Benthic Diatom Communities in Urban Streams and the Role of Riparian Buffers

Round 1

Reviewer 1 Report

This manuscript does an excellent job demonstrating the significant impact that riparian buffers and benthic diatom communities have in urban streams, in particolar focusing on Oslo Fjord basin, well demonostrating how benthic diatoms reduce pollution, mitigate risk and, in general, improve ecosystem in modified landscape. Introduction Row 35 Considering the topic of the paper, I think it should be imporant to define “urban stream syndrome” Row 46 There are some works focusing on the role of riparian vegetation in streams. Please see [1] Row 73 I think it should be important to cite some works about vegetation impacts on flow in freshwater. Please see [2] 2. Materials and Methods Row 112 .. “small trees”. Please define t ypes of common trees (i.e. Poplus Nigra, Willow trees) 2.6 Row 220 “…CNM geographic functions are a type of ‘distance-based 221 eigenvector maps’ (DBEMs), which belong to a general class called ‘Moran's eigenvector maps’ (MEMs)”; please rewrite 3.2 Row 284 “Urban land cover was associated with changes in water quality” At this part of the paper, I think it is a useless ripetition References [1] Pasquino, V., Saulino, L., Pelosi, A., (...), Saracino, A., Chirico, G.B. (2018) Hydrodynamic behaviour of European black poplar (Populus nigra L.) under coppice management along Mediterranean river ecosystems River Research and Applications, Volume34, Issue6 July 2018 Pages 586-594 [2] Aberle J, Järvelä J (2013) Flow resistance of emergent rigid and flexible floodplain vegetation J Hydraul Res 51(1):33–45

Author Response

Dear reviewer,

thank you for your positive comments. Please find our replies in the attachment.

Best regards,

 

Petra Thea Mutinova

Author Response File: Author Response.docx

Reviewer 2 Report

This is a very interesting study with critical implications for management. The manuscript is very decent, well written and organized. Language is clear, aims are well defined and research questions are supported by defined hypotheses.

Riparian buffer zones are an important topic and knowledge from numerous papers has been gained so far. However, the effect of forested riparian buffers on water quality and ecosystem functioning in urban environments is not that much recognized. The authors try to fill this gap and I find the manuscript fully deserves to be published, and I am convinced it will receive special attention.

I do not have any major comments and I feel this manuscript is almost ready for publication. I have only some small remarks that could be taken into account during any possible re-submission.

L199: Ordination is designed for exploratory data analysis and not for hypothesis testing. Please, be more precise here and rephrase this part.

L225: The citation for the vegan package is missing. Also, please checks if all the other packages have been properly cited.

 

Author Response

Dear reviewer,

thank you for your positive feedback. Please find our replies in the attachment.

Best regards,

 

Petra Thea Mutinova

Author Response File: Author Response.docx

Reviewer 3 Report

Review of article water-946816

The manuscript is very well written, and the results are consistent, therefore, it can be recommended for publication. A few minor corrections can be done:

- explicate DBH in line# 112

- insert the correct preposition in line# 125 “All sampling sites, including information on water sampling are listed Table S1 (Supplementary Materials)”

- present centrifugation speed in rcf rather than rounds/minute

Author Response

Dear reviewer,

thank you for your positive feedback. Please find our replies in the attachment.

Best regards,

 

Petra Thea Mutinova

Author Response File: Author Response.docx

Reviewer 4 Report

The article describes the problem called "urban stream syndrome", more specifically the concept of mitigating the effects of urbanization on stream ecosystems flowing through built-up areas. As a biological indicator of flux quality (condition), the authors chose the structure of benthic diatom communities, which should allow the assessment of the impact of forested coastal areas considered as a potential flux management tool. This choice can only be considered extremely accurate, taking into account the diagnostic effectiveness of benthic diatoms proven in the literature.

The adopted method of research and analysis of the collected material does not raise any doubts. Diatoms were collected on 10 pairs of sites with and without plant buffer at the turn of September and October, which is the most convenient time for this type of research. At the same time, samples were taken for chemical determinations of water and a number of indicators describing the diversity of the banks of these streams were determined. All the material obtained in this way was subjected to a series of very sophisticated statistical analyzes, according to various procedures offered in the R language, enabling, inter alia, extinguishing the influence of "dominant" (having a dominant influence on the result of classic analyzes of grouping and arranging) environmental features. All this showed that the forestation of coastal zones of urban streams contributes to the improvement of the "ecological status" of these streams.

The article submitted for review is interesting, inspiring and basically well written, so I recommend publishing it in Water.

However, I propose to consider some remarks that came to mind while reading the manuscript:

• Already in the title, the authors indicate that they will analyze "benthic diatom communities in urban streams", while in the text of the work and in the Supplementary Materials, standard information about this structure cannot be found. I mean the species list (only a few species names are given from the 61 genera labeled (lines 264-274), species richness [and several indices] in Table S3, and "Taxonomic highlights" in several places in Table S5). The phycologist will certainly look for information about the dominant species of diatom communities at individual sites, and above all, for a clear definition of the characteristics (number, biomass, percentage) on the basis of which the structure of these communities was described (and analyzed).
• Similarly, in the description of the obtained results, I miss a comparison of the presence / absence or differences in the abundance of species / species groups (a list of differences) between the selected habitat groups, i.e. indications whether these "Taxonomic highlights" from table S5 were recorded only in these habitat groups, whether they were found everywhere or only more abundantly in certain habitat groups. Such information (details may be included in Supplementary Materials) would provide valuable documentation of research hypothesis 2 (lines 90-92) that “the provision of shading might have positive influences on biodiversity by reducing abundances of dominant, stress-tolerant diatoms and increasing the presence of rare species with ecological preferences for shaded conditions”.
• In the description of the results and their discussion, there is no quantification of the differences in habitat features between the groups of sites determined with the use of statistical methods, and thus no possibility of indicating what gradient of habitat parameters accompanied the increase or decrease in the presence of species with clear ecological preferences.
• Consequently, there is no list of the habitat features preferred by potential indicators (species) for the site types listed in lines 330-334.
• The analyzes of environmental parameters were based on the averaged results of the tests carried out in two dates (Table S1), one of which was more than six months after the collection of biological samples (diatoms). I understand that the authors assume that the situation recorded in July-August 2018 will be repeatable over time, but are therefore the values from the second period significantly different from those from September 7-15, 2017? Do they strongly affect the average of the two measurements? After all, it is said in the discussion that “... several sites (eg, Hoffselva FBF, # 29) were impacted by point-source discharges of unknown composition and origin, potentially contributing to the minimal taxa richness observed at these sites (16-17 diatom taxa; Table S1) ”(lines 415-417). However, elsewhere it is emphasized that: "We sampled all our sites within a narrow time frame during a hydrologically stable period, which may help to explain some of the discrepancy between our results and those reported by Hlúbiková et al. [37] (lines 456-457).

 

Other remarks:

• Figure 3 is erroneously cited in line 309 as "Figure 3a".
• Figure 3 caption says that "In both models the unexplained (residual) variation was 41%" (line 326). It's not in the text. I also do not know which two models it applies to, because the drawing shows only one model.

Author Response

Dear reviewer,

thank you for your positive feedback. Please find our replies in the attachment.

Best regards,

 

Petra Thea Mutinova

Author Response File: Author Response.docx