wen-Cheng Liu and Hong-Ming Liu.
Numerous legal regulations have been issued to protect lake water quality around the world such as the Clean Water Act in the United-States of America and the Water Framework Directive (WFD) in Europe. However, uncertainties in the evaluation of lake ecological status have repeatedly been pointed out . Problems may arise from properties of the ecosystem, which are not well addressed by the sampling protocol, such as spatial and temporal heterogeneities, which are observable from multi-sites or more frequent in situ sampling. Such spatio-temporal heterogeneities have profound effects on, or result from, the interactions between organisms themselves and their environment. They thus have consequences on a lake ecosystem quality assessment and might lead to misleading results and erroneous assignments to ecological status classes. An-other alternative is to utilize mathematical modeling, which can be employed to describe spatiotemporal variations in hydrodynamics, water quality, and ecological variables and can be applied to predict the water quality and ecological conditions due to human activities and after adjustment strategies. The objective of this study was to develop a three-dimensional hydrodynamic-ecological coupled model (SCHISM-Ecol) to simulate the hydrodynamics, water quality, and biomass of phytoplankton, zooplank-ton, and fish in Tsuei-Feng Lake (TFL), which is located in the north-central mountains of Taiwan.
From the scientific point of view but also for the restoration practice the work jest very essential, I would strongly support a publication of this study, although in my opinion a reorganization of its content is necessary.
The abstract is informative enough. Keywords are informative and relevant. Defining the objectives of the article is adequate and appropriate to the subject. The methods are presented correctly and sufficiently informative to enable the repetition of tests, the work is research-specific. Nevertheless, I think the chapters 3. Model Validation and 4. Results and Discussion are badly organized and need reorganization i shortenings, transfer of some tables / figures to the supplement. In my opinion, the article should not be published without changes in key chapter (Results and Discussion). In this chapter, the scientific discussion of the results has not been carried out, it is necessary to supplement it. The interpretations and conclusions sound, justified by the data and consistent with the objectives.
SOME COMMENTS
- Introduction
The last paragraph of the introduction : “This article is organized as follows. Section 2 presents…..” - I consider it unnecessary and suggest its removal
- Model Validation
Introductory sentences in chapters 3.1, 3.2., such as:
"The accurate prediction of water levels using models is an important key for water resource management in lakes"
"Water temperature in lakes is an important variable that affects biological metabo-lism and processes and biochemical reactions of water quality in the water column"
they are trivial and obvious and seem unnecessary.
Results (chapter 3. Model Validation) are presented too lengthily, I suggest shortening them. I leave the decision to the authors to transfer some of the illustrative materials to the supplement - nevertheless, I consider such a procedure necessary. For example: Figure 6. Comparison of vertical water temperature profiles between model simulations and observations at the buoy station in 2017 and 2018 - its content can be condensed and presented synthetically.
In my opinion: Table 3. Governing parameters, descriptions, values, and units adopted in the water quality-ecological model - please move to the supplement materials.
Author Response
Please see the attached file for response to Reviewer.
Author Response File: Author Response.pdf
Reviewer 3 Report
Very interesting paper, I like to read it and probably use in my work. I highly appreciate using sensitivity analyses.
Author Response
Very interesting paper, I like to read it and probably use in my work. I highly appreciate using sensitivity analyses.
Response: Thanks for the encouragement by the Reviewer.
Author Response File: Author Response.pdf
Reviewer 4 Report
This article sounds very coherent and the English is very readible. I think more information about the base zoo and phytoplankton values provided for the model should be given as these parameters also vary substantially with temporal and spatial "locations". References are necessary considering the natural fluctuations over the last ten years (it would be great as this time span is considered the minimum to understand natural dynamics of zoo and phytoplankton) and also throughout the year.
One of my main questions is that this model and these variables are only applicable in this case study. Shouldn't they be a model that could, with due precautions, be developed so that it could be "extrapolated" and applied to other case studies?
Author Response
See the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Second review for the paper "A Three-Dimensional Coupled Hydrodynamic-Ecological Modeling to Assess the Planktonic Biomass in a Subalpine Lake" by Wen-Cheng Liu and co-authors submitted to "Sustainability".
The authors considered all may comments and substantially improved the text.
I think that this paper may be accepted after some revisions as follows:
L 31. Change “an important and valuable resource” to “important and valuable resources”
L 60. Change “much information” to “such information”
L 98. Change “buoy station” to “the buoy station”
L 105. Change “water sample” to “a water sample”
L 112. Change “back to laboratory” to “back to the laboratory”
L 114. Change “composed” to “is composed”
L 118. Change “Leica research microscope” to “a Leica research microscope”
L 123. Change “desiccator” to “a desiccator”
L 127. Change “accuracy” to “an accuracy”
L 179. Change “preyed by zooplankton” to “preyed on by zooplankton”
L 312. Change “are display” to “are displayed”
L 332. Change “the basal metabolism” to “basal metabolism”
L 398. Change “a biomass” to “biomass”
L 444. Change “plankton group” to “plankton”
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Reviewer 4 Report
I do not have any further comments. I think that the authors have integrated the questions raised. There are just some english spelling errors. I suggest a quick reading.
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
