Functional Diversity of Macroinvertebrate Communities in River Nature Reserves of Spain

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents the results of a study of functional diversity of macroinvertebrates inhabiting running waters in river nature reserves (RNRs) in Spain. An extensive number of communities in 128 river nature reserves were sampled on a single occasion in spring-summer 2017. Invertebrates were identified to family and functional traits were analyzed in several ways. The results confirmed that RNRs generally do a good job in protecting functional diversity of river macroinvertebrates as well as taxonomic diversity. The results of the study are valuable and provide a basis for assessing the ecological value of the surveyed RNRs over time and also new ones which may be established. The paper has a sound scientific base with the methods being generally well chosen and described. Some of the writing could be improved by judicious editing.

My first comment is that I would like to see a brief description of the fauna provided from a taxonomic perspective. Although the paper is primarily about functional diversity most readers will want to visualize the general nature of the fauna. To this end I suggest inserting a table at the start of results showing the classes and orders of invertebrates present and perhaps the (10?) most abundant families. The information can be obtained from the Supplementary table matrix but is really a fundamental basis for the study.

Throughout the paper the word taxonomical is used (as well as taxonomic) on occasions.  I suggest the term taxonomic is preferable throughout.

Specific points

Lines 22, 106. What is a “punctual disturbance”? Do you mean occasional?

Line 50. Do all organisms really play a central role in providing ecosystem services? I don’t think so. Reword.

Line 81. Can you define “full biodiversity” here?

Line 84 and elsewhere. The term “figure” does not seem right in this context. I cannot think what the appropriate term would be.

Line 146. Discharge was calculated from water velocity times mean cross-section area. How was it decided where to measure velocity? Were several measurements made at each site? The calculation of discharge would require an average value of velocity.

Line 168. Family level identification may well give a reasonable indication of structure and function, but it is well known that not all genera and species in a family have the same/or even close ecological roles.   You would be best to state that here but indicate that family level does provide a useful approximation.

Table 1. I suggest maximum not maximal, and still (?) rather than null.  Is nymph the same thing as pupa as used by English speakers? What are flags?

Line 245. It might be worth defining biocoenoses, by putting “communities” in parentheses.

Figure 2. Define the components of the box plots in the figure legend/caption. Not all workers use the same conventions.

Line 274. Shredders typically chew on dead plants (leaves and wood). I assume that scrapers feed on the surfaces of dead plant material. Clarify.

Figure 4. The individual boxes are not identified and need to be labelled. See also Figure 6.

4.3 Functional diversity – Can you indicate what the median values mean in descriptive terms?

Lines 302, 303.  The very high Spearman’s R values suggest P would be much stronger than <0.05. Perhaps <0.01 or even <0.001.

Figure 6 legend. By “as a whole” do you mean with all RNRs combined?

Figure 7. Can the axes be labelled?

Figure 8. There seems little justification for this figure which comprises only four percentage values. A short sentence in the text would suffice.

Line 333. By net do you mean network?

Line 334. I suggest inserting “their catchments” before “...such as cropping...”.

Line 370. Are these traits resilience/resistance traits? Make clear.

Line 370. What is “The fact”. Clarify.

Line 403. “Due to time constraints” – On whom?

Line 417. ”though this is counter-intuitive for the own authors”. Meaning unclear. What authors?

Line 429. What were the most abundant taxa in the communities? State.

Line 455. What is the integrative approach? Briefly define.

Line 465. Would “establishment” be a better term than “declaration”?

Supplementary file: What are the abundance units for invertebrates, and what are the N and P units? I suggest these be included.

Author Response

This manuscript presents the results of a study of functional diversity of macroinvertebrates inhabiting running waters in river nature reserves (RNRs) in Spain. An extensive number of communities in 128 river nature reserves were sampled on a single occasion in spring-summer 2017. Invertebrates were identified to family and functional traits were analyzed in several ways. The results confirmed that RNRs generally do a good job in protecting functional diversity of river macroinvertebrates as well as taxonomic diversity. The results of the study are valuable and provide a basis for assessing the ecological value of the surveyed RNRs over time and also new ones which may be established. The paper has a sound scientific base with the methods being generally well chosen and described. Some of the writing could be improved by judicious editing.

My first comment is that I would like to see a brief description of the fauna provided from a taxonomic perspective. Although the paper is primarily about functional diversity most readers will want to visualize the general nature of the fauna. To this end I suggest inserting a table at the start of results showing the classes and orders of invertebrates present and perhaps the (10?) most abundant families. The information can be obtained from the Supplementary table matrix but is really a fundamental basis for the study.

                  RESPONSE: We have included a new figure (now figure 2, and we have renumbered the following) with the densities of all the families. We have also included a sentence for explaining this figure at the beginning of the results section (“Merging all, 98 families of macroinvertebrates were recorded, represented by more than 192000 individuals. When combining the data from all the RNRs, Chironomidae was, by far, the most abundant family, followed by Baetidae, and a group of four families also quite abundantly represented (Gammaridae, Simuliidae, Leuctridae and Elmidae; Figure 2). Most of the other families were more scarce or even quite rare in the whole RNRs”).

 

Throughout the paper the word taxonomical is used (as well as taxonomic) on occasions.  I suggest the term taxonomic is preferable throughout.

                  RESPONSE: We have changed all taxonomical to taxonomic, thank you.

 

Specific points

Lines 22, 106. What is a “punctual disturbance”? Do you mean occasional?

                  RESPONSE: Yes, we have changed them to occasional, thank you.

 

Line 50. Do all organisms really play a central role in providing ecosystem services? I don’t think so. Reword.

                  RESPONSE: We have changed “All” by “Many”.

 

Line 81. Can you define “full biodiversity” here?

                  RESPONSE: We have changed “full biodiversity” by “total biodiversity of these ecosystems”.

 

Line 84 and elsewhere. The term “figure” does not seem right in this context. I cannot think what the appropriate term would be.

                  RESPONSE: We have changed the term to “category”.

 

Line 146. Discharge was calculated from water velocity times mean cross-section area. How was it decided where to measure velocity? Were several measurements made at each site? The calculation of discharge would require an average value of velocity.

                  RESPONSE: We have clarified this including the following: “…water velocity, together with depth, was measured in different points of a transversal section of the reach using a propeller-meter with a scale in it (Global Water Digital FP-211) and mean values of both variables were obtained to calculate discharge after measuring the width of the channel”.

 

Line 168. Family level identification may well give a reasonable indication of structure and function, but it is well known that not all genera and species in a family have the same/or even close ecological roles.   You would be best to state that here but indicate that family level does provide a useful approximation.

                  RESPONSE: We are aware of it, so we have reworded the sentence as follows, thank you: “As pointed out by several authors (e.g. García-Roger et al. 2013), this level is useful approximation to account for the structure and function of macroinvertebrate communities, despite the intrinsic differences in particular ecological roles of different genera and species within the same family”.

 

Table 1. I suggest maximum not maximal, and still (?) rather than null.  Is nymph the same thing as pupa as used by English speakers? What are flags?

                  RESPONSE: “Maximal” is what the authors of the database use and other authors also using this trait classification, so we would prefer to keep this term as they do. The same occurs with null (is the category other authors use). Yes, nymph refers to the pupa stage. Flags are massive, plain stones. Maybe is not a common term, but again is to keep the nomenclature of the original (and posteriors) database.

 

Line 245. It might be worth defining biocoenoses, by putting “communities” in parentheses.

                  RESPONSE: Ok, we have included it.

 

Figure 2. Define the components of the box plots in the figure legend/caption. Not all workers use the same conventions.

                  RESPONSE: Ok, we have included “(representing median, interquartile range and maximum and minimum, with white points indicating outliers)” in the figure legend (Figure 2, now Figure 3), thank you. We have made this clarification also in Figures 4 (now Figure 5) and 6 (now Figure 7).

 

Line 274. Shredders typically chew on dead plants (leaves and wood). I assume that scrapers feed on the surfaces of dead plant material. Clarify.

                  RESPONSE: We agree, the order was changed in the sentence, thank you. We have reordered the sentence as follows: “Scrapers and shredders (feeding on biofilm and living microphytes, and on dead, coarse particulate organic matter, respectively)”

 

Figure 4. The individual boxes are not identified and need to be labelled. See also Figure 6.

                  RESPONSE: Thank you. We have redrawn Figure 4 (now Figure 5). Regarding Figure 6 (now Figure 7), the label is in the Y axis because each box represents a unique index.

 

4.3 Functional diversity – Can you indicate what the median values mean in descriptive terms?

                  RESPONSE: The median is less sensitive to extreme or outlier values, so the information it gives us is the same than the mean but even more representative of the whole dataset, as it is not so influenced by the extreme values in it. In fact, if there are no extreme values, in some cases the mean and median coincide.

 

Lines 302, 303.  The very high Spearman’s R values suggest P would be much stronger than <0.05. Perhaps <0.01 or even <0.001.

                  RESPONSE: Yes. We have updated the p values accordingly, thank you.

 

Figure 6 legend. By “as a whole” do you mean with all RNRs combined?

                  RESPONSE: Yes. We have changed it by “combined” in that figure (now Figure 7), thank you.

 

Figure 7. Can the axes be labelled?

                  RESPONSE: In that figure (now Figure 8), the Y axis corresponds, in each row, with the label in the right box (e.g., NumbTaxa, FRic, etc.), and the X axis corresponds, in each column, to the upper box (e.g., NumbTaxa, FRic, etc.), so that is why they are not labeled independently. We think that it would be so repetitive.

 

Figure 8. There seems little justification for this figure which comprises only four percentage values. A short sentence in the text would suffice. 

                  RESPONSE: We agree, but anyway we would like to keep it (now Figure 9), as it is so graphical of the great differences between taxonomic and functional diversity… Nonetheless, if you find it necessary, we will delete it and will include the information in a sentence.

 

Line 333. By net do you mean network?

                  RESPONSE: Yes, we have changed it, thank you.

 

Line 334. I suggest inserting “their catchments” before “...such as cropping...”.

                  RESPONSE: Ok, we have included it.                      

 

Line 370. Are these traits resilience/resistance traits? Make clear.

                  RESPONSE: We have clarified it, thank you.

 

Line 370. What is “The fact”. Clarify.

                  RESPONSE: We have reformulated that sentence in the following way to make it clearer: “This highlights the increased vulnerability of RNR communities under the current conditions of global change in the Mediterranean area”.

 

Line 403. “Due to time constraints” – On whom?

                  RESPONSE: By this we mean that, in most cases, these monitoring programs are carried out by technicians from public administrations or basin organisations who cannot devote much time to the identification of organisms to genus or species level, as they have to deliver their results some months after sampling, in order for the monitoring of streams to be effective. To clarify it, we have reformulated the sentence as follows: “Due to the time constraints of public agencies, with samples of a comparatively large spatial scale as in the presented study, subsequent identification of specimens to species level is hardly feasible, especially due to the absence of morphological characteristics in the immature stages of many species, which makes correct and rapid identification even more difficult.”

 

Line 417. ”though this is counter-intuitive for the own authors”. Meaning unclear. What authors?

                  RESPONSE: We refer to authors cited in that same sentence. We have clarify it in the parenthesis, reformulated as follows: “(though these authors pointed out this was counter-intuitive for them)”.

 

Line 429. What were the most abundant taxa in the communities? State.

                  RESPONSE: We have included a new figure in the manuscript and commented on the most abundant taxa in the results section, thank you.

 

Line 455. What is the integrative approach? Briefly define.

                  RESPONSE: We have clarified it including “combining taxonomic and functional analyses”.

 

Line 465. Would “establishment” be a better term than “declaration”?                RESPONSE: Yes, thank you, we have changed it.

 

Supplementary file: What are the abundance units for invertebrates, and what are the N and P units? I suggest these be included.

                  RESPONSE: Thank you. Units for those parameters have been included in the table.

Reviewer 2 Report

Comments and Suggestions for Authors

This study examined functional diversity of macroinvertebrates in river reserve areas of Spain. The results presented in this work are interesting and can be useful for assessment and monitoring of biodiversity in reserved areas. Following are my comments and suggestions:

- L129, I think it will be useful to provide additional information of 18 typologies of the study sites.

- Results, It will be useful to report more details of macroinvertebrates collected in the present study e.g. number of families, number of specimens for each family. Also, the physicochemical parameters (e.g. summarization of the characteristics of the sampling sites) should be provided.

- L330, I try to find for the meaning of R-T01, R-T06 ….. but did not found. Therefore, I think it will be helpful to provide brief information about these typologies.

 

- L450-451, the conclusion here stated that RNRs protected “great diversity” but I did not found that the results were compared with non-protected areas or other protected areas. Therefore, please provide this comparison to support the conclusion that diversity is higher in the RNR.

Author Response

This study examined functional diversity of macroinvertebrates in river reserve areas of Spain. The results presented in this work are interesting and can be useful for assessment and monitoring of biodiversity in reserved areas. Following are my comments and suggestions:

- L129, I think it will be useful to provide additional information of 18 typologies of the study sites.

                  RESPONSE: As that information can be found in the cited reference and explaining each one would require a lot of space, we have included a new table in the Supplementary material with the names and codes of each typology, together with the references where this information can be consulted. Thank you.

 

- Results, It will be useful to report more details of macroinvertebrates collected in the present study e.g. number of families, number of specimens for each family. Also, the physicochemical parameters (e.g. summarization of the characteristics of the sampling sites) should be provided.

                  RESPONSE: We have added new information and a new figure at the beginning of the Results section. Regarding the physicochemical characterization, that information can be found in tables as Supplementary Data, and we think it could be repetitive. Also, we would need to include a new subsection in the Results section, as it begins with the taxonomic diversity.

 

- L330, I try to find for the meaning of R-T01, R-T06 ….. but did not found. Therefore, I think it will be helpful to provide brief information about these typologies.

                  RESPONSE: We have included a new table in Supplementary information and the reference where those typologies come from, together with an official web page where information on each typology can be found. Including all that in the manuscript, would need of a lot of additional space.

 

- L450-451, the conclusion here stated that RNRs protected “great diversity” but I did not found that the results were compared with non-protected areas or other protected areas. Therefore, please provide this comparison to support the conclusion that diversity is higher in the RNR.

                  RESPONSE: We did not do a comparative analysis because that was not the objective of the study, as that would require a different methodological approach. Our aim was to characterize the taxonomic and, mainly, the functional diversity of the studied reaches, and we provided indexes for that. Those indexes can be interpreted on their own, so not comparison would be needed. Nonetheless, we have modified this sentence to avoid misleading interpretation of the conclusion, thank you: “Our results support the fact that most RNRs are protecting communities of great diversity, not only taxonomic (shown by the overall high values of the indexes calculated), but also functional, which contributes to the proper functioning of the ecosystems found in these stream reaches”.