Diagnosis of the Condition of Aquatic Ecosystems Using a Partial Assessment of Ecological and Trophic States: An Example of Small Lakes in Northern Poland

Round 1

Reviewer 1 Report

Different approaches to assessing the ecological and trophic state, using the example of small lakes in northern Poland

The current suggestions do not represent, in any way, a criticism or an offense to the authors, on the contrary, they, like the "Overall Recommendation", are intended to help significantly improve the manuscript and encourage the authors.

Although the authors have done important field work, the chosen title is not in complete agreement with the results provided in the study! In the article, more than once, the ecological and trophic assessment of the lakes is declared (that means complete!), or, in fact, this state is only partially estimated, based on measurements made on the shore during two days! and on vertical profiles not identified on any map. A full assessment has a different spatial and temporal scope! Two possible titles could be "Different approaches to the assessment of ecological and trophic status on a buffer in the contiguous area of ​​the shore, using the example of small lakes in northern Poland." or "Different approaches for partial assessment of ecological and trophic status, using the example of small lakes in northern Poland."

In other words, the clear purpose of the article is not defined by distinct sentences, neither at the end of the abstract nor at the end of the introductory part, but only mentioned sequentially through the mentioned structures.

Also, the Introduction chapter, which usually represents a "State of Art" on the chosen topic, is far from this stage, the authors quoting themselves in a proportion of 50%, to the detriment of some international references, which abound in the literature on this topic.

On line 42, a term appears that has no business there, but in the Data and Methods chapter, the authors do not even mention it: interpolation. It is a basic term in GIS spatial analysis that needs to be well specified as an algorithm in such a paper.

Another element, which confirms the study/partial analysis of the ecological and trophic stage of the lakes, is mentioned by the authors themselves in the range of lines 51-53, as well as in the range of lines 58-60. You cannot declare an ecological and trophic stage of some lakes with partial analyzes and incomplete sequential measurements.

In lines 59-60, the authors talk about vertical measurement profiles, the data of which are represented in figure 2. Where are these profiles located on the surface of the lakes and based on what criteria were they chosen? Is it somehow just a vertical profile on each lake, be it also in the area of ​​maximum depth or representativeness? If so, the authors have a problem. You cannot do a spatial analysis in plan and 3D using a single vertical profile. All areas with specific characteristics within the lake must be reached.

Sorry, but in figure 1, a foreign reader, ignorant of Poland, has a hard time figuring out where the study area is located ... How about placing a map of Poland in that medallion, on which a border is placed how small ...

On lines 192 and 193, the mentioned parameters appear to be in English, and their acronyms in parentheses appear to be in Polish. A less experienced reader might be confused...

Starting with line 208 ... no, somehow, the "shoreline" you are talking about is the well-known "perimeter" in limnological literature, and its exaggerated length, compared to other lakes, represents another well-known limnological parameter, called "index of sinuosity/convolution"?

Line 226 - maybe ”4.2. Some/several physico-chemical parameters ... You present only several ...

Beginning with line 229, the authors provide some information about the physical appearance of the lakes (areas, depths, etc.). How would it be for the reader to see the 3D models or at least plans (with isobathes) of these lakes inserted in the text? It is so quickly and easily solved in GIS ... The reader would be fully edified on the shape of their cuvettas ...

Figure 2 - from my practical and quite extensive limnological knowledge, I know that the depths are either represented in positive form, in which case the isobathes contain absolute topographic elevations!, or in the form of negative values ​​(so with a minus), in which case they contain relative topographic elevations, so located below "0 water", such as the Y axis of the graphs, within the figure.

Line 347 - the authors talk, again, about interpolation ... Coming back to the previously mentioned idea, please put in the Methodology chapter some sentences about the GIS software used and the interpolation algorithms used! Don't tell me that at such a low density of points in the lake plane you used another interpolation algorithm than "Topo to Raster"...

In lines 367-369, the authors say some elements well-known by any limnologist. If they want to keep this phrase, then they must also refer it to research in the literature (cite some titles here, which abound in the literature), because they did not discover these things.

In Figure 7, how about we also see the correlation curves between the two elements plotted and display the parameters that indicate the quality of the correlation (R2, equation, etc.)? We know, you will say that we do not have enough elements, to define a credible median ... It is the problem of the authors ... The correlations are made, as well as the consistent evaluation of ecological and trophic stages based on multiple series and campaigns of measurements, not based on two days, located on successive days ...

Figure 8 - I have rarely seen such a less expressive and difficult to understand representation. The authors believe that scientific articles are read only by renowned scientists, or, we also have young researchers who are pursuing the path of science and need to see classifications and logical representations, learned in the faculties. How about using very light points to represent the minimum values, and gradually monochrome, darker to black, the points with higher values ​​to the maximum? Thus, on the map, the reader sees an illogical mixture of colored points, the values ​​of which he still has to investigate, with some focused attention.

Again, and at the beginning of subchapter 4.5 "Ecological and trophic state" you must add the correct wording with partial or how you will reformulate. It is like in the case of the hydrological regime, where you come and represent in the hydrograph two days of measurements, and those for a few flows, after which you start talking about the hydrological regime, which, in fact, is multi-annual and over the longest series possible, plus seasonal manifestations or extreme runoff phases .......

Please do not trait simplified the "Discussion" chapter and separate it from the "Conclusions" chapter. Also, boost them both as per the suggestions previously provided. The "Discussion" chapter must be something other than the raw results, respectively it must be their detailed interpretation with statistics, etc. and consistent compared to the results of other researchers, who have published in the literature on the subject. Even some statistics presented in the "Results" chapter can be translated into the following "Discussions" chapter.

The list of references must be seriously updated and some of the authors' contributions removed, because they represent a multiplication of their own citations in the literature and not all of them support the current proposed theme.

Author Response

Alle comments are in attached 'Reviewer_1_response.docx' file

Author Response File: Author Response.docx

Reviewer 2 Report

Manuscript ID: limnolrev-2808372

Manuscript title: Different approaches to assessing the ecological and trophic state, using the example of small lakes in northern Poland"

The paper “Different approaches to assessing the ecological and trophic state, using the example of small lakes in northern Poland” analyzing the eutrophication, ecological state and shoreline changes of four lakes (Święte, Ocypelek, Czarne Południowe and Kałębie) in two rivers systems in Poland. The work is interesting, but I have a few concerns. According to Framework Water Directive (FDW), to analyze the ecological state of lakes, it is necessary to assess four biological components (phytoplankton, phytobenthos, macrophytes and macrozoobenthos). In this paper, the assessment is based only on one sample of macrozoobenthos taken in July. It is suggested to collect macrozoobenthos during April or May, because that is the time when the number and diversity of taxa is usually the highest, especially if hypoxia/anoxia occurs in the bottom layer of water in summer. Also, according to FDW it is necessary to have 12 samples of physical and chemical parameters to assess ecological state of lakes. So, my opinion is that these results are indicative. I suggesting to change the title, to define more precisely aims of the manuscript and emphasize result to eutrophic state not on the assessment of the ecological state due to the lack of data. Furthermore, in the chapter Discussion and Conclusion are missing data about the discussion of the results in this manuscript with other known data.

Other suggestions

Expand the introduction - describe in more detail the condition of the lake, the known results, the role of the meiofauna in the lakes.

p.1, l.13-14: It is not usually to state references in Abstract.

p.1, l.20-21: Please delete the sentence (this sentence is the same as l.21).

p.1, l.24-26: Please define „below the good category“.

p.2, l.62: specific electrical conductivity – what means specific?

Material and Methods - please define how many samples were taken, length of the transect, how many subsamples.

Study area – mark lakes on the map (Święte, Ocypelek, Czarne Południowe and  Kałębie).

Results

p.5, l.186-195: This part belongs to chapter Introduction or chapter Materials and Methods. Please explain classes in Table 3 in Material and Methods (natural shoreline, natural, strongly modified…).

p.6, l.233: “similar pattern” – not for chlorophyll a content?

Figure 2. Please add nitrogen concentrations in the Table 4.

The results contain parts of the text that belong to the Discussion i.e. p.8, l. 303-307 (this part of text is better for chapter Discussion).

Discussion and Conclusion

In this part, the chapter Discussion is missing, it seems like an expanded conclusion. So please compare your results with other known data.

Or I suggest to expand the chapter Results and make a new chapter Results and Discussion. In the Results are already discussion e.g. about physical and chemical parameters such as p.8, l. 303-307.; p.9, l. 325-326.

In conclusion, the formal presentation of the paper needs a major revision.

Author Response

Alle comments are in attached 'Reviewer_2_response.docx' file

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Manuscript title: Different approaches to assessing the ecological and trophic state, using the example of small lakes in northern Poland

The authors have improved all chapters of the manuscript according to suggestions. So, I suggest to accept it.