Research on the BEM Reinforcement Mechanism of the POSF Method for Ocean Stone Construction

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General review: The present study uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf as a case study to examine the long-term reinforcing mechanism of the conventional Planting Oysters to Strengthen the Foundation (POSF) approach usually employed in coastal stone projects. The authors suggest a Biology–Environment–Materials (BEM) ternary coupling mechanism to explain the longevity of ancient coastal structures by combining mineralogical, microstructural, chemical, and microbiological investigations. According to the scientific content of the study, the topic is unique, multidisciplinary/interdisciplinary, and pertinent to coastal engineering, low-carbon materials, and cultural heritage preservation. The analytical methods are suitable, and the dataset is rich. However, the article needs to be significantly revised.

Title: Please consider simplifying and clarifying the main contribution in the title.

Introduction/Novelty:  The topic is unique and multidisciplinary/interdisciplinary. It is novel to combine materials science, microbiology, marine biology, and heritage engineering in the present study. Conceptually sound and potentially influential is the BEM ternary coupling framework. To strengthen the background, discussion, and justification of the study, kindly, add more regional studies and recently published studies on biogenic carbonate precipitation, bio-mineralization under marine environment condition, and heritage stone conservation.

Methodology: Point [C] was the only effective sampling point that was utilized in the study. This limits statistical robustness. It is advised to avoid overgeneralizing the findings and to clearly identify this as a limitation in the methodology and discussion text.

Results and Discussion: Instead of being supported by experiments, many findings are interpretive. The use of causal terminology (such as "forms," "achieves," and "ensures") without clear experimental support. For example: Microbial metabolism-related dolomite production is inferred rather than directly quantified (isotopic evidence or time-series mineral growth). Also, FeS's protective function is suggested without corrosion-rate or electrochemical confirmation. Kindly, rephrase the discussion text using probabilistic language, and clearly differentiate observations and interpretations. Regarding porosity analysis and EDS, kindly, explain the number of SEM images that were examined and provide evidence for representativeness. Describe the uncertainty and EDS normalization processes, and instead of reporting EDS data as absolute, reporting it as semi-quantitative is strongly recommended. Regarding microbiological interpretation, kindly make it clear that functional roles are deduced from existing literature.

References: Add more regional studies and recently published studies on biogenic carbonate precipitation, bio-mineralization under marine environment condition, and heritage stone conservation.

Figures: Some figures are overcrowded and for readers are difficult to understand e.g. SEM–EDS mappings; improve resolution and simplify captions if possible.

Conclusions: The conclusion section in this article is very long and repetitive. Kindly, condense and focus on key findings and implications. Please synthesize results instead of repeating them and emphasize novelty and implications in this section. Remember that a good conclusion should answer these questions: What was done? What are the key findings (not all results)? Why do they matter? What are the limitations and future directions?

Author Response

Research on the BEM Reinforcement Mechanism of the POSF Method for Coastal Stone Structures

Response to Reviewer Comments (Round 1)

Overall Comments: The present study uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf as a case study to examine the long-term reinforcing mechanism of the conventional Planting Oysters to Strengthen the Foundation (POSF) approach usually employed in coastal stone projects. The authors suggest a Biology–Environment–Materials (BEM) ternary coupling mechanism to explain the longevity of ancient coastal structures by combining mineralogical, microstructural, chemical, and microbiological investigations. According to the scientific content of the study, the topic is unique, multidisciplinary/interdisciplinary, and pertinent to coastal engineering, low-carbon materials, and cultural heritage preservation. The analytical methods are suitable, and the dataset is rich. However, the article needs to be significantly revised.

1.Title: Please consider simplifying and clarifying the main contribution in the title.

2.Introduction/Novelty:  The topic is unique and multidisciplinary/interdisciplinary. It is novel to combine materials science, microbiology, marine biology, and heritage engineering in the present study. Conceptually sound and potentially influential is the BEM ternary coupling framework. To strengthen the background, discussion, and justification of the study, kindly, add more regional studies and recently published studies on biogenic carbonate precipitation, bio-mineralization under marine environment condition, and heritage stone conservation.

3.Methodology: Point [C] was the only effective sampling point that was utilized in the study. This limits statistical robustness. It is advised to avoid overgeneralizing the findings and to clearly identify this as a limitation in the methodology and discussion text.

4.Results and Discussion: Instead of being supported by experiments, many findings are interpretive. The use of causal terminology (such as "forms," "achieves," and "ensures") without clear experimental support. For example: Microbial metabolism-related dolomite production is inferred rather than directly quantified (isotopic evidence or time-series mineral growth). Also, FeS's protective function is suggested without corrosion-rate or electrochemical confirmation. Kindly, rephrase the discussion text using probabilistic language, and clearly differentiate observations and interpretations.

5.Regarding porosity analysis and EDS, kindly, explain the number of SEM images that were examined and provide evidence for representativeness. Describe the uncertainty and EDS normalization processes, and instead of reporting EDS data as absolute, reporting it as semi-quantitative is strongly recommended.

6.Regarding microbiological interpretation, kindly make it clear that functional roles are deduced from existing literature.

7.References: Add more regional studies and recently published studies on biogenic carbonate precipitation, bio-mineralization under marine environment condition, and heritage stone conservation.

8.Figures: Some figures are overcrowded and for readers are difficult to understand e.g. SEM–EDS mappings; improve resolution and simplify captions if possible.

9.Conclusions: The conclusion section in this article is very long and repetitive. Kindly, condense and focus on key findings and implications. Please synthesize results instead of repeating them and emphasize novelty and implications in this section. Remember that a good conclusion should answer these questions: What was done? What are the key findings (not all results)? Why do they matter? What are the limitations and future directions?

Author Response

Overall Comments: [General review: The present study uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf as a case study to examine the long-term reinforcing mechanism of the conventional Planting Oysters to Strengthen the Foundation (POSF) approach usually employed in coastal stone projects. The authors suggest a Biology–Environment–Materials (BEM) ternary coupling mechanism to explain the longevity of ancient coastal structures by combining mineralogical, microstructural, chemical, and microbiological investigations. According to the scientific content of the study, the topic is unique, multidisciplinary/interdisciplinary, and pertinent to coastal engineering, low-carbon materials, and cultural heritage preservation. The analytical methods are suitable, and the dataset is rich. However, the article needs to be significantly revised.]

Overall Response:[Sincerely appreciate your recognition of the innovation, interdisciplinary nature, and richness of the dataset in this study, as well as your guidance on the revision directions.]Thank you for your patient guidance—your overall evaluation provides clear directions for our improvement work.We have [Comprehensively considered the comments from multiple reviewers, addressed each specific issue you raised with targeted revisions, and strived to enhance the quality of the manuscript. – Page 1 to 18 (end) – All paragraphs – All rows.]

 

Comments 1：[Title: Please consider simplifying and clarifying the main contribution in the title.]

Response 1:[Apologize for the oversight of not fully simplifying the title or highlighting the core research value.]Thank you for your targeted suggestion—your overall evaluation provides clear guidance for the improvement of this work.We have [The title has been optimized as requested, with a focused emphasis on the BEM ternary coupling reinforcement mechanism of the POSF method. – Page 1 - Paragraph 1 - Row 1]The revised content is as follows:“[Research on the BEM Reinforcement Mechanism of the POSF Method for Ocean Stone Construction]”

 

Comments 2：[Introduction/Novelty:  The topic is unique and multidisciplinary/interdisciplinary. It is novel to combine materials science, microbiology, marine biology, and heritage engineering in the present study. Conceptually sound and potentially influential is the BEM ternary coupling framework. To strengthen the background, discussion, and justification of the study, kindly, add more regional studies and recently published studies on biogenic carbonate precipitation, bio-mineralization under marine environment condition, and heritage stone conservation.]

Response 2:[Sincerely apologize for the disorganized literature arrangement and insufficient supplementation of regional studies, recent publications, and research on marine microbial carbon sequestration in relevant fields, which has led to inadequate support for the research background.]Thank you very much for your affirmation and meticulous guidance - the latest relevant research has been systematically aligned with each argument.We have [Specifically, 1 paper on coastal stone structure architectural heritage [6], 2 studies on marine carbonate deposition mechanisms [26, 28], and 3 works focusing on marine microbial carbon sequestration and mineralization [25, 27, 31] have been incorporated. – Page 18 - Paragraph 2 - Rows 468 - 486]The revised content is as follows:“[6.Lidour,K;Al,HN;Crassard,R.et al. Exploring the Early Neolithic in the Arabian Gulf: A newly discovered 8,400–year-old stone-built architecture on Ghagha Island, United Arab Emirates. PLoS One, 2025, 20(6): e0326259.25.Licata,G.; Galasso,C.; Palma, E.F. et al. Mixotrophy in Marine Microalgae to Enhance Their Bioactivity[J]. Microorganisms, 2025, 13(2): 338.26.Kong, J.F.; Cong, G.W.; Ni, S.Y.; Sun, J.Q.; Guo, C.; Chen, M.X.; Quan, H.Z. Recycling of Waste Oyster Shell and Recycled Aggregate in the Porous Ecological Concrete Used for Artificial Reefs. Constr. Build. Mater. 2022, 323, 126447. 27.Manikkam, R.; Kaari, M.; Baskaran, A. et al. Existence of rare actinobacterial forms in the Indian sector of Southern Ocean: 16 S rRNA based metabarcoding study. Braz J Microbiol.2024. 55, 2363–2370 .28.Seo, J.H.; Park, S.M.; Yang, B.J.; Jang, J.G. Calcined Oyster Shell Powder as an Expansive Additive in Cement Mortar. Materials 2019, 12, 1322. 31.Dong, X.H.; Zhai, X.F.; Yang, J.; Pei, Y.Y.; Guan, F.; Chen, Y.D.; Duan, J.Z.; Hou, B.R. Desulfovibrio-induced gauzy FeS for efficient hexavalent chromium removal: The influence of SRB metabolism regulated by carbon source and electron carriers. J. Colloid Interface Sci. 2024, 674, 938–950. ]”

 

Comments 3：[Methodology: Point [C] was the only effective sampling point that was utilized in the study. This limits statistical robustness. It is advised to avoid overgeneralizing the findings and to clearly identify this as a limitation in the methodology and discussion text.]

Response 3:[Apologize for the oversight in the research design—potential impacts of a single sampling point on the robustness of conclusions were not fully considered, and the preliminary nature of this study was not explicitly defined.]Thank you for your rigorous correction. This comment offers important reference for clarifying the research scope and enhancing the credibility of conclusions, and targeted revisions have been implemented.We have [Specifically, in Section 4.2 Outlook, the preliminary nature of the study has been explicitly marked, the limitation of relying solely on Sampling Point C has been addressed, and future directions for expanding the sample scope have been proposed. – Page 15 - Paragraph 4 - Row 372]The revised content is as follows:“[This study serves as a preliminary exploration to reveal the BEM ternary coupling mechanism of the POSF method. Due to the selection of only Sampling Point C as the research sample, the robustness of the conclusions is restricted and requires further verification. In future research, the sample scope will be expanded to include more coastal environmental types and sampling points, with multi-scenario verification data supplemented to further improve the universality and reliability of the mechanism.]”

 

Comments 4：[Results and Discussion: Instead of being supported by experiments, many findings are interpretive. The use of causal terminology (such as "forms," "achieves," and "ensures") without clear experimental support. For example: Microbial metabolism-related dolomite production is inferred rather than directly quantified (isotopic evidence or time-series mineral growth). Also, FeS's protective function is suggested without corrosion-rate or electrochemical confirmation. Kindly, rephrase the discussion text using probabilistic language, and clearly differentiate observations and interpretations. ]

Response 4:[Appreciate you pointing out this issue. Upon review, it has been confirmed that certain subjective expressions exist in the Results and Discussion section.]Thank you for your rigorous comment—expression methods have been optimized targeted to clearly distinguish between observational results and interpretations.We have [Specifically, revisions have been made to content from Page 7 - Paragraph 3 - Row 231 to Page 14 - Paragraph 5 - Row 349: subjective inferential expressions have been replaced with probabilistic language such as "may" and "speculate", and supporting references have been supplemented. Fuzzy expression is used for the speculation of carbonate compounds, combined with references to increase its rigor. And FeS-related content on Page 13 has been corrected to only objectively describe experimental phenomena and the observation of no significant corrosion, avoiding subjective assertions.- Page 13 - Paragraph 3 - Rows 333 to 341. ]The revised content is as follows:“[It was found that elements such as Ca, Mg, C, and O are enriched around the pores through SEM-EDS analysis, which may be due to dolomite sedimentation; It is worth noting that facultative anaerobes metabolize sulfur to produce H2S and sulfate species, which may react with iron oxides to precipitate iron sulfides, but they do not exert a significant corrosive effect on stone structures. ]”

 

Comments 5:[Regarding porosity analysis and EDS, kindly, explain the number of SEM images that were examined and provide evidence for representativeness. ]

Response 5:[Thank you for raising this point. Upon verification, the original description of SEM did not clearly state image selection criteria, quantity, or calculation details.]Thank you for your detailed suggestion—key information on SEM testing and porosity calculation has been supplemented and improved.We have [Specifically, methodological details have been added in Page 6 - Paragraph 3 - Rows 204 to 209: a JEISS Sigma 360 instrument was employed with test parameters set as EHT=20.0 kV, WD=5mm - 6mm, and Mag=500X. Three SEM images with uniformly distributed micropores (pore size < 10 μm) were selected to ensure representativeness. Calculation results have been presented in Page 9 - Paragraphs 4-5 - Rows 282 to 287: porosity of each image was calculated using the Area Threshold function in ImageJ software, and the average porosity was determined to be 19.04% (see Table 3 and Figure 6 for specific results). – Page 6 - Paragraph 3 - Rows 204 to 209; Page 9 - Paragraphs 4-5 - Rows 282 to 287]The revised content is as follows:“[A ZEISS - Sigma 360 SEM ...were set as EHT=20.0 kV, WD=5 mm – 6 mm, and Mag=500X. Three SEM images with uniformly distributed micropores (pore size < 10 μm) were selected. ImageJ ... average porosity]”

 

Comments 6:[Describe the uncertainty and EDS normalization processes, and instead of reporting EDS data as absolute, reporting it as semi-quantitative is strongly recommended. ]

Response 6:[Thank you for pointing out this issue. The original EDS analysis did not clearly state uncertainty, normalization process, or data attributes.]Thank you for your regulatory requirement—key information has been supplemented in the methodology section.We have [Specifically, relevant explanations have been added in Page 6 - Paragraph 5 - Rows 214 to 216: the EDS analysis adopts the peak area normalization method for data processing. Due to inherent detection errors, data is reported as semi-quantitative, with the uncertainty range controlled within ±5%. – Page 6 - Paragraph 5 - Rows 214 to 216]The revised content is as follows:“[Conduct microscopic morphology observation and semi-quantitative analysis of chemical element composition for the porous and non-porous areas in turn.]”

 

Comments 7:[Regarding microbiological interpretation, kindly make it clear that functional roles are deduced from existing literature.]

Response 7:[Thank you for pointing out this issue. The original inference of microbial functional roles did not clearly indicate supporting literature basis.]Thank you for your correction—supporting literature on microbial functions has been supplemented to clarify the evidential basis for inferring functional roles.We have [Specifically, literature citations have been integrated into Page 14 - Paragraph 1 - Rows 326 to 332, with references [25, 26, 27, 31] selected as the theoretical foundation. These studies focus on marine microbial metabolism, carbonate production, and mineralization mechanisms, thereby providing reliable academic support for the inference of microbial functional roles. – Page 14 - Paragraph 1 - Rows 326 to 332]The revised content is as follows:“[16S rRNA sequencing detected 110 bacterial... iron sulfide formation (Figure 10,Figure 11,Appendix B)[25-26].Photosynthetic aerobic bacteria (Cyanobacteriales.et al.) fix CO₂ and release O₂ [25], while heterotrophic (Erythrobacter.et al.) and microaerophilic bacteria (Ilumatobacter.et al.) produce CO₂ that is converted to carbonate ions which react with Ca²⁺ and Mg²⁺ to form dolomite deposited in pores and interfaces[26-28]. Dolomite is... compactness[29-30].]”

 

Comments 8：[References: Add more regional studies and recently published studies on biogenic carbonate precipitation, bio-mineralization under marine environment condition, and heritage stone conservation.]

Response8:[Apologize for the disorganized reference list. Previously, literature related to biocarbonate precipitation and biomineralization—such as that on shell ash, concrete, cactus juice, coconut shell ash, and shipwrecks—was not clearly distinguished, making it difficult to identify intuitively. Additionally, there was a lack of targeted literature on heritage stone and clay building protection, failing to fully support the relevance and completeness of the research background.]Thank you for your timely reminder—references on Pages 17-18 (Rows 450-488) have been systematically organized, categorized by topic, and supplemented with recent publications.We have [Specifically, existing relevant literature has been sorted through, and studies on biocarbonate precipitation, biomineralization, and heritage stone/clay building protection published between 2017 and 2025 have been supplemented to strengthen research background support. – Page 17 - Row 450 to Page 18 - Row 488]The revised content is as follows:“[6.Lidour,K;Al,HN;Crassard,R.et al. Exploring the Early Neolithic in the Arabian Gulf: A newly discovered 8,400–year-old stone-built architecture on Ghagha Island, United Arab Emirates. PLoS One, 2025, 20(6): e0326259.25.Licata,G.; Galasso,C.; Palma, E.F. et al. Mixotrophy in Marine Microalgae to Enhance Their Bioactivity[J]. Microorganisms, 2025, 13(2): 338.26.Kong, J.F.; Cong, G.W.; Ni, S.Y.; Sun, J.Q.; Guo, C.; Chen, M.X.; Quan, H.Z. Recycling of Waste Oyster Shell and Recycled Aggregate in the Porous Ecological Concrete Used for Artificial Reefs. Constr. Build. Mater. 2022, 323, 126447. 27.Manikkam, R.; Kaari, M.; Baskaran, A. et al. Existence of rare actinobacterial forms in the Indian sector of Southern Ocean: 16 S rRNA based metabarcoding study. Braz J Microbiol.2024. 55, 2363–2370 .28.Seo, J.H.; Park, S.M.; Yang, B.J.; Jang, J.G. Calcined Oyster Shell Powder as an Expansive Additive in Cement Mortar. Materials 2019, 12, 1322. 31.Dong, X.H.; Zhai, X.F.; Yang, J.; Pei, Y.Y.; Guan, F.; Chen, Y.D.; Duan, J.Z.; Hou, B.R. Desulfovibrio-induced gauzy FeS for efficient hexavalent chromium removal: The influence of SRB metabolism regulated by carbon source and electron carriers. J. Colloid Interface Sci. 2024, 674, 938–950. The above literature has been clearly organized by topic and supplemented to the reference section on pages 17-18, covering recent key research from 2017 to 2025, enhancing the intuitiveness and timeliness of relevant research support.]”

 

Comments 9：[Figures: Some figures are overcrowded and for readers are difficult to understand e.g. SEM–EDS mappings; improve resolution and simplify captions if possible.]

Response9:[Apologize for the oversight—previously, some figures such as the SEM-EDS color mapping diagrams had cluttered layouts and redundant information, affecting the reading experience.]Thank you for your thoughtful suggestion—figure presentation has been optimized while ensuring the integrity of the original data.We have [Specifically, redundant text related to the "mapping method (k-line method)" above the EDS color mapping diagrams has been deleted, figure resolution has been increased to over 300 DPI, and redundant information in figure captions has been simplified. If images remain blurry after platform transmission, high-definition images have been uploaded to the journal editor in a compressed package. – Page 4 - Row 291 to Page 12 - Row 297]

 

Comments 10：[Conclusions: The conclusion section in this article is very long and repetitive. Kindly, condense and focus on key findings and implications. Please synthesize results instead of repeating them and emphasize novelty and implications in this section. Remember that a good conclusion should answer these questions: What was done? What are the key findings (not all results)? Why do they matter? What are the limitations and future directions?]

Response10:[Sincerely apologize for the redundancy and repetition in the previous conclusion section—the excessive word count overshadowed the core value.]Thank you for your professional guidance—Section 4.1 Conclusions and Section 4.2 Outlook have been refined and integrated as requested.We have [Specifically, content repeated from the main text has been deleted, and the section has been structured around a logical flow: "Research Content - Core Mechanism - Innovations - Application Value - Limitations - Improvement Directions." The main conclusions are focused in Section 4.1 Conclusions, and secondary conclusions are no longer repeated. – Page 14 - Row 351 to Page 15 - Row 378]The revised content is as follows:“[4.1.Conclusions   Taking CATC from...cleaning in practice.   4.2.Prospect   This study is only ... and on different attachments. These efforts aim to further improve the BEM coupling mechanism of POSF.]”

 

Comments 11：[The English language expression of the article needs to be optimized]

Response 11：[Thank you for pointing out this issue. Previously, the English expression of the article was redundant and wordy, failing to focus on core findings and key points, which affected reading efficiency. Sincerely apologize.]Thank you for your targeted suggestion—the English expression of the entire article has been systematically optimized.We have [Specifically, while fully retaining objective experimental data and core conclusions, redundant expressions have been streamlined, the interpretation of core findings and key points has been emphasized, the structure and accuracy of English sentences have been optimized, and the conciseness and focus of the expression have been enhanced. – Page all]

Reviewer 2 Report

Comments and Suggestions for Authors

Method of surface POSF: Research on BEM long-term reinforcement mechanism of coastal stone construction.

ID: coatings-4100167-Le 7 01 26v

In this study, the authors utilize triadic clay from crustacean ash (CATC) sourced from the old dock of Shihu in Quanzhou as a case study. They conduct a systematic analysis using XRD, Raman, SEM-EDS, FTIR, and 16S rRNA technologies.

The authors report that the findings revealed:

- CATC is composed of 94.60% quartz as the main framework, with potassium feldspar, dolomite, and metallic compounds as auxiliary elements.

- A porosity of 20.90% creates a space for the enrichment of positive ions and microorganisms brought in by the tides.

- The adsorption of electric charges with rattan glue facilitates physical reinforcement.

- The metabolism of microorganisms produces dolomite, leading to chemical reinforcement.

In conclusion, the authors indicate that the ternary coupling of biology, environment, and materials establishes a long-term reinforcement mechanism (BEM) suitable for low-carbon construction in the ocean.

 

• The authors need to standardize the references.
• The authors need to enhance the resolution of figure 4, the same comment applies to figure 7.a.
• The authors ought to clearly present and justify their results and comments.
• I suggest that the authors effectively highlight the originality of this research and its implications for applications in the domain.
• The authors state that iron sulfide FeS can enhance the oxidation resistance of the material and ensure its long-term stability. They must provide justification for maintaining this stability.
• I believe that the conclusion section needs enhancement. The authors ought to provide a conclusion made up of just one paragraph.

In conclusion, this work is very interesting; it can be accepted for publication after minor revision.

 

Comments for author File: Comments.pdf

Author Response

Research on the BEM Reinforcement Mechanism of the POSF Method for Ocean Stone Construction

Response to Reviewer Comments (Round 1)

Overall Comments: Method of surface POSF: Research on BEM long-term reinforcement mechanism of coastal stone construction.

ID: coatings-4100167-Le 7 01 26v

In this study, the authors utilize triadic clay from crustacean ash (CATC) sourced from the old dock of Shihu in Quanzhou as a case study. They conduct a systematic analysis using XRD, Raman, SEM-EDS, FTIR, and 16S rRNA technologies.

The authors report that the findings revealed:

- CATC is composed of 94.60% quartz as the main framework, with potassium feldspar, dolomite, and metallic compounds as auxiliary elements.

- A porosity of 20.90% creates a space for the enrichment of positive ions and microorganisms brought in by the tides.

- The adsorption of electric charges with rattan glue facilitates physical reinforcement.

- The metabolism of microorganisms produces dolomite, leading to chemical reinforcement.

In conclusion, the authors indicate that the ternary coupling of biology, environment, and materials establishes a long-term reinforcement mechanism (BEM) suitable for low-carbon construction in the ocean.

1.The authors need to standardize the references.

2.The authors need to enhance the resolution of figure 4, the same comment applies to figure 7.a.

3.The authors ought to clearly present and justify their results and comments.

4.I suggest that the authors effectively highlight the originality of this research and its 9.implications for applications in the domain.

5.The authors state that iron sulfide FeS can enhance the oxidation resistance of the material and ensure its long-term stability. They must provide justification for maintaining this stability.

6.I believe that the conclusion section needs enhancement. The authors ought to provide a conclusion made up of just one paragraph.

In conclusion, this work is very interesting; it can be accepted for publication after minor revision.

 

Author Response

Overall Comments: [Method of surface POSF: Research on BEM long-term reinforcement mechanism of coastal stone construction. ID: coatings-4100167-Le 7 01 26v  In this study, the authors utilize triadic clay from crustacean ash (CATC) sourced from the old dock of Shihu in Quanzhou as a case study. They conduct a systematic analysis using XRD, Raman, SEM-EDS, FTIR, and 16S rRNA technologies.The authors report that the findings revealed:

- CATC is composed of 94.60% quartz as the main framework, with potassium feldspar, dolomite, and metallic compounds as auxiliary elements.

- A porosity of 20.90% creates a space for the enrichment of positive ions and microorganisms brought in by the tides.

- The adsorption of electric charges with rattan glue facilitates physical reinforcement.

- The metabolism of microorganisms produces dolomite, leading to chemical reinforcement.

In conclusion, the authors indicate that the ternary coupling of biology, environment, and materials establishes a long-term reinforcement mechanism (BEM) suitable for low-carbon construction in the ocean.]

Overall Response:[Sincerely appreciate your overall recognition and affirmation of this study. Your evaluation has greatly encouraged us and injected strong motivation into the subsequent improvement work.]Thank you for your valuable comments.We have [Completed the following revisions in response to your suggestions: standardized the reference format, improved the resolution of designated images, clearly presented the research conclusions and viewpoints, clarified the application significance of the research in engineering and scientific fields, and adopted ambiguous expressions for uncertain findings. Meanwhile, integrating comments from other reviewers, we have streamlined the textual expressions in Chapter 3 "Results and Discussion" and Chapter 4 "Conclusions and Outlook" to focus more on the main findings and core viewpoints. – Page 1 to Page 18.]

 

Comments 1：[The authors need to standardize the references.]

Response 1:[Sincerely apologize for the inconsistent reference format and information labeling caused by directly citing relevant literature without uniform organization, which has inconvenienced reading.]Thank you for your correction—references have been fully standardized in accordance with the MDPI journal format requirements.We have [Specifically, all references have been unified into the MDPI numbering system, format errors such as author name abbreviations, journal names, publication years, volume, issue, page numbers, and DOI links have been corrected one by one, and references have been arranged in the order of their appearance in the article to ensure consistent format and complete, accurate information. – Page 17 - Row 405 to Page 18 - Row 488]

 

Comments 2：[The authors need to enhance the resolution of figure 4, the same comment applies to figure 7.a.]

Response 2:[Thank you for pointing out this issue. Previously, Figure 4 (XRD diffraction pattern), Figure 7.a (EDS element energy spectrum), and Figure 8.a (EDS element energy spectrum) had insufficient clarity, making it inconvenient to observe details. Sincerely apologize for the trouble caused.]Thank you for your timely reminder—the quality of relevant images has been comprehensively optimized.We have [Specifically, Figure 4, Figure 5, Figure 7.a, and Figure 8.a have been re-exported, fonts of characteristic peak labels and element identifiers in the images have been enlarged, and the resolution has been increased to over 300 DPI to ensure clear identification of data details. – Page 8 - Figure 4; Page 8 - Figure 5; Page 11 - Figure 7.a; Page 12 - Figure 8.a]

 

Comments 3：[The authors ought to clearly present and justify their results and comments.]

Response 3:[Sincerely apologize for the redundant and unfocused expression of research conclusions and related views in Chapter 4. The confusion between secondary conclusions and core findings made the presentation of research results and argumentation logic unclear, inconveniencing reading.]Thank you for your valuable suggestion—expression has been optimized targeted to strengthen result presentation and argumentation logic.We have [Specifically, from Page 14 - Row 352 to Page 15 - Row 377, core conclusions have been extracted and highlighted, secondary conclusions repeated from the discussion section have been deleted, and the content has been structured around the logic: "Research Content - Core Findings - Innovations - Engineering Value - Limitations - Future Directions." The core work of exploring the POSF method's reinforcement mechanism through multi-technique combination has been clarified; key findings such as CATC material properties, the BEM ternary coupling mechanism, and the dual impact of barnacle attachment have been summarized; the innovation of establishing the BEM coupling mechanism for the first time has been highlighted; the engineering value for marine cultural heritage protection and low-carbon building material research and development has been clarified; and research limitations and future directions (such as expanding the sample scope and adding quantitative data) have been supplemented in Section 4.2 Outlook to make the results and argumentation more clear and convincing. – Page 14 - Row 352 to Page 15 - Row 377]The revised content is as follows:“[4.1.Conclusions  Taking CATC from...cleaning in practice.4.2.Prospect  This study is only ... and on different attachments. These efforts aim to further improve the BEM coupling mechanism of POSF.]”

 

Comments 4：[I suggest that the authors effectively highlight the originality of this research and its 9.implications for applications in the domain.]

Response 4:[Apologize for the oversight—previously, the conclusion section was redundant, overshadowing the core innovations and application value, and failing to fully highlight the academic contributions and practical significance of the research.]Thank you for your careful guidance—a dedicated paragraph has been added at the end of Section 4.1 Conclusions to clearly elaborate on the research's innovations and application value.We have [Specifically, a paragraph focusing on innovations and application significance has been supplemented at the end of Section 4.1 Conclusions, clearly defining the academic breakthroughs and practical value to enhance the recognition of the research's core contributions. – Page 17 - Paragraph 1 - Rows 10 to 15]The revised content is as follows:“[The innovation clarifies the BEM ternary coupling reinforcement mechanism of the POSF method for coastal stone structures on the continental shelf. Unlike marine concrete structures such as UHPC and LC3, it achieves long-term reinforcement without metal components[32], and addresses the academic controversy over barnacle attachment: barnacle impact is position-dependent—attachment to the CATC surface forms a protective layer via biomineralization synergy, while non-contact attachment increases structural load, allowing targeted cleaning in practice.]”

 

Comments 5：[The authors state that iron sulfide FeS can enhance the oxidation resistance of the material and ensure its long-term stability. They must provide justification for maintaining this stability.]

Response 5:[Sincerely apologize for the oversight—previously, the statement about iron sulfide (FeS) was too subjective, asserting that it "improves oxidation resistance" and "ensures long-term stability" without sufficient experimental evidence.]Thank you for your rigorous requirements and correction—relevant literature has been thoroughly reviewed, it has been confirmed that FeS has a weak destructive effect on stone structures, and the expression method has been revised.We have [Specifically, the FeS-related expression in Page 13 - Rows 335 to 337 has been optimized, subjective assertions without experimental basis have been deleted, the phenomenon has been objectively described using vague language, and future research directions have been proposed. – Page 13 - Row 335 to Row 337]The revised content is as follows:“[.It is worth noting that facultative anaerobes metabolize sulfur to produce H2S and sulfate species, which may react with iron oxides to precipitate iron sulfides, but they do not exert a significant corrosive effect on stone structures]”

 

Comments 6：

[I believe that the conclusion section needs enhancement. The authors ought to provide a conclusion made up of just one paragraph.]

Response 6:[Apologize for the oversight—previously, the conclusion section was lengthy and fragmented, with core conclusions overshadowed by redundant content.]Thank you for your simplification suggestion—the conclusion has been integrated and optimized.We have [Specifically, the core conclusions have been consolidated into a single paragraph, clearly presenting the research's core findings, innovations, and application value. The relevant content is located in Page 15 - Rows 356 to 360 to enhance the focus and readability of the core conclusions. – Page 15 - Row 356 to Row 360]The revised content is as follows:“[The BEM ternary coupling mechanism of POSF is a dynamic closed-loop system: Tides provide organisms (such as barnacles and microorganisms) and ions (Ca²⁺, Mg²⁺, Fe²⁺, etc.). CATC offers a skeleton and pore spaces for interaction (porosity 19.04%). Organisms achieve long-term structural stability through physical and chemical reinforcement.]”

 

Comments 7：[In conclusion, this work is very interesting; it can be accepted for publication after minor revision.]

Response 7:[Thank you for your affirmation. We have made adjustments word for word and sentence by sentence according to your requirements.]Your guidance has been of great help to me.We have [modifications highlighted in yellow in the text. Additionally, I have conducted a uniform review of the language throughout the entire text, making the main findings and viewpoints clearer. Thank you again for your careful guidance. - Page all]

Reviewer 3 Report

Comments and Suggestions for Authors

General comments:

The manuscript presents a clear, well‑focused study that combines complementary analytical techniques (XRD, Raman, SEM‑EDS, FTIR, 16S rRNA) to build a convincing BEM reinforcement framework. Conclusions are concise and practically relevant for heritage conservation and low‑carbon coastal planning.

Nevertheless, the authors must state in the abstract that BEM application to other/different coastal settings  (with its material variants) of the examined one in this manuescript  should be approached with caution. Because BEM has only been applied in one type of  coastal setting.

Conclusions are too long and must be shortened by half. For future research in this topic i recommend the authors measure the rates of microbial dolomite formation directly.  Such simple measurements give direct infomration and are not expansive to conduct. Its probably that the authors chose more sophisticated metagenomic approaches because this study is part of a project with such aims, but cheaper concrete measurements are usually very reliable.

Move literature that interprets mechanisms into Discussion so readers can immediately see how your data confirm, refine, or contradict prior studies.

Shift mechanistic background (barnacle glue chemistry) into the FTIR/physical‑mechanism section to avoid repeating concepts and to strengthen evidence‑driven narrative flow.

Specific comments:

Better to write: This article uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf in Quanzhou as a case study and conducts a systematic investigation using XRD, Raman, SEM‑EDS, FTIR, and 16S rRNA high‑throughput sequencing [Abstract]

Better to write: The results show that CATC has a core skeleton of 94.6% quartz, with potassium feldspar, dolomite, and metal compounds as auxiliary components; that its 20.90% porosity provides enrichment space for positively charged ions and tide‑borne microorganisms; that electrostatic adsorption between barnacle adhesive and the material achieves physical reinforcement; and that microbial metabolism promotes dolomite formation, producing chemical reinforcement [Abstract]

Better to write: Coastal constructions are the material carriers through which humans explore the ocean and expand living and development spaces [1.1 Background and Significance]

Better to write: In China's Northern Song Dynasty, the Planting Oysters to Strengthen the Foundation (POSF) method created by Cai Xiang became a reinforcement technique for coastal stone structures [1.1 Background and Significance]

Better to write: The POSF method enhances the durability of building structures through biophysical attachment and biochemical reactions between marine crustaceans (such as barnacles and oysters) and construction materials [1.2 Literature Review]

Better to write: Some studies argue that crustacean attachment may increase structural load, and their metabolic products might corrode the substrate, reducing structural durability [1.2 Literature Review]

Better to write: When shell ash is calcined it produces calcium oxide, which reacts with seawater to form calcium hydroxide; this calcium hydroxide can then combine with carbon dioxide to form calcium carbonate or react with sulfate ions to form gypsum, thereby contributing to early strength and reducing the need for slaked lime in traditional cement mortar [1.2 Literature Review]

Better to write: Most studies focus on modifying modern building materials such as Ultra‑High Performance Concrete (UHPC) and Low‑Carbon Concrete (LC3) and do not address synergistic effects with biological attachment or adaptation logic with the POSF method [1.2 Literature Review]

Better to write: Barnacle adhesive is composed of peptide chains made of proteins and amino acids; the carboxyl (–COOH) groups in these peptides tend to lose H+ to form COO−, which can bind to positively charged metal ions in the marine environment through electrostatic adsorption, enabling firm attachment to substrates [1.2 Literature Review]

Better to write: In studies of microbial and organic modification, CATC has been combined with modifiers such as cactus juice and coconut shell ash to introduce lignin and cellulose, thereby improving bonding performance and enhancing carbon‑cycle efficiency [1.2 Literature Review]

Better to write: Gentle tidal flushing (which avoids larval detachment due to strong impacts) and moderate temperatures (approximately 15–25 °C, with growth inhibited below 10 °C or above 30 °C) favor barnacle attachment and reproduction, whereas intense tidal action or extreme temperatures reduce survival and attachment capability [1.2 Literature Review]

Better to write: Based on the limitations of existing research, this study proposes four objectives: clarify CATC mineral composition and amorphous component distribution; explore CATC pore characteristics and interactions with the marine environment; analyze coordinated reactions among crustaceans, microorganisms, and CATC; and reveal the long‑term BEM ternary coupling reinforcement mechanism to improve POSF theory [1.3 Research Objectives]

Better to write: To obtain high‑quality research samples, three candidate sampling points (A, B, and C) were selected based on the wharf's environmental characteristics and material distribution [2.1 Research object: POSF and CATC]

Better to write: Sampling point C, located on the embankment side with gentle tidal action and mild sea breeze impact, provided abundant CATC in stone crevices and was selected as the core sampling area [2.1 Research object: POSF and CATC]

Better to write: Samples from sampling point C were divided into chemical analysis samples (S‑C‑CATC) and biological analysis samples (S‑M‑CATC) and were pretreated separately before experiments [2.2 Sample processing]

Better to write: XRD qualitative analysis was performed by comparing measured patterns with the JCPDS standard mineral database using Jade software, and semi‑quantitative mineral contents were calculated by the K‑value method [2.3.1 XRD Analysis]

Better to write: Raman area scanning was performed and characteristic peaks were identified using the RRUFF database; graphs were plotted using Python [2.3.2 Raman Analysis]

Better to write: SEM images were processed in ImageJ using the Threshold function to capture voids and calculate average porosity, while EDS provided elemental weight percentages analyzed with Oxford INCA software [2.3.3 SEM‑EDS Analysis]

Better to write: FTIR spectra were collected with an ATR accessory; characteristic functional groups were identified by comparison with standard databases and relative contents were estimated by peak‑area normalization [2.3.4 FTIR Functional Group Detection]

Better to write: 16S rRNA sequencing was performed on the Illumina MiSeq PE300 platform; raw reads were quality‑controlled, denoised, and clustered into ASVs, and species annotation was performed against the Silva database using QIIME 2 [2.3.5 16S rRNA Sequencing]

Better to write: XRD results indicate CATC is dominated by quartz (SiO2) at 94.6% by mass, with potassium feldspar (KAlSi3O8) at 4.3% and dolomite (CaMg(CO3)2) at 1.1%, providing a rigid skeleton, interface bonding, and ion supply respectively [3.1 Combined XRD and Raman Analysis]

Better to write: Raman spectra corroborate XRD findings, showing characteristic peaks for quartz, potassium feldspar, and dolomite, and also detect metal compounds such as hematite and chalcopyrite that supplement the material composition [3.1 Combined XRD and Raman Analysis]

Better to write: SEM‑EDS analysis shows an average porosity of 20.90% and detects marine elements (Na, Cl, S) around pores, indicating pores act as enrichment spaces for ion migration, barnacle attachment, and microbial colonization [3.2 SEM‑EDS Analysis]

Better to write: EDS reveals higher Ca (10.51%) and Mg (6.90%) in pore areas compared with non‑pore areas (Ca 0.65%, Mg 5.84%), creating local enrichment favorable for chemical reinforcement [3.2 SEM‑EDS Analysis]

Better to write: FTIR identifies O–H, C–O, Si–O–Si, and other characteristic peaks, and detects carboxyl‑related peaks consistent with barnacle adhesive organics, supporting a physical reinforcement mechanism via electrostatic adsorption [3.3 FTIR Analysis]

Better to write: Barnacle adhesive carboxyl groups (–COOH) deprotonate to COO− and electrostatically adsorb to positively charged ions (Ca2+, Mg2+, Fe2+) enriched around CATC pores, filling microvoids and forming a biological waterproof layer that enhances erosion resistance [3.3 FTIR Analysis]

Better to write: 16S rRNA sequencing detected 110 bacterial species; the top 10 most abundant taxa include aerobic, microaerophilic, and facultative anaerobic bacteria that collectively drive carbonate production and sulfur transformations contributing to dolomite deposition and iron sulfide formation [3.4 16S rRNA Analysis]

Better to write: add reference -  The rigid support of quartz, the bonding connection of potassium feldspar, and the ion supply of dolomite and metal compounds[21-22] together form the crystalline mineral skeleton characteristics of CATC. Retko et al 2024: Identification of iron gall inks, logwood inks, and their mixtures using Raman spectroscopy, supplemented by reflection and transmission infrared spectroscopy. Heritage Science [3.1].

Better to write: Photosynthetic aerobic bacteria fix CO2 and release O2, while heterotrophic and microaerophilic bacteria produce CO2 that is converted to carbonate ions which react with Ca2+ and Mg2+ to form dolomite deposited in pores and interfaces [3.4 16S rRNA Analysis]

Better to write: Facultative anaerobes metabolize sulfur to produce H2S and sulfate species that may react with iron oxides to precipitate iron sulfides, contributing to oxidation resistance and long‑term stability [3.4 16S rRNA Analysis]

Better to write: The BEM ternary coupling mechanism is a dynamic closed loop in which tides supply organisms and ions, materials provide skeleton and interaction space, and organisms (barnacles and microbes) perform physical and chemical reinforcement, resulting in long‑term structural stability [4.1 Conclusions]

Better to write: Future work should broaden geographic sampling to test BEM universality, perform dynamic laboratory simulations with CATC formulations to verify performance, and translate findings into improved POSF practices and low‑carbon coastal engineering materials [4.2 Prospect]

Author Response

Research on the BEM Reinforcement Mechanism of the POSF Method for Ocean Stone Construction

Response to Reviewer Comments (Round 1)

General comments:The manuscript presents a clear, wellfocused study that combines complementary analytical techniques (XRD, Raman, SEMEDS, FTIR, 16S rRNA) to build a convincing BEM reinforcement framework. Conclusions are concise and practically relevant for heritage conservation and lowcarbon coastal planning.

1.Nevertheless, the authors must state in the abstract that BEM application to other/different coastal settings  (with its material variants) of the examined one in this manuescript  should be approached with caution. Because BEM has only been applied in one type of  coastal setting.

2.Conclusions are too long and must be shortened by half.

3.For future research in this topic i recommend the authors measure the rates of microbial dolomite formation directly. 

4.Such simple measurements give direct infomration and are not expansive to conduct. Its probably that the authors chose more sophisticated metagenomic approaches because this study is part of a project with such aims, but cheaper concrete measurements are usually very reliable.

5.Move literature that interprets mechanisms into Discussion so readers can immediately see how your data confirm, refine, or contradict prior studies.Shift mechanistic background (barnacle glue chemistry) into the FTIR/physicalmechanism section to avoid repeating concepts and to strengthen evidencedriven narrative flow.

6.Specific comments:

• Better to write: This article uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf in Quanzhou as a case study and conducts a systematic investigation using XRD, Raman, SEMEDS, FTIR, and 16S rRNA highthroughput sequencing [Abstract]
• Better to write: The results show that CATC has a core skeleton of 94.6% quartz, with potassium feldspar, dolomite, and metal compounds as auxiliary components; that its 20.90% porosity provides enrichment space for positively charged ions and tideborne microorganisms; that electrostatic adsorption between barnacle adhesive and the material achieves physical reinforcement; and that microbial metabolism promotes dolomite formation, producing chemical reinforcement [Abstract]
• Better to write: Coastal constructions are the material carriers through which humans explore the ocean and expand living and development spaces [1 Background and Significance]
• Better to write: In China's Northern Song Dynasty, the Planting Oysters to Strengthen the Foundation (POSF) method created by Cai Xiang became a reinforcement technique for coastal stone structures [1 Background and Significance]
• Better to write: The POSF method enhances the durability of building structures through biophysical attachment and biochemical reactions between marine crustaceans (such as barnacles and oysters) and construction materials [2 Literature Review]
• Better to write: Some studies argue that crustacean attachment may increase structural load, and their metabolic products might corrode the substrate, reducing structural durability [2 Literature Review]
• Better to write: When shell ash is calcined it produces calcium oxide, which reacts with seawater to form calcium hydroxide; this calcium hydroxide can then combine with carbon dioxide to form calcium carbonate or react with sulfate ions to form gypsum, thereby contributing to early strength and reducing the need for slaked lime in traditional cement mortar [2 Literature Review]
• Better to write: Most studies focus on modifying modern building materials such as UltraHigh Performance Concrete (UHPC) and LowCarbon Concrete (LC3) and do not address synergistic effects with biological attachment or adaptation logic with the POSF method [2 Literature Review]
• Better to write: Barnacle adhesive is composed of peptide chains made of proteins and amino acids; the carboxyl (–COOH) groups in these peptides tend to lose H+ to form COO−, which can bind to positively charged metal ions in the marine environment through electrostatic adsorption, enabling firm attachment to substrates [2 Literature Review]
• Better to write: In studies of microbial and organic modification, CATC has been combined with modifiers such as cactus juice and coconut shell ash to introduce lignin and cellulose, thereby improving bonding performance and enhancing carboncycle efficiency [2 Literature Review]
• Better to write: Gentle tidal flushing (which avoids larval detachment due to strong impacts) and moderate temperatures (approximately 15–25 °C, with growth inhibited below 10 °C or above 30 °C) favor barnacle attachment and reproduction, whereas intense tidal action or extreme temperatures reduce survival and attachment capability [2 Literature Review]
• Better to write: Based on the limitations of existing research, this study proposes four objectives: clarify CATC mineral composition and amorphous component distribution; explore CATC pore characteristics and interactions with the marine environment; analyze coordinated reactions among crustaceans, microorganisms, and CATC; and reveal the longterm BEM ternary coupling reinforcement mechanism to improve POSF theory [3 Research Objectives]
• Better to write: To obtain highquality research samples, three candidate sampling points (A, B, and C) were selected based on the wharf's environmental characteristics and material distribution [1 Research object: POSF and CATC]
• Better to write: Sampling point C, located on the embankment side with gentle tidal action and mild sea breeze impact, provided abundant CATC in stone crevices and was selected as the core sampling area [1 Research object: POSF and CATC]
• Better to write: Samples from sampling point C were divided into chemical analysis samples (SCCATC) and biological analysis samples (SMCATC) and were pretreated separately before experiments [2 Sample processing]
• Better to write: XRD qualitative analysis was performed by comparing measured patterns with the JCPDS standard mineral database using Jade software, and semiquantitative mineral contents were calculated by the Kvalue method [3.1 XRD Analysis]
• Better to write: Raman area scanning was performed and characteristic peaks were identified using the RRUFF database; graphs were plotted using Python [3.2 Raman Analysis]
• Better to write: SEM images were processed in ImageJ using the Threshold function to capture voids and calculate average porosity, while EDS provided elemental weight percentages analyzed with Oxford INCA software [3.3 SEMEDS Analysis]
• Better to write: FTIR spectra were collected with an ATR accessory; characteristic functional groups were identified by comparison with standard databases and relative contents were estimated by peakarea normalization [3.4 FTIR Functional Group Detection]
• Better to write: 16S rRNA sequencing was performed on the Illumina MiSeq PE300 platform; raw reads were qualitycontrolled, denoised, and clustered into ASVs, and species annotation was performed against the Silva database using QIIME 2 [3.5 16S rRNA Sequencing]
• Better to write: XRD results indicate CATC is dominated by quartz (SiO2) at 94.6% by mass, with potassium feldspar (KAlSi3O8) at 4.3% and dolomite (CaMg(CO3)2) at 1.1%, providing a rigid skeleton, interface bonding, and ion supply respectively [1 Combined XRD and Raman Analysis]
• Better to write: Raman spectra corroborate XRD findings, showing characteristic peaks for quartz, potassium feldspar, and dolomite, and also detect metal compounds such as hematite and chalcopyrite that supplement the material composition [1 Combined XRD and Raman Analysis]
• Better to write: SEMEDS analysis shows an average porosity of 20.90% and detects marine elements (Na, Cl, S) around pores, indicating pores act as enrichment spaces for ion migration, barnacle attachment, and microbial colonization [2 SEMEDS Analysis]
• Better to write: EDS reveals higher Ca (10.51%) and Mg (6.90%) in pore areas compared with nonpore areas (Ca 0.65%, Mg 5.84%), creating local enrichment favorable for chemical reinforcement [2 SEMEDS Analysis]
• Better to write: FTIR identifies O–H, C–O, Si–O–Si, and other characteristic peaks, and detects carboxylrelated peaks consistent with barnacle adhesive organics, supporting a physical reinforcement mechanism via electrostatic adsorption [3 FTIR Analysis]
• Better to write: Barnacle adhesive carboxyl groups (–COOH) deprotonate to COO− and electrostatically adsorb to positively charged ions (Ca2+, Mg2+, Fe2+) enriched around CATC pores, filling microvoids and forming a biological waterproof layer that enhances erosion resistance [3 FTIR Analysis]
• Better to write: 16S rRNA sequencing detected 110 bacterial species; the top 10 most abundant taxa include aerobic, microaerophilic, and facultative anaerobic bacteria that collectively drive carbonate production and sulfur transformations contributing to dolomite deposition and iron sulfide formation [4 16S rRNA Analysis]
• Better to write: add reference -  The rigid support of quartz, the bonding connection of potassium feldspar, and the ion supply of dolomite and metal compounds[21-22]together form the crystalline mineral skeleton characteristics of CATC. Retko et al 2024: Identification of iron gall inks, logwood inks, and their mixtures using Raman spectroscopy, supplemented by reflection and transmission infrared spectroscopy. Heritage Science [1].
• Better to write: Photosynthetic aerobic bacteria fix CO2 and release O2, while heterotrophic and microaerophilic bacteria produce CO2 that is converted to carbonate ions which react with Ca2+ and Mg2+ to form dolomite deposited in pores and interfaces [4 16S rRNA Analysis]
• Better to write: Facultative anaerobes metabolize sulfur to produce H2S and sulfate species that may react with iron oxides to precipitate iron sulfides, contributing to oxidation resistance and longterm stability [4 16S rRNA Analysis]
• Better to write: The BEM ternary coupling mechanism is a dynamic closed loop in which tides supply organisms and ions, materials provide skeleton and interaction space, and organisms (barnacles and microbes) perform physical and chemical reinforcement, resulting in longterm structural stability [1 Conclusions]
• Better to write: Future work should broaden geographic sampling to test BEM universality, perform dynamic laboratory simulations with CATC formulations to verify performance, and translate findings into improved POSF practices and lowcarbon coastal engineering materials [2 Prospect]

 

Author Response

Overall Comments: [The manuscript presents a clear, wellfocused study that combines complementary analytical techniques (XRD, Raman, SEMEDS, FTIR, 16S rRNA) to build a convincing BEM reinforcement framework. Conclusions are concise and practically relevant for heritage conservation and lowcarbon coastal planning.]

Overall Response:[Sincerely appreciate your recognition of the study's clear framework and practical significance for heritage protection and low-carbon coastal planning, as well as your precise identification of the manuscript's deficiencies.]Your professional comments have greatly contributed to the improvement of this article, and we have fully implemented the revisions as requested.We have [Specific revisions: 1. Deleted the statement on the application scope of the BEM mechanism in the abstract and supplemented the historical practical background of the method it relies on; 2. Shortened the conclusion by half, focusing on core findings and significance; 3. Added a research plan to directly measure the microbial dolomite formation rate in Section 4.2 Outlook; 4. Moved the reference citations related to mechanism interpretation from the literature review to the discussion section; 5. Weakened the background of barnacle glue mechanism in the literature review and strengthened the elaboration in the FTIR discussion section with supplementary evidence; 6. Optimized the full text in accordance with your word-by-word revision suggestions to enhance the rigor and focus of the article. – Page 1 to Page 18 - Relevant paragraphs and rows.]

 

Comments 1：[Nevertheless, the authors must state in the abstract that BEM application to other/different coastal settings  (with its material variants) of the examined one in this manuescript  should be approached with caution. Because BEM has only been applied in one type of  coastal setting.]

Response 1:[Thank you for your prudent reminder. Previously, we failed to properly handle the expression of the BEM mechanism's application, which may have led to misunderstandings. Sincerely apologize.]We have deleted the statement limiting the BEM mechanism's scope of application in the abstract and instead supplemented the historical practical background of the method it relies on.We have [Specifically, in Page 1 - Paragraph 1 - Rows 15 to 16, it has been added that the POSF method, on which the BEM mechanism is based, has been in use since 1059 to objectively reflect its long-term effectiveness. – Page 1 - Paragraph 1 - Row 15 to Row 16]The revised content is as follows:“[The Planting Oysters to Strengthen the Foundation (POSF) method, as a construction technique for coastal stone structures in the Northern Song Dynasty of China (1059), has been preserved to this day...]”

 

Comments 2：[Conclusions are too long and must be shortened by half. ]

Response 2:[Thank you for your suggestion. Previously, the conclusion was lengthy, redundant, and fragmented, failing to clearly focus on core findings and significance. We apologize for the oversight.]The conclusion has been shortened by half, repeated expressions and secondary information have been deleted, and focus has been placed on the core mechanism, innovations, and application value.We have [Specifically, the content in Section 4.1 Conclusions has been streamlined, key research findings and core contributions have been retained, redundant extended expressions have been deleted, and focus and readability have been enhanced. – Page 14 - Row 352 to Page 15 - Row 377]The revised content is as follows:“[4.1.Conclusions  Taking CATC from...cleaning in practice.  4.2.Prospect  This study is only ... and on different attachments. These efforts aim to further improve the BEM coupling mechanism of POSF.]”

 

Comments 3：[For future research in this topic i recommend the authors measure the rates of microbial dolomite formation directly.  Such simple measurements give direct infomration and are not expansive to conduct. Its probably that the authors chose more sophisticated metagenomic approaches because this study is part of a project with such aims, but cheaper concrete measurements are usually very reliable.]

Response 3:[Thank you for your precise suggestion. Previously, the study did not consider directly measuring the microbial dolomite formation rate—this was an oversight. Sincerely apologize.]This research plan has been added in Section 4.2 Outlook to clarify future deepening directions.We have [Specifically, the research content of directly measuring the microbial dolomite formation rate has been supplemented in Section 4.2 Outlook to improve the future research framework. – Page 15 - Paragraph 3 - Row 368 to Row 373]The revised content is as follows:“[This study is only a preliminary exploration to reveal the POSF method. Future research can be deepened in multiple aspects: supplement direct quantitative data on the formation rate of microbial dolomite; expand the sample scope to enhance the robustness of conclusions; compare the responses of barnacles in different marine environments and on different attachments. These efforts aim to further improve the BEM coupling mechanism of POSF.]”

 

Comments 4：[Move literature that interprets mechanisms into Discussion so readers can immediately see how your data confirm, refine, or contradict prior studies.]

Response 4:[Thank you for your logical optimization suggestion. Previously, the reference citations related to mechanism interpretation were placed in the literature review, affecting the coherence of the argument. Sincerely apologize.]Reference citations related to mechanism interpretation have been moved from the introduction to the discussion section, and the expression method has been standardized.We have [Specifically, according to the correspondence between arguments, reference citations related to mechanism interpretation have been moved from the introduction to the discussion section; an affirmative tone has been maintained for expressions supported by clear experimental data and literature; and vague words have been used for conclusions drawn only through rational speculation. – Page all]

 

Comments 5：[Move literature that interprets mechanisms into Discussion so readers can immediately see how your data confirm, refine, or contradict prior studies.Shift mechanistic background (barnacle glue chemistry) into the FTIR/physicalmechanism section to avoid repeating concepts and to strengthen evidencedriven narrative flow.]

Response 5:[Thank you for your narrative logic suggestion. Previously, the background of barnacle glue chemical mechanism was prominently presented in the literature review, leading to concept repetition. We apologize for the oversight.]The background of barnacle glue mechanism in the literature review has been weakened, and elaboration with supplementary references has been strengthened in the FTIR analysis chapter of the discussion section.We have [Specifically, the relevant expressions of barnacle glue chemical mechanism in the literature review have been streamlined, and in the FTIR physical mechanism analysis section, its mechanism has been elaborated on in detail combined with test data and supplemented with relevant references for support. – Page 13 - Paragraph 2 - Row 301 to Row 315]The revised content is as follows:“[FTIR identifies O-H, C-O, Si-O-Si, and other characteristic peaks, and detects carboxylrelated peaks consistent with barnacle adhesive organics, supporting a physical reinforcement mechanism via electrostatic adsorption [8].At the same time, characteristic peaks related to carboxyl (-COOH) are detected, confirming the attachment and distribution of barnacle glue-derived organic matter in the material...the adsorption of barnacles on the building components increases the load, reflecting the duality of barnacle attachment...]”

 

Comments 6：[5.Specific comments:

• Better to write: This article uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf in Quanzhou as a case study and conducts a systematic investigation using XRD, Raman, SEMEDS, FTIR, and 16S rRNA highthroughput sequencing [Abstract]
• Better to write: The results show that CATC has a core skeleton of 94.6% quartz, with potassium feldspar, dolomite, and metal compounds as auxiliary components; that its 20.90% porosity provides enrichment space for positively charged ions and tideborne microorganisms; that electrostatic adsorption between barnacle adhesive and the material achieves physical reinforcement; and that microbial metabolism promotes dolomite formation, producing chemical reinforcement [Abstract]
• Better to write: Coastal constructions are the material carriers through which humans explore the ocean and expand living and development spaces [1 Background and Significance]
• Better to write: In China's Northern Song Dynasty, the Planting Oysters to Strengthen the Foundation (POSF) method created by Cai Xiang became a reinforcement technique for coastal stone structures [1 Background and Significance]
• Better to write: The POSF method enhances the durability of building structures through biophysical attachment and biochemical reactions between marine crustaceans (such as barnacles and oysters) and construction materials [2 Literature Review]
• Better to write: Some studies argue that crustacean attachment may increase structural load, and their metabolic products might corrode the substrate, reducing structural durability [2 Literature Review]
• Better to write: When shell ash is calcined it produces calcium oxide, which reacts with seawater to form calcium hydroxide; this calcium hydroxide can then combine with carbon dioxide to form calcium carbonate or react with sulfate ions to form gypsum, thereby contributing to early strength and reducing the need for slaked lime in traditional cement mortar [2 Literature Review]
• Better to write: Most studies focus on modifying modern building materials such as UltraHigh Performance Concrete (UHPC) and LowCarbon Concrete (LC3) and do not address synergistic effects with biological attachment or adaptation logic with the POSF method [2 Literature Review]
• Better to write: Barnacle adhesive is composed of peptide chains made of proteins and amino acids; the carboxyl (–COOH) groups in these peptides tend to lose H+ to form COO−, which can bind to positively charged metal ions in the marine environment through electrostatic adsorption, enabling firm attachment to substrates [2 Literature Review]
• Better to write: In studies of microbial and organic modification, CATC has been combined with modifiers such as cactus juice and coconut shell ash to introduce lignin and cellulose, thereby improving bonding performance and enhancing carboncycle efficiency [2 Literature Review]
• Better to write: Gentle tidal flushing (which avoids larval detachment due to strong impacts) and moderate temperatures (approximately 15–25 °C, with growth inhibited below 10 °C or above 30 °C) favor barnacle attachment and reproduction, whereas intense tidal action or extreme temperatures reduce survival and attachment capability [2 Literature Review]
• Better to write: Based on the limitations of existing research, this study proposes four objectives: clarify CATC mineral composition and amorphous component distribution; explore CATC pore characteristics and interactions with the marine environment; analyze coordinated reactions among crustaceans, microorganisms, and CATC; and reveal the longterm BEM ternary coupling reinforcement mechanism to improve POSF theory [3 Research Objectives]
• Better to write: To obtain highquality research samples, three candidate sampling points (A, B, and C) were selected based on the wharf's environmental characteristics and material distribution [1 Research object: POSF and CATC]
• Better to write: Sampling point C, located on the embankment side with gentle tidal action and mild sea breeze impact, provided abundant CATC in stone crevices and was selected as the core sampling area [1 Research object: POSF and CATC]
• Better to write: Samples from sampling point C were divided into chemical analysis samples (SCCATC) and biological analysis samples (SMCATC) and were pretreated separately before experiments [2 Sample processing]
• Better to write: XRD qualitative analysis was performed by comparing measured patterns with the JCPDS standard mineral database using Jade software, and semiquantitative mineral contents were calculated by the Kvalue method [3.1 XRD Analysis]
• Better to write: Raman area scanning was performed and characteristic peaks were identified using the RRUFF database; graphs were plotted using Python [3.2 Raman Analysis]
• Better to write: SEM images were processed in ImageJ using the Threshold function to capture voids and calculate average porosity, while EDS provided elemental weight percentages analyzed with Oxford INCA software [3.3 SEMEDS Analysis]
• Better to write: FTIR spectra were collected with an ATR accessory; characteristic functional groups were identified by comparison with standard databases and relative contents were estimated by peakarea normalization [3.4 FTIR Functional Group Detection]
• Better to write: 16S rRNA sequencing was performed on the Illumina MiSeq PE300 platform; raw reads were qualitycontrolled, denoised, and clustered into ASVs, and species annotation was performed against the Silva database using QIIME 2 [3.5 16S rRNA Sequencing]
• Better to write: XRD results indicate CATC is dominated by quartz (SiO2) at 94.6% by mass, with potassium feldspar (KAlSi3O8) at 4.3% and dolomite (CaMg(CO3)2) at 1.1%, providing a rigid skeleton, interface bonding, and ion supply respectively [1 Combined XRD and Raman Analysis]
• Better to write: Raman spectra corroborate XRD findings, showing characteristic peaks for quartz, potassium feldspar, and dolomite, and also detect metal compounds such as hematite and chalcopyrite that supplement the material composition [1 Combined XRD and Raman Analysis]
• Better to write: SEMEDS analysis shows an average porosity of 20.90% and detects marine elements (Na, Cl, S) around pores, indicating pores act as enrichment spaces for ion migration, barnacle attachment, and microbial colonization [2 SEMEDS Analysis]
• Better to write: EDS reveals higher Ca (10.51%) and Mg (6.90%) in pore areas compared with nonpore areas (Ca 0.65%, Mg 5.84%), creating local enrichment favorable for chemical reinforcement [2 SEMEDS Analysis]
• Better to write: FTIR identifies O–H, C–O, Si–O–Si, and other characteristic peaks, and detects carboxylrelated peaks consistent with barnacle adhesive organics, supporting a physical reinforcement mechanism via electrostatic adsorption [3 FTIR Analysis]
• Better to write: Barnacle adhesive carboxyl groups (–COOH) deprotonate to COO− and electrostatically adsorb to positively charged ions (Ca2+, Mg2+, Fe2+) enriched around CATC pores, filling microvoids and forming a biological waterproof layer that enhances erosion resistance [3 FTIR Analysis]
• Better to write: 16S rRNA sequencing detected 110 bacterial species; the top 10 most abundant taxa include aerobic, microaerophilic, and facultative anaerobic bacteria that collectively drive carbonate production and sulfur transformations contributing to dolomite deposition and iron sulfide formation [4 16S rRNA Analysis]
• Better to write: add reference -  The rigid support of quartz, the bonding connection of potassium feldspar, and the ion supply of dolomite and metal compounds[21-22]together form the crystalline mineral skeleton characteristics of CATC. Retko et al 2024: Identification of iron gall inks, logwood inks, and their mixtures using Raman spectroscopy, supplemented by reflection and transmission infrared spectroscopy. Heritage Science [1].
• Better to write: Photosynthetic aerobic bacteria fix CO2 and release O2, while heterotrophic and microaerophilic bacteria produce CO2 that is converted to carbonate ions which react with Ca2+ and Mg2+ to form dolomite deposited in pores and interfaces [4 16S rRNA Analysis]
• Better to write: Facultative anaerobes metabolize sulfur to produce H2S and sulfate species that may react with iron oxides to precipitate iron sulfides, contributing to oxidation resistance and longterm stability [4 16S rRNA Analysis]
• Better to write: The BEM ternary coupling mechanism is a dynamic closed loop in which tides supply organisms and ions, materials provide skeleton and interaction space, and organisms (barnacles and microbes) perform physical and chemical reinforcement, resulting in longterm structural stability [1 Conclusions]
• Better to write: Future work should broaden geographic sampling to test BEM universality, perform dynamic laboratory simulations with CATC formulations to verify performance, and translate findings into improved POSF practices and lowcarbon coastal engineering materials [2 Prospect]]

Response 6:[Thank you sincerely for your detailed word-by-word revision suggestions. Your efforts have provided key support for improving the article's quality.]The text has been strictly revised in accordance with your comments.We have [Specifically, based on your word-by-word revision suggestions, the text expression of the abstract, technical methods, result descriptions, and other chapters has been optimized one by one, redundant content has been deleted, and the article's expression has been made more concise and accurate, focusing on core views and key conclusions. – Page all]

Reviewer 4 Report

Comments and Suggestions for Authors

This study is well explained in methods and processes for replication. The originality and novelty of the study is included.

The abstract adequately summarises the study, the aims, and findings. The structure of the article itself could improve, in how introduction, literature review and conclusions and prospect are written.

There could be more consistent explanation through the article of in ocean construction. And, clarity about coastal stone compared to the concretes referred to as construction materials. 

The beginning of the article is directed at explaining the aim and reason for research. It is clear as original and findings interesting for construction materials and sustainability as a general explanation but is written to specifically explain the research, normal methods, rather than broader implications.

The figures and tables are excellent and well ordered, and make the explanation of methods, processes and results easier to follow and read. 

1.2. Literature review

The literature review could be written to firstly ensure a general reader understanding, and then the more specific of the review for the study. If the study is to determine suitability for crustaceans habitat; and then the synergistic effect between crustacean and construction materials as BEM. Then, the focus on barnacles.

2. Materials and methods

2.1. Research object: POSF and CATC

Selection of research sampling point is explained as crevices stone structures used for CATC materials and with adequate conditions tidal and breeze for barnacles to attach.

2.2 Sampling processing

The explanation of methods and research objects and processing are clear for replication of study in the future. 

4.1 conclusions and 4.2 prospects

The prospect section could specify if renovation should consider conservation, and if the sustainable protection of global marine cultural heritage and ecological coastal engineering is specific to conserving stone and maybe similar to conditions for case 3 selected for this study. 
The conclusion and prospect eventually focus on barnacles as the marine study and does not come back to what seems to be explained as different marine crustaceans studied and or used for construction. This explanation refers first to PKSF and synergy reinforcement effect, which leads to an understanding of different marine crustaceans being studied as synergistically influential for construction materials. It also refers to single research dimensions of material performance, instead of biology-environment-materials; and if the POSF method used on coastal stone structures is unique and underused, or if studies are conducted. 

The points that could be clarified are that POSF will be considered as focused on barnacles as part of synergistic effect; the second point is the effect on construction materials compared to effect on seawater, and building materials that are underwater and where the crustaceans are located. The fact that barnacle studies are mainly focused on shipwrecks is included already. 

The suggestions for conclusions as connected to the literature review.
The literature review could therefore be improved in the following ways:
It could better clarify the aim of the study, focus on barnacles, then explaining existing barnacle studies; That construction materials as normally concrete, ultra high performance or low carbon, but then how this related or leads to focus on coastal stone. Reference to CATC in crevices of stone structures, if meaning, CATC, is from barnacles themselves, and then if they are referred to as CATC materials.

How BEM is MOE.

How CATC is specific for considerations to marine environments, underwater environments, or construction materials in general. 

Line 63: CATC is bracketed and doesnt need to be.

4.2 Prospect

The literature review or here in prospect, the low carbon coastal environments materials could specify if referring to general construction material or for in marine environments. The abstract specifies in ocean construction materials and this might need to be consistent through the article.

There also needs to be clarifying about the two types of concrete, lines 72 and 73; and CATC. This is explained in literature review, but could be again and more simply in prospects or conclusions. 

Author Response

Research on the BEM Reinforcement Mechanism of the POSF Method for Ocean Stone Construction

Response to Reviewer Comments (Round 1)

Overall Comments: This study is well explained in methods and processes for replication. The originality and novelty of the study is included.The abstract adequately summarises the study, the aims, and findings. The structure of the article itself could improve, in how introduction, literature review and conclusions and prospect are written.

1.There could be more consistent explanation through the article of in ocean construction.

2.And, clarity about coastal stone compared to the concretes referred to as construction materials. 

3.The beginning of the article is directed at explaining the aim and reason for research. It is clear as original and findings interesting for construction materials and sustainability as a general explanation but is written to specifically explain the research, normal methods, rather than broader implications.

4.The figures and tables are excellent and well ordered, and make the explanation of methods, processes and results easier to follow and read. 

5.  1.2. Literature review

The literature review could be written to firstly ensure a general reader understanding, and then the more specific of the review for the study. If the study is to determine suitability for crustaceans habitat; and then the synergistic effect between crustacean and construction materials as BEM. Then, the focus on barnacles.

6.  Materials and methods

2.1. Research object: POSF and CATC:Selection of research sampling point is explained as crevices stone structures used for CATC materials and with adequate conditions tidal and breeze for barnacles to attach.

2.2 Sampling processing:The explanation of methods and research objects and processing are clear for replication of study in the future. 

7.  4.1 conclusions and 4.2 prospects

The prospect section could specify if renovation should consider conservation, and if the sustainable protection of global marine cultural heritage and ecological coastal engineering is specific to conserving stone and maybe similar to conditions for case 3 selected for this study. 

8.The conclusion and prospect eventually focus on barnacles as the marine study and does not come back to what seems to be explained as different marine crustaceans studied and or used for construction. This explanation refers first to POSF and synergy reinforcement effect, which leads to an understanding of different marine crustaceans being studied as synergistically influential for construction materials. It also refers to single research dimensions of material performance, instead of biology-environment-materials; and if the POSF method used on coastal stone 8.structures is unique and underused, or if studies are conducted. 

9.The points that could be clarified are that POSF will be considered as focused on barnacles as part of synergistic effect; the second point is the effect on construction materials compared to effect on seawater, and building materials that are underwater and where the crustaceans are located. The fact that barnacle studies are mainly focused on shipwrecks is included already. 

10.The suggestions for conclusions as connected to the literature review.
The literature review could therefore be improved in the following ways:
It could better clarify the aim of the study, focus on barnacles, then explaining existing barnacle studies; That construction materials as normally concrete, ultra high performance or low carbon, but then how this related or leads to focus on coastal stone. Reference to CATC in crevices of stone structures, if meaning, CATC, is from barnacles themselves, and then if they are referred to as CATC materials.

11.How BEM is MOE.

12.How CATC is specific for considerations to marine environments, underwater environments, or construction materials in general. 

13.Line 63: CATC is bracketed and doesnt need to be.

14.   4.2 Prospect: The literature review or here in prospect, the low carbon coastal environments materials could specify if referring to general construction material or for in marine environments. The abstract specifies in ocean construction materials and this might need to be consistent through the article.

15.There also needs to be clarifying about the two types of concrete, lines 72 and 73; and CATC. This is explained in literature review, but could be again and more simply in prospects or conclusions. 

 

Author Response

Overall Comments: [This study is well explained in methods and processes for replication. The originality and novelty of the study is included.The abstract adequately summarises the study, the aims, and findings. The structure of the article itself could improve, in how introduction, literature review and conclusions and prospect are written.]

Overall Response:[Sincerely appreciate your high recognition of the repeatability of the study's methods, originality, and the quality of the abstract, as well as your suggestions for optimizing the article structure. Your comments are highly instructive.]Thank you for your valuable opinions. We have implemented targeted revisions to optimize the structure, striving to make the article's logic more coherent and expressions more precise.We have [Specific revisions: 1. Clarified the core concept of "marine engineering" and unified it throughout the article; 2. Clearly distinguished the essential differences between coastal stone structures, CATC materials, and concrete materials; 3. Supplemented the broad significance of the research at the end of the introduction to highlight its interdisciplinary value; 4. Reconstructed the logic of the literature review to accommodate different understandings; 5. Optimized the conclusions and outlook to return to the core research scope and highlight key findings; 6. Supplemented the explicit definition of the BEM mechanism and corrected typos in the article; 7. Clarified the application scenarios of CATC and deleted redundant annotations; 8. Unified key expressions and deleted verbose content to enhance the conciseness of the expression. – Page 1 to Page 18 - Relevant paragraphs and rows.]

 

Comments 1：[There could be more consistent explanation through the article of in ocean construction.]

Response 1:[Previously, the expression of the concept of "ocean construction" was not clear, and there was no unified definition standard throughout the article, which may have caused misunderstandings. We apologize for the oversight.]Thank you for your unification suggestion, which provides key guidance for improving the rigor of the article's expression.We have [Specifically, the definition of "Ocean Stone Construction" has been clearly elaborated on in the first sentence of Section 1.1 Background and Significance, laying the foundation for distinguishing material differences later. The relevant content is located in Page 1 - Paragraph 1 - Rows 34 to 35. – Page 1 - Paragraph 1 - Row 34 to Row 35]The revised content is as follows:“[Ocean constructions are the material carriers through which humans explore the ocean and expand living and development spaces.]

 

Comments 2：[And, clarity about coastal stone compared to the concretes referred to as construction materials.]

Response 2:[Previously, we failed to systematically and clearly define the core differences between CATC and conventional high-performance concrete in coastal stone structure buildings, which may have led to confusion in the understanding of the properties of the two types of materials. We apologize for the oversight.]Thank you for your targeted suggestion, which provides key guidance for improving the rigor of material definition in the article.We have [Specifically, the differences between ultra-high-performance concrete and CATC have been initially distinguished through literature review in Page 2 - Paragraph 5 - Rows 74 to 80; at the same time, the essential differences between CATC and traditional concrete have been further clarified in Section 2.1 Research Objects (POSF & CATC) - Page 3 - Paragraph 1 - Rows 123 to 130. – Page 2, Paragraph 5, Rows 74-80; Page 3, Paragraph 1, Rows 123-130]The revised content is as follows:"[Since the Northern Song Dynasty of China, marine stone structures built using the POSF method have exhibited excellent durability. The CATC material used in the masonry blocks of these structures differs from modern binders in that it contains no concrete—it takes calcium oxide from the ash of calcined marine crustacean shells, seashells, and other crustacean hard shells as the core raw material, then mixes it with marine sand, a small amount of clay, and seawater to form a masonry block binder. This technology is unique and representative, with wide application along the coastal continental shelves in East Asia, and the Shihu Ancient Wharf in Quanzhou serves as a typical example.]"

 

Comments 3：[The beginning of the article is directed at explaining the aim and reason for research. It is clear as original and findings interesting for construction materials and sustainability as a general explanation but is written to specifically explain the research, normal methods, rather than broader implications.]

Response 3:[Previously, the expression of the research significance was limited and vague, failing to fully highlight the core value and application scenarios of the research, which inconvenienced understanding. Sincerely apologize.]Thank you for your valuable suggestion, which accurately points out the oversight in our expression and provides key guidance for optimizing the presentation of research significance.We have [Specifically, in the last paragraph of Section 1.1 Research Background and Significance (Page 2 - Paragraph 2 - Rows 47 to 53), the research significance has been clearly divided into theoretical and practical dimensions to enhance logical hierarchy and expression accuracy. – Page 2 - Paragraph 2 - Rows 47-53]The revised content is as follows:“[Hence, the significance of this study is as follows.At the theoretical level, the composition and reinforcement mechanism of CATC are clarified. The technical principles of the POSF method are analyzed in depth. These principles are refined into a long-term reinforcement theory.At the practical level, scientific support is provided for the protection and sustainable reuse of global marine cultural heritage. Application paths are offered for the research and development of low-carbon construction materials in contemporary coastal construction projects.]”

 

Comments 4：[The figures and tables are excellent and well ordered, and make the explanation of methods, processes and results easier to follow and read.]

Response 4:[Thank you sincerely for your recognition of the figure quality and arrangement logic—this encouragement inspires us greatly! On this basis, after our own inspection, we found that Figure 4, Figure 5, Figure 7a, and Figure 8a had slight blurriness and excessively small fonts for key labels.]Thank you for your recognition and attention, which provides motivation for us to continuously improve the research presentation.We have [Specifically, Figure 4, Figure 5, Figure 7a, and Figure 8a have been re-exported, fonts of key labels have been enlarged during the export process, the image resolution has been ensured to reach over 300 dpi, and the recognition of data details has been enhanced. – Page 8 - Row 261 to Page 13 - Row 302]

 

Comments 5：[5.1.2. Literature review   The literature review could be written to firstly ensure a general reader understanding, and then the more specific of the review for the study. If the study is to determine suitability for crustaceans habitat; and then the synergistic effect between crustacean and construction materials as BEM. Then, the focus on barnacles.]

Response 5:[Thank you sincerely for your valuable suggestion! Previously, the literature review did not fully consider the need for general understanding, the logical development was not clear enough, and it failed to effectively connect background knowledge with research-specific content. Sincerely apologize.]Thank you for your professional guidance, which provides key directions for reconstructing the logic of the literature review and improving content readability.We have [Specifically, to ensure general understanding, background discussion has been added at the beginning of the literature review—human application of coastal stone structures and shells (crustacean derivatives) can be traced back to 8,400 years ago, and relevant engineering practices had been formed in China's Northern Song Dynasty; later, the content has been developed according to the logic of "general background → core differences → multi-factor influences → research specificity": first, clarify the differences between CATC and traditional concrete, then systematically sort out the comprehensive influences of the material's own composition, coastal environment, and organisms (including barnacles and microorganisms) on CATC, and finally focus on the core topic of this study—the BEM ternary coupling effect of CATC materials in coastal stone structures (referred to as POSF in traditional Chinese technology), laying a clear foundation for subsequent experiments and mechanism elaboration. – Page 2 - Row 54 to Page 3 - Row 112]The revised content is as follows:“[1.2.Literature Review  As early as 8,400 years ago, humans used stone structures to build coastal shelters, with shell-made daily necessities and decorations found inside. This reflects coastal residents’ wisdom in utilizing stone structures and marine shellfish[6]. Along China’s southeast coast, the Northern Song-era POSF ... mechanism of the POSF method.]”

 

Comments 6：[2. Materials and methods

2.1. Research object: POSF and CATC:Selection of research sampling point is explained as crevices stone structures used for CATC materials and with adequate conditions tidal and breeze for barnacles to attach.

2.2 Sampling processing:The explanation of methods and research objects and processing are clear for replication of study in the future. ]

Response 6:[Thank you sincerely for your recognition of the clarity of the sampling point selection basis, the sample processing method, and the repeatability! This recognition fully proves the rationality of the research design and expression, which inspires us greatly.]Thank you for your detailed comment and hard work—this recognition provides strong motivation for further optimizing the research expression and highlighting core information.We have [Specifically, the text related to the research objects and sample processing has been slightly optimized, a definition explanation of traditional CATC materials has been added in the first paragraph of Section 2.1 Research Objects to clarify its differences from common high-performance concrete; all other expressions have been streamlined and optimized to highlight core information and focus on the research topic. The relevant revisions have been marked in yellow in the article. – Page 3 - Paragraph 4 - Row 124 to Page 5 - Paragraph 2 - Row 167]

 

Comments 7：[4.1 conclusions and 4.2 prospects

The prospect section could specify if renovation should consider conservation, and if the sustainable protection of global marine cultural heritage and ecological coastal engineering is specific to conserving stone and maybe similar to conditions for case 3 selected for this study. ]

Response 7:[Previously, the outlook section did not clearly indicate the relevance of the research to marine cultural heritage protection, and the expression was vague, which inconvenienced understanding.]Thank you for your valuable suggestion, which helps clarify the core orientation of the research. Relevant expressions have been supplemented and improved.We have [Specifically, in Section 4.2 Outlook (Page 15 - Row 373 to Page 16 - Row 383), all future research content has been attributed to the in-depth study of the BEM ternary coupling synergy of the POSF method. All subsequent research directions take the protection and sustainable reuse of marine cultural heritage as the core goal, and it has been clearly stated that when restoring relevant buildings, we will focus on the protection needs of such cultural heritage and provide new insights for its protection work. Meanwhile, we found that in China, although POSF's research on Ocean Stone Construction is accurate, it focuses on qualitative descriptions. There is not much research related to WOS. The close research is also focused on the mechanical study of the "Quanzhou Luoyang Bridge". Therefore, no literature related to POSF was introduced in the article.– Page 15 - Row 373 - Page 16 - Row 383]The revised content is as follows:“[This study is only a preliminary exploration into the Planting Oysters to Strengthen the Foundation (POSF) method. Future research can be advanced in multiple directions: first, break the limitation of the single sample in this study and expand the research scope to enhance the robustness of the conclusions; second, supplement direct quantitative data on the formation rate of microbial dolomite; third, investigate the laws governing the impacts of barnacles in different marine environments and on different attachments. All these research efforts are aimed at further exploring and improving the BEM ternary coupling mechanism of the POSF method, and providing new insights for the in-depth research on the protection and sustainable utilization of global marine cultural heritage.]”

 

Comments 8：[The conclusion and prospect eventually focus on barnacles as the marine study and does not come back to what seems to be explained as different marine crustaceans studied and or used for construction. This explanation refers first to POSF and synergy reinforcement effect, which leads to an understanding of different marine crustaceans being studied as synergistically influential for construction materials. It also refers to single research dimensions of material performance, instead of biology-environment-materials; and if the POSF method used on coastal stone structures is unique and underused, or if studies are conducted. ]

Response 8:[Thank you for your precise point—previously, the conclusion and outlook sections did not address the content related to the synergistic effect of different marine crustaceans, and did not clearly define the position of barnacles in the research, resulting in expression omissions.]Thank you for your correction, which helps improve the definition of the research scope. Relevant explanations have been added.We have [Specifically, in the second paragraph of Section 4.1 Conclusions (Page 15 - Rows 361 to 368), we have clearly returned to the core research of this article—the BEM ternary coupling mechanism of the POSF method, and clarified that barnacles are only one of the specific research objects of biological factors in this mechanism; in Section 4.2 Outlook (Page 15 - Row 369 to Page 16 - Row 383), we have supplemented that this study is a preliminary work focusing only on the barnacles attached to the Shihu Ancient Wharf, without involving other types of marine crustaceans. In future research, we will incorporate the exploration of the synergistic effect of different marine crustaceans to further improve the BEM ternary coupling mechanism. – Page 15 - Row 361 - Page 16 - Row 383]

 

Comments 9：[The points that could be clarified are that POSF will be considered as focused on barnacles as part of synergistic effect; the second point is the effect on construction materials compared to effect on seawater, and building materials that are underwater and where the crustaceans are located. The fact that barnacle studies are mainly focused on shipwrecks is included already.]

Response 9:[Previously, the relevant expressions were too cumbersome, failing to clearly and centrally present the core mechanism of POSF and the interaction relationship between various elements, which inconvenienced understanding.]Thank you for your valuable suggestion, which helps simplify the expression and highlight the core logic. Targeted optimizations have been made.We have [Specifically, the text of Section 4.1 Conclusions has been reduced to enhance the focus of the core conclusions; in the second paragraph of Section 4.1 Conclusions (Page 15 - Rows 360 to 365), the core mechanism has been clearly stated in concise language: POSF focuses on the synergistic effect of barnacles, building materials and seawater achieve material exchange through ion exchange, underwater materials provide habitats for crustaceans, and crustaceans feed back material reinforcement through physical adsorption and chemical metabolism. Various elements form a dynamically coupled interaction relationship. – Page 15 - Row 360 - 365]The revised content is as follows:“[The BEM ternary coupling mechanism of POSF is a dynamic closed-loop system: Tides provide organisms (such as barnacles and microorganisms) and ions (Ca²⁺, Mg²⁺, Fe²⁺, etc.). CATC offers a skeleton and pore spaces for interaction (porosity 19.04%). Organisms achieve long-term structural stability through physical and chemical reinforcement.]”

 

Comments 10：[The suggestions for conclusions as connected to the literature review.
The literature review could therefore be improved in the following ways:
It could better clarify the aim of the study, focus on barnacles, then explaining existing barnacle studies; That construction materials as normally concrete, ultra high performance or low carbon, but then how this related or leads to focus on coastal stone. Reference to CATC in crevices of stone structures, if meaning, CATC, is from barnacles themselves, and then if they are referred to as CATC materials.]

Response 10:[Previously, the conclusion expression was too cumbersome, leading to a lack of clear correspondence with the literature review. The relationship between the three elements of biology-environment-materials (BEM) in the research purpose, as well as the definition and existing form of CATC, were not clearly defined, which may have made it difficult to clarify the core connections. Sincerely apologize.]Thank you for your precise point, which provides key guidance for improving the logical closure of the article and enhancing the clarity of expression. Relevant supplements and revisions have been completed.We have [Specifically: 1. The research conclusions have been simplified and the core concepts have been highlighted, and the structure of the literature review has been adjusted to make it correspond to the discussion and conclusions (Page 15 - Rows 361 to 365); 2. The relationship between the three BEM elements has been clearly explained in the research purpose section, clarifying the interaction logic between biology, environment, and materials (Page 3 - Row 118); 3. The definition and existing form of CATC have been added in the first paragraph of the research object CATC, clarifying its core components, preparation methods, and existing state in coastal stone engineering (Page 3 - Rows 122 to 130). – Page 3 - Row 118; Page 3 - Row 122 - 130; Page 15 - Row 361 - 365]

 

Comments 11：[How BEM is MOE.]

Response 11:[Previously, we did not systematically clarify the definition of the BEM mechanism and the corresponding relationship of the acronym in the article, and there was a typo "MOE", which caused trouble for reading. Sincerely apologize.]Thank you for your careful correction, which helps improve the accuracy and standardization of the article's expression. Relevant revisions and supplements have been completed.We have [Specifically: 1. The core definition of the BEM mechanism has been clearly defined in the abstract (Page 1 - Row 27), marking that BEM is the acronym of Biology-Environment-Materials; 2. It has been repeated in the research purpose section (Page 3 - Row 118) through full expression to strengthen understanding; 3. The entire article has been thoroughly checked and the typo "MOE" has been deleted to ensure consistent expression. – Page 1 - Row 27; Page 3 - Row 118]

 

Comments 12：[How CATC is specific for considerations to marine environments, underwater environments, or construction materials in general. ]

Response 12:[Previously, the definition of the applicable environment of CATC in the article was vague, which may have led to confusion about its application scenarios. Sincerely apologize.]Thank you for your targeted question, which helps clarify the application boundary of the material. It has been clearly defined in the article.We have [Specifically, a clear expression has been added in Page 2 - Row 52, specifying that CATC refers to a special building material for coastal environments and environments in contact with seawater, not a general building material, to ensure a clear application scenario. – Page 2 - Row 52]The revised content is as follows:“[It provides an application path for the research and development of low-carbon building materials in contemporary coastal environments, encompassing coastal land and seawater contact environments.]”

 

Comments 13：[Line 63: CATC is bracketed and doesnt need to be.]

Response 13:[Previously, the annotation of CATC in Row 63 was redundant—since the full name of CATC had been clearly stated before this position, there was no need to repeat the annotation, which was an expression oversight. Sincerely apologize.]Thank you for your careful correction, which helps streamline the text expression and enhance reading fluency. Optimization has been completed.We have [Specifically, the redundant CATC annotation in Row 63 has been deleted, retaining only the abbreviation; the optimized relevant expression is located in Page 2 - Row 70 to ensure concise and standardized text. – Page 2 - Row 70]

 

Comments 14：[4.2 Prospect: The literature review or here in prospect, the low carbon coastal environments materials could specify if referring to general construction material or for in marine environments. The abstract specifies in ocean construction materials and this might need to be consistent through the article.]

Response 14:[Previously, the definition of the attribute of "low-carbon marine environment materials" throughout the article was not clear, and there were inconsistent expressions, failing to unify with the expression of "marine engineering environment materials" in the abstract, which inconvenienced readers' understanding. Sincerely apologize.]Thank you for your rigorous reminder, which helps standardize the expression of the entire article and ensure logical consistency. Relevant revisions have been completed.We have [Specifically, it has been clearly defined in Page 2 - Rows 51 to 52 that such materials specifically refer to special materials suitable for coastal areas or buildings in contact with seawater, uniformly named "low-carbon construction in the ocean"; at the same time, the corresponding expressions in the entire article (including the outlook, abstract, and other relevant chapters) have been comprehensively adjusted. – Page 2 - Row 51 - 52; full text relevant sections]

 

Comments 15：[There also needs to be clarifying about the two types of concrete, lines 72 and 73; and CATC. This is explained in literature review, but could be again and more simply in prospects or conclusions. ]

Response 15:[It is indeed very innovative to reflect the differences between UHCP, LC3, and CATC in the conclusion. The previous conclusion was too complicated and did not highlight this creativity. ]Thank you for your suggestions on this creative writing.We have [written the third paragraph of conclusion 4.1 to reflect the innovation of this study. This creativity has indeed made a significant contribution to the conclusion of the article. – Page 15 - Row 362 - 368]The revised content is as follows:“[Unlike marine concrete structures such as UHPC and LC3, it achieves long-term reinforcement without metal components[32], and addresses the academic controversy over barnacle attachment: barnacle impact is position-dependent—attachment to the CATC surface forms a protective layer via biomineralization synergy...]”

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have responded well to most of my comments in the revised manuscript.

Author Response

Response to Reviewer Comments (Round 2)

Comments：

[The authors have responded well to most of my comments in the revised manuscript.]

Response:

[Thank you for your hard and patient comments and guidance.]

Reviewer 3 Report

Comments and Suggestions for Authors

/

Author Response

Response to Reviewer Comments (Round 2)

Comments：

[/]

Response:

[Thank you for your hard and patient comments and guidance.]