Preliminary Survey of Horse Mussels (Modiolus modiolus) in the Voluntary Berwickshire Marine Reserve, East Coast Scotland

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript describes the occurrence of the horse mussel Modiolus modiolus in a marine reserve on the east coast of Scotland. Data were obtained from a wide range of sources including ROV surveys, diver surveys, and towed video surveys. The analyses showed that most live mussels were found singly, although some were in small aggregates or groups. Large aggregates forming mussel beds were not detected.

I have no major criticisms. However, given that a substantial portion of the data were gleaned from underwater images, I thought it would be helpful for the reader if the authors provided 4-6 photographs of the mussels in situ on different substrata to show how they appear when alive. It would also be useful to provide the range of densities at which the mussels occur in the marine reserve. How do these values compare with previous studies of horse mussel abundance elsewhere in the northern Atlantic Ocean?

Other comments are provided directly on the attached pdf.

Comments for author File: Comments.pdf

Author Response

Thank you for your comments. We have answered all your comments directly in the PDF you provided your comments in

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study conducted the first systematic assessment of ​​horse mussel distribution​​ within Scotland’s voluntary BMR, integrating historical records, public sightings, scuba diving, and ROV surveys. Key findings include mapping ​​217 live horse mussels​​ and identifying ​​five potential PMF sites​ meeting semi-infaunal density criteria (≥5 individuals/m²), validating Marine Scotland’s undocumented report of a local bed. The research establishes a critical baseline for monitoring this vulnerable habitat-forming species and demonstrates how community engagement can enhance conservation efforts in data-poor marine protected areas. Based on careful review, the authors should address the following points to improve clarity and scientific rigor:
（1）​​Line 76, 192, 218​​: Replace placeholder text "(Error! Reference source not found.)"with right numbers;
(2)Line 115​​: "online [https://forms.gle/Xpg65YEZrUz1YyHN8]", move the public survey link to ​​References;
(3)Results Section Structure​: Current monolithic text impedes readability. Subheadings will highlight key findings ;3.1 Historical Records (Lines 179–185)  
3.2 Contemporary Survey Data (Lines 186–201)  
3.3 Spatial Distribution and PMF Identification (Lines 202–230)
(4)Table 2, Column "30% cover over 25 m²"​​: Replace subjective terms ("Possible", "Less likely") with ​​confidence metrics:High confidence,Moderate confidence,Low confidence.

Author Response

Comment 1: ​​Line 76, 192, 218​​: Replace placeholder text "(Error! Reference source not found.)"with right numbers

Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we have fixed the broken field codes and put in the correct text to refer to the figures and tables. Figure 1 (ln 83), Figure 2 (ln 201), Table 2 (ln 238)

 

Comment 2: Line 115​​: "online [https://forms.gle/Xpg65YEZrUz1YyHN8]", move the public survey link to ​​References

Response 2: Thank you for suggesting this. We agree with this comment. Therefore, we have added the link in the references. Text updated on line 123 (reference 18) and reference added on ln 510

 

Comment 3: Results Section Structure​: Current monolithic text impedes readability. Subheadings will highlight key findings ;3.1 Historical Records (Lines 179–185)  

Response 3: Thank you for suggesting this. We agree with this comment. Therefore, we have added subheadings. 3.1. Historical records (ln 194), 3.2. Contemporary survey data (ln 199), 3.3. Spatial distribution and PMF identification (ln 234), 3.4. Other species (ln 263)

 

Comment 4: Table 2, Column "30% cover over 25 m²"​​: Replace subjective terms ("Possible", "Less likely") with ​​confidence metrics: High confidence, Moderate confidence, Low confidence.

Response 4: Thank you for suggesting this. We agree with this comment. Therefore, we have made the suggested changes in Table 2 (ln 262)

Reviewer 3 Report

Comments and Suggestions for Authors

Preliminary surveys in the Berwickshire Marine Reserve found over 200 horse mussels and identified five potential priority sites, indicating the need for further research. The protection of freshwater mussels is of great importance. Here are some minor revisions for your consideration.

1. It is advisable to enhance the description of the urgency and significance of the research in the abstract and introduction.
2. The draft mentioned the recording of individuals and five potential locations, but lacked more specific information about environmental characteristics, such as whether there was velocity, dissolved oxygen, sediment discharge, temperature, ammonia, and other related indicators? There are relevant references that have mentioned that information about this area is also available.
3. Lines 241-248: Could other species be compiled into an appendix for the reference of researchers and managers?
4. The discussion touched upon many connections between human activities and climate. Can models be used for prediction? And should scenario analysis be supplemented?
5. The discussion, conclusion and management measures are not closely linked. It is suggested that the protective value of potential PMF and the specific implications for managers (such as monitoring and protection areas) should be clearly pointed out.
6. Lines 428-430: The Marine Recorder Online data seems to be difficult to access and view the information.
7. You mentioned a lot of data from video records. It would be more informative if we could also provide the video attachments.
8. Lines 76, 192, 218: Reference citations are missing.

Author Response

Comment 1: It is advisable to enhance the description of the urgency and significance of the research in the abstract and introduction.

Response 1: Thank you for suggesting this. We agree with this comment. There for text has been added to both the abstract (ln 17-21) and the introduction (ln 48-53).

 

Comment 2: The draft mentioned the recording of individuals and five potential locations, but lacked more specific information about environmental characteristics, such as whether there was velocity, dissolved oxygen, sediment discharge, temperature, ammonia, and other related indicators? There are relevant references that have mentioned that information about this area is also available.

Response 2: Thank you for suggesting this. Whilst we agree with this comment, unfortunately none of these environmental characteristics were specifically (or fully) measured as part of this pilot study. Therefore the generic information for the area as a whole mentioned in the discussion is not available at a small enough scale to look specifically at individuals or the five possible PMF.

 

Comment 3: Lines 241-248: Could other species be compiled into an appendix for the reference of researchers and managers?

Response 3: Thank you for your suggestion. Whilst we understand the value to this, and agree in principle, this was not part of this project. All other species that were identified are listed in the results text (ln 263-271)

 

Comment 4: The discussion touched upon many connections between human activities and climate. Can models be used for prediction? And should scenario analysis be supplemented?

Response 4: Thank you for your comment. Models for prediction have been done by Gormley et al. 2013 (ref 8), which we mention in the discussion, and now in the introduction as well. Unfortunately, any modelling or scenario analysis is beyond the scope of this work and the data we have available.

 

Comment 5: The discussion, conclusion and management measures are not closely linked. It is suggested that the protective value of potential PMF and the specific implications for managers (such as monitoring and protection areas) should be clearly pointed out.

Response 5: Thank you for your suggestion. We have added text to the discussion and conclusion to improve the link with relation to consultation and management

Habitat suitability: ln 294-296 “To aid future consultations and possible changes to management, it is important to understand whether the habitat within the BMR is suitable for the expansion of horse mussels, or whether the habitat may be a limiting factor.”

Future monitoring & mitigation measures: ln 431-436 “In terms of horse mussel PMFs and towed fishing the Berwickshire and North Northumberland Coast SAC is considered to already be well managed [55], however, since then, the Government has identified the need to consult on further protection measures for MPAs and PMFs [56]. This preliminary survey will be able to contribute to these consolations, and also highlights the need to gain a better understanding of horse mussels in the area to more adequately inform future consultations.”

Conclusion: ln 442-443 “…and will contribute to future consultations”

 

Comment 6: Lines 428-430: The Marine Recorder Online data seems to be difficult to access and view the information.

Response 6: Thank you for pointing this out. We agree with this comment. This is why we have also included the link to Mendeley Data. Unfortunately we do not manage Marine Recorder, therefore cannot make access to this particular database any easier.

 

 

Comment 7: You mentioned a lot of data from video records. It would be more informative if we could also provide the video attachments.

Response 7: Thank you for your suggestions. We will work towards getting some video footage uploaded with our Mendeley data entry

 

Comment 8: Lines 76, 192, 218: Reference citations are missing.

Response 8: Thank you for pointing this out. We agree with this comment. Therefore, we have fixed the broken field codes and put in the correct text to refer to the figures and tables. Figure 1 (ln 83), Figure 2 (ln 201), Table 2 (ln 238)