Comparison of Distribution and Density of Nemopilema nomurai by Water Columns Using Echo Counting and Echo Integration Methods

Round 1

Reviewer 1 Report

Dear Author, 

 

thanks for your paper. 

It is very well-written and deserves the interest of plankton researchers. 

The method tested is valid and well developed and the combination of echo  counting and echo integration gives important news in the detection of jellyfish distribution in the water column and within a determined area. 

Despite your paper is clear and the methods are well reported my suggestion in to add some information useful to clarify some points.

Please consider the following: 

• in keywords avoid the use of terms already used in the title

• "An adult N. nomurai can grow up to 1 m or more in its bell diameter and up to 200 kg in weight." This sentence is off-context, consider to move it sequently including other information on the species studied; also, please explain how you are sure that the censed species is N. nomurai. 

• Please explain why in the discussion you focus on another species "Aurelia aurita" belonging to a different order. Moreover, I suggest to deepen discussion section relating it to distribution of N. nomurai and on other census methods and potential problems related to the massive presence of this jellyfish.
• Please consider to add a conclusion section in order to give importance to your study. 

All the best

 

 

 

 

Author Response

I attached the response letter to the reviewer's comments. 

 

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,

Many thanks for this nice contribution and research in the field of echo-sounding method and echo-integration method to count water organisms. Overall, I can see and appreciate the effort that has been invested in the data collection/acquisition, processing, interpretation, and statistical analysis.

However, I feel that there still needs to be some work done to polish the manuscript before it can be accepted for publication.

Abstract section:

• The abstract section can be improved. The final part of the abstract must contain the most important conclusions from the entire paper (for example for which dimension/size of jellyfish individuals the methods are applicable, and for which are not).

Introduction section:

• The introduction is well defined and provides sufficient information about the novelty of the method used in the manuscript. It contains the most important parts of an introduction, namely the objectives of the research, and a brief informative outline of the following research methods.

Material and methods:

• The resolution of figure 1 must be improved. Due to the low resolution, the name of the transects cannot be identified. Also, for figure 1 it is important to pay attention to figure captions and provide sufficient text so that it is clear what you are trying to convey without having to look up the text.
• I suggest adding some explanations about the used instrument for the data location records [Line 89]. Also, it is important to mention which was the time-step frequency used of data location.
• At line 92 is mentioned “as recommended by the acoustic stock assessment method” – what regulation/methodology/standard is imposed for this affirmation. Also, need to add references for this recommendation.
• For equation (1) and (2) need to provide references. If these equations are developed by the author, it needs to be added to this information in the manuscript.
• Overall, the materials and methods section is described in an appropriate way, on condition that the above suggestions will be applied.

Results section:

• At line 94-96 authors write „ A visual survey of the jellyfish was conducted in parallel for each 10 m section of the port and the starboard side of the vessel to count the number of observed jellyfish individuals.” - in the results section of the manuscript, nothing is written about the comparison between echo-methods and visual assessment of jellyfish individuals. In this point of view, I suggest improving the results section with statistical analysis about the correlation between echo-methods and visual numbering of jellyfish individuals.
• The description of figures attached in subsection 3.3 is missing - the reviewer was concerned that every figure and table should be described in the content of the article. It is not enough to mention them. They should be clearly described.

 

Conclusions section:

• The most important, namely the conclusion part of this paper is missing. The conclusion section must be supported by the results of this manuscript. The manuscript presents interesting methods but if the conclusion is missed the paper cannot be considered finished.

 

General comments and suggestions for Authors

References - there are some references missing. Please go through the text and support your statements with references to other literature and published works. For example, your first para and some of the statements need support or statements such as “The echo integration method, which receives echo signals of all organisms in a mixture to estimate the biomass, is regarded to have a higher degree of certainty than the echo counting method when estimating the biomass of aquatic organisms aggregated in schools” needs a reference or is this your statement and if so, what is this based on?

Please add newer references for similar studies, for example:

• Mano, T., Guo, X., Fujii, N., Yoshie, N., Tsutsumi, E., & Saito, R. (2019). Moon jellyfish aggregations observed by a scientific echo sounder and an underwater video camera and their relation to internal waves. Journal of Oceanography, 75(4), 359-374.
• Yoon, E. A., Lee, K., Chae, J., Yoon, W., Han, C., Lee, H., ... & Oh, W. (2019). Density Estimates of Moon Jellyfish (Aurelia coerulea) in the Yeongsan Estuary using Nets and Hydroacoustics. Ocean Science Journal, 54(3), 457-465.

 

Figures - It is important to pay attention to figure captions and provide sufficient text so that it is clear what you are trying to convey without having to look up the text.            

 

Overall, I think the central idea of the manuscript is interesting and potentially interesting for others. The paper just needs more polishing! I would like to encourage you to improve this document and re-submit.

Author Response

I attached the response letter to the reviewer2's comments. 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear Authors,

Overall, I think the central idea of the manuscript is interesting and potentially interesting for others. In this form, the paper became more scientifically and more interesting. The conclusion part is supported by the result and give accordance between all scientific steps made to achieve the main purpose of this paper. 

The overall recommendation to the editors, from my opinion, is to accept the manuscript in the presented form.

 

Author Response

I appreciate for your kind comments.