Review Reports - Inventory of the Ichthyofauna of the Mpem and Djim National Park (Center, Cameroon) Provides Baseline Data for a Conservation Project

Round 1

Reviewer 1 Report

The study is interesting but must be restructured based on the main objective, whether it is an inventory and its conservation status or an ecological study (due to the inclusion of diversity and similarity indices). If it is the second option, analyzes should be included that allow assess the impact of the environmental parameter on the fish richness and abundance

Comments for author File: Comments.pdf

Author Response

Diversity_1960931

October 31^th, 2022

Author responses to Reviewer 1 (R1)

Dear Referee,

I am pleased to resubmit our revised manuscript Diversity_1960931 entitled “Inventory of the ichthyofauna of the Mpem and Djim National Park (Center, Cameroon) provides baseline data for a conservation project” with revisions.

The authors (A) have considered all of the suggestions done by the referee R1 and incorporated the requested changes.

Authors responses to R1 general comments:

General comment: The study is interesting but must be restructured based on the main objective, whether it is an inventory and its conservation status or an ecological study (due to the inclusion of diversity and similarity indices). If it is the second option, analyzes should be included that allow assess the impact of the environmental parameter on the fish richness and abundance.

A: The authors have considered that this study is the first one realized in the MpDNP, with the principal objective being an inventory and evaluation for the conservation status of the different species found there. However, given the overall framework in which this study is being conducted (characterization of the MpDNP because of planned ecological compensation measures), it is useful to characterize the communities. An insufficient number and detail of environmental parameters was collected to allow for a detailed analysis of the factors influencing richness, abundance and diversity in the study area.

Authors responses to R1 specific comments:

L28: Please review the concept of endemic vs native species. The former include species exclisivo of a geographic region. I do not if it is the case?

A: In this manuscript, we considered endemic species as those that are restricted to the Sanaga basin and do not occur naturally in any other part of the world while native species are those indigenous in this basin (but also present outside of the basin) and resulting of only local natural evolution (without human intervention/introductions). According to the references available [11] [21], at least 169 freshwater species are reported in the Sanaga basin including at least 163 native species (24 of them are endemic) and at least one non-indigenous species.

L56: check if the journal allows this type of citation or reference

A: Checked. The journal allows this type of citation [4]

L61: include reference of the IUCN used here

A: This category is not applied to the study area, so it is deleted.

L65: does not include species mentioned by IUCN?

A: It is included

L87: references?

A: Done: [5,6]

L90: River?

A : Ok, corrected

L166-168: Indicate references that support your argument. Otherwise, the category that corresponds to them according to the IUCN List should be applied and it should be discussed why said category does not apply to the study area, if that is the case.

A : Ok, reference [6] is added

L170: reference?

A : Added: [5]

L183: ok, but what does means a or b?

A: a, b and c are the letters used to compare results obtained with the statistical pair-wise comparison test for each parameter measured in different localities. Consequently, one or two letters can be reserved for one seasonal sample depending of number of times this sample is different or equal to others. For the sampling site comparisons, values assigned with different letters in a given column are statistically different and those with the same letter are not different from the 5% threshold; no letter was indicated for seasonal comparisons as they were not statistically different (in any of the sampling sites).

L190-193: write the details of each family separately and avoid confusing reading

A: Ok it is done

Figure 3: Number

A: Ok, corrected

Table 3: see comments above

A : Please see the author comment above concerning concept of endemic species used in this manuscript. All the species considered as endemic to the Sanaga River basin are referenced at least by [17] and [21].

Table 3: Authors should mention to which species of this genus it is related. Mus be removed from the list

A : The authors think that this undetermined species is different from all others inventoried in the study site and from all species of the same genus referenced in the basin. In this case, the undetermined species can be taken into account in the specific richness and diversity indexes calculations as reported in the same journal by Kitio [4], although the species may be described later.

Table 3: This could correspond to any other species of the genus of which several are reported, unless the author considers that it could be a taxon not recorded before or that it could correspond to a new species. Must be removed from the list

A : See comment above

L207: insert lines above and below

Corrected

L220-221: as well as the Pielou´s index

A : Ok, it is taken into account by adding that the ichthyofauna was less diverse and aggregated in the Mvouring River during the rainy season

L 225: to discussion

A : The Mpem and the Djim Rivers have in common a high rate (60%) of inventoried species, which could be explained by the fact that the Mpem River is the main tributary of the Djim River and the habitats of these two rivers are physiochemically closer to each other than with their respective sub-tributaries (Mey and Mvouring).

L228: indicate that the values are in percentage of similarity and highlight the maximum and minimum

A: It is added in legend that these values are expressed as percentage of similarity. Nevertheless, the authors think that the maximum and minimum values should not be highlighted to save same style with other tables that show maximum and minimum values in the manuscript

L230-239: this is fine, but the study does not show any analysis that allows evaluating the effect of environmental variables on the richness and abundance of fish species, that allow to refute or confirm what has been established in other studies

A: The authors added more habitat description and anthropogenic pressure in material and methods; although no multivariate analysis is done, this allows to discuss the potential effects of environmental variables and pressures

L242-252: This paragraphps should be included after assessment of fish inventory

A : Ok, it is done

L254: should be removed from the list or discuss its inclusion

A: As explained above, the authors think that these two undetermined species are different from all others inventoried in the study site and from all species of the same genus referenced in the basin. They may be new species to described later. In this case, the undetermined species can be taken into account in the specific richness and diversity indexes calculations as reported in the same journal by Kitio [4], although the species may be described later.

L259-264: If these species were not registered, why mention this and try to discuss their absence with vague arguments? Another thing would be to discuss what they have been recorded in the area and the possible causes of why they did not appear during the study.

A: The species rarefaction curve is added in the results. It allowed us to hypothesize secondly that a possible sampling bias may have contributed to their absence in the samples

L269: these data and their respective analysis are not included

A: Ok, deleted

L269: what species? Include their name here

A : The two names (O. niloticus and C. gariepinus) are included

L270: Low abundances are not necessarily the result of being exotic species, since these species are generally highly invasive. Perhaps it is a consequence of the seasonality and/or the type of sampling and the selectivity of the fishing gear

A: Ok; taking into account.

L270: How the authors determined this?

A: The authors have experience feedback showing that these species generally have low abundances during all seasons, excepted in dam lakes [11].

L279: Really are endemics of this river basin? How was determined this conservation status?

A: At least the references mentioned [11,17,21] clearly show that these species are endemic in the Sanaga River basin.

L280-281: Confused!! Rare is not equal to endemic!!

A: For the authors, there is really not confusion, since these species are considered so longer as endemic in the Sanaga basin (see references cited).

Thank you,

The authors.

Reviewer 2 Report

Inventory of the ichthyofauna of the Mpem and Djim National 2 Park (Center, Cameroon) provides baseline data for a conservation project

In general a straightforward paper on the severely data deficient fish fauna of Cameroon, but could do with extra information/clarification, an overhaul for grammar and punctuation, and an edit which removes some of the more out of place statements regarding temperature/forestry etc. It is clear the paper is aiming to influence policy but the scope of the paper is only the fish fauna. The integrity of the riparian forests is important, but this paper does not explicitly look at any of that and the focus ought to be shifted.

Abstract

L29: Why were the non-natives surprising? – state which ones

Intro

L48: please change this phrase : “the situation of continental waters remains just as worrying” to something else more along the lines of inland waters or freshwater habitats being overlooked

Intro is missing a section on the relevance of freshwater fish conservation in the area, ie ecosystem services, cryptic diversity etc, as well as issues re hydropower and drought in the region

L76-81: these sentences need rephrased for clarity

Methods

Please clarify whether collections were made representatively across all species caught? Or was it just species which had died during collection?

Please clarify whether abundance data was measured? And whether this was standardised by catch per unit effort. Equally if abundance wasn’t measured, how can you calculate H and J?

L121: dead fish, not died fish

L122: change LS and LT to SL and TL throughout, this is more standard terminology

L130: please give indication of the refs 16,17 here as it doesn’t read well at the moment

The equations need to be built in equation builder and put on separate lines for readability and per journal requirements

L150: this is confusing, the jaccard similarity was conducted between stations, rather than survey events? Please clarify in text

Results

Please complete a rarefaction curve to assess sampling efficiency

Please provide abundance data

Please state whether the species are native or non native in the table

L190: replace for, with with

L201: strange phrasing in this line

L207: stand diversity analysis – stand? Check phrasing

Table 3: give SD for H and J

L214:index revealed, in general, the higher vaues – add the commas

L220-222: this is very vague, please specify which species, and also please consider that sampling efficiency is less in the rainy season due to increased habitat

L230-240: the conclusions from the paragraph are completely irrelevant from the results or purpose of the paper. Suggest toning it down and including at the end of the discussion and using para 2 to start. The temps of rivers in Africa are high because theyre linked to air temperature, this is an irrelevant statement, as are the rest of the sentences regarding temperature and fish growth. These are tropical species adapted to these temperatures, their growth curves are in line with this

L241: rephrase this sentence for readability

L248: this is fine, but please refer to the flood pulse concept to frame the assertions

L255: please add punctuation to this sentence

L264: if you conduct a rarefaction analysis on the sampling efficiency you can comment more accurately on whether they were missed or whether they may be extirpated

L266: please comment on the possible invasion impacts of the non natives

Author Response

Diversity_1960931

October 31^th, 2022

Author responses to Reviewer 2 (R2)

Dear Referee,

Authors responses to R2 general comments:

In general, a straightforward paper on the severely data deficient fish fauna of Cameroon, but could do with extra information/clarification, an overhaul for grammar and punctuation, and an edit which removes some of the more out of place statements regarding temperature/forestry etc. It is clear the paper is aiming to influence policy but the scope of the paper is only the fish fauna. The integrity of the riparian forests is important, but this paper does not explicitly look at any of that and the focus ought to be shifted.

The authors (A) have considered all of the suggestions proposed by the referee R2 and incorporated the requested changes.

Authors responses to R2 specific comments:

L29: Why were the non-natives surprising? – state which ones

A: Their presence in this park is surprising because in the Sanaga basin they are usually found around the man-made lakes, fish ponds and floodplains. For the authors, their presence in the MpDNP relatively well-conserved is surprising, of course.

L48: please change this phrase: “the situation of continental waters remains just as worrying” to something else more along the lines of inland waters or freshwater habitats being overlooked

A: Sentence modified

Introduction is missing a section on the relevance of freshwater fish conservation in the area, ie ecosystem services, cryptic diversity etc, as well as issues re hydropower and drought in the region

A: Added to the previous sentence for general overview in continental waters; the pertinent ones observed in the MpDNP in particular were already added below in the introduction

L76-81: these sentences need rephrased for clarity

A: Rephrased

Methods: Please clarify whether collections were made representatively across all species caught? Or was it just species which had died during collection?

A: Yes, all collections made (live or dead fish) were registered. To be more clear, we have specified in the text that the living specimens caught but unidentified in the field were immediately anaesthetized with phenoxyethanol and stored in the 10% formalin to be further processed in the laboratory with others fishes caught that were already dead.

Methods: Please clarify whether abundance data was measured? And whether this was standardised by catch per unit effort. Equally if abundance wasn’t measured, how can you calculate H and J?

A: Yes, the number of specimens caught and weighed were measured as abundance data; the first parameter has been used to calculate relative abundance of each species (see Table 3) which have been used to estimate Shannon and Pielou indices. The authors state that the objective of this paper was not to study abundance per site, nor was the objective to evaluate catch per unit effort per se, but only in so much as to allow for a calculation of Shannon and Pielou diversity indices

L121: dead fish, not died fish

A: Corrected

L122: change LS and LT to SL and TL throughout, this is more standard terminology

A: Corrected

L130: please give indication of the refs 16,17 here as it doesn’t read well at the moment

A: Corrected

L130: The equations need to be built in equation builder and put on separate lines for readability and per journal requirements

A: Done

L150: this is confusing, the jaccard similarity was conducted between stations, rather than survey events? Please clarify in text

A: Clarified (similarity among stations)

Results: Please complete a rarefaction curve to assess sampling efficiency

A: The species rarefaction curve is completed.

Results: Please provide abundance data

A: Yes, number of specimens caught and weight were measured as abundance data; the first parameter has been used to calculate relative abundances (see Table 2) which have been used to estimate Shannon and Pielou indexes. The authors state that the objective of this paper was not to study abundance per site. There was noreal objective to evaluate catch per unit effort per se (it was a fish inventory/diversity study), but only in so much as to calculate Shannon and Pielou.

Results: Please state whether the species are native or non native in the table

A: Done in table 3

L190: replace for, with with

A: Rephrased

L201: strange phrasing in this line

A: Rephrased

L207: stand diversity analysis – stand? Check phrasing

A: Rephrased

Table 3: give SD for H and J

A: SD are added, except for stations with sample data less than 3

L214: index revealed, in general, the higher values – add the commas

A: Rephrased

L220-222: this is very vague, please specify which species, and also please consider that sampling efficiency is less in the rainy season due to increased habitat

A: Rephrased with adding the four species concerned (E. martorelli, E. aspilus, S. rebeli and H. odoe)

A: Discussion is restructured and this paragraph is rephrased and toning down at the end of the discussion

L241: rephrase this sentence for readability

A: Rephrased and move above early in the discussion

L248: this is fine, but please refer to the flood pulse concept to frame the assertions

A: Ok, this concept is taken into account and the paragraph concerned is moved to and re-structured. To be more exhaustive secondly hypothesized that a possible bias related to the low number of samples (only one site was sampled in both seasons in Mvouring River) may be considered.

L255: please add punctuation to this sentence

A: Rephrased and move above early in the discussion

L264: if you conduct a rarefaction analysis on the sampling efficiency you can comment more accurately on whether they were missed or whether they may be extirpated

A: Done.

Thank you,

The authors.

Reviewer 3 Report

In this article, the authors provide an interesting snapshot of the fish community in a protected area in Cameroon, useful for management and conservation purposes.

I found the work well done and well written, and I believe it could already be published in the present form.

I would only suggest that the part on environmental parameters should be expanded slightly.

For example, the authors could add information on the inter-annual variability of environmental parameters (with graphs or tables added to the manuscript or as supplementary materials). Also, if I understand correctly, the authors tested the differences between the mean values of environmental parameters, but it might be interesting to assess whether significant differences also exist between the dry and rainy seasons.

I would also change the caption of figure 2. In my opinion, this is not a frequency distribution, but rather the percentage abundance of the different orders (in terms of number of species) that form the fish community under investigation.

Author Response

Diversity_1960931

October 31^th, 2022

Author responses to Reviewer 3 (R3)

Dear Referee,

The authors (A) have considered all of the suggestions done by the referee R3 and incorporated the requested changes.

Authors responses to R3 general comments:

I would only suggest that the part on environmental parameters should be expanded slightly.

A: Ok, done

Authors responses to R3 specific comments:

add information on the inter-annual variability of environmental parameters (with graphs or tables added to the manuscript or as supplementary materials).

A: The objective of this study was to study the overall fish composition of these rivers (first study in this region) and given that not all sampling sites were sampled in every season, interannual comparisons cannot be added at this stage.

Nevertheless Table 1 is added; it contains details of sampling stations, sampling points and frequencies or season. The sampling was seasonal and discontinuous.

Also, if I understand correctly, the authors tested the differences between the mean values of environmental parameters, but it might be interesting to assess whether significant differences also exist between the dry and rainy seasons.

A: In table 2, intra and interseason differences are tested. No significant variation was observed between seasons

A: Ok, corrected. Percentage abundance of the different orders.

Thank you,

The authors.

Round 2

Reviewer 1 Report

After reviewed the manuscript, I find that it has bee substantially improved. Thus, I consider that it will be publisable once the document can be edited.

Author Response

Diversity_1960931

November 3^rd, 2022

Author responses to Reviewer 1 (round 2)

Dear Referee,

I am pleased to resubmit again our revised manuscript Diversity_1960931 entitled “Inventory of the ichthyofauna of the Mpem and Djim National Park (Center, Cameroon) provides baseline data for a conservation project” with minor revisions.

The authors (A) have considered all of the suggestions done by the referee R1 (round 2) and incorporated the requested changes.

Authors responses to R1 (round 2) comments:

General comment: After reviewed the manuscript, I find that it has bee substantially improved. Thus, I consider that it will be publishable once the document can be edited

A: The authors would like to thank the Referee 1 for its helpful comments which allowed to improve the document.

Reviewer 2 Report

I have read through the comments and revisions and am largely happy with them.

I would still advise some comment on the abundance and gear in the discussion at least because each gear has a selectivity and the rarefaction curve is not plateaued - it is not a deficiency but it needs to be at least mentioned, especially as the diversity indices are calculated using it. Similarly, i would remove the statement about non natives being surprising, the two that were found - O. niloticus and C. gariepinus are extremely widespread and spreading even further across the continent - i do not find it surprising at all that they are in the basin, and in fact could be expanded on even more so. Especially re the authors comment that theyre usually found in the artificial systems (this is a stepping stone dynamic).

Regardless, i am satisfied with the edits, especially in the discussion - and the authors should be commended on the inventory as it is greatly needed

Author Response

November 3^rd, 2022

Author responses to Reviewer 2 (round 2)

Dear Referee,

The authors (A) have considered all of the suggestions proposed by the referee R2 (round 2) and incorporated the requested changes.

Authors responses to R2 general comments:

General comment: I have read through the comments and revisions and am largely happy with them.

A: Thank you.

Authors responses to R2 specific comments:

A: Ok, added (lines 347-350 and line 352).

“The fact that the species rarefaction curve is not plateaued could be explained also by gear selectivity; it is considered that each gear used has a selectivity, although the combination of these different gears aimed to reduce this selectivity [11]. We suggest that investigations continue over several years before concluding on their persistence or not in this protected area and estimating abundances by catch-weighted per unit effort”.

Similarly, i would remove the statement about non natives being surprising, the two that were found - O. niloticus and C. gariepinus are extremely widespread and spreading even further across the continent - i do not find it surprising at all that they are in the basin, and in fact could be expanded on even more so. Especially the authors comment that they’re usually found in the artificial systems (this is a stepping stone dynamic).

A: Ok, “surprisingly” is replaced by “furthermore” in the abstract (line 29).

The authors would like to thank the Referee 1 for its helpful comments which allowed to improve the document.