Mesophotic Reefs of the Largest Brazilian Coastal Protected Area: Mapping, Characterization and Biodiversity

Round 1

Reviewer 1 Report

The paper entitled "Mesophotic reefs of the largest Brazilian coastal protected area: mapping, characterization, and biodiversity" uses multiple methodologies to select habitats of particular geomorphologies and assess macro invertebrate and fish diversity. This is a descriptive paper that provides qualitative data for shallow mesophotic reefs near the Costa dos Corais MPA. This paper would benefit greatly from providing more information (quantitative) and comparisons to gauge the importance of this data locally.

Some concerns that may be easily rectified are:

1.     Define the upper limit of the mesophotic ecosystem. Why did the authors choose 21m depth?

2.     From the title it sounds like the MPA already includes mesophotic reefs, but from the discussion it sounds like the mesophotic reefs have an undetermined status (no-take?)

3.     Define which geomorphological characteristics of the bottom were used to select areas 1, 2 and 3. Higher complexity? If so provide measures of bottom complexity and also how representative of the bottoms are (by comparing to habitat cover data from the multibeam echosounder).

4.     Provide the depth data (min, max and mean) for BRUV, ROV and DRONE, and Transects. From the figures 3 and 4 it is not clear (please rectify the color legend so that the figures are readily comparable) at which depths these methods were used. Provide location data for deployments BRUVs deployments were separated enough to avoid interfering. This information is not in the text (consider including in line 161), also not clear in figure 2. I think that a table with deployments and depths is lacking. See also:

Scott et al. 2022. Variation in abundance, diversity, and composition of coral reef fishes with increasing depth at a submerged shoal in the northern Great Barrier Reef. Rev Fish Biol Fisheries 32, 941-962. doi:10.1007/s11160-022-09716-9.

5.     Provide statistical comparisons between the areas sampled (use measures of richness from each methodology for example) and or between shallow reefs (if the data exists) and mesophotic reefs. Also species cumulative curves taken from each method would be important to show.

6.     Provide data for the minimum depth for each species (corals, sponges, macroalgae – how many species? - and fish). That way you can potentially identify, which species are restricted to shallow and mesophotic depths. You can further use this categorization to show any changes in functional group frequencies between shallow and mesophotic reefs (instead of figure 9).

7.     On biodiversity results, I do not really understand why the focus of the benthic community is on sponges and corals, and why there are groups that were not registered (lines 228-229). As depth is an important factor here, I suggest remake figure 6 including depth bands. The text alternates the present and past forms (e.g., lines 240-248). Which are encrusting species? Algae?

8.      All of the suggestions taken together will allow you to for example identify which habitats are present at mesophotic reefs (and not in the shallow reefs) that need to be protected, as well as which species they harbor (that may not be present in shallow areas), and ultimately justify WHY extending the MPA to include mesophotic reefs. 

Minor suggestions:

Abstract

[Line 1] “Greatecological” add space between words

[Line 26] Replace “various sampling techniques were used, such as…” by “various sampling techniques were used:…”

[Lines 31-32] Replace “…and an image library of mesophotic ecosystems with record of new species in the region and description…” by “…and an image library of mesophotic ecosystems with the species descriptionand whether it is a new record in the region…”

[Line 32-35] “High biodiversity data…” you do not explain why is this biodiversity high; high compared to what? Shallower species? Other mesophotic reefs in Brasil?

[Line 35-38] “Our results demonstrate the importance of mesophotic reefs for the MPA Costa dos Corais as reserves of regional biodiversity, and with that, the need to protect these reefs through the application of local conservation strategies, such as the creation of “no take” zones.”

Unless you show how unique these mesophotic systems are (compared to shallower areas or other mesophotic reefs or other areas in the region), or how important they may be for (for example) reproduction, it is not immediately clear.

[Lines 38-39] “In addition, we also highlight the need to carry out further research in the region with the aim of learning more about these important ecosystems.”

Why is this justified? This sentence is a little vague.

Keywords

Remove “remote sensing”, it is NOT what you do here. Remote sensing is “the scanning of the earth by satellite or high-flying aircraft ...”

Introduction

[Lines 45-48] The United Nations Decade of Ocean Science for Sustainable Development (2021- 2030) aims to reverse the cycle of declining ocean health caused by intense human activity during the Anthropocene [1]. Coral reef ecosystems…

[Line 51] replace “predator outbreaks” by “coral predator outbreaks” (I think you mean Acanthaster outbreaks here…); replace “biological invasion” by “biological invasions”

[Lines 59-60] Mesophotic ecosystems are not just in tropical and subtropical regions, they are also in temperate regions. Their depth range is also variable and defined by light penetrance. The deeper limit of mesophotic reefs is defined by 1% of the light measured at the surface. Even in the tropics the deeper limit of mesophotic reefs can be beyond the 150m. Consider: Bell et al. 2022. Global status, and management of rocky temperate mesophotic ecosystems. Conserv Biol. 2022 May 19:e13945. doi: 10.1111/cobi.13945.

[Line 65] replace “particulars” by “particularity” or “uniqueness”

[Line 69] it is never explained what these areas of geomorphological diversity are.

[Line 68] remove “investigative” 

Merge paragraphs 2 and 3 as they are on the exact same subject and this way you avoid repeating information on the same subject.

In the last paragraph of the introduction, you should clearly state the objectives of the paper. Something like: 1. Identify and characterize highly diverse geomorphological mesophotic habitats; 2. characterize the fauna and flora of these mesophotic habitats; 3. Provide a brief description of these mesophotic ecosystems and provide new species records for these areas.    

Methods

Describe not only the location but also how many BRUV, ROV, Transects you did. Ideally in your tables you can detail which species were detected with each method (which you do); and then compare it (which you don’t) - this way you justify WHY you used different approaches. 

Beyond the mean, max and min values for each method per site consider providing cumulative species curves to compare methods and determine if your sampling effort was adequate. 

It might be worth looking into how geomorphological diversity relates to biodiversity

Results 

why don’t you provide a DEM for Area3?

Discussion

In the discussion there are sentences [lines 335-337] that do not have references associated to them and they must. 

Additionally:

Figure 2. Numbers meaning is not clear (e.g., Jarapatinga – 2 sites in text but 1 in map). Also, the eleven sectors are not recognizable, just nine. I guess that red stars are the two remaining, but these are missing in legend. I would also point out Areas 1-3 in the small rectangles.

Tables 1 and 2. Is this previous knowledge? I would include a depth range. From max depths reported here, there are no new records, as all values overpass the sampled depth. But maybe, some taxa were not known at intermediate depths. Also, “Benthic cover record” in title of table 1 but only included scleractinians and sponges.

Figure 7. Names in italics.

Author Response

All comments attached at the rebuttal letter.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript by Pereira et al., deals with the mapping of the extensivemost MPA of the Brasil focussing on its mesophotic environments.

I found the manuscript of a certain interest for general audience.

Comments are in the uploaded pdf. Please pay attention to the species names often in regular instead italics.

I wonder a new section illustrating the new geological/geomorphologiacal results that the authors discuss briefly.

I reccomend moderate revision.

Comments for author File: Comments.pdf

Author Response

All comments attached at the rebuttal letter.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Make sure the answers to my concerns are also clarified in the paper (the readers might have the same questions when they read your paper); for example: From the title it sounds like the MPA already includes mesophotic reefs, but from the discussion it sounds like the mesophotic reefs have an undetermined status (no-take?) Response: The area that corresponds to the mesophotic reefs explored in the study is outside the “no-take” areas of MPA Costa dos Corais, which has these areas only in the shallow portion of its territory. The mesophotic reefs studied herein are known in the MPA management plan as “multiple use areas”. 

Also there are still spelling mistakes in the text (I am not sure I found them all) which you need to carefully review before resubmitting. 

While the acceptance of this ms does not hinge on there being a more quantitative analysis of your data, and potential comparison with other published data, I think you would have broadened your reader audience if you had included them. Even if you are using distinct methodologies to access communities you can use relative frequencies (and mention the potential limitations of your comparison). 

Comments for author File: Comments.pdf

Author Response

Make sure the answers to my concerns are also clarified in the paper (the readers might have the same questions when they read your paper); for example: From the title it sounds like the MPA already includes mesophotic reefs, but from the discussion it sounds like the mesophotic reefs have an undetermined status (no-take?) Response: The area that corresponds to the mesophotic reefs explored in the study is outside the “no-take” areas of MPA Costa dos Corais, which has these areas only in the shallow portion of its territory. The mesophotic reefs studied herein are known in the MPA management plan as “multiple use areas”. 

Thanks for the wise comment. 

We have now included most of the answers for your comments on the paper to make it clear for the readers. For instance, “While this MPA is the largest in the Brazilian coast, with more than 120 km of coastline, little protection is provided for mesophotic habitats. Currently, the area that corresponds to the mesophotic reefs explored in the study is outside the “no-take” zones of MPA Costa dos Corais. The mesophotic reefs studied herein are known in the MPA management plan as “multiple use areas” allowing fishing activities. Hence, we reinforce the ecological importance of those habitats and the need for full protection.”

Also there are still spelling mistakes in the text (I am not sure I found them all) which you need to carefully review before resubmitting. 

An additional English review was performed on the paper for all the authors and a native English speaker to solve all the spelling mistakes in the text.

While the acceptance of this ms does not hinge on there being a more quantitative analysis of your data, and potential comparison with other published data, I think you would have broadened your reader audience if you had included them. Even if you are using distinct methodologies to access communities you can use relative frequencies (and mention the potential limitations of your comparison). 

We do understand and agree with your comments, however, as previously mentioned different methodologies and different experimental design will make those comparison biased with the present data. Therefore, this is the reason we do not included those comparison on the present ms. We are getting back to the field soon to collect more data and prepare more robust comparisons that would generate another ms in the future. Your comments towards those comparisons will be properly addressed and remembered. Thanks!

Reviewer 2 Report

Congrats to the authors.

Author Response

Dear Reviewer,

Thanks for the kind feedback and constructive criticism on our ms.

Another detailed English review has been performed on the ms to improve English language and style.

We are pleased to have our study improved and published at Diversity.

Best.

Pedro

Pedro