Influence of Riparian Conditions on Physical Instream Habitats in Trout Streams in Southeastern Minnesota, USA

Round 1

Reviewer 1 Report

General comments

The authors did not use the potential of the latest publications, and recently many important articles have been published regarding the fine sediments input and their impact on in-stream habitats, fish and benthic macroinvertebrates; and ways to minimize the nagative impact. One of the most important forms of human activity is forest management, which is not equivalent to the "deforestation" mentioned by the authors. The study offers limited information about the field methods used to quantify the site characteristics (e.g., substrate measurements, etc.). Given the site characteristics and differences across sites are part of the analyses, more information is needed to understand how these data were collected. The goal of the methods is to present enough information so that the study could be repeated. I also suggest some additional work to describe the conditions/relationships among habitat conditions at individual sites which might provide some insight into the spatial challenge. Was there any spatial auto-correlation in these data?

Introduction:

Page 1, paragraph 1: „ Freshwater streams and rivers provide a variety of ecosystem services important for both aquatic communities and the riverscape [1], and human activities that alter land-scapes can affect those ecosystem services.” – in the manuscript, the authors do not refer in more detail to ecosystem services (ES). I propose to delete these sentences from the Introduction. Or you can leave them, but consistently, please describe what ES were assessed and what ES are provided by the studied catchment (in Methods, Results and Discussion, respectively).

Page 1, paragraph 1: „… Activities such as deforestation in northwestern Europe…” – Here, the authors should rather refer to forest management, which is one of the most important sources of fine sediments in flowing waters, apart from agriculture. Forest management, of course, concerns not only the northwestern part of Europe, and actually definitely not only Europe. I propose to expand on the topic of forest management in the Introduction, Discussion, and then in the Conclusions. The buffer provided by riparian vegetation may be of key importance in protecting flowing water ecosystems (Please see the papers:  2020. Synergistic impacts of sediment generation and hydrotechnical structures related to forestry on stream fish communities, Science of The Total Environment 737: 139751.;

 Page 2, paragraph 2: ”… healthy ripar-ian zone in agricultural settings…” – please also elaborate on the problems related to forest management.

 Page 2, paragraph 3: „…such as intensive agricultural practices, urbanization, and industrialization..” – and again - what about forest management? – see the latest publications:  2020. Synergistic impacts of sediment generation….;  Page 2, paragraph 3: „…Landscape alterations are well known to have negative impacts in the structure and functioning of lotic ecosystems [40].” – Please expand on "functioning of lotic ecosystems". Perhaps this is where the impact of landscape alterations on fish and macrozoobenthos should be expanded upon (please see my comments below).

 Aims:

„We hypothesized that grassy, wide riparian zones would benefit physical instream structure, but poor riparian conditions within the study watershed would correlate with widespread, negative instream impacts.” – the hypothesis formulated in this way is confusing. How to understand its second part, i.e. "…but poor riparian conditions within the study watershed would correlate with widespread, negative instream impacts."? Did the authors include the results of verifying this hypothesis in the same sentence in which they present the hypothesis to the reader?

Fig.1 – no sampling sites marked(!) - If placed in, you may also need parts b) and c). Please mark the boundaries of the regions according to what is in the manuscript, i.e. North, Middle, South (see e.g. Fig. 2).

 Methods

The study offers limited information about the field methods used to quantify the site characteristics (e.g., substrate measurements, etc.). Given the site characteristics and differences across sites are part of the analyses, more information is needed to understand how these data were collected. The goal of the methods is to present enough information so that the study could be repeated.

„Specifically, we examined the possible in-fluences of riparian zones on physical instream habitat within a network of highly valued trout streams” – please see my further comments regarding fish

 2.2. Stream surveys: „… we surveyed stream habitats (riparian and instream) at 57 sites within the three forks of the Whitewater River catchment (North = 20 sites, Middle = 18, South = 19).” – please mark the sampling sites on the map (Fig. 1)

 „… Habitat surveys - At each study site, instream and riparian variables were assessed along a representative, 150-m stream reach with transects every 10 m (15 transects/site). At each transect spanning the width of the stream, four variables each were assessed at four equidistant points along the transect:…” – a graphical presentation of field research methods would make the descriptions very clear. I propose to add a methodological a graphical presentation of field research methods would make the descriptions very clear. I propose to add a methodological diagram as part of to Fig. 1

Habitat surveys: „…Wentworth scale: clay, silt, sand, gravel, cobble, boulder, plus muck, vegetation, and detritus)” – please provide the sizes for various fractions of the bottom substrate, i.e. clay, silt, sand, gravel, cobble, boulder... (E.g. did boulders mean substrate larger than 256 mm in the study?)

Habitat surveys: „…embeddedness (the percent of large substrates such as cobbles covered by fine materials, estimated visually -  visually, i.e. how?

Table 1 and further in the text on page 7 - there is no expansion of the abbreviation „AOV”

Table 1 – there is no expansion of the CV abbreviation

Fig. 4. – please increase the font size for variables

Discussion

In the discussion, do not forget about forest management as one of the human activities that generate fine sediments. The role of riparian vegetation buffers is crucial in such areas! (see mentioned above: 1) 2020. Synergistic impacts of sediment generation

Page 8, paragraph 1: This paragraph is not a discussion, but a repetition of the results.

Page 8, paragraph 2: Please start with your results, then refer to the literature

Str. 11: „BMP” – please explain, as well as all abbreviations used in the paper

Page 9, paragraph 1: please standardize the text formatting

Page 9, paragraph 2: Too long a paragraph in which it is difficult to distinguish the results obtained in the study from those quoted from the literature. Please highlight your findings better.

Page 9, paragraph 3: „The Whitewater River catchment has a long history of deforestation and agricultural” – how much area has been deforested? Or maybe it's about forest management that does not involve total forest clearing?

Page 10, paragraph 1: „(Sweden, [67]; Australia, [68]; Europe, [69]; U.S., [70])” – Of course, Sweden is also Europe. Here the authors quote publications from almost 20 years ago (!). There really is a rich, much newer literature.

4.2. Management Implications

Here, too, there is no reference to forest management impact

Conclusion

Page 11, paragraph 2: „However, due to decades of land abuse and legacy sediment accumulations, these sensitive ecosystems are impaired, negatively impacting important sensitive taxa Ephemeroptera, Plecoptera, and Trichoptera (collectively EPT taxa) [52].” – Here, unrelated to the previous parts of the article, mayflies, stoneflies and caddisflies appear. It is good that the authors finally refer to some details related to the functioning of stream biocenoses. But references to benthos, benthic macroinvertebrates (or aquatic invertebrates) are essential in the Introduction and Discussion. So far, invertebrates have only appeared in the description of the study area, and their assemblage has been described as "poor".

Similarly, the authors assessed "Fish cover", but not once in the Introduction and later in the discussion did they refer to this part of the biocenosis of flowing waters. On the other hand, in the description of the area, the authors show that the studied streams are full of trout, and they also mention the species living there. Since "fish cover" and sediments cover on the stream bottom were assessed, the authors should definitely refer to the habitat requirements of salmonids. Similar to the requirements listed in the conclusions of invertebrates from the EPT group. (mayflies, caddisflies, stoneflies).

Author Response

Please see the attachment. 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments for author File: Comments.pdf

Author Response

Please see attachment. 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

General Comments:

The authors made considerable efforts to revise the manuscript. They largely followed the advice of reviewers. The paper has been improved, focusing on the key messages of the paper. I support its publication in its current form.