Assessment of Non-Sessile Invertebrates Associated with Mats of the Red Alga Phyllophora crispa at Giglio Island, Mediterranean Sea

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General recommendation to the authors (minor comments and corrections are directly inserted into the file:

The manuscript deals with the study of abundances and diversity of “mobile” invertebrates associated with Phyllophora crispa mats in the Giglio Island, Western Mediterranean. The matter is certainly interesting and would represent an enrichment of data, adding to what is recently published for the same area regarding the sessile fauna associated to P. crispa. The theme of the work is worthy of being published. However, there are some weaknesses, a fundamental one regarding the biodiversity data processing, which are not clearly explained.

The most problematic points regard the following aspects:

- First of all, for scientific rigor, we recommend avoiding vague and generic terms like "organisms" and "taxa," but specifying whether the research deals with “specimens” or “species”. This is especially true given that biodiversity is being discussed, and indices are calculated, it's essential to clearly explain how the analyses were conducted.

- I'm not very convinced about the use of the term “mobile”. “Non-sessile" instead of "mobile" would be more appropriate since marine mobile organisms are generally large sized, whereas this study includes mainly mm-sized taxa. Furthermore, among amphipods, I suggest to verify whether all species are benthic or some are planktonic.

- The authors cite gorgonian forests as the only existing coralligenous (pag.2 line 49). I suggest a main reference to be cited in this regard (Ballesteros 2006, Belmonte et al. 2020). Furthermore, Coralligenous habitats dominated by calcareous algae show high biodiversity having associated numerous invertebrates and soft algae. Among these, P. crispa is reported by Donato et al. (2024) from the Ionian Sea. This recent paper also provides biodiversity values and related indices and therefore should be included in the study to compare diversity values in the Results and Discussion. Values of these indices would be inserted in fig. 3. Also, since authors write that more than a third of all organisms belonged to Copepoda and Ostracoda (Lines 239-240), what is the reason for not including them in the biodiversity study? Their specific determination would have made the work complete.

The reported references are appropriate. Figures are not even appropriate, I suggest slightly modifying Fig. 3, eliminating the families of sessile molluscs. This will make the text more readable and the terms more spaced out. Data on P. crispa from the coralligenous of the Ionian sea would be added in Fig. 5

Considering the above observations and various comments reported in the text, I encourage the authors to resubmit the manuscript that, in my opinion, can be published with major revision.

Comments on the Quality of English Language

The manuscript is in some parts unclear regarding the English language and I strongly suggest checking the text by a native speaker.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors • What is the main question addressed by the research? R. This study is innovative in that it sheds light on associated fauna of Posidonia oceanica meadows, as well as for further environmental management actions.   • Do you consider the topic original or relevant to the field? Does it address a specific gap in the field? Please also explain why this is/ is not the case. R. Yes, although Posidonia is well-known, studies of its associated fauna are still in their infancy, as in this case.   • What does it add to the subject area compared with other published material? R. To study of associated invertebrates.   • What specific improvements should the authors consider regarding the methodology? R. Seek to refine identification at the genus or species rank, as possible. Take photographs of each identified morphotype/taxon to demonstrate the visual richness/diversity of the associated invertebrates.   • Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed? Please also explain why this is/is not the case. R. It remains to highlight the associated invertebrates identified, and which were the most abundant.   • Are the references appropriate? R. Yes.   • Any additional comments on the tables and figures. R. Yes. Take photographs of each identified morphotype/taxon to demonstrate the visual richness/diversity of the associated invertebrates.

I consider this manuscript version ready for publication.

Author Response

We would like to thank you for your positive feedback.

Reviewer 3 Report

Comments and Suggestions for Authors

Review for the paper submitted to “Diversity”.

Title: Assessment of mobile invertebrates associated with mats of the red alga Phyllophora crispa at Giglio Island, Mediterranean Sea

Authors: Alexander Töpfel, Melissa Steinhoff, Christian Wild

 

The authors focused on the ecological implications of the mat-forming red alga Phyllophora crispa in the Mediterranean Sea, specifically its role in supporting mobile invertebrate diversity in its habitats. Their study revealed that, despite the prevalent stressors affecting marine ecosystems, such as warming and pollution, P. crispa can be a significant contributor to biodiversity. The implications of the authors' work are significant for conservation strategies aimed at protecting Mediterranean marine ecosystems. By identifying P. crispa as a biodiversity hotspot, their findings advocate for the inclusion of these algal habitats in broader conservation measures. This underscores the importance of recognizing less popular marine habitats that might be crucial for maintaining marine biodiversity. The authors suggest that proactive management efforts should consider these algal communities to mitigate the impacts of anthropogenic stressors and safeguard the ecological integrity of the Mediterranean Sea.

 

Suggestions for improving the paper:

 

Introduction.

 

L 46. The authors should specify which driving factors are particularly severe in the Mediterranean and why their impact is more pronounced compared to other regions.

 

L 62. The authors should clarify the specific thresholds or temperature ranges that induce these physiological stresses and how they vary across the Mediterranean.

 

L 74-76. The authors should explain whether P. crispa is opportunistic or whether external factors, such as disturbance events, create favorable conditions for its proliferation.

 

Materials and Methods.

 

L 101. The authors should explain what specific current conditions were considered and include the main current in the map of the study area. The authors should provide additional information about the environmental variability of the study sites, such as water temperature, salinity, turbidity, and sediments to contextualize the findings.

 

L 113. The authors should explain why this threshold was chosen and whether it reflects typical P. crispa mat thickness in the region.

 

Results.

 

Figure 2. Why did the authors pool the data for the two studied sites?

 

L 182-183. Were these differences statistically significant? It would be useful to compare them. Additionally, it would be useful to compare the entire communities between sites using a multivariate test.

 

L 185-186. It would be useful to include the unique taxa for each site in the text.

 

L 207. In Table 1, the authors should change " Resent study" to "Present study" in 4 rows.

 

The authors claimed that they calculated the surface area of P. crispa samples to correlate the results to the data (L 142). However, the text contains no data regarding correlations between the surface area of P. crispa and invertebrate density and/or diversity indices.

 

Discussion.

 

L 220. The authors should elaborate on what "traditional habitats" are being displaced, the extent of this displacement, and its ecological implications.

 

L 229. The authors should provide more detail about what specific sampling techniques were used in the Bonifazi et al. study and explain how their method improves accuracy.

 

L 258-259. The authors should clarify how echinoderms specifically contribute to these processes in P. crispa habitats.

 

L 265. Were the environmental conditions similar in the present study and Bonifazi et al. (2017)?

 

L 274. Can the authors provide more explanatory detail on the 41 unique taxa? Were these unique taxa functionally or ecologically relevant to the P. crispa mats?

 

The authors should include a short section on the conservation or management implications of their findings to bridge the gap between research outcomes and marine resource protection.

Author Response

Please see the attachment.

Author Response File: Author Response.docx