Characteristics of Ammonia Removal and Nitrifying Microbial Communities in a Hybrid Biofloc-RAS for Intensive Litopenaeus vannamei Culture: A Pilot-Scale Study

Round 1

Reviewer 1 Report

WATER Manuscript. No.: 953678

Overall, I found that the manuscript is well written - clear, professional, and articulate English has been used throughout. The results from the study exhibit merit in enhancing the prospects of utilizing nitrifying microbial communities in ammonia removal in shrimp culture processes.

Please see detailed comments/ suggestions below for the improvement of the manuscript.

Abstract:

Line 17: remove ‘to be solved’

Introduction:

Line 37: rephrase ‘most lucrative segment’ for better language clarity and usage

Lines 51-53: run on sentence, need to rephrase this for better language clarity

Lines 53-55: run on sentence, need to rephrase this for better language clarity

Line 57-58: needs citations

Line 65: replace showed with ‘demonstrated’

Lines 66-68: run on sentence, need to rephrase this for better language clarity

Lines 68 – 71: run on sentence, need to rephrase this for better language clarity

Lines 71-74: run on sentence, need to rephrase this for better language clarity

Line 79: authors mention ‘studies’ here but cite only one reference. This needs more citations

Line 93: replace ‘information’ with ‘community structure’

Lines 52 and 96: should this is coastal?

Materials and methods:

Line 101-104: Due to the language, it is unclear if these are the modification made to the cited paper? The use of ‘which’ in this sentence is slightly confusing from language perspective.

Line 193-195: I am unsure how one could ‘quantify’ DNA from an agarose gel electrophoresis. It could be analyzed for mixed DNA in it or whether or not DNA was present in the sample but not for exact quantity. This needs to be clarified here.

Lines 204-206: More information on qPCR and standard generation is required here. How were these plasmids constructed? What were the final concentrations of the primers in each of the reactions (note that volume does not reflect on concentration). What was the qPCR threshold? Were the concentrations normalized to starting DNA concentrations? If so, how did you measure concentration of genomic DNA in the first place? In line 191, I see 100 ml of water was filtered, while in figure 4 I see the copy numbers are reported as copies per mg, how did the authors obtain this per mg value? All of these need to be clarified in this section.

Results and Discussions:

Lines 402-406: Could this correlation result be displayed as a figure? I see in Figure 7 TAN production and removal rate both increasing over time. I am unclear how the removal efficiency is depicted to be significantly high in this case? This needs to be addressed.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript (MS) brings interesting finds regarding the use of a Hybrid Biofloc-RAS system in intensive shrimp production. M&M utilized actualized references. Results were clearly described and the discussion was well balanced according to the results.

On the other hand, some points in the M&M and text need to be clarified. Why are missing crucial water quality data such as DO, pH, alkalinity, salinity, and temperature? It’s well known that the nitrogen dynamic is strictly related to those parameters, and also according to feed inputs/stocking densities. No discussions were made in this regard. Also, few discussions/comparisons were made regarding the production parameters (survival, FCR, growth, etc) with other similar works in similar intensive systems (RAS, or pure BFT, etc).

And what’s the point in having a “practical production trial tested in parallel” if no data, comparison, and/discussion was provided. Why the authors didn’t compare with it? Please justify.

Authors need to better define the origin of “Biofloc” and “Biofilm” in the text, Tables and figures. In addition, For the microorganisms’ characterization, I don’t believe “biofilm” itself is the best definition. I would suggest e.g. “BFT Water” and “RAS biofilter”. My title suggestion would be: “Characteristics of Ammonia Removal and Bacterial Communities in a Hybrid Biofloc-RAS System for Intensive Litopenaeus vannamei Culture: A Pilot-scale Study”

The MS needs major arrangements and the inclusion of some critical information.

Paper accepted with major revisions.

Other minor suggestions were provided below.

Abstract: Treatments/objectives are not clear described in the abstract

L129: Does the practical production trial was considered a treatment? Please clarify. If yes, details in this “control” treatment need to be provided.

L132: What are the main water quality characteristics of this BFT nursery inoculum (DO, pH, salinity, TAN, NO2, NO3, PO4, alkalinity, TSS, SS, etc). It’s important to have an idea of the trophic state of such pond.

L141: What are the BFT management applied? External carbon source? C:N ratio? If you do used BFT in the nursery, what were the management applied?

L148: Please provide details (DOC ?, characteristics, etc.) for start-up phase, transition phase and at stabilization phase.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I am happy this the current (revised) version. No more comments to add.