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Lactic acid bacteria have been widely used as feed additives in aquaculture to improve the absorption of nutrients, as well as the immunity and growth performance of fish. According to the lactic acid bacteria to decompose organic matter, this study aims to improve the utilization efficiency of solid waste resources with high nutrients in aquaponics systems. Fishderived bacteria were screened with strong resistance and better mineralization function, in order to enhance the fermentation and mineralization of fish waste. The experiments were conducted to take the biofilter media and fish from the aquaponics system as the source of lactic acid bacteria. A series of tests were then performed on the high-temperature tolerance, acid and alkali tolerance, high salt tolerance, and the mineralization performance of various nutrients in fish waste. Two strains were obtained with mineralization function and application potential, which were identified as Lactococcus lactis L1 and Lactobacillus dextrinicus L2, respectively. A comparison was also made on the growth performance of the strains at 10, 20, 30 and 40 °C. The results revealed that the growth of L1 and L2 was inhibited at 10 and 20 °C, while they proliferated normally at 30 and 40 °C. The survival rate of L1 and L2 after 30 min of heating at 50, 60, and 70 °C was examined to verify the high-temperature tolerance of the strains. It was found that the L1 was achieved the better high-temperature tolerance. The survival rate of L1 was 96.60% at 50 °C, which was significantly higher than that of L2 (80.35%). According to the range of water acidity and alkalinity in the environment of aquaculture, the tolerance of the two strains was examined at pH 5.0-9.0. The results showed that the survival rates of L1 (65.43% and 71.25%) were higher than those of L2 (31.10% and 52.22%) at both pH 5.0 and 9.0 (P<0.05). The tolerance of the strains was examined at 15, 30, and 60 g/L salinity, where the mariculture and salinity were considered after the thickening of mariculture sludge. The survival rate of the strains gradually decreased with the increase of salinity. Once the salt concentration was 60 g/L, the survival rate of L1 was 37.33%, while there was no L2 survival. In terms of tolerance to temperature, acid, and alkali, L1 was selected as the subsequent experimental object for the fish waste fermentation mineralization experiment. The control group (no lactic acid bacteria added) and the L group (with Lactococcus lactis added) were divided to last for seven days. A comparison was made on the contents of nitrogen, phosphorus and various mineral elements in the fermentation broth at days 0, 1, 3, 5 and 7. The results showed that better degradation and mineralization of organic matter were achieved in the L group. The highest concentrations of total ammonia nitrogen (TAN) and total nitrogen (TN) in the fermentation broth of the L group were 192.82 and 342.00 mg/L, respectively, which were much higher than the control group (30.29 and 79.00 mg/L, respectively). Potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn) in the fermentation broth of the L group were significantly higher than those of the control group, except for sulfur (S) and all reached the highest values (27.59%-94.67%) in the 3d. In conclusion, Lactococcus lactis presented the better resistance to heat, salt, acid, and alkali, indicating better fermentation and mineralization of fish waste. Furthermore, 3 d was the optimal cycle of fermentation and mineralization. The finding can provide a strong reference to apply the lactic acid bacteria to the mineralization of solid wastes, in order to improve the nutrient utilization efficiency in aquaponics systems. [ABSTRACT FROM AUTHOR]

Aquaponics is an innovative compound production system composed of recirculating aquaculture and hydroponic cultivation, which has the characteristics of high resource utilization rate, no chemical fertilizers and antibiotics, low consumption, high efficiency and sustainability. It is considered as a modern agricultural farming system of ecological protection. Although aquaponics system has developed rapidly in recent years and has been widely promoted and applied, it still lacks systematic cognition and holistic analysis. This paper summarized the technological development of aquaponics system, the main research contents, research progress and development trend at home and abroad. Combined with the development status of aquaponics system, it was predicted that the future aquaponics system construction would tend to be decoupled and ecological, the layout would move toward urbanization and three- dimensional, the large-scale intelligent and commercial implementation would be carried out, and the trend would be diversified and integrated innovation. Meanwhile, relevant improvement suggestions were put forward, which aimed to provide scientific ideas for the efficient construction and sustainable development of aquaponics complex system. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A synergy model of the aquaponic system was integrated with soil-based cultivation, particularly for the recycling use of aquaculture wastewater and solids. A three-way water cycle process was also designed in this study. A pilot system was built at Yaomo village, Ningxia Hui Autonomous Region, China in 2020. Three parts were composed mainly of the recirculating aquaculture system (RAS), hydroponics, and soil-based cultivation unit, specifically including the fish tank, radial-flow clarifier, micro-screen drum filter, moving bed biofilm reactor (MBBR), mineralization tank, ultraviolet sterilizer, sump tank, hydroponic troughs, and farmland. In a three-way water cycle process, the first way was a circulation loop of the RAS unit, where the effluent first went through the physical filters under gravity, and then lifted into the MBBR by pump to remove ammonia nitrogen, and nitrate. Finally, the water flowed into the ultraviolet sterilization, and then returned to a fish tank. The second way was a circulation loop of “aquaculture unit to hydroponics unit”, where the aquaculture effluent was loaded with the nutrients, filtered into the hydroponic troughs where the plant roots were fertilized, then recycled back to the fish tank, and remediated cumulated nutrients. The third way was the “aquaculture unit to soil-based cultivation unit” cycle, where the fish sludge solids were accumulated into the mineralization tank, and then irrigated to the farmland after being mineralized by the pump. In the RAS unit, the respiration and metabolism of fish and the decomposition of the residual feed produced ammonia nitrogen and then converted to nitrate nitrogen under the effect of microorganisms in the MBBR and on the surface of plant roots. In the hydroponics unit, the plants absorbed nitrate nitrogen produced from the RAS unit, and then purified the aquaculture wastewater. In the soil-based cultivation unit, the fish sludge solids (mainly composed of degradable organic matter) were degraded to small molecules in a mineralisation tank, whereas, the macronutrients (i.e. N, P, and K) and micronutrients (i.e. Fe, Mn, and Zn) that were bound to the organic molecules were released into the water in their ionic forms to complete the process of nutrient mineralization. The key parameters (including the biomass ratio of fish and vegetables) were calculated to propose the capacity of the mineralization device. According to the calculation, the system was designed to farm 1 400 kg fish in a tank of 28.3 m³, to plant 3 648 vegetables in 96 circular pipes each of 8 m, and the mineralization tank volume was set to 2 m³ . Taking the largemouth bass as the case, the lettuce and tomato as the culturing object for 160 days from May 21st to October 28th. The experiment results showed that better growth of fish was achieved, where the final culture density reached up to 41.6 kg/m³, the specific growth rate was 0.42%, the survival rate was 99.95%, and the feed coefficient was 1.4. The better growth of vegetables was also obtained, where 1205 kg of hydroponic lettuce and 2 400 kg of tomato were harvested during the period. Consequently, the water quality was stable: the average concentration of total ammonia nitrogen (TAN) was (0.83±1.46) mg/L, the average concentration of nitrite (NO2 - -N) was (0.035±0.062) mg/L, the average concentration of nitrate (NO3 - -N) was (25.1±8.06) mg/L, the concentration range of dissolved oxygen was 4.25-7.16 mg/L, and the average pH was 6.8. More importantly, the average concentration of total phosphorus and potassium in water increased by 141% and 7%, respectively, during the mineralization process. The excellent economic and ecological benefits of the system were obtained: the annual profit was about 46 000 Yuan, the use of chemical fertilizers was reduced by 4/5, the use of pesticides was reduced by 3/4, and the daily water exchange was less than 5%. [ABSTRACT FROM AUTHOR]

Copyright of Commerce & Management Quarterly is the property of Chinese Association of Business & Management Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Penaeus monodon was one of the three main cultured prawns in the world, which had the characteristics of fast growth, large individual, strong disease resistance, a wide range of temperature and salt, delicious meat, and high market price. Guangdong, Fujian, Hainan, and other places were the main areas for rearing and breeding of Penaeus monodon in China, and the traditional extensive production method was its main production method. As the model’s shortcomings continue to emerge, this water and soil resource-dependent and ecologically destructive production method had become one of the major problems that restricted the sustainable development of Penaeus monodon. Circulating the aquaculture system was the current development direction of advanced aquaculture productivity, but so far there were still few reports on pond aquaculture and related research. In order to explore the feasibility and application development value of Penaeus monodon recirculating aquaculture, two sets of recirculating aquaculture systems composed of a pond, a protein separation unit, an inner circulating fluidized bed, and a circulating pump were designed and constructed in Rudong Base of Institute of Fishery Machinery and Instrument, Chinese Academy of Fishery Sciences in 2019, and the aquaculture experiments were carried out. In the whole breeding process, the aeration aerator assembly was opened, and the water truck aerator was opened in the later breeding stage. The water circulation treatment system operated in the middle and late stages of aquaculture, and the circulation capacity was 26.50 m3/h (middle stage) and 33.00 m3/h (late stage). The amount of sewage discharged was 4%-10% (middle stage) and 10%-12% (later stage) of the aquaculture water body. In this paper, the key equipment was designed in detail and the circulating capacity was calculated, and the water quality condition, the growth of Penaeus monodon culture, the water purification function of protein separation combined device, internal circulating fluidized bed, and other equipment under the corresponding control mode in different culture stages were studied. Finally, the economy of culture operation was comprehensively analyzed. The results showed that the system operated smoothly for 120 days. During the culturing period, dissolved oxygen concentration was 5.30-7.14 mg/L, the pH value was 7.23-8.44, ammonia nitrogen concentration was 0.43-1.38 mg/L (after stable operation), nitrite nitrogen concentration was 0.15-0.56 mg/L(after stable operation). The results indicated that the removal load of suspended solids was (43.19±7.25) g/m3·h, the removal rate of ammonia nitrogen was (9.95±1.90)%, the dissolved oxygen was (9.45±0.87)%, the removal load of ammonia nitrogen was (122.34±22.56)g/m3·d, and the nitrification ability was better in the later stage than in the middle stage. The Penaeus monodon grew normally in the aquatic ecological environment of recirculating aquaculture mode and went through a rapid growth period, a stable growth period, and a slow growth period successively. The final culture density was 3.02 kg/m2, and the high-efficiency culture result was achieved. The final feed coefficient was 1.67, and the income per square meter of a single crop was 211.40 yuan according to the sales price of 70 yuan/kg. After deducting the cost, the profit per square meter per stubble was 34.78 yuan, the annual profit per square meter was 69.56 yuan based on two crops per year, which had achieved good economic benefits. The results show that the Penaeus monodon circulating aquaculture system offers a water quality control method for its growth characteristics and water environment requirements at different stages, realizes scientific feeding, and provides technical support for the application of the Penaeus monodon circulating aquaculture model. [ABSTRACT FROM AUTHOR]

Fish feeding behavior can provide effective decision-making information for accurate feeding in aquaculture. Most previous studies were usually conducted in a laboratory environment to understanding fish feeding behavior. The limited application cannot reveal the actual production status of fish due to the influence of light conditions and farming environment in practice. Particularly, the cameras placed over the water surface cannot work well in most methods, due to serious light reflection resulted from the complex illumination conditions. For instance, the light reflection is so serious that many fishes are blocked out. In this study, an attempt was made to introduce an underwater video dataset for the feeding behavior of Atlantic salmon. In the dataset, the video clips were captured from an industrial recirculating aquaculture system. Each sample that labeled as eating or noneating was a 5-second clip with the frame rate of 30 Hz. A total of 3 791 samples were marked in the dataset, where 3 132 samples were marked as noneating and 659 samples eating. A novel video classification method based on Variational Auto-Encoder and Convolutional Neural Network (VAE-CNN) was proposed to identify the fish-feeding behavior from the video clip. Two steps were as followed. In the first step, a Variational Auto-Encoder (VAE) model was trained to extract the spatial feature of video frames. All video frames were encoded as a multivariate Gaussian probability distribution function in a latent space, indicating that represented by a Gaussian mean vector and a Gaussian variance vector. Specifically, the frames in a video clip were input into a trained VAE encoder to produce Gaussian mean vectors and Gaussian variance vectors, then to combine them in column order separately, finally to obtain the Gaussian mean feature matrix and Gaussian variance feature matrix of the video. In this step, the video clip of fish feeding behavior was coded as a feature map with two channels for the subsequent classification. In the second step, the fish feeding behavior was classified by inputting the feature matrix into the CNN. The VAE output features were input to train the CNN, while the spatio-temporal features in fish feeding behavior videos were extracted for the final classification. To verify the CNN, the VAE output features were also input into the backpropagation neural network (VAE-BP) and support vector machine (VAE-SVM) to classify the feeding behavior of fish. The results showed that VAE-CNN performed better. The main reason is that the CNN with a local receptive field function can allow it to better learn the spatio-temporal features in fish feeding behavior videos, while the other two methods only consider the output features of VAE as a common feature map. In real factory farming, the accuracy of the proposed method reached 89%, the recall reached 90%, and the specificity reached 87%. Compared with the single-image classification method, VAE-CNN recall increased by 15 percentage points, and other performance indexes of video classification method improved significantly. In terms of running time, the proposed algorithm only needed 4.15 s to process 5 s (150 frames) for the video of fish feeding behavior. This novel method can build a solid foundation for the future system with feedback control based on the fish feeding behavior. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to discuss the effects of plant density on nitrogen transformation in aquaponics system, the purpose is to obtain the suitable arrangement of plant density for greenhouse aquaponics in Fuzhou. The experiment was conducted in a solar greenhouse in Fuzhou China-Israel Demonstration Farm in Fujian province from July to August in 2017. An experimental aquaponics system based on NFT (Nutrient Film Technique) cultivation was set up in the greenhouse. The cultivated variety of vegetable in the experiment was Ipomoea aquatica. The aquacultured variety of fish in the experiment was Carassius auratus gibelio. The cultivated area was 1.0 m2 and the aquaculture water amount was 350 L. The treatments comprised three plant densities(A(60 plants/m2), B(45 plants/m2),C(30 plants/m2)) with 10kg/m3 aquaculture density. The three treatments were experimented totally and every treatment was replicated three times. There were three harvests of vegetables without root during these experiments. The water quality and the growth of fish and vegetable during the 33d operation of system were investigated. The conversion of added nitrogen and the influence of time and plant density on the mass concentration of nitrogen compounds were discussed. The results showed that the water quality of different plant density systems, including water temperature, pH, DO and EC, was relatively stable and suitable for the growth of fish and vegetable. The main index of biological characteristics of fish and vegetable increased to different degrees. By analysis of variance, plant density had positive impact on the increment of total fresh quality of vegetables (P=0.000) and the increment of total nitrogen accumulation in vegetables (P=0.002), which indirectly meant the plant areas could be expanded. There was no significant interaction between plant density and relative growth rate of the main index of biological characteristics of fish and vegetable. Regardless of loss of nitrogen such as N2O, N2, 49.32%-68.41% of added nitrogen from feed were accumulated in fish and vegetable. Nitrogen content in fish and vegetable were negative increased and not better than that in ordinary aquaculture and NFT cultivation, which meant optimization measures such as biological filter and medium culture could be adopted. Mass concentrations of ammonia, nitrite and nitrate nitrogen changed significantly with time (P=0.000). Under the action of nitrification and denitrification, the mass concentration of nitrogen compounds fluctuated and ammonia nitrogen was converted to nitrate nitrogen. At the late stage of the system operation, the mass concentration of nitrogen compounds was basically stable, and the mass concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen were about 2.50, 0.20 and 5.00 mg/L, respectively. The mass concentration of nitrate nitrogen in different plant density systems was significantly different (P=0.028), and the system with plant density of 45plants/m2 had a higher accumulation advantage of nitrate nitrogen. Plant density had no significant impact on the mass concentrations of ammonia nitrogen and nitrite nitrogen. Nitrogen conversion can be further enhanced by expanding cultivation area, installing biological filter and adjusting cultivation mode. In conclusion, the plant density of 45plants/m2 for Ipomoea aquatica is an appropriate plant density for greenhouse aquaponics in Fuzhou and other measures should be combined to improve the nitrogen conversion effect. [ABSTRACT FROM AUTHOR]