Hidden Fish Assemblages in Mediterranean Posidonia oceanica Meadows Are Less Diverse and Abundant than in the Cryptic Spaces of Neighboring Habitats

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Summary
This study to refine a sampling protocol for hidden microhabitats within Posidonia oceanica meadows in order to provides a quantitative assessment of fish assemblages inhabiting these environments and compares them with those in neighbouring non-Posidonia habitats. Based on sampling conducted at multiple sites in the Adriatic Sea, the authors report a gradient of increasing fish abundance and species richness from inside Posidonia meadows to their edges and surrounding habitats. Differences in community composition were mainly driven by the relative dominance of Labridae within Posidonia and Gobiidae outside seagrass habitats. Overall, the results, together with the methodological description, provide a useful framework for future research

General comments

The manuscript is generally well written (only few minor grammatical errors), with clearly described methodology and data analysis, supported by available data and producing reliable results. However, I note that access to the video data is restricted, despite their deposition in Zenodo. It would be preferable to remove this restriction to improve the FAIRness of the work.

Regarding the quality of Figures 6 and 7, in the PDF provided for review, their quality was below that of the other figures. In particular, Figure 7 would benefit from improvement to enhance readability for readers.

Specific comments

L.18-19: has not been studied -> have not been studied
L.24: occurence -> occurrence
L.29: against -> compared to
L.52: fishing gears -> fishing gear
L.56: inevitably samples also other habitats -> inevitably also samples other habitats
L.92: occuring -> occurring
L.96: hardly fit to the  “microbenthic” fish concept -> hardly fit the  “microbenthic” fish concept
L.111: even decade -> even decades
L.111: protion -> portion
L.121: itself -> themselves
L.145: average density for square meter -> average density per square meter
L.179-180: The resulting method roughly corresponds -> The resulting method is broadly comparable to
L.225: on every dive -> during each dive
L.250-254: few extra spaces
L.555-556: considered uniquely -> considered a uniquely
L.557: regarded as nursery area -> regarded as a nursery are
L.557: highly productive ecosystem -> a highly productive ecosystem
L.565: by the end of 20th century -> by the end of the 20th century
L.566: the knowledge on -> the knowledge of
L.572: remove last comma [10,12,13,]
L.582: remove extra space

Author Response

Comments 1: This study to refine a sampling protocol for hidden microhabitats within Posidonia oceanica meadows in order to provides a quantitative assessment of fish assemblages inhabiting these environments and compares them with those in neighbouring non-Posidonia habitats. Based on sampling conducted at multiple sites in the Adriatic Sea, the authors report a gradient of increasing fish abundance and species richness from inside Posidonia meadows to their edges and surrounding habitats. Differences in community composition were mainly driven by the relative dominance of Labridae within Posidonia and Gobiidae outside seagrass habitats. Overall, the results, together with the methodological description, provide a useful framework for future research

Response 1: We thank the reviewer for the comment.

Comments 2: The manuscript is generally well written (only few minor grammatical errors), with clearly described methodology and data analysis, supported by available data and producing reliable results.

Response 2: We thank the reviewer for the comment.

Comments 3: However, I note that access to the video data is restricted, despite their deposition in Zenodo. It would be preferable to remove this restriction to improve the FAIRness of the work.

Response 3: Supplementary video files for Kovacic et al Hidden fish assemblages in the Mediterranean Posidonia oceanica meadows submission to Ecologies 10.5281/zenodo.19065853

and Dataset 10.5281/zenodo.19091462 are now public. We apologize for the originally set them in the restricted mode.

Comments 4: Regarding the quality of Figures 6 and 7, in the PDF provided for review, their quality was below that of the other figures. In particular, Figure 7 would benefit from improvement to enhance readability for readers.

Response 4: The Figure 7 was replaced with improved one. The both figures 6 and 7 are submitted also as separate files in original resolution and quality.

Comments 5: L.18-19: has not been studied -> have not been studied

Response 5: Corrected

Comments 6: L.24: occurence -> occurrence

Response 6: Corrected

Comments 7: L.29: against -> compared to
Response 7: Corrected

Comments 8: L.52: fishing gears -> fishing gear

Response 8: Corrected

Comments 9: L.56: inevitably samples also other habitats -> inevitably also samples other habitats

Response 9: Corrected

Comments 10: L.92: occuring -> occurring

Response 10: Corrected

Comments 11: L.96: hardly fit to the  “microbenthic” fish concept -> hardly fit the  “microbenthic” fish concept

Response 11: Corrected

Comments 12: L.111: even decade -> even decades

Response 12: Corrected

Comments 13: L.111: protion -> portion

Response 13: Corrected

Comments 14: L.121: itself -> themselves

Response 14: Corrected

Comments 15: L.145: average density for square meter -> average density per square meter

Response 15: Corrected

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript provides a valuable and genuinely original dataset, offering the first quantitative insight into fish assemblages inhabiting hidden microhabitats within Posidonia oceanica meadows. The methodological approach is innovative and successfully captures components of the fish community typically overlooked by standard fishing techniques. The study fits the scope of Ecologies and has the potential to advance our understanding of seagrass‑associated fish assemblages in the Mediterranean. However, the manuscript requires substantial revision.

Although the study design and statistical treatment are sound, the narrative is burdened by excessive length and detail. Both the Introduction and Discussion contain large review‑style sections that obscure the main aims and findings. As a result, the central hypotheses and the broader ecological message are difficult to follow. These two sections should be considerably shortened and focused more directly on the context necessary for this particular study. The Introduction could be reduced by roughly half. Lengthy digressions on Posidonia ecosystem paradigms, marine caves, cryptobenthic fish history, and methodological debates are not essential and should be trimmed. A clear and concise statement of objectives and hypotheses at the end of the Introduction would greatly improve the overall structure. The Methods are well documented but overly detailed for a research article. Step‑by‑step procedural descriptions, diver actions, and technical details should be transferred to Supplementary Materials. A short overview table summarising sampling effort (e.g., cuboids per habitat, depths, seasons, localities) would help readers grasp the study design more efficiently. The Results are robust, yet the text occasionally repeats information already given in tables and figures. Repetition concerning gobiid dominance, the scarcity of fish inside Posidonia, and the prominence of Odondebuenia balearica should be removed. The Results section should focus on patterns and statistical outcomes, leaving interpretation to the Discussion. The Discussion is informative but unnecessarily long, with several sections repeating material already presented in the Introduction or offering broad literature syntheses only loosely connected to the data. A more concise discussion centred on the three main findings (the low abundance of hidden fish in Posidonia; the contrasting roles of gobiids and labrids across habitats, and the transitional nature of the meadow edge) would significantly strengthen the manuscript. A short, focused paragraph on implications for monitoring and conservation would provide a clearer conclusion. The English requires polishing. Sentence structure is often overly complex, and some terminology is used inconsistently. Minor technical issues (duplicated abbreviations, formatting inconsistencies) should also be corrected. In summary, the study is methodologically strong and addresses an important gap, but major revisions are needed to improve clarity, focus, and readability. With a more concise Introduction and Discussion, and with streamlined Methods and Results, the manuscript could make a meaningful contribution to the literature on Mediterranean seagrass ecology.

Best regards.

Author Response

Comments 1: The manuscript provides a valuable and genuinely original dataset, offering the first quantitative insight into fish assemblages inhabiting hidden microhabitats within Posidonia oceanica meadows. The methodological approach is innovative and successfully captures components of the fish community typically overlooked by standard fishing techniques. The study fits the scope of Ecologies and has the potential to advance our understanding of seagrass‑associated fish assemblages in the Mediterranean. Although the study design and statistical treatment are sound, the narrative is burdened by excessive length and detail. Both the Introduction and Discussion contain large review‑style sections that obscure the main aims and findings. As a result, the central hypotheses and the broader ecological message are difficult to follow. These two sections should be considerably shortened and focused more directly on the context necessary for this particular study.

Response 1: We thank the reviewer for the comment, we addressed each of the questions separately in the responses below and we revised the ms accordingly.

Comments 2: The Introduction could be reduced by roughly half. Lengthy digressions on Posidonia ecosystem paradigms, marine caves, cryptobenthic fish history, and methodological debates are not essential and should be trimmed.

Response 2: The introduction was reduced to roughly half, as requested.

Comments 3: A clear and concise statement of objectives and hypotheses at the end of the Introduction would greatly improve the overall structure.

Response 3: The last paragraph of Introduction rewritten, as requested.

Comments 4: The Methods are well documented but overly detailed for a research article. Step‑by‑step procedural descriptions, diver actions, and technical details should be transferred to Supplementary Materials. A short overview table summarising sampling effort (e.g., cuboids per habitat, depths, seasons, localities) would help readers grasp the study design more efficiently. Response 4: The studied area and sampling design in Material and Methods were significantly shortened, although the concise version was kept in the maintext, following the practise of earlier papers using sampling of  Mediterranean cryptobenthic fishes (Kovačić et al., 2012; Glavičić et al., 2016, 2020, Kovačić et al., 2021; 2024) and opinions of reviewers 1 and 3.

Comments 5: The Results are robust, yet the text occasionally repeats information already given in tables and figures. Repetition concerning gobiid dominance, the scarcity of fish inside Posidonia, and the prominence of Odondebuenia balearica should be removed. The Results section should focus on patterns and statistical outcomes, leaving interpretation to the Discussion.

Response 5: The Results were revised as requested. Any repetition of the subjects listed above was deleted i.e. only single mentioning of the problem kept. The sentences repeating or pointing out the Results in the Table 1 also deleted. Any sentence looking like discussion or comment was removed from the Results. The presence of the same species as outcome in different analyses was kept, since being the independent result of a separate and different analysis from previous one.

Comments 6: The Discussion is informative but unnecessarily long, with several sections repeating material already presented in the Introduction or offering broad literature syntheses only loosely connected to the data. A more concise discussion centred on the three main findings (the low abundance of hidden fish in Posidonia; the contrasting roles of gobiids and labrids across habitats, and the transitional nature of the meadow edge) would significantly strengthen the manuscript. A short, focused paragraph on implications for monitoring and conservation would provide a clearer conclusion. The English requires polishing. Sentence structure is often overly complex, and some terminology is used inconsistently. Minor technical issues (duplicated abbreviations, formatting inconsistencies) should also be corrected.

Response 6: The Discussion was revised as requested, with polished and simplified sentences, the original Discussion significantly shortened, although new paragraphs and sentences added on the reviewers' requests. The low abundance of hidden fish in Posidonia; the contrasting roles of gobiids and labrids across habitats, and the transitional nature of the meadow edge were addressed in 4.1. Fish abundance in the Mediterranean Posidonia meadows. Other chapters in Dicussion were significantly shortened. The English of revised manuscript was edited.

Comments 7: In summary, the study is methodologically strong and addresses an important gap, but major revisions are needed to improve clarity, focus, and readability. With a more concise Introduction and Discussion, and with streamlined Methods and Results, the manuscript could make a meaningful contribution to the literature on Mediterranean seagrass ecology

Response 7: We thank reviewer for the comment and we put the effort in the manuscript revision to meet his expectation.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I reviewed the ms (ecologies-4234728) and suggested a major revision for it. The ms reported the first quantitative assessment of fish assemblages inhabiting the hidden microhabitats of Posidonia oceanica meadows in the Mediterranean using a modified cube and suction sampler method.  I want to provide some suggestions to the authors, which may be helpful for polishing the ms. Furthermore, I am not a native English speaker, so my comments will mainly not involve it.

 

Major Concern:

• Thems provided important information for fish assemblages in habitats inside Posidonia meadows, and the sampling protocol developed in their study proved suitable for the quantitative assessment of fishes inhabiting hidden Posidonia microhabitats and provides a methodological basis for future research. Therefore, the discussion section of this paper should be based on their research findings and focus on two key aspects: 1) Discuss the potential mechanisms underlying the formation of the observed characteristics and their impacts on the ecological functions of seagrass beds, with regard to the composition, abundance, and distribution patterns of fish assemblages within the seagrass beds; 2) Discuss the advantages and limitations of the new method, and demonstrate its complementary role relative to other methods. The current discussion part is overly broad and lacks focus, for example, 4.1. The Mediterranean Posidonia ecosystem paradigm and current knowledge of Posidonia meadow fish assemblages, 4.3. Knowledge of the role of fishes in Mediterranean Posidonia ecosystem trophodynamics and of the Posidonia meadows as fish shelter, food source and nursery area.
• The authors need to evaluate the new method objectively. According to the sampling results, among 60 sampling occasions using this method, only 166 individuals representing 26 fish species were collected, and merely 8 species had more than 2 individuals captured. Furthermore, the complex internal structure of seagrass beds may affect the sampling efficiency of this patch habitat, as reflected in the results of the present study. The authors should comprehensively assess and discuss whether such sampling efficiency is relatively low, and whether it can reflect the true composition and distribution characteristics of fish assemblages, is it appropriate to overemphasize its application?

 

Specific comments:

Title: what means “neighbouring cryptic habitats”?

Line 30: “non-Posidonia”, Why is this word underlined here?

Lines 46, 54, 69: The citation format of the paper is rather odd, especially for citations like “[1] conducted a systematic review...”.

Lines 108-138: Both the first and third paragraphs of the introduction emphasize the importance of survey methods, which appears repetitive. It is recommended to merge and simplify them.

Figure 1: It is recommended to use a real photograph for supplementary illustration.

 

 

Comments on the Quality of English Language

 I am not a native English speaker, so my comments will mainly not involve it.

Author Response

Comments 1: Thems provided important information for fish assemblages in habitats inside Posidonia meadows, and the sampling protocol developed in their study proved suitable for the quantitative assessment of fishes inhabiting hidden Posidonia microhabitats and provides a methodological basis for future research.

Response 1: We thank reviewer for the comment.

Comments 2: Therefore, the discussion section of this paper should be based on their research findings and focus on two key aspects: 1) Discuss the potential mechanisms underlying the formation of the observed characteristics and their impacts on the ecological functions of seagrass beds, with regard to the composition, abundance, and distribution patterns of fish assemblages within the seagrass beds; 2) Discuss the advantages and limitations of the new method, and demonstrate its complementary role relative to other methods. The current discussion part is overly broad and lacks focus, for example, 4.1. The Mediterranean Posidonia ecosystem paradigm and current knowledge of Posidonia meadow fish assemblages, 4.3. Knowledge of the role of fishes in Mediterranean Posidonia ecosystem trophodynamics and of the Posidonia meadows as fish shelter, food source and nursery area.

Response 2: All Discussion is significantly shorten. Regarding the first point, the lack of published data prevent any hypothesizing on the subject, which is elaborated in the revised 4.2. Knowledge of the role of fishes in Mediterranean Posidonia ecosystem trophodynamics and of the Posidonia meadows as fish shelter, food source and nursery area. The second point is discussed in the added the second paragraph of  4.1. Fish abundance and species richness in the Mediterranean Posidonia meadows.

Comments 3: The authors need to evaluate the new method objectively. According to the sampling results, among 60 sampling occasions using this method, only 166 individuals representing 26 fish species were collected, and merely 8 species had more than 2 individuals captured. Furthermore, the complex internal structure of seagrass beds may affect the sampling efficiency of this patch habitat, as reflected in the results of the present study. The authors should comprehensively assess and discuss whether such sampling efficiency is relatively low, and whether it can reflect the true composition and distribution characteristics of fish assemblages, is it appropriate to overemphasize its application?

Response 3: Discussed and elaborated in the Discussion as the second paragraph of  4.1. Fish abundance and species richness in the Mediterranean Posidonia meadows.

Comments 4: Title: what means “neighbouring cryptic habitats”?

Response 4: Rephrased. The „neighbouring habitats” refers to habitats located in close proximity, in the immediate surrounding area, or within a specific "focal radius". “Neighbouring” is a better match to the relationship among habitats in the research than “adjacent” or any other near-synonym for which we analyzed the range of meanings.

Comments 5: Line 30: “non-Posidonia”, Why is this word underlined here?

Response 5: Checked, no underline present in the revised manuiscript.

Comments 6: Lines 46, 54, 69: The citation format of the paper is rather odd, especially for citations like “[1] conducted a systematic review...”.

Response 6: Corrected.

Comments 7: Lines 108-138: Both the first and third paragraphs of the introduction emphasize the importance of survey methods, which appears repetitive. It is recommended to merge and simplify them.

Response 7: Rewritten and significantly shorten. The first and third paragraphs now joint.

Comments 8: Figure 1: It is recommended to use a real photograph for supplementary illustration.

Response 8: We initally tried with real photos for the Figure 1, but the microhabitats were hard to empashize and to mark them in photos of Posidonia meadow, so we turned to painted figure done over real photo with modifications. Anyway, if the editorial team is not satisfied with Figure 1, we can delete it from the manuscript. 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have submitted a thoroughly revised version of their manuscript. I have carefully examined the changes, and I am satisfied with the overall quality of this revision. My previous comments and suggestions regarding both the text and figures have been addressed appropriately, and the manuscript has been modified in line with the recommendations provided. The revisions have improved the clarity and presentation of the work, and the submission now meets the standards expected for publication.

It is therefore my pleasure to recommend that the manuscript be accepted for publication in its revised form.