Oil Pollution in Mangroves: A Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Oil pollution in mangroves is a relevant issue in countries that extract oil along the coast. This manuscript compiles several studies addressing the physiological, anatomical, and mutational effects on mangrove trees, which tend to be scattered. However, I believe the topics are addressed superficially. As I indicated in the PDF, they need to be explained in greater depth concisely. For example, when the authors state that oil pollution affects metabolism, they should explain how and summarize the documents they reviewed. I also point out that Avicennia germinans has thin, non-woody adventitious roots at the base of the stem in areas with prolonged flooding and/or higher salinity. How is this associated with oil pollution? They explain that hydrocarbons erode the bark and expose the xylem. But what about the aerenchyma in the cortex and the phloem? Does the phloem remain functional? What about the parenchyma and anomalous cambium? The same applies to the first images. They summarize the main topics, but they don't provide a greater understanding of the subject.  The TEM micrographs look very good.

The conclusions are consistent with the presented arguments, but they remain superficial.

The bibliography seems sufficient for a review paper, but more discussion is needed to understand the effects of oil pollution in greater depth.

Comments for author File: Comments.pdf

Author Response

Reviewer #1

This review addresses the physiological, anatomical, and mutational effects on mangroves in a systematic manner, organised under specific headings: propagules, roots, leaves, mutations, root abnormalities, and bioindicators. The effects of oil pollution on metabolism are further explained, and additional references are now provided. The reviewer draws attention to the mangrove A. germinans. The effects of oil are the same for any species. Oil erodes all tissues, starting with the bark and proceeding inward. All points raised have been clarified in the text through additional discussion.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses a highly relevant topic (sublethal effects of oil on mangroves) and synthesises valuable ecological, anatomical, and physiological evidence. However, it requires substantive corrections in:

Internal consistency and accuracy (e.g., overall figures and contradictions).

MDPI style and format (title/article type, keywords, nomenclature, figures, units).

Quality and consistency of references (form errors and breaks),

Risk of presenting original data in a review article (Fig. 5) without explicit attribution/permission.

In summary, I recommend: unequivocally declaring the type of article as a Review and cleaning up the cover page/metadata; restructuring the abstract (problem-mechanisms-bioindicators-gaps-implications) and keywords; correcting inconsistencies in the Introduction (latitudinal range of mangroves, actual percentage of global forest area and carbon stock with CO₂-eq units and primary source); standardising terminology (e.g., cycloalkanes, hydrophobic waxy layer, plastid genome) and resolving physiological contradictions (antioxidants/SOD) by citing tissue, compound and exposure time; standardise units and style (μg kg⁻¹, en-dash in ranges, thin space before units, capitalisation of headings, single English variant); ensure taxonomic nomenclature in italics and abbreviations after first mention; add a brief section ‘Methods of the review’ (searches/criteria) and a summary table of bioindicators (species × organ × route × latency × performance); audit and renumber all citations and references with DOIs (if possible), correcting truncated entries and the TROPICS case; review figures (units, feet, permissions/credits; if Fig. 5 includes unpublished data, remove it or change it to Article); in Results/Discussion, report effect sizes and CIs and explain management implications and limitations; update the bibliography with recent studies on sublethal chronicity and methodological guidelines.

I also recommend reading for better contextualisation of work on mangroves in other areas, such as:

https://doi.org/10.3390/jmse11020250
DOI: 10.5772/intechopen.78947
https://www.jstor.org/stable/26978241

 

Good luck!

Comments on the Quality of English Language

Use a scientific register: avoid colloquialisms (e.g., replace “cocktail” with “mixture”), keep tense parallel (present for general facts; past for specific studies), ensure subject–verb agreement (“data are”), hyphenate compound modifiers (“oil-exposed seedlings”), italicize Latin binomials (Avicennia marina), define abbreviations at first use, and unify units/typography (SI with non-breaking space: μg kg⁻¹; en dashes for ranges: 2–6). A light professional language edit focused on clarity and concision would further improve readability.

Author Response

Reviewer #2

 All minor recommendations suggested by the reviewer have been incorporated into the revised submission. I did not see the need for “Methods for the review”, as most of the current relevant literature was reviewed and cited. Furthermore, I saw no need for a separate “Table of Bioindicators” as there is little to no information available, except for those suggested in this review. Bioindicators suggested include the production of chlorophyll-deficient propagules and abnormal root development on the stems. A reference is provided for Fig. 5. The management implications and limitations of the work are also included. The list of references has been updated with additional studies on the sublethal effects of oil.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The review article titled “Oil Pollution in Mangroves: A Review” was an overview of the current information on the sublethal effects of oil pollution on mangroves. This author also evaluated oil effects on propagules, roots and leaves and the underlying ecophysiological mechanisms involved. It also identifies biological indicators of oil pollution in mangroves. Why the review would have been a great step in exploring the current state of mangroves globally and the impacts of oil spills on their survival, I am afraid to say that the author did not do a thorough job in this review. First, how did you come about the articles you used in your review? I didn’t see your inclusion and exclusion criteria. How did you select articles to come to your conclusion in this study? You also mentioned that you identified biological indicators of oil pollution in mangroves- your section 8 which was dedicated to this, did not clearly state the bioindicators. Second, your introduction which would have spoken to the main subject of discussion was not centred on the effects on oil spill on mangrove, please see my comments in the attached document for my detailed concerns. Briefly in your introduction, in line 31 you mentioned “between 30◦ N and 30◦ S latitudes, from the mean sea level to the highest spring tides”- What do you mean by this? Please tell us. In lines 55-58, I queried your argument style- “Most of your arguments above did not this main aim of your review- I would suggest you centre your argument on the introduction section and other section on the sublethal effects of oil pollution on mangrove:” Third, in your section 3, I was a bit worried about your reporting style of the articles your review- please highlight some of the reviews here, and tell us the conclusion of such reviews, mainly on the implications of such. Further, most of your claims were not substantiated- you only mentioned briefly what some authors have done, but you didn’t mention the implications or conclusion of their findings. I was also worried about the presentation of figures from other people’s work- most worrisome is that you did not state in these figures which studies they emanated from- where these figures from your personal research or what? Based on these concerns and many others which you can find on the attached document, I am afraid your review was more or less a mere narration or definition of how oil spill affect mangrove. Please see the attached document for other detailed comments.

Comments for author File: Comments.pdf

Author Response

Reviewer #3

For this work, a literature search was conducted, and publications in accredited journals that made a significant contribution to the understanding of the sublethal effects of oil pollution on mangroves were selected. The section on mangrove distribution was revised to clarify many of the issues raised. Information obtained from other sources, including reviews, has been incorporated into the text, accompanied by relevant references. All the figures presented are from my own published work. This is indicated in this review in the appropriate locations. Most of the minor comments on the manuscript have been incorporated into the revised version.

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Title

The title should accurately reflect the scope of the review. While mangroves represent a unique and complex ecosystem, this review does not consider all major ecosystem compartments (e.g., sediment, biota, water; https://doi.org/10.1007/s11157-022-09625-0 ). The title of the paper is the oil pollution but mainly presented PAHs (that is about 50% but not entire, PAHs are one of the major components of crude oil; for example, the PAHs proportion of light oil, heavy oil, intermediate fuel oil and bunker oil is 10–35%, 15–40%, 40–60% and 30–50%, respectively).

The data presented focus primarily on the effects of PAHs on mangrove propagules, leaves, and roots. Therefore, the title is not fully consistent with the content. It is recommended to revise the title to clearly indicate that the review emphasizes the effects of PAHs on mangrove plant components (propagules, leaves, and roots), rather than the entire mangrove ecosystem. I would write the title as effects of PAHs on mangrove propagules, leaves, and roots: an overview ??

 

Abstract

• Line 13: The purpose and objectives of the paper are weakly articulated. They should be rewritten to more clearly convey the aim and scope of the review. Please refine or rephrase this section to enhance clarity and highlight the specific focus of the study.

 

Introduction

• The section does not clearly identify the data or knowledge gaps that justify the need for this review. Much of the content restates existing general information about mangroves rather than contextualizing why this particular focus (PAHs in mangrove propagules, leaves, and roots) is important.
• It is recommended to include a concise explanation of why the review emphasizes these plant components (roots, propagules, and leaves) and how this focus contributes to advancing understanding compared to previous works.
• Page 2, Lines 50–59: There are several seminal reviews on this topic that have not been cited, and as a result, the novelty of the current review is not well established. This section should be rewritten to acknowledge and discuss previous reviews and clarify how the present work differs or adds new insight. Suggested references include:
• Billah, M. M., Bhuiyan, M. K. A., Amran, M. I. U. A., Cabral, A. C., & Garcia, M. R. D. (2022). Polycyclic aromatic hydrocarbons (PAHs) pollution in mangrove ecosystems: global synthesis and future research directions. Reviews in Environmental Science and Bio/Technology, 21(3), 747–770.
• Duke, N. C. (2016). Oil spill impacts on mangroves: recommendations for operational planning and action based on a global review. Marine Pollution Bulletin, 109(2), 700–715.
• The purpose and objectives of the paper should be explicitly stated to help readers understand what the review aims to achieve and what aspects it will cover.

 

Section: Bioindicators of Oil Contamination (Line 448)

###This section lacks depth and focus, which indicates insufficient synthesis of existing literature. For instance, Avicennia marina is the only species mentioned as a bioindicator of oil or PAH contamination, and no supporting references are provided.

A review article should summarize and integrate updated knowledge on this topic. I recommend expanding this section and adding a summary table listing key mangrove species that have been identified as bioindicators of PAH or oil pollution, including relevant references.
Suggested examples include:

• Avicennia marina — Lu et al. (2005); Billah et al. (2022)
• Aegiceras corniculatum — Qiu et al. (2018)
• Bruguiera gymnorrhiza — Lu et al. (2005); Qiu et al. (2018)

References for suggested inclusion:

• Lu, Z. Q., Zheng, W. J., & Ma, L. (2005). Bioconcentration of polycyclic aromatic hydrocarbons in roots of three mangrove species in Jiulong River Estuary. Journal of Environmental Sciences, 17(2), 285–289.
• Qiu, Y. W., Qiu, H. L., Li, J., & Zhang, G. (2018). Bioaccumulation and cycling of polycyclic aromatic hydrocarbons (PAHs) in typical mangrove wetlands of Hainan Island, South China. Archives of Environmental Contamination and Toxicology, 75(3), 464–475. https://doi.org/10.1007/s00244-018-0548-4
• Billah, M. M., Bhuiyan, M. K. A., Amran, M. I. U. A., Cabral, A. C., & Garcia, M. R. D. (2022). Polycyclic aromatic hydrocarbons (PAHs) pollution in mangrove ecosystems: global synthesis and future research directions. Reviews in Environmental Science and Bio/Technology, 21(3), 747–770.

 

References

• The reference formatting is inconsistent and difficult to follow. Please ensure all references adhere to the journal’s citation style.
  For instance, this reference is unclear and incorrectly formatted:

“C.; Nordhaus, I.; Dahdouh-Guebas, F. A world without mangroves? Science 2007, 317, 41–42.”

Similarly, the following reference has formatting and sequencing issues:

“Naidoo, G.; Naidoo, K. Ultrastructural effects of polycyclic aromatic hydrocarbons in the mangroves Avicennia marina and Rhizophora mucronata. Flora-Morphol. Distribut. Funct. Ecol. Plants 2017a, 235, 1–9. https://doi.org/10.1016/j.flora.2017.08.006.”

Ensure consistent pattern 

 

Author Response

Reviewer #4

In both the abstract and introduction, it is clearly stated that long-term sublethal effects of oil pollution on mangroves are poorly understood. This review summarises the current information on the sublethal effects of oil pollution on mangroves by examining the characteristics of oil and then evaluating the effects of oil on propagules, roots, and leaves. It examines the effects of polycyclic aromatic hydrocarbons on mangroves, including information on the mechanisms of uptake, distribution, physiology, and the underlying ecophysiological mechanisms of toxicity. One cannot separate the effects of PAHs from the other components of oil, as suggested by this reviewer. Oil comes as a package and not as separate components. Long-term sublethal effects are due primarily to PAHs, so this aspect was emphasised. Although the review emphasises the effects on mangrove propagules, leaves, and roots, it also discusses the effects of oil in the sediment, on water, and the general mangrove environment. The purpose and objectives of the review have been modified and expanded. to convey the aim and scope of the review more clearly. An explanation of why the review emphasises these plant components (roots, propagules, and leaves) and how this focus contributes to advancing understanding compared to previous works has been given. Additional reviews on this topic have been cited and included in the reference list. I saw no need for a separate “Table of Bioindicators” as there is little to no information available, except for those suggested in this review.  

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Now, the manuscript are better. Congratulations

Author Response

Thank you for your review.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,

Thanks for re-submitting the revised version of your manuscript. Even though you have tried to improved on the manuscript, I am afraid to state that most of my concern were not addressed. 

You stated that "For this work, a literature search was conducted, and publications in accredited journals that made a significant contribution to the understanding of the sublethal effects of oil pollution on mangroves were selected". My comment on this will be, no doubt about that, but as I stated earlier, what were the inclusion and exclusion criteria you used in arriving at the selected publications you used for your review? 

You also mentioned that  "All the figures presented are from my own published work". You problem about that, but you didn't reference them as such, even though the figures were lifted from your earlier publications, you must cite them appropriately, otherwise it will be viewed as plagiarism, so do the needful by citing them in the body of the work and the figures captions.

From all indications, you didn't pay attention to my concerns, so I have pasted them again for your attention:

"You also mentioned that you identified biological indicators of oil pollution in mangroves- your section 8 which was dedicated to this, did not clearly state the bioindicators.

Second, your introduction which would have spoken to the main subject of discussion was not centred on the effects on oil spill on mangrove, please see my comments in the attached document for my detailed concerns.

Briefly in your introduction, in line 31 you mentioned “between 30◦ N and 30◦ S latitudes, from the mean sea level to the highest spring tides”- What do you mean by this? Please tell us.

In lines 55-58, I queried your argument style- “Most of your arguments above did not this main aim of your review- I would suggest you centre your argument on the introduction section and other section on the sublethal effects of oil pollution on mangrove:”

Third, in your section 3, I was a bit worried about your reporting style of the articles your review- please highlight some of the reviews here, and tell us the conclusion of such reviews, mainly on the implications of such.

Further, most of your claims were not substantiated- you only mentioned briefly what some authors have done, but you didn’t mention the implications or conclusion of their findings.

I was also worried about the presentation of figures from other people’s work- most worrisome is that you did not state in these figures which studies they emanated from- where these figures from your personal research or what? Based on these concerns and many others which you can find on the attached document, I am afraid your review was more or less a mere narration or definition of how oil spill affect mangrove. Please see the attached document for other detailed comments".

 

I would suggest you take your time to address these concerns, before I can reconsider your manuscript for possible acceptance.

Author Response

1. Responses to Reviewer

    

   question 1：what were the inclusion and exclusion criteria you used in
   arriving at the selected publications you used for your review?

   See L75-77
   
   question 2：You also mentioned that "All the figures presented are from
   my own published work". You problem about that, but you didn't reference
   them as such, even though the figures were lifted from your earlier
   publications, you must cite them appropriately, otherwise it will be
   viewed as plagiarism, so do the needful by citing them in the body of
   the work and the figures captions.

   See L185, L191

   L261-265

   L270-277

   L299-302

   L370-389

   L425-427

   L450-466

   The source of the data (mainly my publications) is indicated in the text as shown above.

   Furthermore, in all figure captions, the source of the data is indicated
   
   question 3：You also mentioned that you identified biological indicators
   of oil pollution in mangrovesyour section 8 which was dedicated to this,
   did not clearly state the bioindicators.

   See L480-483
   
   question 4：Briefly in your introduction, in line 31 you mentioned
   “between 30◦ N and 30◦ S latitudes, from the mean sea level to the
   highest spring tides”- What do you mean by this? Please tell us.

   The sentence has been revised, and references are included for those who may need them.

   See [35-38]
   
   question 5：In lines 55-58, I queried your argument style- “Most of your
   arguments above did not this main aim of your review- I would suggest
   you centre your argument on the introduction section and other section
   on the sublethal effects of oil pollution on mangrove:”

   Done

   See Introduction. This section clearly indicates that the focus of the review is an overview of the sublethal effects of oil pollution on mangroves. Moreover, writing style is a personal attribute.
   
   question 6：Third, in your section 3, I was a bit worried about your
   reporting style of the articles your review- please highlight some of
   the reviews here, and tell us the conclusion of such reviews, mainly on
   the implications of such.

   See L52-58

   L60-69

   L75-77

   L126-129

   In the preceding sections, the nature of these reviews was explained, along with the conclusions.
   
   question 7：Further, most of your claims were not substantiated- you
   only mentioned briefly what some authors have done, but you didn’t
   mention the implications or conclusion of their findings.

   See L 185, L191

   L261-265

   L270-277

   L299-302

   L370-389

   L425-427

   L450-466

   In the preceding sections, the implications and conclusions of the findings are discussed in detail.

   
   
   question 8：I was also worried about the presentation of figures from
   other people’s work- most worrisome is that you did not state in these
   figures which studies they emanated fromwhere these figures from your
   personal research or what?

   All the figures are from work by my research group.

   See captions for each figure.

   The source of the information is indicated in the captions.

   
   -----------------------------------
   
   

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

I am okay with the author's responses. I therefore recommend the manuscript for publication.