Aquariums as Research Platforms: Characterizing Fish Sounds in Controlled Settings with Preliminary Insights from the Blackbar Soldierfish Myripristis jacobus

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Manuscript ID: jzbg-3177967 requires changes in terms of:

1. Structures:

- the graphic form (writing in Latin with the full name of all species, organization of the figures (1, 2, 3) on the page in compliance with the presentation requirements for a scientific work - larger title, size/clarity.);

2. The scientific content of the paper:

- the introduction of explanations in correlation with the title of the manuscript in Fig.1, Fig. 2 and Fig. 3, with more extensive description and in the text;

- the Materials and Methods Chapter must be completed with a distinct presentation of the materials used and at the same time the working methods that were the basis for the conception of the presented manuscript. In this sense, the authors are encouraged to present how many specimens of the investigated species were the object of the research, as well as to concretely present the organization of the respective experiments, including the control sample.

- making the correlations of the scientific arguments newly introduced in the manuscript by presenting them in the Results, Discussions and Conclusions Chapters;

- in the Conclusions Chapter, authors are encouraged to detail the conclusions so that they are better integrated with the title of the paper.

- making correlations of the bibliography after restructuring the manuscript, if necessary.

Author Response

Comment 1:Structures: the graphic form (writing in Latin with the full name of all species, organization of the figures (1, 2, 3) on the page in compliance with the presentation requirements for a scientific work - larger title, size/clarity.);

 

Response 1: 

Thank you for your feedback regarding the graphic form and presentation of the manuscript. We have made the necessary revisions to ensure that the species names are consistently written in Latin and follow the correct scientific format throughout the text. Additionally, we have reorganized the figures (1, 2, 3) to comply with the standard presentation requirements for scientific works. This includes adjusting the figures to be larger and ensuring the size and clarity of the figures are appropriate for publication.

Actions Taken:

• All species names have been revised to ensure they are written in full and in Latin, following the scientific convention.
• The figures have been reorganized according to the standard formatting guidelines, with clear titles, appropriate size, and improved clarity for better readability.

Comment 2: The scientific content of the paper:

• the introduction of explanations in correlation with the title of the manuscript in Fig.1, Fig. 2 and Fig. 3, with more extensive description and in the text;
• the Materials and Methods Chapter must be completed with a distinct presentation of the materials used and at the same time the working methods that were the basis for the conception of the presented manuscript. In this sense, the authors are encouraged to present how many specimens of the investigated species were the object of the research, as well as to concretely present the organization of the respective experiments, including the control sample.
•  making the correlations of the scientific arguments newly introduced in the manuscript by presenting them in the Results, Discussions and Conclusions Chapters;
• in the Conclusions Chapter, authors are encouraged to detail the conclusions so that they are better integrated with the title of the paper.

 

Response 2: 

Thank you for your detailed feedback regarding the scientific content of the paper. We appreciate your suggestions and have made several revisions to address each of the points raised.

1.- Introduction of Explanations (Figures 1, 2, and 3):
We have revised the descriptions in the text to provide more extensive explanations that correlate with Figures 1, 2, and 3. These figures now have more detailed descriptions that better align with the title and content of the manuscript, ensuring the reader can easily follow the visual and scientific connections.

New Figure 1 Caption: Diagram of the experimental setup. This figure illustrates the layout of the aquarium, including the positioning of the hydrophones (b,c) and the 360° camera (a) used for video recording during the experiment. The hydrophones were strategically placed in the middle of the tank to minimize directional bias and ensure the best possible sound capture from the fish. The figure highlights the placement of the hydrophones in relation to the fish and the tank walls, which is crucial for understanding the controlled environment and the measures taken to minimize external noise and vibrations.

New figure 2 caption: Spectrogram and oscillogram of a sequence of two pulses. This figure represents an example of the acoustic signals recorded from M. jacobus. The spectrogram shows the frequency distribution over time, while the oscillogram provides a visual representation of the sound wave's amplitude. The two-pulse sequence depicted here is a common sound pattern produced by the species.

New figure 3 caption: Spectrogram and oscillogram of a pulse train. This figure shows a more complex sound event recorded during the experiment, featuring a pulse train composed of multiple pulses in rapid succession. The figure is essential for understanding the variability in M. jacobus vocalizations, as it demonstrates the occurrence of more rapid pulse sequences, which may be associated with specific behaviors or stress responses.

 

2.- Materials and Methods Section:
We have expanded the Materials and Methods section to include a more distinct presentation of the materials used. Specifically, we have provided information on the equipment used for the acoustic recordings and clarified the methods that formed the basis of the research. Additionally, we have included the details of the two specimens of Myripristis jacobus that were the focus of the study (one male and one female, both captive-bred). We have also clarified the organization of the experiments, including the 24-hour recording period and the fact that there was no formal control group, as this was a proof-of-concept study for bioacoustic research in public aquariums.

The materials and methods chapter has been completed explaining in more detail he materials used, the details about the fish, and the experimental setup, providing more context and transparency about the methodology for the reader. This has been done also following the recommendations of the other reviewer

3.- Correlation of Scientific Arguments in Results, Discussions, and Conclusions:
We have made sure to integrate the newly introduced scientific arguments more clearly throughout the Results, Discussion, and Conclusions sections. The Results now include more direct correlations with the methodology and observations, while the Discussion expands on how these results contribute to our understanding of fish bioacoustics in controlled environments. The Conclusions have been detailed to better reflect the findings, including how this study serves as a preliminary step in the characterization of Myripristis jacobus sounds and the potential for using aquariums for future bioacoustic research.

New paragraph in the results section: Each of the two Hydromoths generated 24 uncompressed WAV files, amounting to a total of 12 hours of recordings. The two \textit{M. jacobus} individuals produced sound patterns, which were recorded and analyzed over the 12-hour period. The tank's isolation from other species and limited external noise interference resulted in high-quality recordings, allowing us to distinguish between simple pulse sequences and more complex pulse trains.

Discussion section has been also modified following the recommendations of other reviewer.

4.- Conclusions Section:
The Conclusions have been rewritten and expanded to ensure they are better integrated with the title of the paper. We have emphasized the practical implications of the findings, particularly in relation to the role of aquariums as platforms for bioacoustic research and the potential for identifying species in field recordings based on these findings.

 

New paragraph in the conclusion section:

This study demonstrates the potential of public aquariums as valuable platforms for bioacoustic research. By leveraging the controlled environment of an aquarium, we were able to successfully record and characterize the sounds produced by Myripristis jacobus, providing the first detailed acoustic profile for this species. The controlled setting allowed for the isolation of species-specific vocalizations without interference from other species or external noise, underscoring the role aquariums can play in advancing bioacoustic research.

The findings from this study have important practical implications, particularly for the identification of fish species in natural environments through Passive Acoustic Monitoring (PAM). The acoustic data collected here can serve as a reference for field recordings, aiding in the identification of Myripristis jacobus and potentially other species with similar acoustic traits. This approach could facilitate more accurate assessments of fish biodiversity and contribute to the development of ecosystem monitoring tools.

Furthermore, the study highlights the feasibility of using low-cost methodologies in aquariums to collect high-quality bioacoustic data. This makes bioacoustic research more accessible to institutions with limited resources and opens up opportunities for long-term monitoring of species in both captive and natural settings.

5.- Bibliography Correlations:
After restructuring the manuscript, we have reviewed the references to ensure that they are properly correlated with the revised text. Any additional citations necessary to support the changes have been included.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript explores the potential of aquariums as research platforms for characterizing fish acoustics, specifically focusing on the acoustic features of Myripristis jacobus (blackbar soldierfish) in a controlled environment. The main contribution is a preliminary acoustic characterization of this species, which identifies two distinct vocalization patterns. However, I have some observations:

Abstract

The abstract is well-written overall but could be more concise in some areas, such as the opening sentence. Splitting the sentence for clarity would be beneficial.

Introduction:

L31-32: The phrase "unequivocal identification of sounds produced by specific species" is ambiguous. Clarify what makes the identification "unequivocal" in aquarium settings.

- The transition between paragraphs could be smoother. For instance, the shift from general bioacoustics to public aquariums seems abrupt.

- The research gap is not clearly articulated. What specific gap in knowledge about Myripristis jacobus or aquarium-based bioacoustic research are you addressing?

- The primary objective is stated in the last paragraph, but it could be more specific. What exact "potential of aquariums" are you demonstrating?

How will this research contribute to "developing biodiversity and structural indices for marine ecosystems in the region"?

M&M

The authors should address whether any calibration was performed between the recording devices to ensure consistency in audio capture.

L126-127:    While it is understandable that the study was conducted in a zoo, it would be extremely helpful to include more detailed information about the fish used in the experiment. Information such as the health status of the individuals, their origin (whether they were captive-bred or captured in the wild), and whether the sex of the fish was known could provide additional context and help interpret possible behavioral or acoustic variations.

The description of how the aquarium environment was controlled during the recordings could be more detailed. Although the authors mentioned the stability of parameters such as salinity and temperature, other factors that could impact the results, such as external noise, vibrations, or the presence of other animals near the tank, should also be discussed. It is important to specify the level of control over these variables to ensure that the experimental environment was properly isolated from potential interferences.

Discussion:

The authors should delve deeper into how this groundbreaking data could be used as a basis for future bioacoustic research, not only for this species but also for others with similar acoustic traits. What practical implications do the results have, and how can they guide future studies on behavior and acoustic ecology?

The ms mentions the limitation of using small tanks, but it would be beneficial to have a more detailed analysis of how this affected the results. The authors should explore how the artificial environment, especially in terms of reverberation and resonance, could have affected the quality and propagation of the sounds. They should also consider how these conditions might have influenced the production and capture of the sound events, and how to address these limitations in future studies.

Author Response

Comments 1: The abstract is well-written overall but could be more concise in some areas, such as the opening sentence. Splitting the sentence for clarity would be beneficial.

Response 1: Thank you for your suggestion regarding the abstract. We have revised the opening sentence to make it more concise and have split it for clarity, as recommended.

Revised sentence: "This study highlights the potential of aquariums as research platforms for bioacoustic research. Aquariums provide access to a wide variety of fish species, offering unique opportunities to characterize their acoustic features in controlled settings."

Comment 2: L31-32: The phrase "unequivocal identification of sounds produced by specific species" is ambiguous. Clarify what makes the identification "unequivocal" in aquarium settings.

Response 2: Thank you for pointing out the ambiguity in this phrase. We agree that further clarification is needed to explain why sound identification can be considered "unequivocal" in aquarium settings. We have revised the text to clarify that the controlled environment of aquariums allows researchers to isolate and attribute sounds to specific species without the interference of other species, which often occurs in natural environments.

Revised sentence: "The opportunity to conduct experiments with a wide variety of fish species in controlled conditions allows for the clear identification of sounds produced by specific species, as the controlled aquarium environment eliminates interference from other species and external noise, enabling precise attribution of sounds to the species under study"

 

Comment 3: The transition between paragraphs could be smoother. For instance, the shift from general bioacoustics to public aquariums seems abrupt.

Response 3: Thank you for your comment regarding the transition between paragraphs. We agree that the shift from general bioacoustics to the focus on public aquariums can be made smoother. We have revised the transition to provide a more seamless connection between the two topics, highlighting the relevance of public aquariums as important platforms for bioacoustic research.

Revised sentence: "While bioacoustics research is widely applied across various aquatic environments, public aquariums offer a unique opportunity for such studies."

Comment 4: The research gap is not clearly articulated. What specific gap in knowledge about Myripristis jacobus or aquarium-based bioacoustic research are you addressing?

Response 4: Thank you for your insightful comment. The primary aim of our research is to serve as a proof of concept for the use of public aquariums as platforms for bioacoustic research. Specifically, we sought to demonstrate that simple and cost-effective experimental setups within aquariums can provide valuable preliminary data on species that have not been extensively studied in terms of their acoustic behavior, such as Myripristis jacobus. The gap we are addressing is twofold: the lack of detailed acoustic descriptions for Myripristis jacobus, and the limited exploration of aquariums as controlled environments for bioacoustic studies.

The last two paragraphs of the introduction have been re-written for clarity.

Comment 5: The primary objective is stated in the last paragraph, but it could be more specific. What exact "potential of aquariums" are you demonstrating?

Response 5: Thank you for your suggestion. We agree that the primary objective could be more specific. The potential of aquariums that we are demonstrating is their ability to serve as controlled environments for bioacoustic research, particularly for species with limited acoustic data. This includes the ability to conduct cost-effective, long-term studies that can isolate the sounds produced by specific species without interference from external environmental noise or other species, which is often a challenge in field settings.

Revised sentence: The primary objective of this study is to demonstrate the potential of aquariums as research platforms that allow for the controlled, cost-effective, and species-specific characterization of fish sounds. By providing environments where external noise and interference from other species are minimized, aquariums offer a unique opportunity to gather preliminary acoustic data, particularly for species like Myripristis jacobus that have been under-studied in this context.

 

Comment 6: How will this research contribute to "developing biodiversity and structural indices for marine ecosystems in the region"?

 

Response 6: Thank you for your question. The potential of aquariums to characterize the acoustic profiles of all fish species within their collections can directly contribute to the identification of these species in field recordings. By creating detailed bioacoustic databases of fish species under controlled conditions, we can develop reference libraries that will enhance the ability to recognize species in field recordings made through Passive Acoustic Monitoring (PAM). This, in turn, will allow future studies to calculate fish biodiversity and ecosystem structure indices based on field recordings, contributing to the assessment and monitoring of marine ecosystems.

Clarification added in the manuscript: This research contributes to the development of biodiversity and structural indices for marine ecosystems by providing a foundation for identifying fish species in field recordings through their acoustic signatures. By characterizing the sounds produced by species like Myripristis jacobus in aquariums, future studies can utilize this data to identify species in natural habitats, ultimately allowing the calculation of biodiversity indices and the assessment of ecosystem structures based on acoustic data from field recordings.

MATERIALS AND METHODS

Comment 7: The authors should address whether any calibration was performed between the recording devices to ensure consistency in audio capture.

Response 7: Thank you for your comment. While the recording devices used in this study were not calibrated, we ensured consistency in audio capture through the careful placement of the hydrophones within the aquarium. The relatively small size of the tank and the close proximity of the hydrophones to the fish allowed for high-quality sound recordings. Both HydroMoth devices were positioned to minimize directional bias and maximize signal-to-noise ratio, ensuring that the recordings captured were of consistent and reliable quality.

Sentence added to the manuscript: Although no formal calibration was performed between the recording devices, the dimensions of the aquarium and the close proximity of the hydrophones to the fish ensured high-quality audio capture. The positioning of the devices minimized directional bias, allowing for consistency in the recorded sounds across both hydrophones.

Comment 8: L126-127:    While it is understandable that the study was conducted in a zoo, it would be extremely helpful to include more detailed information about the fish used in the experiment. Information such as the health status of the individuals, their origin (whether they were captive-bred or captured in the wild), and whether the sex of the fish was known could provide additional context and help interpret possible behavioral or acoustic variations.

Response 8: Thank you for your comment. We agree that providing more detailed information about the fish used in the experiment is important for adding context. The two individuals used in this study were one male and one female, both in good health and captive-bred from a reputable fish provider. This information has been added to the Materials and Methods section to help interpret any potential behavioral or acoustic variations.

Paragraph added to the Materials and Methods section:

The two Myripristis jacobus individuals used in the experiment consisted of one male and one female. Both fish were in good health, as confirmed by the aquarium's veterinary team, and were captive-bred from a reputable fish provider.

Comment 9: The description of how the aquarium environment was controlled during the recordings could be more detailed. Although the authors mentioned the stability of parameters such as salinity and temperature, other factors that could impact the results, such as external noise, vibrations, or the presence of other animals near the tank, should also be discussed. It is important to specify the level of control over these variables to ensure that the experimental environment was properly isolated from potential interferences.

Response 9: 

Thank you for your insightful comment. We have added more detailed information regarding the experimental environment and the measures taken to control potential interferences. The experimental tank was located in an auxiliary quarantine area, far from the main aquarium facilities, which helped minimize external noise and vibrations. The only fish present in the area were those in the experimental tank, as the other tanks in the section were occupied exclusively with corals. Since this quarantine area was isolated from the main aquarium, staff were only present for very limited periods of time to monitor the corals, ensuring that the fish were in complete isolation from other fish species and human activity during the recordings.

The following paragraph was added to the Material and Methods section: The experimental tank was located in an auxiliary quarantine area, isolated from the main aquarium facilities. This location minimized external noise and vibrations that could interfere with the recordings. The only fish present in the area were the two Myripristis jacobus individuals in the experimental tank, as the rest of the tanks in the section were occupied by corals. Staff presence in the area was limited to brief periods for coral monitoring, ensuring that the fish were largely undisturbed and isolated from other animals and human activity during the 24-hour recording period.

DISCUSSION

Comment 10: The authors should delve deeper into how this groundbreaking data could be used as a basis for future bioacoustic research, not only for this species but also for others with similar acoustic traits. What practical implications do the results have, and how can they guide future studies on behavior and acoustic ecology?

Response 10: Thank you for your thoughtful question. We agree that expanding on the broader implications of this research is crucial. The data obtained from this study serves as a foundation for future bioacoustic research, both for Myripristis jacobus and other species with similar acoustic traits. By providing a preliminary acoustic profile of Myripristis jacobus, this study contributes to the growing library of species-specific bioacoustic data that can be used for comparative studies. The characterization of fish sounds in controlled environments like aquariums allows future research to investigate behavioral contexts for sound production, such as communication, aggression, or mating, with a clearer understanding of the species' baseline vocalizations.

 

Paragraphs added to the discussion:

Moreover, the acoustic traits identified in this study offer opportunities for comparative research across other species within the Holocentridae family or other soniferous fish. Such studies can explore the evolutionary and ecological significance of sound production in these species, providing deeper insights into their communication strategies, mating behaviors, and territorial interactions. The data can also guide behavioral studies aimed at linking specific acoustic patterns to particular behaviors, such as aggression, courtship, or responses to environmental stressors.

In a broader context, this research paves the way for the development of PAM-based tools for tracking biodiversity and ecosystem health. Future studies can leverage these initial findings to calculate biodiversity indices and develop ecosystem structure models based on acoustic data collected in the field. This underscores the broader relevance of this study, which not only advances the acoustic characterization of Myripristis jacobus but also sets the stage for more extensive research into the bioacoustics of other marine species.

Comment 11: The ms mentions the limitation of using small tanks, but it would be beneficial to have a more detailed analysis of how this affected the results. The authors should explore how the artificial environment, especially in terms of reverberation and resonance, could have affected the quality and propagation of the sounds. They should also consider how these conditions might have influenced the production and capture of the sound events, and how to address these limitations in future studies.

 

Response 11: Thank you for your comment. We acknowledge the importance of discussing the effects of small tanks on sound propagation, including issues related to reverberation and resonance. However, it is important to clarify that the primary goal of this paper was not to perform an in-depth analysis of the acoustic limitations of small tanks. These aspects have been thoroughly examined in the study by Akamatsu et al. (2002), where detailed empirical refinements for recording fish sounds in small tanks are provided. We agree that a brief mention of these factors in our discussion would be beneficial, and we will refer readers to Akamatsu et al. (2002) for further details on how these limitations might influence sound production and capture in future studies.

Paragraph added to the discussion:

While the use of small tanks introduces potential limitations related to reverberation and resonance, which can affect the propagation and quality of recorded sounds, this was not the primary focus of the current study. These factors have been extensively analyzed by Akamatsu et al. (2002), who provide detailed guidance on mitigating these challenges in small-tank environments. For further information on how these conditions may influence sound production and capture, and recommendations for addressing such limitations, we direct readers to Akamatsu et al. (2002). Future studies aiming to address these challenges in more detail should consider the refinements and methodologies outlined in that work.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

No comments.

Author Response

Thank you for your positive feedback on the revisions.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has been satisfactorily revised, with most issues appropriately addressed. However, Figures 2 and 3 are cut off in the provided file. Please center and properly format all figures to ensure complete visibility.

Author Response

Comment 1: The manuscript has been satisfactorily revised, with most issues appropriately addressed. However, Figures 2 and 3 are cut off in the provided file. Please center and properly format all figures to ensure complete visibility.

Response 1: Thank you for your positive feedback on the revisions. We appreciate your attention to the formatting of Figures 2 and 3. In the final version of the manuscript, both figures have been properly formatted and aligned to the left to ensure full visibility. We have confirmed that they are no longer cut off and can now be viewed in their entirety.