Indoor Aquaculture Research Articles

Real‐time estimation of olive flounder growth in indoor aquaculture using cameras combined with a grid

AbstractEstimating fish growth in real time has many benefits for indoor aquaculture farms, such as saving labor time and costs, reducing water pollution during feeding, improving feeding activity and determining when to harvest. Hence, this study proposed a visual‐information‐based method for measuring olive flounder (Paralichthys olivaceus) length, using accurate growth tracking for efficient aquaculture management. Using two cameras, an light‐emitting‐diode (LED) grid was placed at the bottom of the water tank to measure fish length. The pixels unit from the fish length in the captured image was converted to centimeters based on the relationship of a pre‐built dataset. A total of 180 lengths were calculated using images captured by the cameras. The average length of each fish acquired from the cameras was calculated separately, and Lagrange's interpolating polynomial algorithm was implemented to calculate the overall length of each fish. This method reduced the computational complexity, and results were obtained more rapidly and in a user‐friendly environment. The power model generated the length–weight relationship, which allowed us to estimate the body weight of each olive flounder based on the length. The proposed approach enabled us to calculate the length of olive flounders with a highly accurate R2 of 0.995.

Feeding and growth are regulated by light and opsins-mediated phototransduction in sea cucumber Apostichopus japonicus

Light is a crucial environmental ecological factor that affects physiological processes including feeding and growth of marine invertebrates. Although nonvisual photosensitivity has long been known in echinoderms, the underlying molecular regulation mechanism remains unclear. Here, we firstly reported opsins-mediated phototransduction signaling and the cross-talk between light and feeding/growth in Apostichopus japonicus, an important economic species with high medicinal and nutritional values. Molecular characterization analysis of Ajopsins revealed that they were mainly distributed in the epidermis of potential photosensitive tissues (tentacles, papillae and tube feet). And all four Ajopsins including Rhodopsin 5-like (AjRH5), long-wavelength-sensitive opsin (AjLWS), peropsin (AjPOP), and peropsin-like (AjPOPL) exhibited different expression patterns in response to different light conditions. Moreover, four Ajopsins all conjugated with Gαi/o to reduce intracellular cAMP levels. Besides, three Ajopsins (AjRH5, AjPOP and AjPOPL) conjugated with Gαq to activate Gαq/Ca2+/PKC signaling. And all four opsins could activate downstream ERK1/2 phosphorylation. In addition, the photosensitivities of these four Ajopsins were different in response to different wavelength of light, AjPOP and AjPOPL were sensitive to short-medium-long wavelength light, AjRH5 and AjLWS were sensitive to medium-long wavelength light. Furthermore, indoor aquaculture experiment showed that 150 lx and 300 lx light intensity could significantly promote feeding and growth of A. japonicus, which might be mediated by AjOXP1 and AjMAP2K4. Under different light wavelength treatment, red light (655–665 nm) significantly promoted the feeding and growth of A. japonicus, which may be mediated by AjOXP1/2, AjMAP2K4 and AjMegf6. And siRNA experiment further confirmed the crosstalk between AjPOPL and AjOXP1, suggesting AjPOPL may regulate feeding by AjOXP1 in A. japonicus. Our findings showed a comprehensive description of Ajopsins signaling, providing new insights on the molecular mechanism of photoreception involved in regulating feeding and growth in A. japonicus and suggested the optimum light conditions for optimizing the lighting scheme of A. japonicus aquaculture.

Effect of Light-Emitting Grid Panel on Indoor Aquaculture for Measuring Fish Growth.

This study is related to Smart Aqua Farm, which combines artificial intelligence (AI) and Internet of things (IoT) technology. This study aimed to monitor fish growth in indoor aquaculture while automatically measuring the average size and area in real time. Automatic fish size measurement technology is one of the essential elements for unmanned aquaculture. Under the condition of labor shortage, operators have much fatigue because they use a primitive method that samples the size and weight of fish just before fish shipment and measures them directly by humans. When this kind of process is automated, the operator's fatigue can be significantly reduced. Above all, after measuring the fish growth, predicting the final fish shipment date is possible by estimating how much feed and time are required until the fish becomes the desired size. In this study, a video camera and a developed light-emitting grid panel were installed in indoor aquaculture to acquire images of fish, and the size measurement of a mock-up fish was implemented using the proposed method.

Light intensity changes and UVB radiation affect peridinin content and antioxidant activity in the Cassiopea andromeda holobiont

IntroductionThe up-side down jellyfish Cassiopea andromeda represents a yet untapped marine species that could be targeted as a new source for functional ingredients, such as natural pigments and antioxidants. Since C. andromeda hosts endosymbiotic dinoflagellates, this jellyfish contains peridinin pigments, which are linked with high antioxidant capacities and many other health-promoting properties. This study investigates the potential to specifically increase the content of peridinin and overall antioxidant activity in C. andromeda, through the targeted application of different photosynthetic active radiation (PAR) intensities and ultraviolet radiation, cultured in fully controlled indoor aquaculture systems.Materials and MethodsIndoor bred C. andromeda specimens were exposed to five different PAR intensities (50, 100, 200, 400 and 800 µmol photons m−2 s−1) and a combined treatment of narrow-band UVB (λ = 285 ± 10 nm) radiation and intermediate (200 µmol photons m−2 s−1) PAR intensity over a period of four weeks. Before the treatment and after two- and four-week treatment intervals, pigment concentrations and antioxidant activity levels were measured using high-performance liquid chromatography (HPLC) and the Trolox Equivalent AntioxidantCapacity (TEAC) assay, respectively. In addition, relative growth rate, umbrella pulsation and photosynthetic efficiency (measured by pulse amplitude modulated fluorometry) of C. andromeda individuals were also monitored throughout the experiment. ResultsChlorophyll a (Chl a) and peridinin (Per) dominated overall pigment content in C. andromeda endosymbionts, chlorophyll c2 and diadinoxanthin were detected in minor amounts. Over the treatment time, Chl a and Per concentrations, measured as µg g−1 jellyfish dry weight and pg microalgae-cell−1, decreased sharply at higher PAR intensities (200 – 800 µmol photons m−2 s−1) compared to the control treatment (100 µmol photons m−2 s−1). After four weeks Chl a and Per concentrations were lowest at the highest PAR intensity (800 µmol photons m−2 s−1) and highest at the lowest PAR intensity (50 µmol photons m−2 s−1). Moreover, the ratio of Chl a and Per showed a relative decrease of Per with increasing PAR intensity. The combined treatment of narrow-band UVB (λ = 285 ± 10 nm) radiation and intermediate (200 µmol photons m−2 s−1) PAR intensity led to significantly elevated Chl a and Per concentrations compared to the 200 µmol photons m−2 s−1 PAR treatment without UVB. Significantly elevated antioxidant activity levels, measured as Trolox Equivalents mmol g−1 jellyfish dry weight, were only detected in UVB exposed C. andromeda, indicating that Chl a and Per did not determine overall antioxidant capacity. The photosynthetic efficiency of C. andromeda endosymbionts was not affected by elevated antioxidant activity. Opposing that, the jellyfish hosts that were exposed to the UVB treatment shrunk drastically, indicating a strong stress response.DiscussionWith this study, we demonstrate for the first time the application potential of PAR intensity manipulations and UVB irradiation, to increase the content of valuable pigments and antioxidants in C. andromeda jellyfish and their endosymbiotic dinoflagellates that live in hospite within the host tissue. Based on these findings, we propose the culture of C. andromeda under fully controlled and light-optimized conditions as new pathway to harness bioproducts and functional ingredients.

Effects of Shelter on the Hatching, Immune Performance, and Profitability of the Ovigerous Red Swamp Crayfish Procambarus clarkii under High Stocking Density

To develop the intensive breeding technology of the seed of the red swamp crayfish Procambarus clarkii, the survival rates, hatching effects (hatching rate, incubation level, and number of juveniles), and immune performance of ovigerous P. clarkia as well as economic benefits are evaluated under different shelter conditions under a high stocking density in this study. The experimental design includes three different forms of shelter treatments (D1: experiment without any shelters; D2: experiment with closed shelters; D3: experiment with open shelters), each with three replicates. The results show that the concentration of the total antioxidant capacity (T-AOC) and activities of phenoloxidase (PO), catalase (CAT), and acid phosphatase (ACP) in the D3 treatment are higher than those in the D1 treatment (all p < 0.05), with the highest concentrations of total antioxidant capacity (T-AOC) and malondialdehyde (MDA) and the highest activities of phenoloxidase (PO), superoxide dismutase (SOD), catalase (CAT), acid phosphatase (ACP), and alkaline phosphatase (AKP) among the treatments being present in the ovigerous P. clarkii in the D3 treatment. The hatching rates of the three treatments vary from 69.51% to 94.28%, with the highest rate found in the D3 treatment and the lowest in the D1 treatment, but there is no significant difference among them (p > 0.05). The highest incubation level (ind.·m−2) and the highest number of juveniles (ind.·m−2) among treatments are found in the D3 treatment, with the incubation level (ind.·m−2) in the D3 treatment being significantly higher than that in the D1 treatment (p < 0.05). The benefit–cost ratios (BCRs) of the D2 and D3 treatments remain significantly higher than that of the D1 treatment when P. clarkii prices change (all p < 0.05). Our results indicate that a high stocking density habitat with open shelters could effectively improve the hatching and immune performance of ovigerous P. clarkii. Our findings are relevant for the indoor aquaculture management of ovigerous P. clarkii.

Effects of temperature and photoperiod on growth, physiological, and behavioral performance in steelhead trout (Oncorhynchus mykiss) under indoor aquaculture condition

Light and temperature are necessary conditions for migratory fish. The assessment of fish physiology and behavior is important for identifying fish welfare, but also for the assessment of the optimal setting of recirculating aquaculture systems (RASs). This study aimed to explore the interactive effect of photoperiod and temperature on steelhead trout culture. Four treatments were set up with specific settings were as follows: a LP-LT group treated with 16L:8D and 12°C, a LP-HT group treated with 16L:8D and 16°C, a SP-LT group treated with 12L:12D and 12°C, and a SP-HT group treated with 12L:12D and 16°C. Growth performance, behavioral and physiological parameters were measured. Two indexes, locomotor activity and social interaction were used for behavioral analysis, and the results were applied to interpret the behavioral responses to the photoperiod and temperature stimulation in juveniles. The growth performances were significantly lower in treatments LP-LT and SP-LT. The treatment LP-HT had significantly higher growth performance than the other treatments, but no significant differences were noted in survival rate and coefficient of variation. The results of fish behavior indicated that the movement of juveniles should be primarily monitored at high temperatures or long photoperiods, and the state parameters should be primarily monitored at low temperatures or short photoperiods. The results of the physiological parameters showed that the recovery time from stress varied among different treatments. After 60 days of the experiment, superoxide dismutase and alanine aminotransferase dropped back to their initial level. The results of Na+-K+-ATPase showed that although the combined effect of photoperiod and temperature could advance the time of smoltification, it may result in poorer salt tolerance. Our findings underscore the importance of the interaction of photoperiod and temperature on steelhead trout culture. The outcome could provide guidance for the development of effective aquaculture systems.

Agricultural Transformation for Small (Island and Developing) States

Agriculture in the development literature has been postulated as providing impetus for urban industrialization through its role in capital accumulation. While large states with concomitant large export potential of agricultural surpluses may subscribe to this paradigm and may also allow growth of a rural agricultural sector in parallel with an urban industrial sector, small states find it difficult to use the agriculture sector as a springboard toward national economic growth by virtue of size limitations. Small states require alternate capitalization modalities to grow their economies, and some have sidelined agriculture in favor of urban activities, such as manufacturing, finance, banking, and tourism. It is plausible, based on demonstrated successes like Singapore, that structural transformation may take a path in which the agriculture sector is initially sacrificed in favor of more high value urban activities. Since its independence in 1965, Singapore made policy decisions to focus on developing its non-agriculture sectors such as finance, banking, and entrepôt trade. In 1983, the country even reduced its agricultural activities to less than one percent of land area located in six agrotechnology parks. Capital accumulation through the non-agriculture sectors proceeded to consequently make its GDP per capita one of the highest in the world. However, the country did a “U-turn” in the 2010s to re-invest in agriculture, but through high-tech farming, such as indoor plant factories, indoor aquaculture, and alternative (novel) proteins. The increased level of food self-production is strongly augmented by importing food from over 170 countries in diverse geographic regions, so as to confer supply resilience. This alternate development pathway, which emphasizes urban industrialization, may serve as a “leapfrogging” model for small cities and small developing states in a contemporary, technology-enabled landscape.

Trace Determination of Grouper Nervous Necrosis Virus in Contaminated Larvae and Pond Water Samples Using Label-Free Fiber Optic Nanoplasmonic Biosensor.

We developed a fast (<20 min), label-free fiber optic particle plasmon resonance (FOPPR) immunosensing method to detect nervous necrosis virus (NNV), which often infects high-value economic aquatic species, such as grouper. Using spiked NNV particles in a phosphate buffer as samples, the standard calibration curve obtained was linear (R2 = 0.99) and the limit of detection (LOD) achieved was 2.75 × 104 TCID50/mL, which is superior to that obtained using enzyme-linked immunosorbent assay (ELISA). By using an enhancement method called fiber optic nanogold-linked immunosorbent assay (FONLISA), the LOD can be further improved to <1 TCID50/mL, which is comparable to that found by the conventional qPCR method. Employing the larvae homogenate samples of NNV-infected grouper, the results obtained by the FOPPR biosensor agree with those obtained by the quantitative polymerase chain reaction (qPCR) method. We also examined pond water samples from an infected container in an indoor aquaculture facility. The lowest detectable level of NNV coat protein was found to be 0.17 μg/mL, which is one order lower than the LOD reported by ELISA. Therefore, we demonstrated the potential of the FOPPR biosensor as an outbreak surveillance tool, which is able to give warning indication even when the trend of larvae death toll increment is still not clear.

Effects of Nitrite Exposure on the Hematological Properties, Antioxidant and Stress Responses of Juvenile Hybrid Groupers, Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀.

Nitrite concentrations can reach high levels in indoor aquaculture systems, thus it is vital to determine the nitrite tolerance of aquaculture fish species. Here, juvenile hybrid groupers (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀, Family: Serranidae) were exposed to waterborne nitrite at 0, 10, 20, 40, and 80 mg NO2−/L for 2 weeks. Nitrite exposure caused significant reductions in hematocrit and hemoglobin levels, significant increases in plasma calcium and plasma ALP levels, but had no significant effects on magnesium and total protein levels. Of the antioxidant responses investigated, SOD activity increased significantly in the liver and gills, but GST activity and GSH levels were significantly inhibited by nitrite exposure. Stress indicators, such as plasma cortisol and HSP 70 levels, were significantly stimulated by nitrite exposure. In brief, nitrite exposure over 20 mg NO2−/L had toxic effects and affected the hematological properties, antioxidant responses, and stress indicators of juvenile hybrid groupers.

Long‐term exposure to enrofloxacin increases body weight and alters the metabolism of American shad ( Alosa sapidissima ) in indoor aquaculture

Enrofloxacin (ENR) is widely used in animal husbandry, medical treatment and aquaculture, resulting in its discharge into various water environments. Although the toxicity effects of ENR on aquatic animal metabolism have been studied, there is still little information on the long-term toxic hazard on the metabolism of cultured American shad. In this study, American shad juveniles were exposed to 0.1 mg/kg ENR for 10 months. The results showed that ENR could induce body weight gain in American shad. Alterations in metabolic pathways were found in pyrimidine metabolism, arginine and proline metabolism, the calcium signalling pathway and the arachidonic acid metabolism pathway. However, the alteration of neuroactive ligand–receptor interaction pathways was speculated to be related to weight gain through the regulation of the nervous system. The metabolomic and transcriptomic analysis suggested a similar pattern of pathway alterations. The multiomic data revealed that the specific metabolism alteration resulting from ENR exposure was associated with nutrition quality and predation ability in fish. Furthermore, previous works showed that ENR residues in fish tissue and the water environment would ultimately threaten human health and safety through food consumption. In sum, this study, for the first time, reveals that ENR exposure increases body weight in American shad and induces metabolic alteration. The ecotoxicity of antibiotic occurrences in indoor aquaculture systems should be further evaluated.

Effect of Biofloc product‐Rapid BFT TM vs. clear water system in improving the water quality and growth performances of Pacific Whiteleg shrimp, P. vannamei , cultured in indoor aquaculture system

Biofloc technology was known to improve the shrimp growth performance and water quality in several ways. The application of bacterial booster was proven to accelerate the development of biofloc in the culture treatments as well as help improve the water quality, shrimp growth performance and yield production. Due to its importance, a study was conducted to identify the effect of biofloc application using Rapid BFTTM microbial booster formulation versus clear water system to improve shrimp growth performance and water quality condition. Study was conducted for 80 days with every 7 days of interval of data collection. Overall, biofloc treatments were identified successfully in improving the shrimp growth performance and also effectively reduced the nutrient concentrations of total ammonia nitrogen (TAN) from the biofloc culture treatments until the end of culture periods. Nitrate (NO3−) from biofloc treatments was also identified in lower concentration as compared to control of clear water system. The average daily growth (ADG) was at 0.12g much better from biofloc treatments as compared to control with ADG 0.08g of clear water system. The specific growth rate (SGR) was 5.47%/day in biofloc and 2.82%/day in control treatments which identified higher and much better from biofloc about 2.65%/day differences between biofloc and clear water. Meanwhile, the final body weight achieved was much higher from biofloc about 9.55 grams compared with control about 7.06 grams from the same day of culture, DOC80 which recorded at the end of cultured period. The first sampling was started at DOC7 where the average initial weight of shrimp in biofloc treatment was 0.117 grams and 0.077 grams identified in control. The highest biomass achieved from biofloc treatments also much better around 11.0 kg compared with control that produced 7.1 kg as the higher biomass produced. There was only yellow and green colony of Vibrio identified from the TCBS culture and no occurrence of luminescent colony from harmful Vibrio harveyi detected. Therefore, it can be concluded that biofloc technology of Rapid BFTTM help improves the water quality of ammonia nitrogen level in water columns and inhibits pathogenic Vibrio to the culture species as well as help improving the shrimp growth performances in more effective way.

The applications of plasmonics biosensor and bamboo char filtration to the prevention of nervous necrosis virus infection in grouper farming ponds

Fiber optic particle plasmon resonance (FOPPR) biosensors have been useful tools to determine a variety of biological samples including viruses with superior detection limits than using conventional ELISA methods. In addition, without using tedious procedures required in ELISA protocols, FOPPR method can minimize contamination interferences and obtain accurate results in timely fashion. FOPPR biosensor is potentially a suitable virus detection device to implement in fish farms. In Taiwan, aquaculture products such as groupers suffer tremendous loss because of ineffective disease prevention efforts. The infected signs are not detected in the early stage before severe outbreak to cause uncontrollable consequences. Therefore when the virus level is low, using highly sensitive FOPPR biosensors to monitor pond water is a promising means to improve the effectiveness of aquatic product disease prevention by taking water treatment actions. We have also developed FOPPR assays to determine nervous necrosis virus (NNV), which cause massively high mortality rate (∼90%) in larva and juvenile stages of grouper species. Using coat proteins of NNV as standards in 2% salt water, the detection limit of 100 ng/mL is obtained. This limit is nearly 2 orders of magnitude lower than that using ELISA assays and adequate to indicate the severance level of NNV outbreak. Ground meat of infected juvenile grouper was diluted with saline to prepare simulated water samples. Ultra-low virus level of 40k TCID50 per mL is found in filtrate. The comparison determination data between using FOPPR and quantitative PCR methods are acceptable too. Unlike RT-PCR method not able to detect NNV RNA in pond water until severe infection, we demonstrate that FOPPR assay can detect NNV in pond water at very low NNV level at early infection stage, a couple of days prior to the outbreak occurrence. We also show that commercial FOPPR biosensor maintains stable immuno-sensing signal readout in indoor aquaculture settings. We will also discuss the potential applications of using FOPPR to monitor grouper larvae pond water to activate biochar filtration equipment when infection sign occurs.

The Screening and Identification of Heterotrophic Nitrified Aerobic Denitrifier in the Penaeus Vannamei Boone Aquaculture System without Water Renew

The experiments respectively take the artificial substratum (mesh) form the indoor aquaculture systems without water renew of Penaeus vannamei Boone as well as the mature bio-films. Through the complex inoculation on BTB ammonia, nitrite and nitrate medium, screened and obtained the library of the heterotrophic nitrified aerobic denitrifier. Selected 25 single colonies from the bacteria library of two membrane systems to conduct analysis based on the 16s rDNA PCR-RFLP and the results indicated that 50 colonies can be divided into 5 spectral types, in which 2 for the mesh, 3 for the coral sand. After sequencing, the blast comparison shows that all the heterotrophic nitrified aerobic denitrifiers are from the γ-proteobacteria (Gammaproteobacteria), where the bacteria on the mesh belong to the Acinetobacter sp.and Klebsiella sp.; while the bacteria on the coral sand belong to the Pseudomonas sp., Shewanella sp. and Klebsiella sp. According to the analysis on the phylogenetic tree, we know its evolutionary position is basically consistent with the traditional classification. Gram stain analysis indicates that all bacteria are red and belong to the Gram-negative bacteria. The research is of great significance for the selection of the heterotrophic nitrified aerobic denitrifier in the prawn aquaculture systems.

실내외 양식환경에 따른 미꾸라지(Misgurnus mizolepis) 양식장 모니터링과 성장특성

실내외 양식환경에 따른 미꾸라지(Misgurnus mizolepis) 양식장 모니터링과 성장특성

Evaluation of Indoor and Outdoor Aquaculture Systems as Alternatives to Harvesting Hemolymph From Random Wild Capture of Horseshoe Crabs

This study evaluated two approaches to the aquaculture of L. polyphemus with the ultimate goal of harvesting LAL at an industrial scale. To monitor HSCs, a combination of physical, biochemical and cellular components were examined for HSC cohorts in an indoor recirculating aquaculture system (RAS) and an outdoor on-bottom pen culture system (PCS) over a 6-month period. The metrics included body weight, hemocyanin (Hc) concentration, amebocyte density, and LAL reactivity. In addition, a simulated biomedical bleeding event (extracting 30% of the total hemolymph volume) was performed to assess physiochemical properties of the hemolymph and amebocytes after a one-week recovery period. Overall, the HSCs fared better in the RAS compared to the PCS, with higher rebound kinetics with respect to Hc concentrations, amebocyte density, LAL reactivity, and with 100% survival in the RAS cohort. Further, hemolymph reinfusion (after amebocyte removal) was shown to improve HSC recovery time. In summary, outcomes of this research show that a RAS, coupled with adequate nutrition and care can provide HSCs with a suitable environment for sustainable hemolymph extraction and year-round LAL production.

Effects of light intensity and photoperiod on the growth and stress response of juvenile Nile tilapia (Oreochromis niloticus) in a recirculating aquaculture system

Light is an essential natural factor of fish growth and development. A light regime in indoor aquaculture is critical for sustainable fish production. This research aimed to investigate the effect of light intensity and photoperiod on the growth performance and stress response of Nile tilapia (Oreochromis niloticus), which is an important commercial species, in a recirculating aquaculture system (RAS). Fingerlings with an average weight of 5 ± 0.9 g were randomly assigned to nine 1.5 m3 tanks with 145 fish in each tank, cultured under different light intensities (1000, 2000, and 3000 lx) and photoperiods (12L:12D, 18L:6D, 24L:0D), and fed to apparent satiation twice a day for 160 days. The growth of tilapia subjected to 2000 lx was significantly better than that exposed to 1000 and 3000 lx (P < 0.05) as indicated by the final weight (351.17 ± 10.59 g), growth efficiency (0.77 ± 0.26), specific growth rate (2.65% ± 0.21% per day) and feed conversion coefficient ratio (1.30 ± 0.36). No significant difference was observed in the growth rate among different photoperiod groups (P > 0.05). Light intensity and photoperiod manipulation did not cause a significant chronic stress response in tilapia. This study demonstrated that light intensity, especially at 2000 lx, and photoperiod manipulation could stimulate the growth of tilapia in the RAS and significantly affect economic profitability. This study also served as an important reference for tilapia indoor aquaculture.

A Prototype System for Real-Time Monitoring of Arctic Char in Indoor Aquaculture Operations: Possibilities &amp; Challenges

In this exploratory study, we studied and qualitatively evaluated a prototype video data collection system to capture and analyze fish behavior in a small-scale indoor aquaculture operation. The research objective was to design and develop a hardware / software system that would have the potential to capture meaningful data from which to extract fish size, swim trajectory, and swim velocity, ultimately as information toward an assessment of fish health. The initial work presented in this paper discusses the development choices of the prototype system, including various combinations of lighting and camera positions both inside and outside of the aquaculture tanks, and several post-processing techniques to isolate fish in video, calibrate the distance from camera to fish through water, and infer fish trajectories and swim velocities. Preliminary results provided a qualitative assessment of such a system. Specific results on the system’s ability to detect fishes’ positions, trajectories, and velocities are presently limited to observational outcomes and descriptive statistics rather than large-scale quantitative analysis. The present work lays a foundation for a future commercially hardened system that would be required for the collection of larger datasets, which would in turn facilitate the future development of machine learning (ML) algorithms to begin to statistically correlate data to fish conditions and behaviors in near-real time.

Investigation of the Potential Effects of Host Genetics and Probiotic Treatment on the Gut Bacterial Community Composition of Aquaculture-raised Pacific Whiteleg Shrimp, Litopenaeus vannamei

This study presents the potential effects of the genetic background and use of probiotics on the gut bacterial composition of Pacific whiteleg shrimp (Litopenaeus vannamei) grown in an indoor aquaculture facility. The strains investigated were Shrimp Improvement Systems (SIS, Islamorada, FL, USA), a strain genetically selected for disease resistance, and an Oceanic Institute (OI, Oahu, HI, USA) strain, selected for growth performance. BioWish 3P (BioWish Technologies, Cincinnati, OH, USA) was the selected probiotic. The study consisted of two separate trials, where all shrimp were raised under standard industry conditions and fed the same diet. Shrimp were stocked in 2920 L production tanks at a density of 200/m3 and acclimated for 14 days. After the acclimation period, triplicate tanks were supplemented daily for a duration of 28 days with probiotics, while three other tanks did not receive any treatment (controls). During the 28-day trial period, there was no statistically supported difference (p > 0.05) in either performance or health status as a result of genetic background or probiotic treatment. However, differences in gut bacterial composition, as assessed by high throughput sequencing of amplicons generated from the V1-V3 region of the bacterial 16S rRNA gene, were observed. The relative abundance of five major operational taxonomic units (OTUs) were found to vary significantly across experimental groups (p < 0.05). Notably, operational taxonomic unit (OTU) SD_Shr-00006 was at its highest abundance in d43 SIS samples, with levels greater than d71 samples of the same genetic line or any of the OI shrimp samples. OTUs for SD_Shr-00098 displayed a similar type of profile, but with highest abundance in the OI genetic line and lowest in the SIS shrimp. SD_Shr-00004 showed an opposite profile, with highest abundance in the SIS d71 samples and lowest in the SIS d43 samples. Together, these results suggest that host genetic background can be an important determinant of gut bacterial composition in aquaculture-raised whiteleg shrimp and indicate that development of strategies to manipulate the microbiome of this important seafood will likely need to be customized depending on the genetic line.

MARBLED CRAYFISH (PROCAMBARUS VIRGINALIS) AS A PROMISING OBJECT FOR AQUACULTURE INDUSTRY

Marbled crayfish / marmorkrebs, parthenogenetically reproducing decapod crustacean of pet aquarium origin conventionally has been recognized as an undesirable species since it a) is an invasive pest dangerous for aquatic ecosystem resources because of its hardiness, omnivorousness, fast growth, self-cloning abilities; b) has little commercial value for food industry. However, recently an idea has been introduced about marmorkrebs as a promising cheap protein source, which can help to fight world hunger. Accordingly, research performed at Liepaja University (Latvia) was focused on marbled crayfish farming system design issues. Research paper presented discusses marmorkrebs survival capacities in small-volume microcosm tanks (made from recycled material), under harsh abiotic conditions. Pilot research results obtained will be used to develop experimental project on low-input microcosmic indoor aquaculture for marmorkrebs.

Impact of Aquaculture Practices on Intestinal Bacterial Profiles of Pacific Whiteleg Shrimp Litopenaeus vannamei.

Considering the crucial role of the gut microbiome in animal health and nutrition, solutions to shrimp aquaculture challenges, such as improving disease resistance and optimizing growth on lower cost feeds, may lie in manipulation of their microbial symbionts. However, achieving this goal will require a deeper understanding of shrimp microbial communities and how their composition is influenced by diet formulation, environmental conditions, and host factors. In this context, the current study investigated the intestinal bacterial communities of the Pacific whiteleg shrimp (Litopenaeus vannamei—the most widely aquaculture-farmed shrimp worldwide) reared in indoor aquaculture facilities and outdoor pond systems. While samples showed very consistent intestinal bacterial community profiles within each production system, major differences were uncovered between the two practices. Indeed, bacteria affiliated with Rhodobacteraceae (Proteobacteria) and Actinobacteria were significantly more abundant in indoor samples (84.4% vs. 5.1%; 3.0% vs. 0.06%, respectively), while Vibrionaceae (Proteobacteria), Firmicutes, Fusobacteria and Cyanobacteria were predominant in pond samples (0.03% vs. 44.8%; 0.7% vs. 36.0%; 0.0% vs. 7.9%; 0.001% vs. 1.6%, respectively). Accordingly, the abundance of 11 of the 12 most prominent Operational Taxonomic Units (OTUs) were found to be statistically different between the two production environments. Together, these results indicate that aquaculture practices greatly influence the intestinal bacterial profile of the whiteleg shrimp, and further suggest that bacterial communities of this economically important crustacean could be effectively manipulated using diet composition or environmental conditions.