Stream Algal Biomass Associations with Environmental Variables in a Temperate Rainforest

Round 1

Reviewer 1 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

Dear authors,

It is my pleasure to go through the manuscript again and comment on the research. I will continue what I wrote in the last review report, that the concept of this article is indeed novel and publication consideration worthy. Authors have substantially improved the manuscript, ncorporating the comments given in the last review cycle. Some minor comments that can improve the manuscript further are,

1. Line 65-72: I will suggest authors to replace the word 'predicted' with 'hypothesis'. Technically, a hypothesis is what needs to be framed and tested. 

2. Lines 73-86: Its getting a bit jargonous. Please try to list the objectives of the study in points 1 and 2, or write a hypothesis that this research will be testing.

 

Rest of the comments are taken care of by authors in the last review cycle.

 

 

Comments on the Quality of English Language

Fine

Author Response

Response to Reviewer #1:

Please see our responses to each of the reviewer's points - each preceded by "ET et al."

It is my pleasure to go through the manuscript again and comment on the research. I will continue what I wrote in the last review report, that the concept of this article is indeed novel and publication consideration worthy. Authors have substantially improved the manuscript, ncorporating the comments given in the last review cycle. Some minor comments that can improve the manuscript further are,

ET et al.: Thank you very much for revisiting our manuscript and providing your insightful comments. We greatly appreciate your acknowledgment of the novelty of our concept and the improvements we've made based on previous feedback.

1. Line 65-72: I will suggest authors to replace the word 'predicted' with 'hypothesis'. Technically, a hypothesis is what needs to be framed and tested. 

Et et al.: Following your suggestion, we have replaced “predicted” and “predictions” with hypothesized” and “hypotheses” in the Introduction.

2. Lines 73-86: Its getting a bit jargonous. Please try to list the objectives of the study in points 1 and 2, or write a hypothesis that this research will be testing.

Et et al.: We agree that our hypotheses are verbose. We have restructured them to improve clarity and readability.

Rest of the comments are taken care of by authors in the last review cycle.

ET et al.: Thank you again for noting that the remaining comments from the previous review cycle have been addressed in our revised manuscript; we appreciate your feedback and remain committed to ensuring its quality and contribution to the scientific community.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

see attached

Comments for author File: Comments.pdf

Author Response

Response to Reviewer #2:

Please see our responses to each of the reviewer's points - preceded by "ET et al."

In some instances, the reference numbers are in bold, and not in others. See line 279 and many others.

 

ET et al.: Thank you for catching that error. We have reviewed the in-text references to ensure that they are all now uniformly formatted, that is, devoid of bold font.

 

Line 159 to 164 should follow 156 since this justification is directly tied to the method.

 

ET et al.: Thank you for noting this. We agree and have moved this explanation of chl-a to follow directly after the description of this method.

 

positive predictor of sestonic algal biomass, water temperature was a significant, positive predictor of both benthic and sestonic algal biomass, and that maximum water velocity was a significant, negative predictor of benthic algae, which supports our hypothesis that macroinvertebrate predators, temperature, and water velocity are *important abiotic drivers of stream algal biomass.

 

* comment:  These are not all abiotic… The sentence is too long. Break it up to make it clearer.

 

ET et al.: We agree on both fronts. We have removed the term “abiotic” and have split this sentence into two.

 

 Line 288. Shouldn’t nutrient availability be a consideration?

 

ET et al.: While we wish we had access to nutrient data for this study, as we explain in the manuscript, we unfortunately did not. We acknowledge that the inclusion of specific references to oligotrophy and potential nutrient limitation in a paragraph detailing our findings on temperature and canopy cover may be confusing. Consequently, we have eliminated these references to nutrient limitation from the paragraph.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

The objectives of the study are well laid out and are of some value to the field, the actual study itself suffers from limited data, particularly in relation to duration (a single season in a single year) and spatial scale within sites. Thus is it not possible to extrapolate beyond this restricted set of data in this particular area over the 2-month period. A lot of the relationships under investigation operate on small scales and such is the spatial and temporal variability in lotic ecosystems that more extensive temporal and spatial replication is required to fully evaluate the effects of physico-chemical factors on ecological patterns and processes. The restricted data set is then over-analysed and thus some surprising/unexpected relationships found and other expected ones  (from many studies elsewhere) not seen. The caveats described at the end of the manuscript are well made and do, unfortunately, mean that the study, as presented, is insufficient to allow the broad ranging conclusions described to be made.

 

A number of specific comments are presented below.

 

Line 32 Introduction. Need to consult some more recent publications on this topic as many cited references are now a bit dated.

Line 42 – The use of the term ‘autotrophic seston’ is rather odd for heavily afforested (and therefore heavily shaded, light-limited) streams and small streams in general. Much of the algal material caught in flowing water is actually dislodged benthic algae rather than true seston (i.e phytoplankton often found in larger rivers of slow flowing backwaters). Where is the support for autotrophic seston per se as a particular food source being important in heavily forested streams?

Line 45-48. For useful predictions to be developed, need longer term data sets – a single season in a single year is totally insufficient.

Line 49-53. Which of these factors have generally been found to be most important in the large number of other studies on this topic?

Line 79 – It is not clear the extent to which independent seston algae species occur in these heavily shaded forested streams?

Line 91-94. Given this particular study is taken from a longer term watershed experiment why not include data from more seasons and years?

Line 106-120 – It is not clear whether each site was sampled 3-5 times across the study period or samples were taken from each of the 30 sites were collected once across the period?

            This approach represents a very limited sampling  overall in space (within a site) and time (appears to be only 1 sampling occasion per site?

            Composite samples can overcome small scale environment – biotic relationships that are more important than site-level relationships. The question is whether the physico-chemical and biotic factors are sampled at the appropriate scale for the periphyton parameters?

Line 129-132 – It is not clear why a single water velocity measure is taken for the whole site given clear relationships between small scale velocity and periphyton distribution and abundance

Line 147 – Did you undertake an analysis of the relationship between benthic and water column algal abundance across the sites?

Line 159-163 – What about time (sample date) as a possible interaction term?

            It is a shame such a sophisticated analysis was used on such a limited data set.

Line 174 – On line 108 you describe 30 sites here 30?

Line 231-232 – How are these apparent predator-seston relationships explained? Are they real or a due to a mismatch os sampling scales and ecological relationships? Are predators reducing grazing insect abundance hence benthic algal growth increases and more cells from larger algal biomass can be dislodged by current? It is puzzling that no relationship with grazer/scraper abundance and algal biomass found – probably due to mismatch of sampling scale and scale of ecological relationships again.

Line250-252 – these conclusions are being extrapolated much too far based on the limited data set.

Line 265-269 – The limited data and its extent really does not support such specific conclusions to be drawn.

Line 275-280 – Again, such discussion is not warranted by the limited data

Line 281-289 – These caveats are very well made and unfortunately do leave the current data set as insufficient to draw any significant conclusions on the targeted relationships. It is very surprising therefore, having just expounded on the caveats, the MS then provides a final ‘summary’ paragraph reiterating and generalising that clear relationships have been demonstrated. Unfortunately they have not.

Reviewer 2 Report

Comments and Suggestions for Authors

The originality of the manuscript is high. The authors are aware of the study's weaknesses and wrote about them in the discussion part.

I also wonder that there were only salmonoids in rivers. Could you also give more information about fishes in the manuscript. 

They also did not take into account submerged or emerged macrophytes. 

The depth of streams, type of river ground, typed of rocks, stones... etc.

They may also add these parameters as a caveats/weaknesses of their study.

The manuscript may be accepted after minor revision. 

other comments:

It may be better to add statistical or numerical data into abstract part. 

Figure 1 must be redrawn. River tributaries and sampling points are not evident on the map. Can you make a bigger figure or zoom watersheets as next to the figure 1.

Line 174-181.It may be better to give as a new Table (not to much detail for all sampling sites, just show ranges for each parameter).

Please see PDF attachment for my comments. 

Comments for author File: Comments.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Its my pleasure to go through this manuscript and suggest comments aimed at better representation of the research and greater acceptability to the wider readership of "Water". The authors' have used chlorophyll a as a proxy to assess algal biomass. This is a novel approach that significantly reduces the time of estimation and assessment in conventional methods, but authors need to justify why this form of assessment is beneficial over others.

The authors should mention some monitoring and assessment studies where conventional methods have been used and then argue in the introduction section about the benefits of using chrolophyll a, over other methods. Some of such articles are, https://www.inderscienceonline.com/doi/abs/10.1504/IJEP.2021.126971, https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.3903, https://www.sciencedirect.com/science/article/abs/pii/S0043135423002270 etc. Then explain why chlorophyll a estimation may be the best method for riperian phycological assessments. Articles such as https://pubs.rsc.org/en/content/articlelanding/2014/em/c4em00326h/unauth critically compare different methods of algal biodiversity assessment. As chlorophyll a estimation does not give a species-level (beta diversity) estimation of algal species, it is important to rationalize the use of this method over other more exhaustive algal biodiversity assessment methods.

I will suggest the authors to write sample numbers (n=?) in the caption of all the figures togive readers an idea on the sample size.

Why have authors not used any other inferential statistical methods, such as analysis of variance between sites?

I will invite the authors to respond to the comments before considering the article for publication consideration. Overall, I find the manuscript novel and worthy of publication, provided the comments are addressed in the rebuttal. 

Comments on the Quality of English Language

Fine