Evaluation of Pacific Whiteleg Shrimp and Three Halophytic Plants in Marine Aquaponic Systems under Three Salinities

Round 1

Reviewer 1 Report

Interesting work. Please let me expose my main comments, followed by a few minor details

My main comment is:

• ligne [62], and specially because you publish in Sustainability, you aim at addressing sustainability of indoor aquaponics. However, the densities you use are so low that no producer can live with these densities.
• the 4 weeks timing is short to assess stability of a system.
• Commercial size for Vanamei is 20g minimum; you reach 2g. Please say it. Similar comment for the plants. After 4 weeks, are you approaching commercial size?
• lign [36] you introduce air-lift, but in results and discussion, you do not present electricity consumption difference between airlift and pump for moving water inbetween compartments. Nor for oxygenation of compartments. Therefore I do not see the interest of having “water pump less” in the title.
• Opposite, you speak a lot of the benefits of probiotics, ... and probiotics does not appear in the title. It is a pity 
• [397] here you need to adresse need for research with longer time and higher densities comparable to production conditions.

Obviously you cannot change parameters, but please add a few words in Discussion stating density and time are lab conditions and not close to production parameters, and consider amending the title to better fit to your work.

Suggestions for adding details and info :  

• [61] you use NB shrimp/m², when in indoor production, one speaks of kg shrimp/m3. Commercial indoor farms are 3kg/m3 when you reach 80g/m3
• [92] you might want to add pump less in the objectives
• [100] what is the specific surface of the bioball
• [129] is 16 ppt the normal salinity for that shrimp?
• [163] please detail what is done with solids: that is a highfactore of sustainability of aquaponics systems
• [236] or later in Dsicussion, it would be worth explaining the benefit of these higher levels: better nutritional value? Other?
• [293] here or somewhere else, it would be pertinent to write what is normal salinity of Vanamei in the wild: 35ppm, an that this specie is tolerant to less
• [332-335] I suspect that these 2 other studies worked on higher densities, closer to real production densities, or longer period.
• [352] similar comment : I suspect that TSS and VSS are lower in your study because also of lower density and shorter time. Please introduce this concept if it is the case

English/typing errors:

• [100] … filled with bio-balls and fitted with a 25 micron …
• [153] … 10ppm into each of the 3 systems would be more clear than into every system
• [176] volatile ? in other literature, authors speak about dissolved. Is that the same?
• [190] please introduce the acronym WC like you did for oter measurements
• [208-210] FCR results seem logical in comparison with productivity. Therefore I would not us “in contrast” but rather “logically” or “in parallel”
• [210] I would precise … were not significantly different in term of FCR from those …
• [309] … which can and lead to … does not seem correct
• [321] … for of red … does not seem correct
• [369] NH4+ serves as the main source of nitrogen for algae. I’m not a specialist of algae, but is it really NH4 and not NO3 as in plants?
• [390] comparable does not seem to be the right adjective … suitable?
• [396] alternative better adjective than comparable?

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The proposed article deal with a trial at three different salinity for the combinad production of Pacific whitleg shrimp and three plant species.

The topic is of great interest to the scientific community and to the more sustainable production of modern aquaculture, but I cannot reccomend this manuscript for the pubblication in Sustainability for the following reasons:

• The trial was conducted for a too limited a period of time to show an effect in growth of Pacific whitleg shrimp. A minimum period of 45 days could be suitable for this species or for a period suitable to triplicate the initial weight of shrimps
• The growth of shrimps wasn't optimal if compared with other pubblished articles or commercial shrimp farms
• The salinity tested were under the optimal value described for the Pacific whitleg shrimp

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The paper is very interesting and well written.

Many variables are considered and the is significant for acquaculture, but the number and the of experiments are too short, therefore so I would invite the authors to intensify the tests. Furthermore it might add other species including invertebrates in the future experiments.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

Constructive comments to the Authors:

This is an interesting and well done and carefully research paper that provides production information along with salt water or brackish water aquaponics systems.  The results presented in this study are interesting and well-structured and provides some good initial research results combining and managing the halophytic plants for marine aquaponic systems to design a system with an adequate number of plants and response in saline or brackish water.

On the methodology please explain briefly why you choose these three salinities?

During the experimental period shrimps did not show cannibalism; how was it treated?

Do these two parameters (salinity and cannibalism) have an impact on the species physiology and especially on the growth performance of the Pacific whiteleg shrimp, Litophenaeus vannamei? Can you explain briefly on the introduction of the manuscript?

Furthermore, in the results, the authors report on table 3 the TSS and VSS values, but in the methodology (lines 168-176) do not describe how TSS and VSS were analyzed? Please can you explain?

Furthermore, in the manuscript, there are some areas where there are problems of citing eg page 4 line 160 (Xu et al., 2016) which was cited in the references as [60],

Page 8 line 295 Ray and  Lotz (2017)..[?]

Page 9  line 304-305 According to Radhakrishnan et al.,[51]…, Similarly on the same page (9)  line 324 Sai Kachout et al. [36],line334, line338 and Page 10 line 361 by Maica et al. [42] and line 380  Pinheiro et al [23].

Generally, the questions that arise from the manuscript is how this result translates into practice - FCR = 1.67 is not promising? 

Once that is covered, I think this is acceptable for publication. 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I thanks the authors for the kind reply to my observarions. Their observation are correct and I think that with all the improvements done to the manuscript the article is now suitable for the pubblication. 

Observing the results of their experiment I recommend taht authors will repeat the experiment extending the duration of the trial as it seems that after 28 days something has changed in their experimental environment, as data of water quality proved.