Flow–Vegetation Interaction in a Living Shoreline Restoration and Potential Effect to Mangrove Recruitment
Round 1
Reviewer 1 Report
Title: Flow-vegetation interaction in a living shoreline restoration and potential effect to mangrove recruitment.
Kibler et al.
I was excited to review this manuscript because I live on the southeastern coast and I do salt marsh restoration research. I was excited to see the Irma and Mathew Hurricane data embedded in this manuscript, and I particularly pleased to see the positive effects of vegetation on shoreline dynamics. This manuscript is basically written by engineers for a biological / ecological journal, so there are many editorial issues that must be addressed. For example, our sample estimates are called the mean and not m. Organismal scientists and natural resource managers typically present mean + SE for the summary stats, but mean + SD is acceptable if sample size is included. These are two very easy fixes. The authors seem to use the term significant without any statistical support. In addition, the authors suggest differences between Seawall, Restored, and Reference site measures with no statistical support. Many of the figures could probably be removed because they are simply descriptive values…again with no statistical support for differences or no differences.
This study is very interesting and timely. It may show that benefits of living shores over hardened structures, but without any statistical support it is hard to tell. It was fortuitous to see that these data were collected during Hurricane Matthew and Irma events, especially noting the potentially positive influence of vegetation on shoreline stability (figure 6). Please perform statistical analyses, only say things are different if you can support this statistically, and present summary stats (mean + SE). You could probably reduce the number of figures to only those that have statistical support and simply provide those in appendices. Remove the word ‘significant’ unless there is statistical support. Why present shore velocity at 1 and 5 cm above bed in figure 8? Could it be because normalized turbulent kinetic energy results look so different in figure 10 (may be significant at 5 cm, but we do not know without stats). Sediments across sites and organic matter data are mildly interesting, but one has no idea if there are any real differences without any statistical support. If not different, simply state so and have a table with means + SE (probably in the appendices). Figure 13 data looks like it could be analyzed with a 2 way anova (site, time, site*time) for shoreline and then for channel data. If there are significant main effects or interactions, then present those data. The current figure is completely uninformative.
This research has potential.
Author Response
Reviewer 1
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Comments to Author:
1) I was excited to review this manuscript because I live on the southeastern coast and I do salt marsh restoration research. I was excited to see the Irma and Mathew Hurricane data embedded in this manuscript, and I particularly pleased to see the positive effects of vegetation on shoreline dynamics. This manuscript is basically written by engineers for a biological / ecological journal, so there are many editorial issues that must be addressed. For example, our sample estimates are called the mean and not m. Organismal scientists and natural resource managers typically present mean + SE for the summary stats, but mean + SD is acceptable if sample size is included. These are two very easy fixes. The authors seem to use the term significant without any statistical support. In addition, the authors suggest differences between Seawall, Restored, and Reference site measures with no statistical support. Many of the figures could probably be removed because they are simply descriptive values…again with no statistical support for differences or no differences.
Author response: We thank the Reviewer for these suggestions. Statistical testing strengthens conclusions of the paper and have revised according to the Reviewers suggestions, as detailed below.
2) This study is very interesting and timely. It may show that benefits of living shores over hardened structures, but without any statistical support it is hard to tell. It was fortuitous to see that these data were collected during Hurricane Matthew and Irma events, especially noting the potentially positive influence of vegetation on shoreline stability (figure 6).
a. Please perform statistical analyses, only say things are different if you can support this statistically, and present summary stats (mean + SE).
Author response: We have analyzed our data for statistical significance and added tables (Table 3 and 4) summarizing mean + SE. We have revised the text of several sections to reflect the addition of statistical analysis.
b. You could probably reduce the number of figures to only those that have statistical support and simply provide those in appendices.
Author response: We thank the Reviewer for this suggestion. We have reduced the number of sediment figures, moving 2 figures to Appendices. The figures conveying hydrodynamic results have been modified to indicate statistically significant differences.
c. Remove the word ‘significant’ unless there is statistical support.
Author response: We thank the Reviewer for this suggestion. When describing results we have reserved use of the word ‘significant’ to where there is demonstrated statistical support. However, it should be noted that the word ‘significant’ does appear several times in the manuscript in the context of the standard wave parameter ‘significant wave height’, Hs. To avoid reader confusion we have included a definition of ‘significant wave height’ (L319-320).
a. Why present shore velocity at 1 and 5 cm above bed in figure 8? Could it be because normalized turbulent kinetic energy results look so different in figure 10 (may be significant at 5 cm, but we do not know without stats).
Author response: We thank the Reviewer for raising this point, as it is an important outcome of the paper that should be highlighted. Comparison of observations near-bed and higher in the flow profile allow for understanding of the relative influence of flow resistance due to the bed versus vegetation. To supplement existing discussion of this result (L448-454), we added new text in a few places within the revised manuscript (L293-295, L297-299, L419-427) to better clarify this study outcome.
b. Sediments across sites and organic matter data are mildly interesting, but one has no idea if there are any real differences without any statistical support. If not different, simply state so and have a table with means + SE (probably in the appendices). Figure 13 data looks like it could be analyzed with a 2 way anova (site, time, site*time) for shoreline and then for channel data. If there are significant main effects or interactions, then present those data. The current figure is completely uninformative. This research has potential.
Author response: We agree with the Reviewer that statistical testing strengthens conclusions of the paper. However, in the case of sediment analysis we lack sufficient statistical power to demonstrate statistical significance of differences due to high variability and low sample sizes. We therefore can only report observations descriptively. We have adopted the Reviewer’s suggestion to limit reporting of these data and have moved figures to Appendices.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper at hands deals with the effects of coastal vegetation on hydrodynamics, sedimentation and morphology. Data collected in a mature mangrove forest (i.e. reference site) are compared to data collected on a shoreline site without vegetation and another one restored 6.5 years before with marsh grasses and mangrove seedlings. Data collected in both shoreline and adjacent subtidal channel locations include flow velocity, wave height, stem density and diameter within vegetated sites, as well as sediment cores. Attenuation of velocity and wave energy was highest in the reference mangrove forest and lowest in the unvegetated sites, causing differences in morphology, sediment texture, organic matter content, and mangrove propagule recruitment, too. While these results basically are expectable, this is one of only a few studies that quantifies effects of living vegetation and restoration efforts on shoreline stability by field-based observation. Thus, it might help to improve decision making about restoration strategies on disturbed (sub)tropical shorelines. From this point of view the manuscript is highly welcome and deserves publication. Data collection and analyses are sound, the results clear and the discussion in-depth. I have only some minor remarks following next:
L249/250: “…mean density of 83 stems/m2…”: is that really stems or the number of prop roots? Please clarify.
L338: Koca et al 2017: use MDPI style for References, i.e. [37] and subsequently check the order of the References
L438-441: “Here, normalized turbulent dissipation rate at 5.0 cm above the bed is greatest in the Reference shoreline, followed by the Restored shoreline, and lowest in the Seawall site. Here, normalized turbulent dissipation is greatest in the Reference shoreline, followed by the Restored shoreline, and lowest in the Seawall site”: redundant, delete the second phrase.
L 569- 599: The chapter conclusion primarily repeats the evidence given in the results and discussion chapters as well as in the abstract. Redundant information should be discarded.
L641/642: delete “Frontiers in Ecology and the Environment”, use only abbreviation.
L670/671: delete “”
Author Response
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Reviewer 2
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General Comments:
The paper at hands deals with the effects of coastal vegetation on hydrodynamics, sedimentation and morphology. Data collected in a mature mangrove forest (i.e. reference site) are compared to data collected on a shoreline site without vegetation and another one restored 6.5 years before with marsh grasses and mangrove seedlings. Data collected in both shoreline and adjacent subtidal channel locations include flow velocity, wave height, stem density and diameter within vegetated sites, as well as sediment cores. Attenuation of velocity and wave energy was highest in the reference mangrove forest and lowest in the unvegetated sites, causing differences in morphology, sediment texture, organic matter content, and mangrove propagule recruitment, too. While these results basically are expectable, this is one of only a few studies that quantifies effects of living vegetation and restoration efforts on shoreline stability by field-based observation. Thus, it might help to improve decision making about restoration strategies on disturbed (sub)tropical shorelines. From this point of view the manuscript is highly welcome and deserves publication. Data collection and analyses are sound, the results clear and the discussion in-depth. I have only some minor remarks following next:
Specific Comments:
1. L249/250: “…mean density of 83 stems/m2…”: is that really stems or the number of prop roots? Please clarify.
Author response: The Reviewer is correct, the density measure includes all solid elements, including both stems and prop roots. We have thus adopted a more general term when reporting vegetation density.
2. L338: Koca et al 2017: use MDPI style for References, i.e. [37] and subsequently check the order of the References.
Author response: Thank you for this observation; we have corrected the error.
3. L438-441: “Here, normalized turbulent dissipation rate at 5.0 cm above the bed is greatest in the Reference shoreline, followed by the Restored shoreline, and lowest in the Seawall site. Here, normalized turbulent dissipation is greatest in the Reference shoreline, followed by the Restored shoreline, and lowest in the Seawall site”: redundant, delete the second phrase.
Author response: Thank you for this observation; we have corrected the error.
4. L 569- 599: The chapter conclusion primarily repeats the evidence given in the results and discussion chapters as well as in the abstract. Redundant information should be discarded.
Author response: We thank the Reviewer for this observation. We have revised the Conclusion to avoid redundancy where possible (L593-602). The journal specifies that a conclusion section should be optionally included when the study discussion is particularly long and complex. We chose to include a summary Conclusion section given that the results are complex, and many variables are presented. A summation of the most important results and the applications in a conclusion section will be likely to help readers quickly navigate study outcomes.
5. L641/642: delete “Frontiers in Ecology and the Environment”, use only abbreviation.
Author response: Thank you for this observation; we have corrected the error.
6. L670/671: delete “”
Author response: Thank you for this observation; we have corrected the error.
Author Response File: Author Response.docx
Reviewer 3 Report
The manuscript entitled “Flow-vegetation interaction in a living shoreline restoration and potential effect to mangrove recruitment” analyzes the hydrodynamic differences among natural and restored shorelines, 6.5 years after restoration and focusing on the flow velocity, water depth and wave disturbance in the study sites.
I found this manuscript very interesting as it shows how natural techniques of shoreline restoration create similar hydrodynamics to the natural shoreline conditions, where mean velocities and waves are strongly attenuated by the shoreline vegetation.
The manuscript is also very well written, clear and concise. I have no issues with the publication of the manuscript as it is.
Author Response
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Reviewer 3
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General Comments:
The manuscript entitled “Flow-vegetation interaction in a living shoreline restoration and potential effect to mangrove recruitment” analyzes the hydrodynamic differences among natural and restored shorelines, 6.5 years after restoration and focusing on the flow velocity, water depth and wave disturbance in the study sites.
I found this manuscript very interesting as it shows how natural techniques of shoreline restoration create similar hydrodynamics to the natural shoreline conditions, where mean velocities and waves are strongly attenuated by the shoreline vegetation.
The manuscript is also very well written, clear and concise. I have no issues with the publication of the manuscript as it is.
Author response: Thank you for your favorable opinion of our work.
Round 2
Reviewer 1 Report
Good study that will provide valuable information to the effective management of our living shorelines. This paper will be of interest to scientists, engineers, and natural resource managers.
