Anthropogenic Microparticles in Aquaculture and Wild Fish: A Case Study of Three Commercially Important Species in the Eastern Mediterranean

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Journal: Fishes (ISSN 2410-3888)

Manuscript ID: fishes-3878756

Type: Article

Title: Microplastic contamination in three economically important fish species from aquaculture and wild habitats in the Eastern Mediterranean

Authors: Aikaterini Kostoula, Eugenia Moschou-Kounopoioti, Niki Milatou, Persefoni Megalofonou

Section: Biology and Ecology

 

REVIEW

The manuscript submitted to me for review addresses a highly relevant and timely issue, namely, marine pollution by plastics and the consequences of microplastics accumulation in fish, particularly economically important species. An increasing body of evidence highlights the negative effects of microplastic bioaccumulation on marine organisms, with potential adverse impacts on the entire ecosystem's health. Furthermore, given that fish are widely consumed by people, microplastic accumulation in different fish tissues represents a significant pathway for their transfer to humans, with possible health implications. Although the study is focused on the gastrointestinal tract and did not assess the accumulation of microplastics in fish meat, scientific data indicate that transfer from the digestive tract to tissues, including muscles, is possible. One incompleteness of the manuscript is the lack of chemical analysis of the microplastics found in the gastrointestinal tracts of the studied fish. The main remark is that in the Introduction section, the authors should clarify in more detail the specific aim of the study and highlight the innovative elements and contributions of their work. The claim that this is the first study analyzing microplastic accumulation in the gastrointestinal tract of the three fish species examined is inaccurate, as Table 2 itself cites previous studies on the same topic. Also, in the Discussion section, the authors are advised to provide a clearer (hypothetical) explanation for the observed similarities in microplastic ingestion levels between wild and farmed fish, as well as between fish from the different marine habitats.

All comments and remarks have been marked in the manuscript text, which I am attaching as a separate file.

The remarks are:

Abstract

1. Lines 15-16: According to Zoological nomenclature, the first mention of a species' scientific name (Latin name) requires giving the full name of the species with the author’s name. Further, in the text, only the abbreviated name without the author is given.
2. Line 22: Is there a correlation between fish weight and the number of MPs?

Introduction

1. Line 59: The authors may need to cite a more recent publication with data on MP pollution in seas and oceans.

1. Lines 60-61: This is the Surface area of the Mediterranean Sea and the cited authors suggest that "the Sea can be considered as an additional great accumulation zone of floating plastic debris".
2. Line 62: Include as [4] the citation: Estíbaliz Calleja-Setién, Beatriz Rios-Fuster, Carme Alomar, Valentina Fagiano, Natalia Sánchez-García, Inmaculada Bernal-Mondejar, Salud Deudero,
3. Floating microplastics along the western Mediterranean Sea: Are we reaching a “Good Environmental Status” or drifting away?, Marine Pollution Bulletin, Volume 211, 2025, 117372. Because it contains relevant data on floating plastic waste in the Mediterranean Sea.
4. Line 64: The abbreviation for microplastics should be introduced and used consistently throughout the text (either 'MP' or 'MPs').
5. Lines 74-75: Authors may expand the text with information on Mediterranean fish species studied for MP accumulation. Include here Table 2 and a brief comment on the data.
6. Line 86: Highlight the contribution of this article. The main contribution of the article is a comparative analysis of MPs accumulation with their characteristics (shape, size, color) among 3 economically important fish and a comparison between wild and farmed specimens. Separately for these fish species, there are data on MPs accumulation with their characteristics, and the authors provide this reference in detail in Table 2.
7. Lines 87-88: Here and further in the whole text, only the abbreviated name of the species should be presented.

 

Materials and Methods

 

1. Lines 97-98: Here and further in the whole text, only the abbreviated name of the species should be presented. Further, the information in this sentence overlaps with that in the next sentence. I suggest deleting it.
2. Please revise Figure 1 by improving the map quality and more visible research sites. Authors may mark the locations of wild fish species with one color and the locations of farmed ones with another.
3. Line 109: The sentence is repeated with that from section 2.2. The authors need to define what they mean by “round weight” (also in Table 1).
4. Table 1: Mark the letters (a,b,c) as indices in the corresponding places in the table.
5. Page 5, lines 2-3: The sentence is repeated from the previous section. I suggest deleting it.

Results

1. The results are described in great detail in Section 3.1. and repeat already described data (e.g., for the number of species - it is also in the Methods section and in Table 1, and here descriptively). The descriptions can be shortened, since the numbers are shown in the table and do not need to be repeated again.
2. Lines 62-64: Here and further in the whole text, only the abbreviated name of the species should be presented.
3. Line 93: It is good and required by logic if the authors study and present also the correlation between the number of ingested microplastics and the round weight of the fish species, or at least give and explanation of the reason for not doing so.
4. Page 7, lines 96: Abbreviation (MPs) should be entered in the first place where the term is indicated. The abbreviation should be unified in the text (MPs or MP).
5. Lines 99-100: The abbreviated name of the species should be presented.
6. Figure 2 and 3: The figures for wild and farmed fish species can be merged to better illustrate the differences in the shape, size, and color of ingested MPs depending on the environment (wild or aquaculture). The differences can be commented on more easily in the Discussion section.

 

Discussion

 

1. Lines 132-133: The abbreviated name of the species should be presented.
2. Table 2. Delete the information on MPs accumulation by Mytilus galloprovincialis, as the manuscript is directed at fish.
3. Page 14, Line 94: First mention of Scomber colias needs author's name.

 

Conclusion

1. Lines 130-132: Maybe it is good for the authors to define if here they mean future research should focus on the three fish species they studied and in the Mediterranean Sea, because research examining physiological, toxicological, and environmental effects of microplastics in a variety of wild and farmed fish species has recently increased worldwide.

General

The authors are advised to give a clearer (hypothetical) explanation of the results concerning the similarity of ingestion levels of microplastics of the studied wild and farmed species, and also from the different marine habitats.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Responses to Reviewers

 

Reviewer #1:

Response: Thank you very much for your constructive comments and suggestions. All of them were taken into consideration for the improvement of the MS. The responses to the comments are presented below.

 

Specific comments

Comment 1: Abstract: Lines 15-16: According to Zoological nomenclature, the first mention of a species' scientific name (Latin name) requires giving the full name of the species with the author’s name. Further, in the text, only the abbreviated name without the author is given.

Response 1: We thank the reviewer for this important remark. We have revised the manuscript accordingly: in the first mention of each species in the Abstract, Introduction, and Methods sections we now provide the full scientific name with the author’s name (e.g., Sparus aurata Linnaeus, 1758; Dicentrarchus labrax Linnaeus, 1758; Boops boops Linnaeus, 1758). In all subsequent mentions throughout the text, we consistently use the abbreviated form (e.g., S. aurata, D. labrax, B. boops).

Comment 2: Line 22: Is there a correlation between fish weight and the number of MPs?

Response 2: We thank the reviewer for this suggestion. We tested for possible correlations between fish round weight (RW) and the number of ingested microplastics. The analysis showed no statistically significant correlation in any of the species examined (Spearman’s correlation, p > 0.05).

Comment 1: Introduction: Line 59: The authors may need to cite a more recent publication with data on MP pollution in seas and oceans.

Response 1: We appreciate the reviewer’s suggestion. We complemented the global context section with recent publications by Borrelle et al. (2020, Science) and OECD (2022, Global Plastics Outlook) on global plastic production and marine inputs. These updates strengthen the Introduction with the most recent evidence on MP pollution worldwide and in the Mediterranean region.

Comment 2: Lines 60-61: This is the Surface area of the Mediterranean Sea and the cited authors suggest that "the Sea can be considered as an additional great accumulation zone of floating plastic debris".

Response 2: We thank the reviewer for pointing out this inaccuracy. We have corrected the sentence in the Introduction to specify that 2.5 million km² refers to the total surface area of the Mediterranean Sea. The text now states that the Mediterranean Sea can be considered an additional major accumulation zone of floating plastic debris, in line with the cited references.

Comment 3: Line 62: Include as [4] the citation: Estíbaliz Calleja-Setién, Beatriz Rios-Fuster, Carme Alomar, Valentina Fagiano, Natalia Sánchez-García, Inmaculada Bernal-Mondejar, Salud Deudero,

Response 3: We thank the reviewer for this suggestion. We have now included the citation by Calleja-Setién et al. 2025, in the Introduction, to provide updated evidence on floating microplastics in the Mediterranean Sea.

Comment 4: Floating microplastics along the western Mediterranean Sea: Are we reaching a “Good Environmental Status” or drifting away?, Marine Pollution Bulletin, Volume 211, 2025, 117372. Because it contains relevant data on floating plastic waste in the Mediterranean Sea.

Response 4: We thank the reviewer for this helpful recommendation. We have now included the citation: Calleja-Setién, E.; Rios-Fuster, B.; Alomar, C.; Fagiano, V.; Sánchez-García, N.; Bernal-Mondejar, I.; Deudero, S. Floating microplastics along the western Mediterranean Sea: Are we reaching a “Good Environmental Status” or drifting away? Mar. Pollut. Bull. 2025, 211, 117372. https://doi.org/10.1016/j.marpolbul.2025.117372.

Comment 5: Line 64: The abbreviation for microplastics should be introduced and used consistently throughout the text (either 'MP' or 'MPs').

Response 5: We thank the reviewer for pointing this out. We have now introduced the abbreviation for microplastics in the Introduction and ensured that it is used consistently throughout the manuscript.

Comment 6: Lines 74-75: Authors may expand the text with information on Mediterranean fish species studied for MP accumulation. Include here Table 2 and a brief comment on the data.

Response 6: We agree with the reviewer’s suggestion. We have expanded the Introduction to include examples of Mediterranean fish species that have been studied for MP ingestion (e.g., B. boops, M. barbatus, P. erythrinus, S. pilchardus, S. aurata), with reference to Table 2, thereby providing a clearer link between previous research and the present study.

Comment 7: Line 86: Highlight the contribution of this article. The main contribution of the article is a comparative analysis of MPs accumulation with their characteristics (shape, size, color) among 3 economically important fish and a comparison between wild and farmed specimens. Separately for these fish species, there are data on MPs accumulation with their characteristics, and the authors provide this reference in detail in Table 2.

Response 7: We thank the reviewer for this helpful suggestion. We have revised the Introduction section to better highlight the novelty of our work. The manuscript now emphasizes that the main contribution of this study is the comparative analysis of MP accumulation and characteristics (shape, size, color) in three economically important fish species, with a direct comparison between wild and farmed individuals.

Comment 8: Lines 87-88: Here and further in the whole text, only the abbreviated name of the species should be presented.

Response 8: We thank the reviewer for this remark. The manuscript has been revised accordingly: full scientific names with authors are provided only at first mention, and all subsequent occurrences throughout the text use the abbreviated forms.

Comment 1: Materials and Methods: Lines 97-98: Here and further in the whole text, only the abbreviated name of the species should be presented. Further, the information in this sentence overlaps with that in the next sentence. I suggest deleting it.

Response 1: We thank the reviewer for this helpful suggestion. We have revised the manuscript accordingly: species names are now presented only in abbreviated form after their first mention, and the redundant sentence in Lines 97–98 has been deleted to avoid repetition.

Comment 2: Please revise Figure 1 by improving the map quality and more visible research sites. Authors may mark the locations of wild fish species with one color and the locations of farmed ones with another.

Response 2: We thank the reviewer for this helpful suggestion. Figure 1 has been revised to improve the overall quality and visibility of the research sites. Wild fish sampling locations are now indicated with one color and farmed fish locations with another, to clearly distinguish between the two.

Comment 3: Line 109: The sentence is repeated with that from section 2.2. The authors need to define what they mean by “round weight” (also in Table 1).

Response 3: We thank the reviewer for this remark. The repeated sentence has been removed to avoid redundancy. In addition, “round weight” has now been clearly defined in the Materials and Methods section and in Table 1 as the total body weight of the fish measured in grams.

Comment 4: Table 1: Mark the letters (a,b,c) as indices in the corresponding places in the table.

Response 4: We thank the reviewer for this useful suggestion. We have revised Table 1 accordingly: the letters (a, b, c) now appear as superscript indices in the respective places in the table, and their explanations are provided in the caption.

Comment 5: Page 5, lines 2-3: The sentence is repeated from the previous section. I suggest deleting it.

Response 5: We thank the reviewer for this observation. The repeated sentence has been removed as suggested.

Comment 1: Results: The results are described in great detail in Section 3.1. and repeat already described data (e.g., for the number of species - it is also in the Methods section and in Table 1, and here descriptively). The descriptions can be shortened, since the numbers are shown in the table and do not need to be repeated again

Response 1: We thank the reviewer for this helpful remark. Section 3.1 has been revised by shortening the descriptions and removing repeated information (e.g., number of specimens per species), which is already provided in the Methods and Table 1. The section now focuses on the main results regarding MP occurrence and abundance.

Comment 2:    Lines 62-64: Here and further in the whole text, only the abbreviated name of the species should be presented.

Response 2: We thank the reviewer for this remark. The manuscript has been revised accordingly: after the first mention with the full scientific name, all subsequent occurrences now use the abbreviated forms (S. aurata, D. labrax, B. boops).

Comment 3: Line 93: It is good and required by logic if the authors study and present also the correlation between the number of ingested microplastics and the round weight of the fish species, or at least give and explanation of the reason for not doing so.

Response 3: We thank the reviewer for this constructive suggestion. We performed correlation analyses between the number of ingested MPs and the round weight of the examined fish species. The results showed no significant correlation (Spearman’s correlation, p > 0.05), and this information has now been included in the Results section.

Comment 4: 4. Page 7, lines 96: Abbreviation (MPs) should be entered in the first place where the term is indicated. The abbreviation should be unified in the text (MPs or MP).

Response 4: We thank the reviewer for this remark. The abbreviation has now been introduced at the first occurrence of the term “microplastics” in the Introduction, and its use has been unified throughout the manuscript.

Comment 5: Lines 99-100: The abbreviated name of the species should be presented.

Response 5: We thank the reviewer for this suggestion. The abbreviated names of the species have now been introduced after their first mention with the full scientific names, and are used consistently throughout the manuscript (S. aurata, D. labrax, B. boops).

Comment 6: Figure 2 and 3: The figures for wild and farmed fish species can be merged to better illustrate the differences in the shape, size, and color of ingested MPs depending on the environment (wild or aquaculture). The differences can be commented on more easily in the Discussion section.

Response 6: We thank the reviewer for this helpful suggestion. We considered merging the figures; however, we believe that presenting wild and farmed fish separately allows the differences in MP shape, size, and color distributions to be visualized more clearly. To address the reviewer’s concern, we have revised the Discussion to explicitly highlight these differences, while keeping the figures separate for clarity.

Comment 1: Discussion: Lines 132-133: The abbreviated name of the species should be presented.

Response 1: We thank the reviewer for this observation. The abbreviated names of the species have now been introduced after their first mention and are used consistently throughout the manuscript (S. aurata, D. labrax, B. boops).

Comment 2: Table 2. Delete the information on MPs accumulation by Mytilus galloprovincialis, as the manuscript is directed at fish.

Response 2: We thank the reviewer for this remark. The information on Mytilus galloprovincialis has been deleted to keep the focus of the manuscript strictly on fish species.

Comment 3: 3. Page 14, Line 94: First mention of Scomber colias needs author's name.

Response 3: We thank the reviewer for this observation. The author’s name has now been added at the first mention of Scomber colias.

Comment 1: Conclusion: 1.      Lines 130-132: Maybe it is good for the authors to define if here they mean future research should focus on the three fish species they studied and in the Mediterranean Sea, because research examining physiological, toxicological, and environmental effects of microplastics in a variety of wild and farmed fish species has recently increased worldwide

Response 1: We thank the reviewer for this constructive suggestion. We have revised the Conclusions to clarify that, although research on MP ingestion in fish has increased worldwide, future studies should particularly address Mediterranean wild and farmed species—especially S. aurata, D. labrax, and B. boops—through larger sample sizes, seasonal and spatial coverage, and assessments of potential physiological or toxicological effects.

General comments

The authors are advised to give a clearer (hypothetical) explanation of the results concerning the similarity of ingestion levels of microplastics of the studied wild and farmed species, and also from the different marine habitats.

Response: We thank the reviewer for this valuable suggestion. The Discussion section has been revised to provide clearer explanations for the observed similarities. We now propose that comparable MP ingestion levels between wild and farmed fish may be attributed to their exposure to the same coastal environments with high MP loads, overlapping diets, and similar hydrodynamic conditions. These factors may also explain the lack of strong differences among the different marine habitats examined

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The article entitled “Microplastic Contamination in Three Economically Important Fish Species from Aquaculture and Wild Habitats in the Eastern Mediterranean” addresses the presence of MPS in three commercially important fish species from the wild and farmed. This is a necessary contribution to better understand the extent of MP contamination and human health. In general, the manuscript is well written and employs appropriate methods, with only a couple of minor observations that can be added into the discussión section:

First, the authors primarily focus on comparing individual species or their origin (wild vs. farmed), but they do not investigate whether differences in MP ingestion are related to feeding strategies or trophic position. Considering these parameters could help explain interspecific differences in MP burdens. Although no significant differences were observed among the evaluated species , such patterns might be evident in reports of other species, maybe adding this information (trophic levels on table 2), cpuld improve the deep of the discussion section.

Second, while the authors acknowledge that oceanographic conditions modulate MP availability, upon reviewing their map (Figure1), it would be interesting to incorporate oceanographic information as an additional layer. This would expand the analysis by considering that MP concentration and size distribution in water and sediments are strongly influenced by oceanographic processes such as currents, retention zones, riverine inputs, or benthic resuspension. These factors can generate significant spatial heterogeneity even between nearby sites, thereby limiting direct comparisons among the analyzed regions.

 

Author Response

Reviewer #2:

Response: Thank you very much for your constructive comments and suggestions. All of them were taken into consideration for the improvement of the MS. The responses to the comments are presented below.

 

Comment: The article entitled “Microplastic Contamination in Three Economically Important Fish Species from Aquaculture and Wild Habitats in the Eastern Mediterranean” addresses the presence of MPS in three commercially important fish species from the wild and farmed. This is a necessary contribution to better understand the extent of MP contamination and human health. In general, the manuscript is well written and employs appropriate methods, with only a couple of minor observations that can be added into the discussión section:

First, the authors primarily focus on comparing individual species or their origin (wild vs. farmed), but they do not investigate whether differences in MP ingestion are related to feeding strategies or trophic position. Considering these parameters could help explain interspecific differences in MP burdens. Although no significant differences were observed among the evaluated species, such patterns might be evident in reports of other species, maybe adding this information (trophic levels on table 2), could improve the deep of the discussion section.

Second, while the authors acknowledge that oceanographic conditions modulate MP availability, upon reviewing their map (Figure1), it would be interesting to incorporate oceanographic information as an additional layer. This would expand the analysis by considering that MP concentration and size distribution in water and sediments are strongly influenced by oceanographic processes such as currents, retention zones, riverine inputs, or benthic resuspension. These factors can generate significant spatial heterogeneity even between nearby sites, thereby limiting direct comparisons among the analyzed regions.

Response: We thank the reviewer for these constructive comments. We have now expanded the Discussion (Section 4.1) to address both points:

1. Feeding strategies and trophic levels: Although our results showed no significant interspecific differences in MP ingestion among the three studied species, we have added information on their trophic levels and discussed how trophic ecology may influence MP burdens.
2. Oceanographic conditions: We have also incorporated a paragraph at the end of Section 4.1 highlighting the role of oceanographic processes (coastal currents, retention zones, riverine inputs, and benthic resuspension) in shaping MP availability and distribution. We emphasize that these processes can generate spatial heterogeneity even between nearby sites, which should be taken into account when interpreting our results and making direct comparisons among regions.

 

Author Response File: Author Response.pdf