Review Reports - Effect of Vegetable Growth on Content and Composition of Antibiotics in <i>Litopenaeus vannamei</i> Pond Sediments in Crop/Aquacultural Rotation Process

Round 1

Reviewer 1 Report

I have carefully checked the paper and I would say that it is good and suitable for publication. From this point of view this paper contains good scientific data.

Author Response

Dear reviewer,

Thank you so much for your reviewing! We deeply appreciate your recognition of our research work.

Reviewer 2 Report

The title of section 3 should be described as results and discussion.
In Line 156, the authors described “The results suggested that the shading of the stems and leaves does not play a vital role in the reduction of total antibiotics.” But in Line 162, the author described “We doubt that photodegradation was impeded by vegetables above the sediment.” Why are there two totally opposite conclusions?
Can author explain the reasons of increased concentrations of TMP of L2 from Mar 2018 to Apr 2018 and that of OTC of L2 from Dec 2017 to Mar 2018? And there was a similar situation in the concentration of NOF of vegetable groups from Dec 2017 to Mar 2018?
In abstract, the authors described “oxytetracycline in the crop rotation pond decreased faster than in the control pond presumably”, but it cannot be found in the results either in figure 3. And is there any statistically significant result?
The authors concluded that the degradation process was better in vegetable growing ponds. This conclusion was made by comparing the general concentration levels between the beginning and ending. There should be statistical analysis to support it.

Author Response

Point 1: The title of section 3 should be described as results and discussion.

Response 1: We have revised as suggested.

Point 2: In Line 156, the authors described “The results suggested that the shading of the stems and leaves does not play a vital role in the reduction of total antibiotics.” But in Line 162, the author described “We doubt that photodegradation was impeded by vegetables above the sediment.” Why are there two totally opposite conclusions?

Response 2: In the prior period, the improved pond had a slower degradation rate of antibiotics than the control pond. The reason may be the photodegradation impeded by vegetables planting. Although there had a higher degradation in the improved pond in the later period, the shading of the stems and leaves does not play a vital role in the reduction of total antibiotics (in Line 156). We have modified the expression of the related sentences in the manuscript.

Point 3: Can author explain the reasons of increased concentrations of TMP of L2 from Mar 2018 to Apr 2018 and that of OTC of L2 from Dec 2017 to Mar 2018? And there was a similar situation in the concentration of NOF of vegetable groups from Dec 2017 to Mar 2018?

Response 3: The in-suit experiments were conducted to clarify the antibiotic characteristics in the sediment during this phytoremediation process. Some experiences and practices of local farmers (e.g. utilizing the natural river to irrigate the field) does not suggest interference. Due to the drought in winter, the higher concentration of the TMP, OTC and NOF may result by practices of local farmers from Dec 2017 to Mar 2018. The obvious increasing concentration on site L2 may be due to the low-lying area of the pond and the rain water that was collected in certain area in the pond.

Point 4: In abstract, the authors described “oxytetracycline in the crop rotation pond decreased faster than in the control pond presumably”, but it cannot be found in the results either in figure 3. And is there any statistically significant result?

Response 4: The results showed the difference of data comparison, but there was no statistically significant difference the small sample size of this experiment.

Point 5: The authors concluded that the degradation process was better in vegetable growing ponds. This conclusion was made by comparing the general concentration levels between the beginning and ending. There should be statistical analysis to support it.

Response 5: Agree. The comparison of results for the vegetable planting ponds and control ponds showed similar effects (56% and 59%, respectively) (p=0.460) in antibiotic reduction. Photodegradation remains the major pathway of antibiotic removal in natural ponds. The main purpose of this study is to investigate the effect of vegetable planting on the photodegradation of antibiotics. The in-suit experiments results indicated that vegetable planting have little effect on photodegradation of antibiotics.

Author Response File: Author Response.pdf

Reviewer 3 Report

Content and composition of antibiotics in the rice-shrimp rotation system was screened and the phytoremediation effect was proved. Though this work help us to get insight into the ecological effects of rice-shrimp rotation mode.

1.the title is amazing and I can't understand "an in-situ improved process of Litopenaeus vannamei pond sediment"

2.English is poor.

3.No statistical method was applied to test the significant.

4.No discussion in this manuscript

5.Why the content and composition of antibiotics is different? the reason and mechanism should be strengthened.

Author Response

Point :  Content and composition of antibiotics in the rice-shrimp rotation system was screened and the phytoremediation effect was proved. Though this work help us to get insight into the ecological effects of rice-shrimp rotation mode, it is really crude and can't be accepted.

Response : In this study, the shrimp ponds were used to study mitigating antibiotics through growing vegetables on the bottom substrate of the ponds. A new aquaculture method, namely growing vegetables on the bottom substrate of the shrimp pond, was applied to improve sediment quality of the ponds. In order to clarify the effect of plant planting on the photodegradation of antibiotics, we investigated the antibiotic content and composition of the sediment in pond with and without crop rotation (traditional control) and the shrimp yields. The related “crop rotation” was not the key issues of this study. This study can provide scientific basis for the innovative aquaculture approaches to improve the shrimp yield and reduce antibiotics risks.

Point 1: The title is amazing and I can't understand "an in-situ improved process of Litopenaeus vannamei pond sediment".

Response 1: Agree. We have changed the Title to "Effect of vegetable growth on content and composition of antibiotics in Litopenaeus vannamei pond sediments in crop/aquacultural rotation process"

Point 2:  English is poor.

Response 2: The language was further polished in the revised manuscript.

Point 3:  No statistical method was applied to test the significant.

Response 3: The t-text was conducted on the comparison of results for the vegetable planting ponds and control ponds, showing similar effects (56% and 59%, respectively) (p=0.460) in antibiotic reduction. The main purpose of this study is to investigate the effect of vegetable planting on the photodegradation of antibiotics. The in-suit experiments results indicated that vegetable planting have little effect on photodegradation of antibiotics.

Point 4:  No discussion in this manuscript.

Response 4: The title of section 3 should be described as results and discussion. We have revised it.

Point 5:  Why the content and composition of antibiotics is different? the reason and mechanism should be strengthened.

Response 5: The purpose of the study was mitigating antibiotics through growing vegetables on the bottom substrate of the shrimp pond. The in-suit experiments were conducted to clarify the antibiotic characteristics in the sediment during this phytoremediation process. We added some explanations on the difference content and composition of antibiotics among the ponds in the discussion, but the exact mechanism needs to investigate further.