Spatiotemporal Variability in Fish Assemblages in a Coastal and Estuarine System in the Tropical Eastern Pacific during the Anthropause

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Why authors did decide to include in Abstract and Discussion some information about ENSO if this was not appropriately assessed? I recommend removing it.

Line 70, I suggest beginning a new paragraph with "In the Mexican North Pacific...

Line 81, I suggest including ...in the Urías esturarine system...(remove this).

In line 250, remove Posteriorly.

In line 256, remove Finally.

In the Discussion, I suggest to remove the ENSO parts.

In Table 1, the heading most include zone: Abundance (a) and biomass (b, g/m2 ) of the fish species in the Urías system from 2018 to 2021 per zone. EZ=Estuarine zone, SZ= Surf zone, T = total for systems combined and per zone. Also, I suggest to include a total per zone as columns.

Fig 1 is actually a map. So, I recommend the following captioning: Urias estuarine system located in the Mexican North Pacific.

I recommend to include a zoom out additional map of the Mexican Pacific Ocean to include the actual Fig. 1 as an inset for better illustrating the area with respect to the geographic location.

I recommend to have the manuscript reviewed for English grammar and style by professional help.

Author Response

Dear reviewer 

We have attended all your observations and made the suggested modifications to the MS.

In line 70, a new paragraph was started.

Line 81 the text was changed according to the reviewer´s suggestion.

In lines 250 and 256 the words were removed. 

The caption and Figure 1 were changed according to the reviewer's recommendation. 

Regarding Table 1, we have changed the caption according to the reviewer's suggestion and corrected a mistake in the figure caption, as the table already contains information on the total biomass and abundance of the fish species per zone. 

References to the ENSO were removed except in one part of the discussion because it is well-documented that a change from el niño to la niña occurred during that period. However, since this is not something we tested, we have eliminated this in the rest of the document. 

The text was reviewed by a colleague whose first language is english.

 

 

 

Reviewer 2 Report (New Reviewer)

The paper presents an exploration of the anthropause (due to COVID-19 pandemic) effects and spatiotemporal variability on the fish assemblages in coastal ad estuarine ecosystems in the Tropical Eastern Pacific. The paper is very interesting and well written and merits publication after minor revisions (see file attached).

Comments for author File: Comments.pdf

Author Response

Abstract

1. It could be appropriate to add what ENSO acronym means.

We included the meaning of ENSO

 

Key-words

2. The definition of GAM is Generalized Additive Models.

This was changed as suggested by the reviewer

 

Introduction

The introduction session is very well written; it is not too long and capture the attention of the reader, clearly stating what is the hypothesis of the authors.

 

Mat & methods

The section is very well written and the statistical basis used to analyse the data is very robust, applying different methodology to test the different hypotheses.

 

3. Row 96: please clarify how is defined a type II lagoon.

We have added a broader description of the characteristics of a type II lagoon

 

4. Rows 126-128 and 142-156: I suggest to more rows 126-128 before rows 142-156.

The rows were moved according to the reviewer's suggestion.

 

5. Row 258: put reference on Jaccard dissimilarity coefficient.

We have placed the reference for this coefficient

 

6. Row 201: it could be useful to include a sentence explaining the idea behind the estimator, e.g. that is used to estimate the number of species considering the possibility to find new species and taking into account the rare species, recalling the expression mentioned in the following sections “rarefaction model”.

We have included the idea behind the estimator in the sentence indicated.

 

7. Rows 250-255: it is not clear if the period was tested for all the response variables with GAMS. Maybe it could be stressed here because from the results can be understood that the period was tested only on the biomass.

Explanatory variables were specified in the M&M section:

 

8. Rows 250-255: The probability distribution assumed for the error and the link function need to be here indicated for completeness.

This was clarified in that part of the text:

“According to the behavior of the data, the binomial probability distribution was used with a logit link function (biomass, and hill numbers ¹D and ²D), and Gaussian with a natural logarithm link function in the case of species richness”

 

 

9. Row 263: reference reported twice.

We have removed the repeated reference

 

Results

1. Rows 280-282: the description of the results could be rephrased, highlighting that the salinity was found relevant during the COVID pandemic and the results show a separation of the surf zone and the other 2 zones in terms of salinity. The same for suspended sediments and temperature.

This part of the text was changed according to the reviewers suggestion

 

2. Row 377: the deviance explained reported in the text is 53% while in Table 2 is 58.3. How much deviance is explained by the Period? Considering that is not significant, it should be reported the model without Period also, to highlight the gain (I presume is very small) in explained deviance due to the inclusion of this variable in the model. Moreover, how many observations have been used for the GAM? This also should be indicated in Mat & Met; the few years available could explain why the Period is not significant for the GAM, while it is for the previous tests. GAM is very sensitive to the number of points used and this should be also recalled in the discussion.

The explained deviation was a typo that we have corrected to 58.3.

The paragraph was changed to better explain the difference between the model with and without the period factor:

 

The factors involved in the GAMS have already been clarified above in Mat & Met.

 

Discussion

1. Rows 422-423: how this can be explained? Maybe it could be due to the shortness of the time series analysed?

This part was rewritten indicating the shortness of the time series.

 

2. Row 492: maybe is written “analyses” instead of “analyzes”.

This was changed and corrected to be consistent in the whole text

 

References: all references are correctly recalled in the text.

 

Tables and Figures

1. Row 385 and Supplementary materials row 808: Table S4 should be Figure S4.

This was corrected

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

MAJOR COMMENTS
This is an interesting paper and I enjoyed reading it. I consider that it is a job worth published but with some major modifications.
Fundamentally, I believe that the biggest point to reconsider is the inclusion of the COVID-19 lockdown. In my opinion the authors need to include a better description related to the reduction of human activities in the study area. This description will support the question related to an increase in the diversity of the ichthyofauna associated to COVID-19 lockdown. For instance, the authors could include the numbers of landings in the study area of the main target fish species during 2018 and 2019 (pre-COVID). Additionally, the authors could improve this description with the information of bycatch fish species on those small-scale fisheries that operate in the study area. All this information related to human activities in the estuarine system of Urías should be included if the main objective is the impact of the closure of fishing activities on the diversity of the ichthyofauna.

SPECIFIC COMMENTS
Figure 1: It would be helpful if the authors include the same symbol of Fig 2 and 3 for the sampling station (Tidal channel, Lagoon, Surf zone).
I do wonder if is possible to include the spatial distribution of the different types of mangroves or the mangrove forest area on the map, considering the importance of this habitat in the results.

Figure 2: I suggest including the standard deviation as error bars of the estimator Chao 2.

Line 183: Please check the reference (24) for CPUE.

According to SIMPER, I suggest to mention the percentage of dissimilarities between tidal channel, lagoon and surf zone. Additionally, I suggest including in the results the percentage of dissimilarity between before and during COVID-19.

I recommend plotting the results of GAMs. The effect of the significant variables will be better explained if the authors include a figure with these results.

Table 2: This Table could be included in the supplementary information

Table S1 is not referred to within the text

For further studies I strongly recommend the used of remote underwater video cameras (for instance, BRUVs or stereo-BRUVs) instead of sacrificed the specimens. I understand the logistic limitations related to use theses techniques in areas such as surf zone. However, in estuarine systems these non-invasive methods work well even with low visibility.

Reviewer 2 Report

·      The objective is not clearly established.  What do authors refer to “observed changes in fish assemblages”? How do authors distinguish between “reduction of human activities” and “climate events”? Which components of the fish assemblages were surveyed? Biomass, diversity, density, abundance? These are not mentioned in the objective. However, authors mention the hypothesis that “closure of fishing due to COVID-19 led to increase in fish diversity and biomass, but I expect a better-established objective. Then I am concerned of the geographic location of the work. In title nothing is mentioned nor in the objective, but only in the abstract I leant that the work was done in the Mexican North Pacific. For instance, in the abstract authors mention fish composition, biomass and diversity but never mention if fish species are of commercial importance. I assume these species are. Also, in the objective authors never mention the calculation of alpha and beta diversities.

·      How the results obtained can discriminate effects of COVID-19 and ENSO? Which climate change factors were analyzed and compared? I do not see any robust comparison in the abstract.

·      I consider a throughout review is needed in the introduction addressing potential effects of the COVID-19 lockdown and also in the potential effects derived from climate change. I consider as it stands, the Introduction of the manuscript is way too superficial.

·      What is the rationale behind the study design in relation to location selection in the estuary? It appears to be a traditional survey to describe metrics of fish assemblages in relation to environmental variables.

·      Why did authors decide using a Principal Coordinate Analysis instead of a Canonical Correspondence Analysis?

·      I do not find any study design in which authors are comparing indicators before and after COVID-19.

·      Procedures conducted were just simply to analyze the components derived from fish assemblages.

·      In Results, in the subsection of environmental data, nothing is mentioned on any comparison related to climate change in any given geographic area. In the subsection analysis of fish assemblages, no specific results derived from any comparisons between before and after COVID-19 is mentioned but just lines (321-323) in which authors indicate “these abiotic and biotic variables presented differences between years before and during COVID-19…”. However, this assertion is out of context and unclear.

·      Just until lines 339 and beyond authors mention something of the COVID-19 but it is not clear since in methodology no design was implemented.

·      In the first paragraph of the Discussion, authors claimed that “Our study is the first comparison of fish assemblages in a tropical estuarine system before and during COVID-19. However, no study design was clearly established and it is not clear which comparisons were relevant and outcomes emerged.

·      For instance, authors mention in lines 411-413 , “Multivariate results indicated that changes occurred in the studied area before and during the COVID-19 pandemic, specifically in temperature, total matter suspended, and salinity..” However, which changes authors refer to? High, low, medium? And respect to what?

·      Another unclear expression (lines 439-440) “Multivariate analyses allowed us to determine the fish assemblages were clearly different between the estuarine zone and the surf zone…”. However, which differences the authors refer to? In species composition, biomass? Which were high or low?

·      Just until lines 469 and beyond it is that authors began addressing small-scale fisheries when nothing about the commercial importance of surveyed fishes was mentioned. Also, authors began addressing ENSO “as was likely the case of the observed differences in the environmental variables” when authors never attempted to compare anything.

·      As it stands the manuscript is not addressing the COVID-19 lockdown effects on fish assemblages nor the climate change either. So, I am afraid I recommend rejection.

Reviewer 3 Report

The manuscript is prepared at a high level, the taxonomic composition of fish is indicated, the presentation of data is at a high level.

 

According to a number of other publications, the dependence of changes in the diversity of vertebrates in general on the consequences of the COVID-19 pandemic (Kostina et al., 2021) was also not revealed, in contrast to a long-term reduction in human activity, for example, pain in the territory near the Chernobyl accident (Steinhauser et al., 2014), where the number of faunal complexes increased a number of rare animal species and diversity.

At the same time, in general, the share of ecosystem services is low (Rozenberg, 2021), in the case of fishing.

I recommend the authors to finalize the article "Temporal variability of fish aggregations in the neotropical estuarine system: climate versus the consequences of the COVID-19 pandemic" (diversity-2320654). taking into account the comments of the first reviewer. Actually, there are no comments to the presented material. Any comments (literature analysis?) to formulate the problem and determine the causes.   The distinction between anthropogenic impact and the effects of climate change is a global problem, but here we are dealing with the factor of "reduction of fishing".   The problem of the impact and consequences of COVID-19 in the aspect of short-term cessation of economic activity is relevant, since longer periods of "savagery" are better known - Fukushima, Chernobyl. The problem is new and there are very few publications.   As they say, "It's easy to draw a devil, it's hard to draw a tiger!"

Note:

Kostina, N. V. Spatial Distribution of COVID-19 Under the Influence of Environmental Factors: Correlation and Regression Analysis / N. V. Kostina, R. S. Kuznetsova, G. S. Rozenberg // IOP Conf. Series: Earth and Environmental Science 818, Togliatti, 28–30.04.2021. – Bristol: IOP Publishing, 2021. – P. 12023. – DOI 10.1088/1755-1315/818/1/012023..

Steinhauser, G. Comparison of the Chernobyl and Fukushima nuclear accidents: A review of the environmental impacts / G. Steinhauser, A. Brandl, T. E. Johnson // . – 2014. – Vol. 470-471. – P. 800-817. – DOI 10.1016/j.scitotenv.2013.10.029.

Rosenberg, A. G. Modeling Management of Recreation and Tourist Resources (Samara Oblast Tourism Development Strategy) / A. G. Rozenberg // IOP Conf. Series: Earth and Environmental Science 818, Togliatti, 28–30.04.2021. – Bristol: IOP Publishing, 2021. – P. 12039. – DOI 10.1088/1755-1315/818/1/012039.

 

I recommend it for publication.