Elasmobranch Use of Nearshore Estuarine Habitats Responds to Fine-Scale, Intra-Seasonal Environmental Variation: Observing Coastal Shark Density in a Temperate Estuary Utilizing Unoccupied Aircraft Systems (UAS)
Round 1
Reviewer 1 Report
In the manuscript, the authors have done solid work on the observation of the density of sharks with drones, and the relative data on shark density and environmental variables have been provided as supplementary materials. The relationship between the shark density and environmental variables is analyzed by the statistical tools, Pearson correlation coefficient, and modeled by the generalized linear model.
The manuscript is well organized overall. The work itself is quite meaningful and useful for the study and protection of coastal ecosystem. However, the technical analysis of the relationship between the density of shark and environmental variables is elementary. Hopefully, more insightful work would be done as an improvement.
Author Response
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Reviewer 2 Report
The authors use optical UAS video data and ancillary ground-based environmental data to provide insights on the effects of a variety of environmental conditions (wind speed, water temperature, time, tidal height, location etc.) on shark density within two coastal study areas.
I do not have any issues with the work as the methodology is sound and the results were well presented. While a larger sample area with more study sites would have been preferable, the authors noted this limitation in their work, which was appreciated. I think this is an excellent initial demonstration of the usage of UAV and ancillary environmental data to investigate effects of environmental factors on shark populations in coastal areas and commend the authors for their work.
Aside from a few minor informational comments, I believe the manuscript can proceed towards publication.
Minor comments:
Section 2.2 – Could you provide some information about the sensors used in the UAS? What imaging sensor was used? CMOS? CCD?
Ln 185 – How was the “third review” conducted? Independently by the authors or by the original two reviewers?
Ln 272 – Were the training/test folds in the LOGO-CV identical or dissimilar in size?
Author Response
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Reviewer 3 Report
The paper shows a workflow to obtain the density of sharks across varying environmental conditions. The proposed approach is composed by several stages.
The paper is suitable for this journal. The organization of the paper is designed properly and logically and quality of writing is satisfactory.
The abstract is readable. The introduction provides relatively good description of the topic from biological, oceanographical point of view while the state of art of use of the airborne observation could be more extensive and better described. The further sections provide the methods and materials applied in research and the statistical corelation of variables with shark density analysis was discussed in deep.
The motivations for this study are clear, although in the paper lacks a precise description of the use of AUV in offshore/inland environment for video data acquisition and video image processing methods. I would recommend addressing dedicated tools commonly used for video image analysis in order to quantify the specific future like shark shape.
The conclusions are appropriated and coherent with the paper.
Author Response
Thank you for your comments. Please see the attached responses.
Author Response File: Author Response.docx
