Fish Larval Assemblage Associated with an Eastern Tropical Pacific Coral Reef: Seasonal and Interannual Variability

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments

 

This study systematically evaluated the temporal variations in the structure, species richness, diversity, and similarity of fish larval assemblages associated with the Eastern Tropical Pacific (ETP) coral reef system, using data collected from 2017 to 2019. The research is significant as it not only expands the understanding of fish larval species in the study area (increasing the reported taxa to 162) but also highlights the substantial influence of seasonal changes on fish larval assemblages. These findings provide essential baseline data for understanding species dynamics within coral reef ecosystems, supporting ecological conservation and management initiatives.

 

While the study presents valuable data and insights, there are significant issues in both content and writing that need to be addressed to meet publication standards. Below are detailed suggestions for improvement:

 

Abstract

1. The introduction mentions three problems to be addressed in the study; however, these are not fully reflected in the abstract, particularly the third question concerning the main factors influencing fish larval assemblages. This should be clarified.  

2. Line 17: The letter "P" should be italicized. Ensure this revision is applied throughout the text.

3. Line 18: The letter "R" should also be italicized. Ensure this is consistently corrected throughout the text.  

4. Line 32: Add a period after “[1,2,3].” Similar errors should be checked and corrected throughout the manuscript.

5. Line 72: Remove the period. Similar issues should be reviewed and corrected throughout the text.

 

Results

1. Line 177: The unit “ind/100 m3” should be revised for consistency and clarity. Other units in the manuscript should also be standardized accordingly.

2. Lines 179–182: Provide a detailed analysis of the differences in species composition between March and September. If the differences are significant, they should be analyzed separately to derive more meaningful conclusions.

3. Line 205: Add explanatory notes to Figure 4 to clarify what the numbers in the graph represent (e.g., stations?).

4. Line 221: In Section 3.3, six environmental factors are mentioned, but only three are described in Section 3.2. Explain this discrepancy. Additionally, clarify why salinity was not included in the CCA analysis in Section 3.3.

5. Table 5: Define what “UPS” refers to in the table.

6. Figure 5: Explain why salinity is not included in this figure, even though it is a critical environmental factor. The lack of clarity is confusing.

 

Discussion

1. The manuscript lacks a discussion of the environmental impacts on fish larvae. Consider integrating an analysis of how environmental factors influence larval dynamics.

2. The conclusion section should directly address the three key questions raised in the introduction. Instead of reiterating the discussion, the conclusions should be clearly structured to summarize findings for each question separately. Revise and refine this section accordingly.

 

References

1. The references contain numerous errors, including inconsistencies in the placement of publication years, missing page numbers, and formatting issues. Conduct a thorough review and correction of the reference list to meet journal requirements.

 

Author Response

Abstract

Comments: The introduction mentions three problems to be addressed in the study; however, these are not fully reflected in the abstract, particularly the third question concerning the main factors influencing fish larval assemblages. This should be clarified.  

Response: Abstract was re-writing.

Comments: Line 17: The letter "P" should be italicized. Ensure this revision is applied throughout the text. Line 18: The letter "R" should also be italicized. Ensure this is consistently corrected throughout the text. Line 32: Add a period after “[1,2,3].” Similar errors should be checked and corrected throughout the manuscript. Line 72: Remove the period. Similar issues should be reviewed and corrected throughout the text.

Responses: We agree with the suggestions and incorporate them in the text.

Results

Comments: Line 177: The unit “ind/100 m3” should be revised for consistency and clarity. Other units in the manuscript should also be standardized accordingly.

Response: We agree with the suggestion and modified the units.

Comments: Lines 179–182: Provide a detailed analysis of the differences in species composition between March and September. If the differences are significant, they should be analyzed separately to derive more meaningful conclusions.

Responses: Lines 177-178: Larval density (ind/100 m3) between the study periods did not show significant differences, except between March and September 2018.

Comments: Line 205: Add explanatory notes to Figure 4 to clarify what the numbers in the graph represent (e.g., stations?).

Response: We agree with the suggestions and incorporate the information.

Comments: Line 221: In Section 3.3, six environmental factors are mentioned, but only three are described in Section 3.2. Explain this discrepancy. Additionally, clarify why salinity was not included in the CCA analysis in Section 3.3.

Response: The salinity was included in the analysis.

Comments: Table 5: Define what “UPS” refers to in the table.

Response: We agree with the suggestion and define PSU

Comments: Figure 5: Explain why salinity is not included in this figure, even though it is a critical environmental factor. The lack of clarity is confusing.

Response: The salinity was included in the analysis.

Discussion

Comments: The manuscript lacks a discussion of the environmental impacts on fish larvae. Consider integrating an analysis of how environmental factors influence larval dynamics.

Response: We consider that we carry out analyses (CCA) that integrate the impact of environmental conditions on the abundance of the fish larval assemblage, an issue that we address in the discussion section, where we not only talk about the environmental impact but also other forcing factors in the dynamics of fish larvae such as surface circulation, food availability, reproductive events, among others.

Comments: The conclusion section should directly address the three key questions raised in the introduction. Instead of reiterating the discussion, the conclusions should be clearly structured to summarize findings for each question separately. Revise and refine this section accordingly.

Response: We consider that throughout the document we answer the three questions raised in the work, specifically in the conclusions section we answer it in the following way:

(1) Does ichthyoplankton abundance and community structure differ among the intra-annual contrasting oceanographic periods described for this region? (2) Is the structure of the fish larval assemblage similar on an inter-annual scale?

Lines 358-365: The composition and structure of the fish larval assemblage in all evaluated periods were different and specific for each period. However, a tendency was observed for them to group together or be more similar between the climatic and oceanographic periods described for the study area (cold and warm seasons). This suggests that the intra-annual variation has a greater effect on the fish larval assemblages, where it is evident that the cold period (March) presents better conditions for the fish species to carry out their spawning season; and subsequently there is a higher larval density in the la Azufrada coral reef.

(3) What are the main environmental factors affecting the abundance and community structure of fish larvae in this coral reef formation?

Lines 368-369: “..and particularly the cold season (higher salinity and low dissolved oxygen), have a greater effect on the assemblage of fish larvae..”

References

Comments: The references contain numerous errors, including inconsistencies in the placement of publication years, missing page numbers, and formatting issues. Conduct a thorough review and correction of the reference list to meet journal requirements.

Response: We agree with the suggestion. All references were revised and corrected.

Reviewer 2 Report

Comments and Suggestions for Authors

The experiment is well-designed the data are good and well-represented in many parts of the manuscript. The article is dealing with the larval stages of reef fish in eastern tropical pacific which is a difficult group of organisms since they are very hard to sample, to identify and to standardize their data. Authors did a big effort for three years to study the larval fish community in the area and the work fruited good results indeed. Although the methodology is clear and I am sure it was appropriately applied, it needs to be clarified and re-phrased in the manuscript. many basic information are missing as embedded in the attached pdf. The same could be mentioned about the results where many basic information are missing in the manuscript such as the dominant species in each season, the average size of the collected larvae.

The ecological niches of the recorded species could help understand the dynamics of fish larvae in the area and whether they are demersal or pelagic spawners

 

Attention should be paid to the text more than to the methodology.

Comments for author File: Comments.pdf

Author Response

Abstract

Comments: Please give information about the methods of larval fish sampling, the net used, the mesh size, the duration of haul, the depth at which the hauls were taken?.

Response: We agree with the suggestion and incorporate in line 17-18

“..Fish larvae were collected by daytime and nighttime surface trawls, using a bongo net 30 cm in diameter and 180 cm in length, equipped with mesh sizes of 300 and 500 μm. “

Comments: The first time you mention the species please give the full name of the species

Response: We agree with the suggestion and modified the name of the species

Introduction

Comments: is the COP is a part of ETP? Why did you consider them as different water bodies?

Response: Geographically, the Colombian Pacific Ocean is part, together with the Panamanian Pacific Ocean, of the region called Panama Bight. This region, located at the eastern end of the Eastern Tropical Pacific, is under the seasonal influence of the Panama upwelling process, which causes the entry of subsurface water with high salinity, low temperature and low oxygen concentration to the surface at the beginning of the year (February - April), which affects the oceanic and neritic environment of the region. In addition, between May and January, precipitation records increase in the region, which increases the flow of the numerous rivers that flow into this area, where annual precipitation (concentrated in this period of the year) can exceed 4,500 mm on average in the coastal area of the Colombian Pacific, which leads to lower salinity in the neritic zone. These particular hydroclimatological and oceanographic characteristics lead to the Panama Bight region (including the COP) exhibiting extreme environmental conditions for the development of marine ecosystems such as coral reef formations.

 Comments: Please state the hypothesis of the study and how will you achieve this hypothesis

Response:  Hypothesis was included in Line 68 - 70

 Materials and Methods

Comments: I recommend dividing this section into subsections, unless it is the rule of the journal, to make it easy for the reader: study area, field work, water sampling, ichthyoplankton sampling, lab work, data analysis

Response: We agree with the suggestion and incorporate subsections.

Comments: how many plankton samples were taken? were there any replicates? in the Bray-Curtis cluster there are 54 samples...you must mention here how many samples were taken and analyzed

Response: A total of 108 samples were collected and no replicates were performed. For the analysis of the information it was followed: to reduce the effect of day and night variation in the structuring of the data matrix of fish larvae in the water column of the La Azufrada coral reef, the day and night records made during each sampling campaign were taken together. In addition, the information obtained with the 300 μm and 500 μm nets was consolidated, assuming that they were complementary sources of taxonomic information [53].

Comments: it is preferred to fix in buffered formalin by adding sodium borate to the solution

Response: We use sodium tetraborate (Borax) to buffer formalin.

Results

Comments: Some basic data is missing in this section such as the dominant species and rare species in the area. The size of the collected larvae could give good insights on the spawning time and spawning area which is valuable for the management purposes.

The addition of the table of the species and their abundance is significant.

Response: We agree with the suggestion and incorporate the information in line 172-179. The taxonomic list of fish larvae collected during this study was related in table A1 (appendix). Moreover, the abundance was yet reported in:  Gallego-Zerrato, J. J., Córdoba-Rojas, D. F. y Giraldo, A. (2023). Composición taxonómica de las larvas de peces en el arrecife coralino de La Azufrada, Pacífico colombiano, entre 2017 a 201 Bol. Cient. Mus. Hist. Nat. Univ. Caldas, 27(2), 245-261. https://doi.org/10.17151/bccm.2023.27.2.14

Comments: what is the difference between composition and structure? is it better to use only one of them? if you will use the two words please clarify what each word refers to in your larval assemblages.

Response: We agree with the suggestion and to avoid confusion we will use only the term composition.

Comments: This is not related to Figure 4?? you are taking about the structure and distribution of each group while the figures refers to the monthly and annual samples!!

Response: Figure 4 shows the groupings made by month and year, which is what is described in the previous text, where all the groups formed and the species that had the highest percentage in the formation and distinction of each grouping are mentioned.

Comments: I recommend to add the table of the larval fish and abundance in each season and year in side the manuscript rather than the supplementary material

Response: The taxonomic list of fish larvae collected during this study was related in table A1 (appendix). Moreover, the abundance was yet reported in:  Gallego-Zerrato, J. J., Córdoba-Rojas, D. F. y Giraldo, A. (2023). Composición taxonómica de las larvas de peces en el arrecife coralino de La Azufrada, Pacífico colombiano, entre 2017 a 201 Bol. Cient. Mus. Hist. Nat. Univ. Caldas, 27(2), 245-261. https://doi.org/10.17151/bccm.2023.27.2.14

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author has made some improvements in response to the issues I previously raised, such as revising the abstract and correcting writing errors. However, the key issues affecting the publication of the article have not been adequately addressed.

In the CCA analysis, the author only performed a correlation analysis between environmental factors and the axes, without conducting any statistical tests. Typically, statistical tests are necessary to further validate the reliability of the results (e.g., p-values, etc.).

In the discussion section, the author touches on the influence of several environmental factors but provides minimal discussion on the key environmental factors highlighted in the results. This inconsistency may cause confusion. Are these environmental factors truly significant, and are they the key drivers?

In the main text (including tables and figures), the author presents two different descriptions of salinity. Are these based on the same dataset?

In the conclusion section, the author has made very few revisions. The current version reads more like a discussion rather than a conclusion. The conclusion should be more concise and specific.

Additionally, I have some confusion about the references, for example, why are references 1 and 2 combined into one?Additionally, I have some confusion about the references, for example, why are references 1 and 2 combined into one?

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files

Comments: The author has made some improvements in response to the issues I previously raised, such as revising the abstract and correcting writing errors. However, the key issues affecting the publication of the article have not been adequately addressed. In the CCA analysis, the author only performed a correlation analysis between environmental factors and the axes, without conducting any statistical tests. Typically, statistical tests are necessary to further validate the reliability of the results (e.g., p-values, etc.).

Response: The description of the CCA analysis results is rewritten, specifically presenting the significance (p-value) of the results. The table legend is improved, indicating the variables and measurement units. (lines 260-270

Comments: In the discussion section, the author touches on the influence of several environmental factors but provides minimal discussion on the key environmental factors highlighted in the results. This inconsistency may cause confusion. Are these environmental factors truly significant, and are they the key drivers.

Response: In the discussion section, the obtained result related to the variation in assemblage composition between the study periods (lines 299 to 313) is analyzed, and a relationship is presented with previous studies that have established a pattern similar to that described for the fish larvae assemblage associated with the La Azufrada coral reef, particularly related to environmental parameters (lines 314 to 320).

Lo, W.T.; Hsieh, H.Y.; Wu, L.J.; Jian, H.B.; Liu, D.C.; Su, W.C. Comparison of larval fish assemblages between during and after northeasterly monsoon in the waters around Taiwan, western North Pacific. Plankton. Res. 2010, 32(7), 1079-1095.

Sánchez‐Velasco, L.; Beier, E.; Godínez, V.M.; Barton, E.D.; Santamaría‐del‐Angel, E.; Jiménez‐Rosemberg, S.P.A.; Marinone, S.G. Hydrographic and fish larvae distribution during the “Godzilla El Niño 2015–2016” in the northern end of the shallow oxygen minimum zone of the Eastern Tropical Pacific Ocean. Geophys. Res. Oceans. 2017, 122(3), 2156-2170.

Franco-Gordo, C.; Godínez-Domínguez, E.; Suárez-Morales, E. Larval fish assemblages in waters off the central Pacific coast of Mexico. Plankton. Res. 2002, 24(8), 775-784.

Funes-Rodríguez; R.; Flores-Coto, C.; Esquivel-Herrera, A.; Fernández-Alamo, M.A.; Gracia-Gásca, A. Larval fish community structure along the west coast of Baja California during and after the El Niño event (1983). Mar. Sci. 2002, 70(1), 41-54.

Aceves-Medina, G.; Jiménez-Rosenberg, S.P.A.; Hinojosa-Medina, A.; Funes-Rodríguez, R.; Saldierna, R.J.; Lluch-Belda, D.; Smith, P. E.; Watson, W. Fish larvae from the Gulf of California. Mar. 2003, 67(1), 1-11.

Aceves-Medina, G.; Saldierna-Martínez, R.J.; Hinojosa-Medina, A.; Jiménez-Rosenberg, S.P.; Hernández-Rivas, M.E.; Morales-Ávila, R. Vertical structure of larval fish assemblages during diel cycles in summer and winter in the southern part of Bahía de La Paz, México. Coas. Shelf. Sci. 2008, 76(4), 889–901.

Hsieh, H.Y.; Lo, W.T.; Chen, H.H.; Meng, P.J. Larval fish assemblages and hydrographic characteristics in the coastal waters of southwestern Taiwan during non-and post-typhoon summers. Stud. 2016, 55, 1-18.

Somarakis, S.; Drakopoulos, P.; Filippou, V. Distribution and abundance of larval fish in the northern Aegean Sea—eastern Mediterranean—in relation to early summer oceanographic conditions. J. Plankton. Res. 2002, 24(4), 339-358

Our results do not allow us to concretely establish whether the evaluated environmental parameters are the key factors to explain the temporal variability of the fish larvae assemblage in this locality. However, as presented in our results, and discussed, the parameters evaluated in our study may be important in explain the trend of variability in the composition of the fish larvae assemblage for this coral formation in the tropical Eastern Pacific. Moreover, the discussion  also considers the effect of food availability and local surface circulation (lines: 321-337), the potential protection offered by the coral reef (lines 338-342; ), and the contribution of specific life strategies (line: 343-350; lines: 351-359) on the composition of the fish larvae assemblage in La Azufrada coral reef. 

Comments: In the main text (including tables and figures), the author presents two different descriptions of salinity. Are these based on the same dataset?

Response: Thank you for your observation. he use of the term "salinity" was reviewed throughout the entire manuscript, unifying the definition.

Comments: in the conclusion section, the author has made very few revisions. The current version reads more like a discussion rather than a conclusion. The conclusion should be more concise and specific.

Response: Thank you very much for your comments. The conclusions section has been rewritten according to your suggestions (Lines 361-384)

The composition of the fish larval assemblage varied across all evaluated periods, with each period showing distinct characteristics. However, a tendency was observed for the assemblages to group together or be more similar during the climatic and oceanographic periods described for the study area (cold and warm seasons). This suggests that intra-annual variations in oceanographic parameters have a greater effect on fish larval assemblages than inter-annual variations. It is evident that the cold period (March) presents better conditions for fish species to carry out their spawning season, resulting in a higher larval density in the La Azufrada coral reef compared to the warm period (September).

The results of this study enhance the available knowledge on the fish larvae assemblage associated with the ETP coral reef and its variation throughout the year and between years. The findings indicate that intra-annual variation, particularly during the cold season (characterized by higher salinity and lower dissolved oxygen), has a greater effect on the composition of the fish larvae assemblage associated with the La Azufrada coral reef. Specifically, Cetengraulis mysticetus, Diaphus pacificus, Anchoa sp., Anisotremus sp., Bremaceros bathymaster, Oligoplites saurus, Caranx sp., Seriola sp., Gobiidae sp., Microgobius sp., and Synodus evermanni were the species that most contributed to the intra-annual variability of the fish larvae assemblage.

We recommend implementing complementary sampling strategies to assess the effect of adult fish spawning strategies on the temporal variability of fish larvae assemblages in coral environments. Light traps would likely provide relevant information on fish larvae in more developed stages, which would increase species diversity records. This would improve our understanding of the assemblage composition and its temporal variability in the coral reef formations of the Eastern Tropical Pacific.

Comments:Additionally, I have some confusion about the references, for example, why are references 1 and 2 combined into one?Additionally, I have some confusion about the references, for example, why are references 1 and 2 combined into one?

Response: Thank you for noticing the error in the references. All bibliographic citations have been reviewed, and the sequence of inclusion in the main text has been verified.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The article has been improved. Only one minor comment in the abstract. The sentence describing the methods of sampling must precedes that describing the findings.

Author Response

The authors appreciate the comments and suggestions received from the reviewer. These have substantially improved the quality of the manuscript.

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

The author has given appropriate answers to the relevant questions, and I think the current version has met the requirements for publication in this journal.