Blueprint for Blue Carbon: Lessons from Seychelles for Small Island States

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Review of oceans-2597457

Bennett et al. submitted a Review-type manuscript on the institutionalisation of blue carbon in the Seychelles. They covered much ground, touching on the (fundamental) science aspects and implementation towards payment for ecosystem services. There are some parts, which I recommend for further elaboration and clarification. Other minor improvements are also suggested. These are as follows:

1)    Methods

a)    ‘The literature review comprised a non-exhaustive search…’
Comment: Why is it ‘non-exhaustive’? A review should be as thorough as realistically possible. What were you criterion for inclusion and exclusion of search hits for your literature base?

b)    ‘… because the seaweed breaks down when washed up on the beaches, releasing carbon stored in its tissues…’
Comment: This statement is warranted but I disagree in its context. First: these can contribute as allochthonous inputs of blue carbon (re: Fujita et al. 2022; Ross et al., 2023). Second: The remineralisation of macroalgal detritus would further lower the potential for net blue carbon storage at the ecosystem level. These need inclusion in the text. See also my comments on calcifying macroalgae below.

2)    2.4 Coral reefs

Source-sink balances as a result of biogenic calcification is still a knowledge gap in blue carbon science. Coral reefs are important for other ecosystem services but not of blue carbon. The work by Shi et al. (2021) was constantly referenced, which is not such a strong paper to support your argument. The work by Shi et al. (2021) is not empirical in form and your reference to this work verges towards a review of (other) reviews. Other work, which discusses biogenic calcification in the context of bleu carbon is missing. Such as Macreadie et al., (2017) and Saderne et al., (2019). I recommend that you downplay the coral aspect but more of the calcification processes that occur within blue carbon habitats. The role of calcifying macroalgae is pertinent is here, and deserves further elaboration.

3)    Blue carbon project site

I was looking for a discourse on the setting up of a blue carbon project site / demonstration site in the Seychelles, which would round up this Review nicely. This is missing and I recommend that you suggest at least one viable site that can demonstrate the application of steps 1 to 5 within the framework described by Herr et al. (2016).

Minor comments:

1)    Macreadi et al. 2021 -> Macreadie et al. 2021

2)    Species names should be in italics

3)    Normally there should not be cited references in a Conclusion section

Herr et al. (2016): https://portals.iucn.org/library/node/46606

Fujita et al. (2022): https://doi.org/https://doi.org/10.1016/j.marpol.2023.105747

Ross et al. (2023): https://doi.org/10.1016/j.scitotenv.2023.163699

Macreadie et al. (2017): https://doi.org/10.1002/lol2.10052

Saderne et al. (2019): https://doi.org/10.1038/s41467-019-08842-6

Author Response

REVIEWER 1

Bennett et al. submitted a Review-type manuscript on the institutionalisation of blue carbon in the Seychelles. They covered much ground, touching on the (fundamental) science aspects and implementation towards payment for ecosystem services. There are some parts, which I recommend for further elaboration and clarification. Other minor improvements are also suggested. These are as follows:

The authors thank the reviewer for their constructive feedback and helpful suggestions. 

1)    Methods

1. a)    ‘The literature review comprised a non-exhaustive search…’
   Comment: Why is it ‘non-exhaustive’? A review should be as thorough as realistically possible. What were you criterion for inclusion and exclusion of search hits for your literature base?

The  methods section has been altered to incorporate the comments from the reviewers: 

“With a synoptic approach, this review consisted of desktop study literature review. The literature review comprised a Boolean search of relevant academic articles and studies, publications for development organisations (such as the World Bank and the Blue Carbon Lab), public news articles, and national documents.  Science Direct, Google and Google Scholar were the databases used to gather relevant sources on the study topic online.  Keywords in the literature search included search strings such as “blue carbon”, “operationalising blue resources”, “blue economy”, “ecosystem services”, “blue accounting”, “blue carbon accounting”, “carbon trading”, “SIDS”, and “Seychelles”.  Sources that dealt with blue carbon outside of the context of island countries and SIDS were excluded from the review. However, sources that discussed threats to blue carbon ecosystems, as well as sources discussing the contentious status of potential blue carbon ecosystems (such as kelps and coral reefs) were not excluded from the review, as these topics are directly applicable to operationalising blue carbon in a SIDS context.  The paper incorporates findings from the literature review as well as knowledge from the authors’ experience and professional network of scientists and researchers in the realm of Seychelles blue carbon and Seychelles blue economy development (including with inputs from SeyCCAT, and the Seychelles Seagrass Mapping and Carbon Assessment).  

Blue carbon ecosystems that are reviewed include mangroves and seagrasses. Estimates of blue carbon stocks in the Seychelles were investigated and the most recent assessments are reported as they have been validated with field measurements (Wartman et al. 2022, and Rowlands et al. 2023). The potential of coral reef systems as blue carbon habitats is also discussed. Considering that Seychelles does not have any tidal salt marshes (Adams and Banderia 2011; Lugendo 2016; McOwen et al. 2017), nor is rich in kelp forests, a review of the stock assessments of these habitats have thus been omitted. The islands do experience influxes of floating Sargassum seaweed (as do other SIDS elsewhere), but these influxes of Sargassum are not suitable for use as national blue carbon resources because the seaweed breaks down when washed up on the beaches, releasing carbon stored in its tissues (Duarte et al. 2013; Hill et al. 2015), and moves through multiple national boundaries. 

 

 

Research ethics approval was not applicable nor required for this review article.”

 

 

The name of the search databases used (Science Direct, Google and Google Scholar) have been incorporated into the text.

The criterion for excluding sources from the review have also been incorporated into the text: 

“Sources that dealt with blue carbon outside of the context of island countries and SIDS were excluded from the review. However, sources that discussed threats to blue carbon ecosystems, as well as sources discussing the contentious status of potential blue carbon ecosystems (such as kelps and coral reefs) were not excluded from the review, as these topics are directly applicable to operationalising blue carbon in a SIDS context…Considering that Seychelles does not have any tidal salt marshes (Adams and Banderia 2011; Lugendo 2016; McOwen et al. 2017), nor is rich in kelp forests, a review of the stock assessments of these habitats have thus been omitted.”

b)    ‘… because the seaweed breaks down when washed up on the beaches, releasing carbon stored in its tissues…’
Comment: This statement is warranted but I disagree in its context. First: these can contribute as allochthonous inputs of blue carbon (re: Fujita et al. 2022; Ross et al., 2023). Second: The remineralisation of macroalgal detritus would further lower the potential for net blue carbon storage at the ecosystem level. These need inclusion in the text. See also my comments on calcifying macroalgae below.

The authors thank the reviewer for their constructive feedback. This review is focussed on the blue carbon resources that are plentiful in Seychelles, those being mangroves, seagrasses, and potentially coral reefs. As Seychelles are not particularly rich in kelp forests, these are not discussed. 

The authors agree with the reviewer that the context was not entirely suitable for the statement and this has been altered: 

“The islands do experience influxes of floating Sargassum seaweed (as do other SIDS elsewhere), but these allochthonous influxes of Sargassum are not suitable for use as national blue carbon resources because the seaweed moves through multiple national boundaries, and when it breaks down it releases carbon stored in its tissues (Duarte et al. 2013; Hill et al. 2015).” 

The statement makes reference to allochthonous carbon not being suitable as national blue carbon resources (due to their migrating and unstable nature), and not the influence of allochthonous seaweed inputs on other blue carbon resources. Reference to the discussion of these topics elsewhere has been made, to direct the reader should they wish to delve deeper into the subject. 

 

A note on the potential of allochthonous blue carbon has now been included in the methods section: 

“The islands do experience influxes of floating Sargassum seaweed (as do other SIDS elsewhere), but these allochthonous influxes of Sargassum are not suitable for use as national blue carbon resources because the seaweed moves through multiple national boundaries, and when it breaks down it releases carbon stored in its tissues (Duarte et al. 2013; Hill et al. 2015). The study is limited in that it does not discuss allochthonous inputs of blue carbon (such as migrating Sargassum seaweed), as developing a carbon accounting framework for such allochthonous blue carbon presents numerous challenges involved in the carbon flux accounting of kelp blue carbon resources, the primary being that there is no consensus of allowing migrating blue carbon (and associated carbon fluxes) to count towards national NDCs. Carbon accounting of kelp ecosystems is highly complex and has been discussed elsewhere (Ross et al. 2023, Fujita et al. 2022; Hurd et al. 2022). This paper also does not discuss the blue carbon potential of seaweed (kelp) farming in the context of Seychelles, however this topic has been covered elsewhere (Bennett et al. 2023; Duarte et al. 2017).”

2)    2.4 Coral reefs

Source-sink balances as a result of biogenic calcification is still a knowledge gap in blue carbon science. Coral reefs are important for other ecosystem services but not of blue carbon. The work by Shi et al. (2021) was constantly referenced, which is not such a strong paper to support your argument. The work by Shi et al. (2021) is not empirical in form and your reference to this work verges towards a review of (other) reviews. Other work, which discusses biogenic calcification in the context of bleu carbon is missing. Such as Macreadie et al., (2017) and Saderne et al., (2019). I recommend that you downplay the coral aspect but more of the calcification processes that occur within blue carbon habitats. The role of calcifying macroalgae is pertinent is here, and deserves further elaboration.

The authors thank the reviewer for their critical investigation of this topic in the manuscript, as well as directing the authors to other pertinent research. However, as the reviewer has written, this topic is very much still plagued by a significant knowledge gap in blue carbon science with vigorous debate surrounding the potential of coral reefs as blue carbon systems. This is acknowledged in the altered  text:

“There has been long-standing debate whether coral reefs are net carbon sinks (Kayanne et al. 1995; Chisholm and Barnes 1998;  Yan et al. 2018), carbon sources (Gattuso et al. 1999; Lonborg et al. 2019; Cotoviscz et al. 2020), or shifting between the two (de Goeij et al.2007; Wimart-Rousseau et al. 2020). This is accompanied by a significant knowledge gap surrounding the topic.”

 

Shi et al. (2021) explores the debate from both sides surrounding this topic, as we attempt to do as well. Although the work by Shi et al. (2021) is not empirical, it explores certain aspects of the debate (such as the microbial pump or the mixotrophic nature of corals for example), that non-blue carbon scientists may not be aware of, due to being seldom discussed or referenced.  We discussed the mixotrophic nature of coral reef systems as it directly highlights the main issue in the debate surrounding whether or not to classify coral reef systems as blue carbon systems. The text has been altered to better reflect this: 

“The key point underpinning this debate is that Ccoral systems are mixotrophs, meaning that they can switch between autotrophic (producing energy of their own means, such as through photosynthesis) and heterotrophic (metabolising energy from external inputs, such as filter feeding) modes of energy production.”

 

Reference to the influence of biogenic calcification has been made in the text (italicised here to indicate): 

“...corals are mixotrophs…Corals are likely to shift to heterotrophic production when they are stressed, releasing their photosynthetic algae during bleaching events and subsequently releasing more carbon to the environment. Corals are likely to collapse and disintegrate when dominated by heterotrophic growth (Shi et al. 2021), emphasising the need for protection and addressing environmental climate change to ensure healthy coral systems. In addition to this, biogenic calcification (i.e., the production of calcium-carbonate, CaCO3) releases CO2 during its production (Ware et al. 1992). The presence of calcifying organisms (including corals, molluscs, crustaceans, and algae) thus influence the carbon sink classification and capacity of an ecosystem, including seagrasses and mangroves, and influences the ecosystem carbon budget (Saderne et al. 2019; Macreadie et al. 2017).”

“...Despite the mixotrophic nature of corals and the associated inability to classify them as true blue carbon resources (and carbon sinks)...However,  care needs to be taken with blue carbon projects designed around coral restoration and coral outplanting specifically, as the increased amount of biogenic calcification associated with the coral outplanting, may thus influence the carbon budget of the ecosystem such that the ecosystem becomes a net carbon source, thereby invalidating the purpose of the project. Instead coral reef restoration should be focussed on the conservation of biodiversity and the other ecosystem services coral reefs provide (habitat provisioning, fisheries supplementation, coastal buffering, cultural value).

The authors do not feel it necessary to continue discussing the debate more in depth than currently in the revised manuscript (as this has been discussed elsewhere, as referenced in the manuscript), and also considering there are numerous other factors that also influence the blue carbon budgets of coral reefs. The authors feel they have discussed the primary concern that underpins the ongoing debate, highlighting sufficient interesting points enough that readers may continue to investigate the matter themselves, if they so wish. Discussing this topic more would only lengthen an already dense article and detracts from the main aim of the work.

3)    Blue carbon project site

I was looking for a discourse on the setting up of a blue carbon project site / demonstration site in the Seychelles, which would round up this Review nicely. This is missing and I recommend that you suggest at least one viable site that can demonstrate the application of steps 1 to 5 within the framework described by Herr et al. (2016).

A new section has been included under section 5 to discuss this: 

“5.8 IUCN National Blue Carbon Policy Assessment Framework 

The International Union for the Conservation of Nature (IUCN) has developed a National Blue Carbon Policy Assessment Framework with the goal of helping countries policy development options and priority blue carbon development pathways for the operationalisation of national blue carbon ecosystems (Herr et al. 2016). The five-step framework facilitates a first-order analysis of blue carbon resources and blue carbon policy, identifying the potential for improved coastal ecosystem management at the national policy level (Herr et al. 2016). The approach of the framework allows the user to analyse the application of existing legal and financial incentive schemes (such as payment for ecosystem services schemes) to national blue carbon resources (Herr et al. 2016). This framework is thus recommended for use by SIDS hoping to fully operationalise their national blue carbon resources.

 

While Seychelles is often regarded as a model country for sustainable blue development including blue carbon development, there are no past or present blue carbon development projects that have followed the IUCN National Blue Carbon Policy Framework in its entirety (to the best of the authors’ knowledge). However, the Seychelles Conservation and Climate Adaptation Trust’s (SeyCCAT) “Coastal Wetlands and Climate Change Project” , having started in 2015,  is likely the most developed blue carbon project in terms of restoration, conservation, and already contributes to NDCs, which has been provisioned for in national policy.  The National Blue Carbon Policy Assessment Framework (Herr et al. 2016) can thus be used as a tool for reviewing the development outcomes of the project as well as monitor policy development priorities as relates to blue carbon utilisation and conservation. The associated framework assessment tool is also recommended to be used for the establishment of new Seychelles blue carbon projects in the future (such as on Aldabra Atoll or Saya de Malha Bank in partnership with Mauritius).”

Minor comments:

1)    Macreadi et al. 2021 -> Macreadie et al. 2021

Thanks for picking up this error, we have updated the author’s spelling throughout the manuscript and references have been adjusted according to other reviewer comments. 

2)    Species names should be in italics

All species names have been updated to be in italics.

3)    Normally there should not be cited references in a Conclusion section

All references in the conclusion have been removed, thank you.

Herr et al. (2016): https://portals.iucn.org/library/node/46606
Fujita et al. (2022): https://doi.org/https://doi.org/10.1016/j.marpol.2023.105747
Ross et al. (2023): https://doi.org/10.1016/j.scitotenv.2023.163699
Macreadie et al. (2017): https://doi.org/10.1002/lol2.10052
Saderne et al. (2019): https://doi.org/10.1038/s41467-019-08842-6

The authors thank the reviewer for providing links to the sources in their comments.

Reviewer 2 Report

Comments and Suggestions for Authors

Title:

The title is not catchy. Need to rethink to write the title.

Abstract:

Add an introductory sentence. An ideal abstract comprised of,

-Introduction

-Objective+/hypothesis/research question

-Methodology

-Results

-Conclusions

-Implication of your study.

Please follow the structure for shaping the abstract.

Keywords:

-The yellow highlighted keywords already appeared in the title. Make sure your keywords are different from the title keywords. So, replace these three in new three.

-Some keywords showcased in keywords section are already in the title. Please replace them with new keywords. Your keywords must be different from your title keywords.

Introduction:

-A problem statement is found but I did not find any research question or hypothesis. Which must be added.

-The citations are old enough and need to replace the citations with recent publication. Not older than 5-10 years.

-No problem statement found

-No hypothesis is discussed

-No research question is raised

-Very old citations are observed (yellow highlighted). They must be replace with new citation (not older than 10 years)

-A clear research question/hypothesis is absent in the study.

-Clear research objectives are missing. Please write your objectives according to the journal’s format.

-Implication of the study is absent.

-Introduction is too lengthy. Lot of unnecessary information were presented.

-Write your citations according to the journal format. Please follow this comment over the manuscript.

-The journal do not accept any personal communication. Please replace this citation and reference with new one.

Materials and methods:

-Add a Map of the sample collection site. Using ArcGIS or QGIS.

-Did you follow any previous methods for this? If so, please cite them (preferable new citations)

-Please write about the Ethical approval of your study according to the journal format. If not applicable, please write so.

-Use citations for reducing describing the procedure.

-Cite the previous researches where the methods has been described.

Results:

 

Discussion:

Firstly, you need to write your result and then interpret it according to the existing facts, and then you can add your arguments to support your study. Follow this structure to write the whole section.

Conclusions:

-Please make sure the conclusions are aligned to your objective/research question (s)/hypothesis. NO digit inside.

-The conclusions must be concise and short. Make sure only key findings are described here.

*The conclusion is huge. Tips for writing conclusion,

-No digit inside.

-Key findings of your results.

-Implementation of your study

-Major research gap still not filled according to your findings

-Propose future study based on this current result

References:

 

-Please follow the journal guidelines for preparing the reference section of this manuscript.

Comments for author File: Comments.zip

Author Response

REVIEWER 2

Title:

The title is not catchy. Need to rethink to write the title.

 

We have updated the title to: Blueprint for blue carbon: lessons from Seychelles for SIDS

Abstract:

Add an introductory sentence. An ideal abstract comprised of,

-Introduction

-Objective+/hypothesis/research question

-Methodology

-Results

-Conclusions

-Implication of your study.

Please follow the structure for shaping the abstract.

 

As this is a review article and not scientific study article, the structure of the abstract may not follow the one suggested by the reviewer. 

However, the abstract has been revised incorporating some of the suggestions following this comment as well as for the revised manuscript, as follows: 

“Blue carbon has been proposed as a nature-based solution for climate change mitigation, however a limited number of published works, data, and knowledge gaps hinder the development of SIDS’ national blue carbon resources globally. This paper reviews blue carbon ecosystems of Seychelles as a case-study in the context of SIDS, incorporating recent blue carbon evaluations, blue accounting, and various challenges and opportunities. Mangroves (2195 ha, 80% in Aldabra Atoll) and seagrasses (142 065 ha) dominate in Seychelles, with coral reefs having potential for carbon sequestration (169 000 ha). Seychelles is on track to protecting its blue carbon, but these systems are threatened by rising sea levels, coastal squeeze, erosion, severe storms, and human activities. The importance of national carbon inventories, accounting institutions, and continuous monitoring of blue carbon systems are discussed. Blue accounting is necessary for accurate accounting of carbon sequestration and carbon storage, is essential for generating carbon credits, and representing an impactful reduction of greenhouse gases for NDCs. Challenges and opportunities include policy legislation regarding ownership rights, accreditation and certification for carbon credits, sustainable financing mechanisms like natural asset companies and blue tokens, local engagement for the long term success, and carbon market dynamics following COP27. The restoration and regulation of blue carbon resources for optimal ecosystem services delivery, carbon inventories, and blue carbon policy are recommended development priorities. Blue carbon ecosystems have potential in contributing to NDCs of SIDS, while offering sustainable development pathways for local communities through the multiple ecosystem services they provide.”

Keywords:

-The yellow highlighted keywords already appeared in the title. Make sure your keywords are different from the title keywords. So, replace these three in new three.

 

-Some keywords showcased in keywords section are already in the title. Please replace them with new keywords. Your keywords must be different from your title keywords.

 

These have now been updated to the following 5 keywords: : carbon accounting; carbon sequestration; ecosystem services; nature-based solutions; climate mitigation and adaptation

 

Introduction:

-A problem statement is found but I did not find any research question or hypothesis. Which must be added.

 

This is a review paper, not a scientific study article, therefore it is not standard practice to include a hypothesis or research question.

-The citations are old enough and need to replace the citations with recent publication. Not older than 5-10 years.

 

The majority of the citations in this paper are from 2005 to 2023, with most sources having been published in the last 10 years. The authors acknowledge that although some knowledge does become outdated over time as new discoveries are made, if a source is well cited by other recent published works, then the findings of that paper should stay valid regardless of when the source was published.

This comment is also repeated and addressed below. 

-No problem statement found

 

This conflicts with the reviewer’s previous comment in which they mentioned a problem statement was found. The problem statement is captured in the introduction wherein it is explained that despite a growing interest in operationalising blue carbon projects, they suffer from “... uncertainty on risk-return ratios, implementation pathways, and unclear legislation and policies, and have created a situation where the demand for investable blue carbon projects is currently outweighing supply…”. The introduction goes on to say that “...(m)uch of this is due to key knowledge gaps, with limited research on the operationalisation of blue carbon resources particularly in a SIDS context having been conducted…” which is what this review paper attempts to address. 

-No hypothesis is discussed

 

This is a review paper, not a scientific study article, therefore it is not standard practice to include a hypothesis.

-No research question is raised

 

This is a review paper, not a scientific study article, therefore it is not standard practice to include a research question.

-Very old citations are observed (yellow highlighted). They must be replace with new citation (not older than 10 years)

 

The majority of the citations in this paper are from 2005 to 2023, with most sources having been published in the last 10 years. The authors acknowledge that although some knowledge does become outdated over time as new discoveries are made, if a source is well cited by other recent published works, then the findings of that paper should stay valid regardless of when the source was published.

-A clear research question/hypothesis is absent in the study.

 

This is a review paper, not a scientific study article, therefore it is not standard practice to include a hypothesis.

-Implication of the study is absent.

 

This is a review paper: “This paper reviews blue carbon ecosystems in Seychelles in the context of SIDS, incorporating the most recent blue carbon evaluations, blue accounting, and the challenges and opportunities in operationalising and monetising blue carbon for long term sustainable growth.”

The introduction section explains the context and need for this paper to be published and made available to SIDS and other countries wishing to develop their blue carbon resources. Given that there is limited information published on blue carbon in SIDS, this review paper attempts to address the knowledge gap.

The introduction has since been altered to better reflect the author’s intentions for how the content of the paper is to be used as follows: 

“The aim of this paper is to collate available information on operationalising blue carbon resources in one document, using the Seychelles as a case study country as an example for other SIDS to emulate. The paper aims to suggest actionable steps to be considered by policy makers and conservation biologists, in the operationalising of blue carbon as well as propose novel yet important areas of consideration, identifying gaps where future research and work is required for the successful use of SIDS blue carbon resources in contributing to NDCs as well as commercialising blue carbon resources for national development”

-Introduction is too lengthy. Lot of unnecessary information were presented.

 

It is not clear from this comment which information is necessary and which is not. The introduction has been edited according to the various reviewers' comments.

-Write your citations according to the journal format. Please follow this comment over the manuscript.

The references have been formatted to comply with the style used by the Oceans journal.

-The journal do not accept any personal communication. Please replace this citation and reference with new one.

There are no personal communication references in the manuscript. 

Materials and methods:

-Add a Map of the sample collection site. Using ArcGIS or QGIS.

 

Since this is a review paper, and no new data was generated, there is no sample collection site.

-Did you follow any previous methods for this? If so, please cite them (preferable new citations)

 

No previous research methods were followed for this desktop review article. Literature review search specifications were included in the methods section. 

-Please write about the Ethical approval of your study according to the journal format. If not applicable, please write so.

 

This has now been added at the end of the methods section as follows:

 “Research ethics approval was not applicable nor required for this review article.”

-Use citations for reducing describing the procedure.

The methods have been updated to include all the necessary elements as required by the other reviewers.

-Cite the previous researches where the methods has been described.

 

No previous research methods were followed for this desktop review article. Literature review search specifications were included in the methods section.

However, some of the research from other sources that are discussed have been cited in this section (such as the previous estimates of blue carbon resources).

Results:

 

Discussion:

Firstly, you need to write your result and then interpret it according to the existing facts, and then you can add your arguments to support your study. Follow this structure to write the whole section.

 

This is a review paper, not a scientific paper that presents new findings, therefore it is not standard practice to include a results section since no new data was collected or collated.

Conclusions:

-Please make sure the conclusions are aligned to your objective/research question (s)/hypothesis. NO digit inside.

 

There are no digits in the conclusion section. The conclusion section summarises and recapitulates the main take-aways from the review paper, as actionable steps for policy makers and researchers to pursue in operationalising their blue carbon resources. 

-The conclusions must be concise and short. Make sure only key findings are described here.

 

The conclusion section condenses the main take aways from the entire review paper and every effort has been made to keep it short and concise, without diluting any of the important information therein.The conclusion section summarises and recapitulates the main take-aways from the review paper, as actionable steps for policy makers and researchers to pursue in operationalising their blue carbon resources.  

*The conclusion is huge. Tips for writing conclusion,

-No digit inside.

-Key findings of your results.

-Implementation of your study

-Major research gap still not filled according to your findings

-Propose future study based on this current result

 

The conclusion is 1 page long which the authors feel is sufficiently concise for a review paper that covers much information and many essential topics surrounding blue carbon. 

The conclusion section summarises and recapitulates the main take-aways from the review paper, as actionable steps for policy makers and researchers to pursue in operationalising their blue carbon resources, as was the aim of the paper as explained in the introduction. 

Reviewer 3 Report

Comments and Suggestions for Authors

Comments for author File: Comments.pdf

Comments on the Quality of English Language

a through revision is required 

Author Response

REVIEWER 3

In the introduction, the author could add a sentence or two about why the topic of the text is important and who the target audience is. 

The authors want to thank the reviewer for their helpful comments. 

An introductory paragraph has been added to better introduce the topic of blue carbon systems and their relevance in climate change mitigation through carbon sequestration: 

“Blue carbon has been proposed as a nature-based solution for climate change mitigation, through the reduction of greenhouse-gases through carbon sequestration. This proposal entails the protection, restoration, and conservation of blue carbon ecosystems such that these systems can optimally provide valuable ecosystem services. Challenges remain in funding the conservation and protection efforts blue carbon systems require to function optimally, however the ecosystem services blue carbon systems provide can be capitalised upon through various “payment for ecosystem services” schemes, but these have their own unique challenges to resolve.”

The following has also been added to better describe who the target audience for this work may be (last paragraph of the introduction): 

“The paper aims to suggest actionable steps to be considered by policy makers and conservation biologists, in the operationalising of blue carbon as well as propose novel yet important areas of consideration, identifying gaps where future research and work is required for the successful use of SIDS blue carbon resources in contributing to NDCs as well as commercialising blue carbon resources for national development.”

In the body of the text, the author could use more examples and case studies to illustrate their points.. 

Relevant case studies and examples  have been cited where appropriate, however the authors wish to reiterate that this is a data limited field where not many such case studies have been published. 

The premise of the paper is to use the Seychelles as a case study for other SIDS hoping to develop their blue carbon resources. 

The text is well-written and informative, but it could be more engaging. For example, the author could use more active voice, vivid language, and interesting examples. The text is a bit too long. Consider breaking it up into two or more shorter pieces, or removing some of the less essential information. 

The authors thank the reviewer for their help comments to try and make a dense article more engaging. We have run through the article to simplify the language where possible. The article has been shortened to 12000 words.

The text could be better organized. For example, the author could group related ideas together, and use headings and subheadings to break up the text and make it easier to scan. 

The text has now been re-organised using numbered headings and subheadings, which have also now been  consistently formatted. 

The text needs to be proofread carefully. There are a few minor grammatical errors and typos. The author should start by providing a clear and concise thesis statement. This will help to focus the text and ensure that the author stays on topic. 

The text has been proofread to identify and correct the grammatical errors and typos. 

An introductory paragraph has been added to better introduce the topic of blue carbon systems and their relevance in climate change mitigation through carbon sequestration, and serves as the thesis statement

“Blue carbon has been proposed as a nature-based solution for climate change mitigation, through the reduction of greenhouse-gases through carbon sequestration. This proposal entails the protection, restoration, and conservation of blue carbon ecosystems such that these systems can optimally provide valuable ecosystem services. Challenges remain in funding the conservation and protection efforts blue carbon systems require to function optimally, however the ecosystem services blue carbon systems provide can be capitalised upon through various “payment for ecosystem services” schemes, but these have their own unique challenges to resolve.”

The author should provide more evidence and support for their claims. This could include citing relevant research studies, providing examples from real life, or using personal anecdotes. 

Relevant research studies have been cited throughout the article for the claims referenced therein. 

As an example, an upcoming publication has been referenced about a recent assessment of the seagrass resources of Seychelles (which has never been done to this extent before) wherein theoretical estimates were verified with samples from across Seychelles. Contact with the authors have been made to verify the information and permission was granted to cite the information from the project managers/authors (project: Seychelles Seagrass Mapping and Carbon Assessment).

The author should organize the text in a more logical way. This could be done by using headings and subheadings, or by grouping related ideas together.

The text has now been re-organised using numbered headings and subheadings, which have also now been  consistently formatted. 

Overall, the text is well-written and informative, but it could be improved by making it more engaging, concise, organized, and error-free. I recommends its major revision.

The authors thank the reviewer for their comments. The text has been revisited, re-organised and re-edited to eliminate any grammatical or spelling errors. 

Reviewer 4 Report

Comments and Suggestions for Authors

 

Review report for the paper “Operationalising blue carbon solutions for SIDS: the case of Seychelles”

 The paper under review considered the blue carbon ecosystems. This study reviewed the blue carbon ecosystems in Seychelles within the framework of Small Island Developing States (SIDS). It encompasses recent assessments of blue carbon, blue accounting methodologies, and explores the obstacles and prospects in implementing and monetizing blue carbon for sustainable development. Implementing blue carbon presents both challenging obstacles and significant opportunities. The implementation of clear policy legislation, including ownership regulations, blue carbon certification, and certification of carbon credits, along with sustainable financing mechanisms such as natural asset companies and blue tokens, requires substantial effort. Local participation is crucial for the long-term success of blue carbon projects, and navigating post-COP27 market dynamics adds to the complexity. Drawing upon the authors' research, this article presented a review in  prioritizing the development of blue carbon resources, conducting carbon inventories, and establishing policies for the restoration and regulation of blue carbon.  This article holds both practical significance and literature value. The research may raise questions and open new ways of thinking.

 Overall, this article is relatively clear. However, this article has some shortcomings in the way of explanation and details. I cannot recommend publishing this article yet. I suggest the author make the following modifications. After the modifications, the article can be considered for publication

 In the second section of the article, the author provides an extensive literature review of various methods. However, this section lacks a comparative analysis of these methods. It is recommended that the authors enhance this part by adding a detailed comparison of the various methods. Ideally, a visual representation, such as a chart, a diagram, a picture or a table could effectively convey the comparative insights.

 In section 3 (page 9), the authors briefly reviewed the work done by Failler et al. however, the review missed some details. The authors should consider providing a brief summary from their work to give readers a detailed overview of the diverse approaches they explore.

 On page 10, the authors mentioned the “application of blockchain technology  being investigated by the World Bank”. Please provide more details to explain how blockchain technology is being investigated by the World Bank to reduce the potential for double counting. This can help readers grasp the potential solution and its implications.

 There are a lot of lengthy sentences. For example, “The Blue Carbon Lab has valued Seychelle’s carbon stocks as holding 17 million tonnes of carbon (Blue Carbon Lab 2023) while a first pass assessment of blue carbon stocks by the Blue Carbon Lab estimated available carbon stocks as 250 million tonnes of organic carbon (Blue Carbon Lab 2022b). ” in page 11. I suggest that the authors break down some lengthy sentences to enhance readability and comprehension. 

 After revision, the paper can be considered for acceptance.

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

REVIEWER 4

 The paper under review considered the blue carbon ecosystems. This study reviewed the blue carbon ecosystems in Seychelles within the framework of Small Island Developing States (SIDS). It encompasses recent assessments of blue carbon, blue accounting methodologies, and explores the obstacles and prospects in implementing and monetizing blue carbon for sustainable development. Implementing blue carbon presents both challenging obstacles and significant opportunities. The implementation of clear policy legislation, including ownership regulations, blue carbon certification, and certification of carbon credits, along with sustainable financing mechanisms such as natural asset companies and blue tokens, requires substantial effort. Local participation is crucial for the long-term success of blue carbon projects, and navigating post-COP27 market dynamics adds to the complexity. Drawing upon the authors' research, this article presented a review in  prioritizing the development of blue carbon resources, conducting carbon inventories, and establishing policies for the restoration and regulation of blue carbon.  This article holds both practical significance and literature value. The research may raise questions and open new ways of thinking.

The authors thank the reviewer for their time and feedback in the hopes of producing a stronger piece of work. 

 Overall, this article is relatively clear. However, this article has some shortcomings in the way of explanation and details. I cannot recommend publishing this article yet. I suggest the author make the following modifications. After the modifications, the article can be considered for publication

The authors thank the reviewer for their constructive feedback. 

 In the second section of the article, the author provides an extensive literature review of various methods. However, this section lacks a comparative analysis of these methods. It is recommended that the authors enhance this part by adding a detailed comparison of the various methods. Ideally, a visual representation, such as a chart, a diagram, a picture or a table could effectively convey the comparative insights.

The authors thank the reviewer for their constructive feedback. 

In the previous section 2. “Mapping blue carbon resources and the necessity of MPAs”, the intention of referencing these various assessments of blue carbon was not to use them for comparative analysis, but more as examples of the limited previous work that had been done surrounding the topic (i.e., assessing blue carbon stocks). 

The methods used in these studies do vary owing to the type of study done, as well as the data that were available or not available for any particular study (some of the studies used previous datasets, whereas others collected their own in the field). 

The authors are disinclined to summarise the methodologies used in each of these studies in a figure or table for comparative analysis as each of the studies assess blue carbon resources in unique locations and under unique circumstances (respectfully) - there are no useful comparative insights in comparing the different methodologies, except that there is uncertainty associated with the estimates produced.

However, the authors have made inclusions in the text mentioning the methods that were followed for each study (under previous section 2.1 “Mapping blue carbon resources and the necessity of MPAs”). In doing so, the authors hope to highlight that regardless of the methods that were used for producing assessments of blue carbon stocks and subsequent estimates of carbon storage and sequestration, there are large amounts of uncertainty associated with those estimates. 

The authors wish to conclude that a combination of remote sensing as well as ground-truthing with soil core analysis is the recommended and most accurate method for blue carbon stock analysis, and suggest the use of studies using these methods for blue carbon stock analysis as authoritative references (more so than studies that only use remote sensing, for example) on which to base carbon sequestration and storage estimates. 

Following the comments from other reviewers, the authors have included a table summarising the extent of Seychelles blue carbon resources (mangrove cover, seagrass cover, and the coral cover) from the most recent studies using remote sensing and ground-truthing with field measurements. The blue carbon estimates for these resources are to be published in due course, but the authors of these sources have given permission to allow the inclusion of these values in the current review. 

 

 In section 3 (page 9), the authors briefly reviewed the work done by Failler et al. however, the review missed some details. The authors should consider providing a brief summary from their work to give readers a detailed overview of the diverse approaches they explore.

The text has been altered to include a brief overview of the work done by Failler et al. (2023), as well as recently published relevant work that builds on Failler et al. (2023):

“Failler et al. (2023) review various approaches to blue accounting in an African context. They explore approaches such as environmental satellite accounts (or “Integrated Economic and Environmental Accounts”), green accounting, natural capital accounting, ecosystem services accounting, blue economy (BE) economic accounting, BE social accounting, BE environmental accounting, and the application of BE accounting tools, namely the UNECA Blue Economy Valuation Toolkit (BEVTK) which had been applied in Seychelles (Failler et al 2023). Many of these approaches are based on the United Nations’ (UN) system for Environmental Economic Accounting (SEEA) Central Framework, which is “an international statistical standard for environmental measurement and its impact on the economy” (UN SEEA).  In a recent study, the SEEA framework was used as a base to develop an integrated blue accounting system for China’s coastal blue carbon (Liu et al. 2024). The system was designed as an integrated method that combines the ecological state of the blue carbon stocks, blue carbon accounting, investment payback period (that which was used for restoration costs), and carbon market prices, to provide a comprehensive decision making tool for operationalising national blue carbon resources (Liu et al. 2024). McHarg et al. (2022) followed a different approach, having conducted a scenario analysis to evaluate a SIDS’ (Grenada) blue carbon climate mitigation services. However, it is recommended that the approach used by Liu et al. (2024) be adapted and considered for implementation in SIDS elsewhere.”

Please note that in text citations have been altered  to comply with journal citation format, in the manuscript submitted for review. 

 On page 10, the authors mentioned the “application of blockchain technology  being investigated by the World Bank”. Please provide more details to explain how blockchain technology is being investigated by the World Bank to reduce the potential for double counting. This can help readers grasp the potential solution and its implications.

The text has been modified to include a brief explanation of this concept:

“Furthermore, the application of blockchain technology is being investigated by the World Bank as a method to reduce the potential for the same carbon credit to be counted twice, which may provide a solution to the questions and issues surrounding corresponding adjustments in future (World Bank 2022).  Blockchain technology works by tracking all transactions in a secure and transparent digital ledger. If carbon credits for emissions reductions that are traded between two different parties (such as two national governments, or a government and private parties), are catalogued on the blockchain, the potential for the same carbon credit to be counted twice for contributing to NDCs is reduced, and the associated “corresponding adjustment” can be applied correctly (World Bank 2022).”

 

 There are a lot of lengthy sentences. For example, “The Blue Carbon Lab has valued Seychelle’s carbon stocks as holding 17 million tonnes of carbon (Blue Carbon Lab 2023) while a first pass assessment of blue carbon stocks by the Blue Carbon Lab estimated available carbon stocks as 250 million tonnes of organic carbon (Blue Carbon Lab 2022b). ” in page 11. I suggest that the authors break down some lengthy sentences to enhance readability and comprehension. 

The authors have re-edited the entire manuscript and attempted to shorten lengthy sentences where possible.

Using the example in this comment, the re-edited text reflects as follows:

“A first-pass assessment of Seychelles’ blue carbon stocks has been estimated to be 250 million tonnes of organic carbon, by the Blue Carbon Lab (Blue Carbon Lab 2022b). However, a more thorough assessment has been conducted with the national blue carbon stock being estimated at 17 million tonnes of carbon (Blue Carbon Lab 2023).”

 After revision, the paper can be considered for acceptance.

The authors thank the reviewer for their constructive comments to improve this manuscript. We have revised accordingly.

Reviewer 5 Report

Comments and Suggestions for Authors

Bennett et al. wrote 'Operationalizing blue carbon solutions for SIDS: the case of Seychelles' which is interesting. However this requires major revision on lines of the following points.    

1. The authors should add few points related to role of blue carbon resources in food security. This is very important aspect and should be captured in introduction adequately backed by references. The current introduction is overwhelmingly described only role of blue carbon resources to sequester carbon and related aspects. 

2. Authors are also advised to acknowledge the fact that today ecosystems are degraded or damaged, their carbon sink capacity is lost or adversely affected, and the carbon stored is released, resulting in emissions of carbon dioxide (CO2) that contribute to climate change. Also the areas which are not under protected habitats do not demonstrate globally relevant, long-term climate mitigation potential. These aspects also should be covered. The current introduction portrayed too optimistic a picture and has to have a balanced view. 

3. It has been stated that many SIDS (found in the Pacific, Caribbean as well as Atlantic – Indian – South China Sea Region) are able to benefit from the development of their blue carbon resources, which can contribute substantially to local livelihoods and well-being. Two references are provided to support this statement. This authors would like to see, how this has been achieved as this statement is central to this theme of the current manuscript.

4. This reviewer suggests  authors to incorporate the infographic that can better present the concept of the blue carbon resources in context with SIDs. 

5. Method has vary vague description of desktop study literature review. This reviewer wants to know what are search engines used e.g. google scholar, web-of-science etc. Also this reviewer wants to know what are the ways by which irrelevant data sets were removed from the primary search, that means who refinement has been made. I am sure not all that has been found in the web search is included in the analysis. 

6. It has been written that, knowledge from professional network in the realm of Seychelles blue carbon and Seychelles blue economy development has been used. This reviewer wants authors to clearly state what kind of professional network, e.g. scientific bodies, societies, association, etc. Please define them to make it more scientific. 

7. After methods this reviewer expected some sore of results. But unfortunately such thing is missing. The entire manuscript is too descriptive that reader lose interest. It is highly recommended to make result section separate. As from the methodology it is cleat that is it not the review paper. If authors feel that it is review then, the methodology section is not not needed, please remove.  

8. There are several subheadings given in the manuscript each detailing work in its domain, but what is missing is information in the form of tables and figures. This reviewer strongly suggests the authors to have one or two tables wherever possible to tabulate the data and incorporate an infographic for a couple of subheadings. 

9.  The title is 'Operationalising blue carbon solutions...' that means there must be impediments for which the solutions are provided. This reviewer suggests that the authors must give impediments under each subheadings and then proposed solutions for them. This way the text will be simplified. The current form of the manuscript is very confusing to the readers. 

10. This reviewer also wants to know what are limitations for the study?

11. This reviewer also wants the autos to have some discussion about SIDS other than Seychelles.

12. Finally this reviewer wants authors to give clear recommendations that can be used by researchers, conservation biologists, and policy makers.       

 

     

Author Response

REVIEWER 5

Bennett et al. wrote 'Operationalizing blue carbon solutions for SIDS: the case of Seychelles' which is interesting. However this requires major revision on lines of the following points.    

1. The authors should add few points related to role of blue carbon resources in food security. This is very important aspect and should be captured in introduction adequately backed by references. The current introduction is overwhelmingly described only role of blue carbon resources to sequester carbon and related aspects. 

Reference has been made to the role of blue carbon in food security specifically through the stimulation of fisheries, in the introduction and throughout the manuscript. 

The introduction has been written with a focus on the carbon sequestration abilities of blue carbon to reflect that global interest in blue carbon has arisen mainly for its carbon sequestration capacity (given the challenge in addressing increasing greenhouse gases and climate change) and not really for other associated benefits (like contributing to food security) although being positive for developmental goals.  

2. Authors are also advised to acknowledge the fact that today ecosystems are degraded or damaged, their carbon sink capacity is lost or adversely affected, and the carbon stored is released, resulting in emissions of carbon dioxide (CO2) that contribute to climate change. Also the areas which are not under protected habitats do not demonstrate globally relevant, long-term climate mitigation potential. These aspects also should be covered. The current introduction portrayed too optimistic a picture and has to have a balanced view. 

The authors have acknowledged in the text that some blue carbon systems are degraded: 

“Like many other habitats globally, many blue carbon ecosystems are degraded  reducing their carbon sink capacities, owing to a lack of environmental protection (Senger et al. 2021; Sharma et al. 2020; Trevathan-Tackett et al. 2018; Wiley et al. 2016).”

In addition to this a paragraph has been included in the introduction to establish the premise and the content of the paper: 

“Blue carbon has been proposed as a nature-based solution for climate change mitigation, through the reduction of greenhouse-gases through carbon sequestration. This proposal entails the protection, restoration, and conservation of blue carbon ecosystems such that these systems can optimally provide valuable ecosystem services. Challenges remain in funding the conservation and protection efforts blue carbon systems require to function optimally, however the ecosystem services blue carbon systems provide can be capitalised upon through various “payment for ecosystem services” schemes, but these have their own unique challenges to resolve.”

Other reference to the degradation of blue carbon systems has been made in the manuscript:

“An estimated 50% of global blue carbon ecosystems have disappeared due to human activities (such as harvesting, dredging, and non-extractive activities such as filling and drainage) as well as climate change phenomena (like severe weather events and sea-level rise) resulting in the release of carbon into the environment (McLeod et al. 2011; Pendleton et al. 2012, Palacios et al. 2021).”

 

3. It has been stated that many SIDS (found in the Pacific, Caribbean as well as Atlantic – Indian – South China Sea Region) are able to benefit from the development of their blue carbon resources, which can contribute substantially to local livelihoods and well-being. Two references are provided to support this statement. This authors would like to see, how this has been achieved as this statement is central to this theme of the current manuscript.

There are limited examples of blue carbon success stories that exist in a SIDS context, which is exactly what this paper aims to address. 

New text has been included in the introduction has been altered to reflect this: 

“The aim of this paper is to collate available information on operationalising blue carbon resources in one document, using the Seychelles as a case study country as an example for other SIDS to emulate. The paper aims to suggest actionable steps to be considered by policy makers and conservation biologists, in the operationalising of blue carbon as well as propose novel yet important areas of consideration, identifying gaps where future research and work is required for the successful use of SIDS blue carbon resources in contributing to NDCs as well as commercialising blue carbon resources for national development.”

 

The authors maintain that, like Seychelles, other SIDS have the potential to benefit from fully exploiting their blue carbon resources in a sustainable fashion, and the text has been rephrased to better convey this message:

“ Nevertheless, many of these SIDS (found in the Pacific, Caribbean as well as Atlantic – Indian – South China Sea Region) have the potential to benefit from the development of their blue carbon resources, which can contribute substantially to local livelihoods and well-being…”

Examples of the blue carbon resources of other SIDS are referenced throughout the manuscript. 

 

4. This reviewer suggests  authors to incorporate the infographic that can better present the concept of the blue carbon resources in context with SIDs. 

The authors thank the reviewer for their suggestion. The suitedness of blue carbon ecosystems in addressing the challenges SIDS face is discussed in the text: 

“Small Island Developing States (SIDS) are a categorisation of 37 United Nations (UN) member states which share many specific features, particularly their vulnerability to external shocks from environmental and economic factors. Although having common vulnerabilities, SIDS are diverse states with varying sizes of population, land area, Exclusive Economic Zones (EEZ) and archipelagic fragmentation, with some having economies entirely dependent on tourism and fisheries and others on fossil fuel based exploitation (Pouponneau, 2023)...Blue carbon development is also beginning to factor into the macroeconomic aims of SIDS, as well as having the potential to contribute significantly to multilateral commitments (such as the Paris Agreement), and address several of the unique challenges that SIDS face. This is facilitated by the numerous ecosystem services that blue carbon habitats provide beyond carbon removal, such as coastal protection, contributing to food security through the stimulation of fisheries through nursery ground provisioning, nutrient filtration, and contributing to aquaculture and ecotourism (McLeod et al. 2011, UNEP 2020).”

 

5. Method has vary vague description of desktop study literature review. This reviewer wants to know what are search engines used e.g. google scholar, web-of-science etc. Also this reviewer wants to know what are the ways by which irrelevant data sets were removed from the primary search, that means who refinement has been made. I am sure not all that has been found in the web search is included in the analysis. 

The  methods section has been altered to incorporate the comments from the reviewers: 

“With a synoptic approach, this review consisted of desktop study literature review. The literature review comprised a non-exhaustive search of relevant academic articles and studies, publications for development organisations (such as the World Bank and the Blue Carbon Lab), public news articles, and national documents.  Science Direct, Google and Google Scholar were the databases used to gather relevant sources on the study topic online.  Keywords in the literature search included search strings such as “blue carbon”, “operationalising blue resources”, “blue economy”, “ecosystem services”, “blue accounting”, “blue carbon accounting”, “carbon trading”, “SIDS”, and “Seychelles”.  Sources that dealt with blue carbon outside of the context of island countries and SIDS were excluded from the review. However, sources that discussed threats to blue carbon ecosystems, as well as sources discussing the contentious status of potential blue carbon ecosystems (such as kelps and coral reefs) were not excluded from the review, as these topics are directly applicable to operationalising blue carbon in a SIDS context.  The paper incorporates findings from the literature review as well as knowledge from the authors’ experience and professional network of scientists and researchers in the realm of Seychelles blue carbon and Seychelles blue economy development (Dr Anabelle Constance, Dr Anika Faure from SeyCCAT, and Dr Jerome Hardely as part of the Seychelles Seagrass Mapping and Carbon Assessment).  

Blue carbon ecosystems that are reviewed include mangroves and seagrasses. Estimates of blue carbon stocks in the Seychelles were investigated and the most recent assessments are reported as they have been validated with field measurements (Wartman et al. 2022, and Rowlands et al. 2023). The potential of coral reef systems as blue carbon habitats is also discussed. Considering that Seychelles does not have any tidal salt marshes (Adams and Banderia 2011; Lugendo 2016; McOwen et al. 2017), nor is rich in kelp forests, a review of the stock assessments of these habitats have thus been omitted. The islands do experience influxes of floating Sargassum seaweed (as do other SIDS elsewhere), but these influxes of Sargassum are not suitable for use as national blue carbon resources because the seaweed breaks down when washed up on the beaches, releasing carbon stored in its tissues (Duarte et al. 2013; Hill et al. 2015), and moves through multiple national boundaries. 

 

Research ethics approval was not applicable nor required for this review article.”

 

The name of the search databases used (Science Direct, Google and Google Scholar) have been incorporated into the text.

 

The criterion for excluding sources from the review have also been incorporated into the text: 

“Sources that dealt with blue carbon outside of the context of island countries and SIDS were excluded from the review. However, sources that discussed threats to blue carbon ecosystems, as well as sources discussing the contentious status of potential blue carbon ecosystems (such as kelps and coral reefs) were not excluded from the review, as these topics are directly applicable to operationalising blue carbon in a SIDS context…Considering that Seychelles does not have any tidal salt marshes (Adams and Banderia 2011; Lugendo 2016; McOwen et al. 2017), nor is rich in kelp forests, a review of the stock assessments of these habitats have thus been omitted.”

 

6. It has been written that, knowledge from professional network in the realm of Seychelles blue carbon and Seychelles blue economy development has been used. This reviewer wants authors to clearly state what kind of professional network, e.g. scientific bodies, societies, association, etc. Please define them to make it more scientific. 

The contributions from the author’s professional network of scientists and researchers have been accredited in the Acknowledgements section at the end of the manuscript, but have now also been referenced in the methods section: 

“The paper incorporates findings from the literature review as well as knowledge from the authors’ experience and professional network of scientists and researchers in the realm of Seychelles blue carbon and Seychelles blue economy development (including inputs from SeyCCAT, and the Seychelles Seagrass Mapping and Carbon Assessment).”

 

7. After methods this reviewer expected some sore of results. But unfortunately such thing is missing. The entire manuscript is too descriptive that reader lose interest. It is highly recommended to make result section separate. As from the methodology it is cleat that is it not the review paper. If authors feel that it is review then, the methodology section is not not needed, please remove.  

This is a review paper, not a scientific paper that presents new findings, therefore it is not standard practice to include a results section since no new data was collected or collated.

8. There are several subheadings given in the manuscript each detailing work in its domain, but what is missing is information in the form of tables and figures. This reviewer strongly suggests the authors to have one or two tables wherever possible to tabulate the data and incorporate an infographic for a couple of subheadings. 

The only sections in the article that allow for summarising tables and figures are the stock assessment sub-sections of different blue carbon resources (under section 3 of the manuscript). The rest of the manuscript is descriptive and does not reference specific data, but rather the findings and recommendations from other research. 

The authors appreciate that tables summarising data are usually a more efficient means of presenting data, and  the information and data from the blue carbon stock assessment sections have been synthesised from several different publications with the main relevant data quoted in the text. As many of the previous assessments of Seychelles blue carbon are outdated or inaccurate, these are not presented in a table-format but are discussed in reference to the more recent and accurate estimates of Seychelles blue carbon, specifically highlighting the need for ground-truthing of estimates and continuous monitoring.

A summary table (Table 1) has been included into the text, summarising the most recent and relevant assessments of each of Seychelles blue carbon resources, with references to the original sources. These are then discussed later under each sub-heading. 

9. The title is 'Operationalising blue carbon solutions...' that means there must be impediments for which the solutions are provided. This reviewer suggests that the authors must give impediments under each subheadings and then proposed solutions for them. This way the text will be simplified. The current form of the manuscript is very confusing to the readers. 

Originally, “operationalisation” referred to the commercialisation of blue carbon resources through payment-for-ecosystem-services, such that the conservation, protection, and restoration of the habitats could be funded “by themselves”. The title has been renamed as follows: “Blueprint for blue carbon: lessons from Seychelles for SIDS.” 

Several challenges (or impediments) as well as opportunities are discussed under the “Opportunities and challenges in operationalising blue carbon” heading. The different challenges and opportunities that are discussed were not presented under specific blue carbon subheadings, because they are applicable to all blue carbon and the commercialisation thereof. 

The authors thank the reviewer for their suggestion in trying to better organise the manuscript. The manuscript has now been re-organised with appropriately numbered headings and subheadings, which now should be easier to follow.

10. This reviewer also wants to know what are limitations for the study?

The limitations for this study have been included in the methods section: 

“The study is limited in that it does not discuss allochthonous inputs of blue carbon (such as migrating Sargassum seaweed), as developing a carbon accounting framework for such allochthonous blue carbon presents numerous challenges involved in the carbon flux accounting of kelp blue carbon resources, the primary being that there is no consensus of allowing migrating blue carbon (and associated carbon fluxes) to count towards national NDCs. Carbon accounting of kelp ecosystems is highly complex and has been discussed elsewhere (Ross et al. 2023, Fujita et al. 2022; Hurd et al. 2022). This paper also does not discuss the blue carbon potential of seaweed (kelp) farming in the context of Seychelles, however this topic has been covered elsewhere (Bennett et al. 2023; Duarte et al. 2017).”

 

11. This reviewer also wants the autos to have some discussion about SIDS other than Seychelles.

Other SIDS have been discussed throughout the paper where appropriate:

“ Few studies have valued blue carbon ecosystem services in a SIDS context, and most blue carbon research in the Western Indian Ocean focussed on above ground seagrasses and mangrove carbon (Palacios et al. 2021). One study estimated the value of carbon sequestration and storage provided by seagrass meadows in the British Virgin Islands under different scenarios over 50 years (Tyllianakis et al 2019). The authors estimated a commercial potential between £49 428 - £664 785 in the baseline year, resulting in values between £4.1 million - £29.8 million over 50 years. Another study performed a scenario analysis informed from stakeholder workshops to assess the economic importance of Grenada’s blue carbon resources (McHarg et al. 2022). Their findings suggest that benefits from carbon sequestration diminished under expected habitat loss, but still outweigh losses from carbon emissions, with welfare gains of US$0.5-1.9 million over 50 years. However, the study also concluded that should ecosystems remain protected and maintained, benefits could reach US$10.7 million, with an increase in mangrove cover by 20% (over the next quarter of a century resulting in US$11.1 million between 2020 and 2070 (McHarg et al. 2022). Yet another study has estimated the national blue carbon stock for the mangrove habitats in Belize in the Caribbean to be  25.7 Tg C (Morissette et al. 2023). As has been highlighted for Caribbean SIDS, these studies highlight the extent of opportunity for Seychelles to benefit from the protection and operationalisation of blue carbon resources (Rustomjee, 2016).”

“...However, in low energy environments, carbon sediment deposits could remain intact despite vegetation being overwhelmed by sea level rise, such as the peat bogs in Bermuda, Belize, and Panama (Ellison 2003; Toscano et al. 2018).”

 

The premise of the paper is using Seychelles as a case study for other SIDS to emulate, when operationalising their blue carbon resources. Seychelles are widely known as a model country for blue economy development and it is only logical that this extends to the sustainable exploitation of national blue carbon resources. This has been explained in the introduction section of the paper. 

12. Finally this reviewer wants authors to give clear recommendations that can be used by researchers, conservation biologists, and policy makers.       

Recommendations for operationalising blue carbon resources are discussed throughout the manuscript, and are recapitulated in the conclusion section of the document.  

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thanks for responding to my comments. This review will be a welcome addition to the blue carbon literature. I have no further queries.

Author Response

We thank the reviewer for their constructive feedback to improving the quality of this paper!

Reviewer 2 Report

Comments and Suggestions for Authors

Title: The meaning of SIDS refers to Small Island Developing States, which is not reflected in the title. The abbreviation must not appear on the title.

Abstract:  The author refused to format the manuscript abstract according to the prescribed format. However, a systematic review article must have a methodology. If an article has a methodology, the research question can be added accordingly, targeting which goal they want to achieve and what gap they want to fill through the review article. May be authors missed this section while writing. Arguing with the editor is not a solution at all rather to solve the addressed concern! However, the author might still have time to solve this. I would like to see these changes before it is published in the Oceans journal.

Introduction: Of course, a review article can have a problem statement and research question. I would like to see them in the introduction section.

Citations: Some citations are outdated. A total of 20-40% of back-dated citations can be retained and most of the citations must be from new sources.

Research question or hypothesis: Please add at least one research question.

Implication: Please write why this review synthesis is important for the blue carbon science.

Review synthesis: Please provide some figures/diagrams etc. for a better understanding of the process you described in your texts.

Map: A map of Seychelles will improve the status of the MS.

Diagram of the review synthesis: Please add some diagrams that were described in the texts, for example, process, authority decorum, beneficiary group or organisms, and how they benefit from the blue carbon sequestration.

A list of published papers and their synthesis:  I would like to see a list of published papers in a table with their year of publication, key findings, dimensions of the study (if possible please add them to a table), and their synthesis in the main article version.

Author Response

Thanks again to the reviewer for their time spent providing their feedback. We have revised the title according to the reviewer's suggestion. The rest of the comments relate to preference in writing and formatting styles and upon advice from the editor are not necessary.

 

Reviewer 3 Report

Comments and Suggestions for Authors

article can be accepted

Author Response

We thank the reviewer for their constructive feedback to improve the quality of our manuscript

Reviewer 4 Report

Comments and Suggestions for Authors

I'd like to thank the authors for doing a good good revising the paper. I am satisfied with their response to my comments and concerns.

Author Response

We thank the reviewers for the constructive feedback to improve the quality of our manuscript

Reviewer 5 Report

Comments and Suggestions for Authors

Authors have addresed all the queries those I have raised satisfactorily and thus paper may be accepted.

Author Response

We thank the reviewer for their constructive feedback to improve the quality of our manuscript.