PSTR-D-24-00076

Land use change drives decadal-scale persistence of blue carbon storage in restored mangroves

PLOS Sustainability and Transformation

Dear Dr. Heidi Burdett,

Thank you for submitting your manuscript to PLOS Sustainability and Transformation. After consideration, we feel that it has merit for publication after minor changes. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process, particularly those made by Reviewer#1.

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Kind regards,

Lucas Enrico

Section Editor

PLOS Sustainability and Transformation

Unai Pascual

Editor-in-Chief

PLOS Sustainability and Transformation

Additional Editor Comments (if provided):

Reviewers' Comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does this manuscript meet PLOS Sustainability and Transformation’s publication criteria?>

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?-->?>

Reviewer #1: No

Reviewer #2: I don't know

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3. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: No

Reviewer #2: Yes

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Reviewer #1: 

The ms# PSTR-D-24-00076 is about carbon source and accumulation rate change due to land use since past several decades. Generally, it’s a well written piece but has several unclarity with scope for improvement. There are areas still where Authors need to work in the revision phase.

Introduction

LN 75-80 Provide data in support of this statement

‘Blue C’ refers to OC present in both biomass and sediment in marine habitats, but authors missed out biomass in the first para of introduction. Since sediment is main component here, please write only carbon in sediment and not use ‘blue C’ while referring the same (e.g. avoid writing like LN 103 ‘blue carbon storage in mangrove sediment…”)

LN 63- Going forward, may simply use NBS instead of nature-based solution climate change mitigation

LN 80 – Give data on how much potential blue C economy has than other schemes

81-82- How much areal coverage of mangroves are present in SE Asia and Vietnam ?

“Over 60% of its past 84 mangrove forest cover has been lost” - What’s the timeframe ?

90-91 Don’t split into two paragraphs. This is a continuity of the Vietnam mangrove story

98-99 Add value to this statement on sediment carbon storage over other reservoirs

99 – There is missing link here, the context behind studying sediment chronosequence in relation to conservation is not set out very well by the earlier information. There should be more evidential effort in building up that link.

M&M

Provide some additional relevant details of the study location/period not just mangrove types, for example, when did sampling take place (year, season), are there any rivers? What was the tidal nature during coring? etc..

Check spelling of Aegiceras corniculatum

What is the total depth of sediment cores that could be retrieved from various sites ? What is the total length of the corer? Please provide all relevant details here.

Calculation of carbon stock, pls recheck the formula it does not give unit in g/m2 if we multiply stock with surface area. Hard to understand w/o bulk density how this is calculated. Please provide reference to this and help reader clearly understand. Ideal sediment C stock estimate formula is S = ∑_(i=0)^n▒〖Cn× ρn × l〗 Where Cn is C concentration (mass %) and ρn is the bulk density (g cm-3) of the sample, and l (cm) is length of sample section.

Core chronologie: Provide more details here on estimating procedure for accretion rate and sedimentation rates, finally carbon accumulation rate.

How end member selection was done ? normally the number of endmembers are chosen carefully by keeping the small standard deviation of δ 13C/15N within each end-member and making sure the values are clearly separated with significant differences from each other (ANOVA <0.05). This is generally used in such study to omit large number of end members (see works Gontharet, Chem Geol, 2014; Ray et al., BG 2023; Prasad et al., Ecol. Process. 2017; Ray and Sharaki 2016 STOTEN)

For the radionuclides was it Constant Flux - Constant Sedimentation (CF-CS) mode applied using a single exponential fit, for which all samples were considered ? Authors should mention whether any mixing was assumed in this model or was there shorter lived radioisotope excess 228Th that was detected as mixing indicator.

Add a separate detailed section for statistical analyses

Results and discussion:

234- matter for discussion “….suggesting a higher contribution of plant”

235-40 How C, N stable isotopes are used for sediment reconstruction ? They are used for source determination as also stated in M&M. Please provide clarity here.

Provide more information of CAR and compare data with other global mangroves (avg CAR around 175 g C/m2/yr)

Results are not surprising that greater sedimentation does not mean higher C accumulation neither higher stock refers higher accumulation as rate of accumulation would be dependent on several factors like dilution with minerals, remineralizations etc. Emphasize more on them.

Add a conclusion section

Reviewer #2: 

The study is an important contribution to the literature on temporal and spatial dynamics of blue carbon in different types of mangrove forests.

Of interest are the high sedimentation (and other) rates in shrimp farm-old growth mangrove forests because of particulate sources from the culture ponds. Such blue carbon contributions provide another reason for integrating mangroves with aquaculture in what has been called “Mangrove-Friendly Aquaculture.” The Discussion section could be enriched by the early papers below that mention the co-existence of, if not synergism between, aquaculture and mangroves in the same area:

Barbier EB, Koch EW, Silliman BR, Hacker SD, Wolanski E, Primavera J, Granek ED, Polasky S, Aswani S, Cramer LA, Stoms DM, Kennedy CJ, Bael D, Kappel CV, Perillo GME and DJ Reed. 2008. Coastal ecosystem-based management with non-linear ecological functions and values. Science 319: 321-323

Kautsky, N., H. Berg, C. Folke, J. Larsson, and M. Troell. 1997. Ecological footprint for assessment of resource use and development limitations in shrimp and tilapia aquaculture. Aquacult. Res. 28: 753–766.

Primavera, J.H., J.P. Altamirano, M.J.H.L. Lebata, A.A. delos Reyes Jr. and C.L. Pitogo. 2007. Mangroves and shrimp pond culture effluents in Aklan, Panay Is., central Philippines. Bull. Mar. Sci. 80: 795-804

A minor comment is the mis-spelling of scientific names in pages 117-119: Kandelia obovate, Aegiseras corniculatum

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Reviewer #1: No

Reviewer #2: No

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Land use change drives decadal-scale persistence of sediment organic carbon storage of restored mangrove

PSTR-D-24-00076R1

Dear Dr. Heidi Burdett,

We're pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

The revised version of the manuscript satisfactorily includes the changes and/or clarifications requested by both reviewers. In this regard, I appreciate the authors' thoughtfulness in each response.

I would also like to take this opportunity to personally apologize for the delay in processing this manuscript.

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Kind regards,

Lucas Enrico

Section Editor

PLOS Sustainability and Transformation