Development Of Aquaculture Industry Research Articles

Immunoprotective efficacy evaluation of OmpTS subunit vaccine against Aeromonas hydrophila infection in Megalobrama amblycephala

Bacterial septicemia in freshwater fish is mainly caused by Aeromonas hydrophila infection, which affects the development of aquaculture industry. In the context of sustainable aquaculture, subunit vaccines are of great values because they play positive roles in reducing the overuse of antibiotics and protecting aquatic animals against bacterial infection. In this study, the recombinant outer membrane protein OmpTS of A. hydrophila were used as subunit vaccine to immunize Megalobrama amblycephala, and its immunoprotective effect and host immune responses were evaluated. The survival rates of the vaccinated groups after bacterial infection were significantly higher than that of the control group, especially of the OmpTS high-dose vaccinated group. The better protective effects of vaccinated groups might be attributed to the increased levels of serum IgM-specific antibody titer, the reduced relative abundance of A. hydrophila in various tissues, the increased number of immune-positive cells with different epitopes, the up-regulated expression levels of immune-related genes, and the enhanced activities of antibacterial enzymes. In conclusion, OmpTS subunit vaccine could strongly induce host immune responses in M. amblycephala, thereby enhancing both cellular and humoral immunity, which exhibited excellent and effective immunoprotective efficacy.

Coordination compensated metal-organic framework fluorescent sensor for highly selective and sensitive dual-detection of phosphate and hydrogen sulfide

With the rapid development of aquaculture industry, it is of great significance to monitor the level of multiple related species in water for the sustainable development of the aquaculture industry and the protection of the surrounding ecological environment. In this paper, a novel fluorescent MOF sensor UiO-66-NH2@NDBPA has been developed conveniently based on coordination compensated strategy and applied for simultaneous dual-detection of both phosphate and hydrogen sulfide with non-interference to each other, which are two very important relative species in aquaculture water. The detection limits of phosphate and hydrogen sulfide were as low as 45 nM and 120 nM, respectively. Additionally, the practicability for the simultaneous dual-detection based on this sensor was further proved by the detection of phosphate and hydrogen sulfide in actual water samples and the recovery rate ranged from 98.8% to 103.2%.

Research on the Development of Aquaculture Industry in Shanwei City

Research on the Development of Aquaculture Industry in Shanwei City

Integrated analysis of transcriptome and metabolome reveals the regulatory mechanism of largemouth bass (Micropterus salmoides) in response to Nocardia seriolae infection

Nocardia seriolae is a severe bacterial pathogen that has seriously affected the development of aquaculture industry. Largemouth bass (Micropterus salmoides) is a commercially significant freshwater fish that suffers a variety of environmental threats, including bacterial pathogens. However, the immune responses and metabolic alterations of largemouth bass to N. seriolae infection remain largely unclear. We discovered that N. seriolae caused pathological alterations in largemouth bass and shifted the transcript of immune-related and apoptotic genes in head kidney after infection. To answer the aforementioned question, a combined transcriptome and metabolome analysis was employed to explore the alterations in genes, metabolites, and metabolic pathways in largemouth bass following bacterial infection. A total of 3579 genes and 1929 metabolites are significant differentially changed in the head kidney post infection. In response to N. seriolae infection, host modifies the PI3K-Akt signaling pathway, TCA cycle, glycolysis, and amino acid metabolism. The integrated analysis of transcriptome and metabolome suggested that with the arginine metabolism pathway as the core, multiple biomarkers (arg gene, arginine) are involved in the antibacterial and immune functions of largemouth bass. Thus, we hypothesized that arginine plays a crucial role in the immune responses of largemouth bass against N. seriolae infection, and increasing arginine levels suitably is beneficial for the host against bacterial infection. Our results shed light on the regulatory mechanism of largemouth bass resistance to N. seriolae infection and contributed to the development of more effective N. seriolae resistance strategies.

Transcriptomic profiling reveals the immune response mechanism of the Thamnaconus modestus induced by the poly (I:C) and LPS

Aquatic animals immune response to pathogenic is a hotspot and related to high-quality development of aquaculture industry and the conservation of fisheries resources. Thamnaconus modestus is an important commercial and economical species which is suffering from various pathogens but by now lack relevant research about revealing the immune response mechanism to the pathogens invasion. In the study, the polyriboinosinic polyribocytidylic acid [poly (I:C)] and Lipopolysaccharides (LPS), respective mimics of viral and bacterial infections, were used to demonstrate the immune response of the species via transcriptome analysis. The results showed that T. modestus had sensitive responses to the viral analog infection at 6 h and 48 h, and at 6 h, the first five major functional genes were NFKBIA, IL1B, JUN, IGH, FOS, and at 48 h, the genes were NFKBIA, IL1B, JUN, IGH, FOS. The genes IL1B, IRF3, PTGS2, THBS1 could helping the fish to fight against the bacterial infection in both the times. Similarly for the bacterial infection, the species had a sensitive response at 6 h, and the first five major functional genes were NFKBIA, JUN, FOS, L1B, GRIN2C. Our study provided an insight about the immune response mechanism of this species and demonstrated that if need for treatment of the virus and bacteria by the biotechnology, the artificial interferential time would be suggested before 6 h since the pathological features occur and the genes NFKBIA, JUN, IL1B, FOS, TRAF2, IL8, SOCS3, PTGS2 should be payed more attention.

Resource-process approach to the aquaculture industry development

Aquaculture is one of the most promising industries in the world. The relevance of the research topic is due to the fact that in order to effectively use the potential of this industry, the organizational and economic mechanisms for ensuring business processes in fish farming developed by world practice were studied. Business processes are considered in general for aquaculture. During the research, a resource-process matrix was developed for the aquaculture sector. The result of the study is the identified mechanisms for ensuring business processes in aquaculture, which can help improve the situation of this industry in Ukraine. As a conclusion, the relevance of applying an integrated approach based on business processes along the value chain in combination with resource provision is determined. Also, the research proposes organizational and economic mechanisms for the development of each link of the matrix "resources-processes" of the chain of value creation in the aquaculture sector.

Combined effects of dietary carbohydrate levels and ammonia stress on growth, antioxidant capacity and glucose metabolism in juvenile oriental river prawn (Macrobrachium nipponense).

Ammonia is a common environmental stress factor that constrains aquaculture industry development. This study evaluated the effect of carbohydrate levels and ammonia stress in oriental river prawn (Macrobrachium nipponense). The experiment had six treatments containing two water ammonia levels (0 and 5 mg/L) and three dietary carbohydrate levels (low carbohydrate diet (LCD, 10%), medium carbohydrate diet [MCD, 20%], and high carbohydrate diet [HCD, 30%]), and lasted six weeks. The results showed that the prawns fed on MCD had higher weight gain than those fed on LCD and HCD during ammonia stress. Moreover, the prawns fed on MCD had significantly lower acid phosphatase and alkaline phosphatase activities during ammonia stress. Feeding the prawns on the MCD increased B cells in the hepatopancreas during ammonia stress. Interestingly, the prawns fed on MCD had significantly lower superoxide dismutase activity compared to LCD and HCD during ammonia stress. Moreover, the prawns fed on MCD had significantly lower pyruvate kinase activity and pyruvate and lactic acid contents, while those fed on LCD had significantly higher succinic dehydrogenase, 6-phosphogluconic dehydrogenase, and phosphoenol pyruvate carboxykinase activities during ammonia stress. The prawns fed on the MCD increased significantly glutaminase activity and decreased the ammonia content in the serum during ammonia exposure. In addition, feeding the prawns on MCD decreased significantly the expression of apoptosis and inflammation-related genes. Taken together, the MCD supplied energy required to counteract ammonia stress, which increased growth, improved antioxidant capacity, facilitated ammonia excretion, and alleviated inflammation and apoptosis of the oriental river prawn.

Toxic effect of chronic exposure to polyethylene nano/microplastics on oxidative stress, neurotoxicity and gut microbiota of adult zebrafish (Danio rerio)

The rapid development of aquaculture industry has provided a large amount of high-quality animal protein, while the food safety caused by microplastics and nanoplastics (MP/NPs) has become a major concern. In addition, recent evidence has shown the potential toxic effect of PE-MP/NPs, highlighting the need for further research into their environmental and health impacts. Chronic exposure of polyethylene microplastics (PE-MPs) and nanoplastics (PE-NPs) on adult zebrafish were conducted in the present study for 21 d. Organ-dependent oxidative damage induced by MP/NPs was observed. Insignificant differences in neurotoxicity and dysbiosis of gut microbiota were found between MPs and NPs. Changes in glutathione S-transferase (GST), glutathione (GSH), catalase (CAT), lipid peroxidation (LPO), and superoxide dismutase (SOD) showed that MP/NPs induced oxidative damage in gill and intestinal cells of zebrafish. The inhibited AChE activity suggested the potential neurotoxicity of microplastics and nanoplastics (MP/NPs). In addition, chronic exposure increased the alpha-diversity of intestinal microbiota. At the phylum level, the average relative abundance of Proteobacteria increased from 29.73% (control group) to 66.10% (microplastics), 54.84% (nanoplastics) and 60.03% (combined exposure), respectively. Tenericutes decreased from 55.43% (control group) to 20.02% (microplastics), 22.44% (nanoplastics) and 31.77% (combined exposure), respectively. Overall, this study provides new insights and objective evidence for the toxicity assessment of PE-MPs.

Food and Feeding Habits of Schilbe mystus from the Lower River Benue at Makurdi

A study on food and feeding habit of Schilbe mystus in the Lower River Benue at Makurdi, was carried out. Two hundred (200) fish samples were examined for stomach content. The body weight (WT), Total Length (TL) and Standard Length (SL) of each specimen was measured to the nearest gram and centimeters using a weighing balance and tape/ meter rule on a dissection board. The length weight relationship was determined by plotting a graph of Length-Weight. The gut for each fish specimen was cut open using a pair of scissors and scrapped onto a grease-free glass slide and examined for stomach contents and viewed microscopically. Result revealed the following food items; insects (64.42%), fish (20.2%), crustaceans (10.6%), detritus (15.4%) and unidentified materials (50.1%). Insects recorded the highest percentage in the stomach both on frequency of occurrence and gastro-somatic index methods while crustacean recorded the least percentage in both frequency of occurrence and gastro-somatic index. Smaller fish within the length range of 10.1-15.0 cm weighing between 0.1- 50 g were more of empty stomach (65.0% and 67.2%) than those with food (35.0% and 32.8%). Fish within the length range of 25.1- 30.0cm and 35.1- 40.0cm weighing 100.1- 200.0g and 200.1- 350.0g were found to contain stomach with full diet components, particularly insects, fish and crustaceans. Length weight relationship (LWR) and Length- length relationship (LLR) indicated that values of correlation coefficient (r2) are highly correlated, r2 > 0.7 and r2 > 0.8 at p < 0.05. Therefore, Schilbe mystus tropical features in the lower River Benue showed that it is a carnivorous and the pray type is influenced by their availability. This study provides data for the better understanding of the biology and ecology of Schilbe mystus in the Benue River which will also contribute to the development of aquaculture industry.

Identification of candidate growth-related SNPs and genes using GWAS and transcriptome analyses in leopard coral grouper (Plectropomus leopardus)

Leopard coral grouper, Plectropomus leopardus with gorgeous body color and rich nutritional value, which is favored by consumers and has high economic value and breeding value. Growth trait is one of the most important economic traits of fish, and its improvement has contributed to the development of aquaculture industry. However, there has been less research related to the growth properties of the leopard coral grouper. Thus, two strategies of genome-wide association study (GWAS) and RNA-seq were used for five growth traits in 307 leopard coral groupers. We identified 12 significant and 4 suggestive SNPs located predominantly on 23 chromosomes associated with growth traits. Within the 50 kb window of significant and suggestive SNPs, 12 growth-related genes candidates were detected, four of which were located in exon regions, corresponding to the genes zgc:63572, coro2a, btn1a1 and per2, respectively. Interestingly, SNP 23: 17993215 for per2 and SNP 23: 19213238 for btn1a1 occur as non-synonymous mutations in the exon. At the same time, we performed RNA-seq on both the high- and low-weight groups in 6 leopard coral groupers. The results show that 549 differentially expression genes (DEGs) were obtained, DEGs significant enrichment in fatty acid metabolism, amino acid metabolism and other metabolic pathways by GO (Gene Ontology) enrichment and KEGG pathway analysis. Finally, the per2 and acadvl were identified by GWAS and RNA-seq, which play an important role in locomotor activity and metabolism. Our findings could improve the mapping efficiency of leopard coral grouper growth candidate genes, which will provide a theoretical basis for molecular assisted breeding of leopard coral grouper.

Structure of the Spring Viraemia of Carp Virus Ribonucleoprotein Complex Reveals Its Assembly Mechanism and Application in Antiviral Drug Screening.

Spring viremia of carp virus (SVCV) is a highly pathogenic Vesiculovirus infecting the common carp, yet neither a vaccine nor effective therapies are available to treat spring viremia of carp (SVC). Like all negative-sense viruses, SVCV contains an RNA genome that is encapsidated by the nucleoprotein (N) in the form of a ribonucleoprotein (RNP) complex, which serves as the template for viral replication and transcription. Here, the three-dimensional (3D) structure of SVCV RNP was resolved through cryo-electron microscopy (cryo-EM) at a resolution of 3.7 Å. RNP assembly was stabilized by N and C loops; RNA was wrapped in the groove between the N and C lobes with 9 nt nucleotide per protomer. Combined with mutational analysis, our results elucidated the mechanism of RNP formation. The RNA binding groove of SVCV N was used as a target for drug virtual screening, and it was found suramin had a good antiviral effect. This study provided insights into RNP assembly, and anti-SVCV drug screening was performed on the basis of this structure, providing a theoretical basis and efficient drug screening method for the prevention and treatment of SVC. IMPORTANCE Aquaculture accounts for about 70% of global aquatic products, and viral diseases severely harm the development of aquaculture industry. Spring viremia of carp virus (SVCV) is the pathogen causing highly contagious spring viremia of carp (SVC) disease in cyprinids, especially common carp (Cyprinus carpio), yet neither a vaccine nor effective therapies are available to treat this disease. In this study, we have elucidated the mechanism of SVCV ribonucleoprotein complex (RNP) formation by resolving the 3D structure of SVCV RNP and screened antiviral drugs based on the structure. It is found that suramin could competitively bind to the RNA binding groove and has good antiviral effects both in vivo and in vitro. Our study provides a template for rational drug discovery efforts to treat and prevent SVCV infections.

Microalgal bioremediation of brackish aquaculture wastewater

Rapid aquaculture industry development contributed to a major increase in aquaculture wastewater generation. In the context of a circular economy, aquaculture wastewater treatment should simultaneously recover nutrients from the wastewater. Among many treatment methods, bioremediation using microalgae could be a cost-effective and environmentally friendly system that can be applied to treat aquaculture wastewater and simultaneously produce high-value microalgal biomass. This study explored the feasibility of treating brackish wastewater (0.8 % NaCl) generated from a Qatari commercial tilapia farm by microalgae. At first, 10 strains were grown using wastewater from the local farm in an indoor experiment. Based on nitrogen assimilation, biomass yield, biomass quality, and ease of harvesting, 4 candidate strains (Haematococcus sp., Neochloris sp., Monoraphidium sp., and Nostoc sp.) were shortlisted for outdoor growth experiments. Although Nostoc sp. could not grow outdoor in the wastewater, the other three strains were able to assimilate at least 70.5 % of the total nitrogen in the wastewater. Haematococcus sp. and Neochloris sp. could be harvested using self-settling, whereas Monoraphidium required an energy-intensive tangential flow filtration membrane process. Hence, the overall energy requirement for bioremediation, including biomass dewatering, for Haematococcus sp., Neochloris sp., and Monoraphidium sp. were determined as 0.64, 0.78, and 5.68 MJ/m3, respectively. Neochloris sp. had almost twice the biomass yield compared to Haematococcus sp. – suggesting that Neochloris sp. could be a potential candidate for aquaculture wastewater treatment.

CRISPR/Cas9-Mediated Disruption of Endo16 Cis-Regulatory Elements in Sea Urchin Embryos

Sea urchins have become significant mariculture species globally, and also serve as invertebrate model organisms in developmental biology. Cis-regulatory elements (enhancers) control development and physiology by regulating gene expression. Mutations that affect the function of these sequences may contribute to phenotypic diversity. Cis-regulatory targets offer new breeding potential for the future. Here, we use the CRISPR/Cas9 system to disrupt an enhancer of Endo16 in developing Lytechinus variegatus embryos, in consideration of the thorough research on Endo16’s regulatory region. We designed six gRNAs against Endo16 Module A (the most proximal region of regulatory sequences, which activates transcription in the vegetal plate and archenteron, specifically) and discovered that Endo16 Module A-disrupted embryos failed to undergo gastrulation at 20 h post fertilization. This result partly phenocopies morpholino knockdowns of Endo16. Moreover, we conducted qPCR and clone sequencing experiments to verify these results. Although mutations were not found regularly from sequencing affected individuals, we discuss some potential causes. In conclusion, our study provides a feasible and informative method for studying the function of cis-regulatory elements in sea urchins, and contributes to echinoderm precision breeding technology innovation and aquaculture industry development.

The possibility of replacing corn meal with coconut waste on the growth performance of African Catfish (Clarias gariepinus)

In Malaysia, the development of aquaculture industry faces general feed cost problems. Feed cost is about 70% to 80% of total production. One of the reason is the usage of corn meal which is expensive. Thus, the alternative way is by using plant waste. This idea develop interest towards the aquaculture industry. Hence, this study investigated the replacement of corn meal with coconut waste in different percentages and assess the growth development of the African catfish, Clarias gariepinus. The study design used 5 feed treatments with 3 replications treatments each. The percentage replacement of corn meal to coconut waste become the variables and labelled the treatments by P1 (10% replacement), P2 (20% replacement), P3 (30% replacement) P4 (40% replacement) and control treatment (0% replacement). The suitability of coconut waste feed product had been determine by using the growth performance based on the survival rate of the fish, absolute body weight gains, feed conversion rate and specific growth rate of the fish. Proximate analysis of the formulated feeds was also conducted. Result shows that formulated feed using 30% of coconut waste could possibly replace the corn meal and increase the growth of juvenile African catfish.

Fish seed and feed value chains analysis and their critical factors for aquaculture development in Tanzania

AbstractSeeds and feeds are among the most important inputs required for sustainable aquaculture industry development in any country worldwide. However, the value chain analysis of seeds and feeds in most developing countries including Tanzania has not been mapped, and the key actors are not identified and characterized. To address this knowledge gap, we mapped the fish seed and feed value chains in Morogoro, Dar es Salaam, Coast and Lindi regions in Tanzania, evaluated their performances, analyzed their contributions to aquaculture growth and finally assessed the critical factors impending aquaculture development before proposing appropriate strategies for upgrading. We found that the fish seed value chain comprised broodstock suppliers, seed producers, seed marketers, traders and fish farmers. Tilapia (Oreochromis sp.) and African sharptooth catfish (Clarias gariepinus) seeds produced were primarily sold to farmers at an advanced fry stage (1 to 5 g) at a price ranging from USD 0.09 to 0.13 and USD 0.22 to 0.27, respectively. The feed value chain consisted of suppliers, producers, importers, traders and fish farmers. The feeds produced were powdered, compressed and extruded pellets and granules sold at an average price of USD 2.50/kg. The seed and feed value chains in the four regions drive the aquaculture development and employ 137 and 109 people, respectively. The fish farming was mainly affected by insufficient seeds and feeds; inadequate extension services, inadequate technical skills in seed and feed production; limited farming equipment; insufficient capital and limited access to market. We propose increasing seed and feed production through collaborative research between researchers and the private sector, enhancing delivery of extension services to all fish farmers, providing fiscal incentives to hatchery and feed investors, organizing hatchery owners into associations, and undertaking marketing awareness campaign for aquaculture growth in the country for food, income and employment generation.

Immune-antioxidant trait, growth, splenic cytokines expression, apoptosis, and histopathological alterations of Oreochromis niloticus exposed to sub-lethal copper toxicity and fed thyme and/or basil essential oils enriched diets

Two experiments were conducted in this study, using 250 Oreochromis niloticus (O. niloticus) (average weight 30.28 ± 0.27 g). The first experiment was conducted to investigate the 96-h lethal concentration 50 (LC50) of copper chloride (CuCl2) using the probit analysis, seventy fish was divided into seven different concentration of CuCl2 (0, 22, 23, 24, 25, 26, and 27 mg/L), the accurate Cu concentrations were (1.23, 5.36, 6.02, 6.98, 7.05, 7.93, 8.12 mg/L Cu). The second experiment was conducted for investigating the effect of dietary supplementation with thyme (Thymus vulgaris, T. vulgaris) and sweet basil (Ocimum basilicum, O. basilicum) essential oils (TEO and BEO respectively) against sub-lethal Cu exposure (1/10 96-h LC50 of CuCl2). About 180 fish was divided into six groups in triplicate (10 fish/replicate, 30 fish/group). Group 1 (C) was kept as a control group with no Cu exposure and was fed the control basal diet. Group 2 (C–Cu) was fed the control basal diet and simultaneously exposed to 1/10 of the 96 h LC50 of CuCl2 (2.574 mg/L) as a sub-lethal concentration of Cu, where the realistic Cu concentration was 3.976 mg/L. Group 3 (TEO) and group 4 (BEO) were fed the diets fortified with 1%TEO and BEO, respectively without exposure to Cu. Group 5 (TEO-Cu) and group 6 (BEO-Cu) were fed the diets fortified with 1%TEO and 1%BEO, respectively, and simultaneously exposed to 1/10 of the 96 h LC50 of CuCl2 (2.574 mg/L). The growth and behavioral performance, immunological response and its related gene expression, antioxidant status, stress biomarker indicators, apoptosis biomarkers, and histopathological alteration were investigated. The results of the first experiment showed that the 96-h LC50 of CuCl2 in O. niloticus was 25.740 mg/L with lower and upper confidence limits of 25.152 and 26.356 mg/L, respectively. The results of the second experiment showed that sub-lethal Cu exposure induced growth retardation (lowered final body weight, total weight gain, and specific growth rate %), behavioral abnormalities (slower swimming activity and feeding performance), immunosuppression (lowered nitric oxide, complement-3, lysozyme, total proteins, albumin, and globulin), and lowering the hepatic antioxidant functions (higher MDA, and lower SOD, CAT, and GPx) in the exposed fish. Furthermore, alteration in the immune-related genes expression (down-regulation of IL-10 and TGF-β and up-regulation of IL-1β, IL-6, IL-8, and TRL-4), hepato-renal dysfunction (elevated ALT, AST, urea, and creatinine), and high levels of serum stress indicators (cortisol and glucose) were markedly evident. sub-lethal Cu toxicity induced significant up-regulation of apoptosis biomarkers involving, nuclear factor-κβ (NF-κβ), Bcl-2 Associated X-protein (BAX), meanwhile, the expression of B-cell lymphoma 2 (BCL2) and Proliferating cell nuclear antigen (PCNA) was remarkably down-regulated. In addition, apoptosis was also evident by histopathological investigation of branchial, hepatic, and renal sections. TEO and/or BEO dietary supplementation mitigate the destructive impacts of sub-lethal Cu exposure in O. niloticus, depending on the results of our study, it could be concluded that TEO and BEO with a 1% dietary level could be a promising antioxidant, immunostimulant, anti-stress factors, and anti-apoptosis mediators against heavy metal contaminants (Cu) in O. niloticus, providing a solution to the problem of aquatic bodies pollution, consequently aiding in the development of aquaculture industry.

Histological characteristics of spermatogenesis stages in annual reproductive cycles of male Siberian sturgeons in various types of industrial fish farming

The modern development of aquaculture industry is inseparably associated with brood stock formation and reproduction, breeding of seeding and commercial production. Specific breeding conditions, with longer periods of water temperatures favourable for fish growth, simultaneously affect the development of the reproductive system of fish. Studies of these processes enable the best approach to obtaining reproductive products whenever the farm needs them. The study was performed at the Konakovo Division of the Branch for Freshwater Fisheries of the Federal State Budget Scientific Institution ‘Russian Federal Research Institute of Fisheries and Oceanography’ (VNIIPRKH), in a recirculating aquaculture system (RAS) and flowthrough industrial farm. Even-aged Siberian sturgeons of generation 2017 were used in the study. Samples were taken by biopsy and fixed in 70% ethanol. The paper presents the data on spermatogenesis in Siberian sturgeons in a flow-through industrial farm with annual thermal constant of 5600 degree days and with combination housing of brood fish. During the first stage, the fish are kept in a recirculating aquaculture system for 210 days, with the thermal constant of 1511 degree days, with subsequent housing and breeding in a flow-through farm for 150 days, with the thermal constant of 2340 degree days. The histological characteristics of spermatogenesis and reproductive cycles of Siberian sturgeons are presented, with a detailed description and illustrations of the processes and respective differences depending on housing conditions. The studies showed that specific temperature conditions can prolong the spawning season by 2–3 months by shifting the reproductive cycles of male Siberian sturgeons at first spawning with combination housing in flow-through tanks and RAS (prolonged wintering conditions).

어구부표의 표시 방법 개선에 대한 입법론적 고찰 - 어구 손상사고 사례를 중심으로 -

Accidents between small ships and small fishing vessels sailing in the coastal waters of Korea and facilities installed for fishing on the coast occur frequently every year. These accidents are mainly caused by aquaculture farms, fishing nets, and gill nets installed in coastal waters. Common causes of ship accidents include the negligence of the officers of the crew on a sailing vessel, non-compliance with course maintenance, confirmation of ship position, and general navigation. It can be in various ways, such as non-compliance with the principles and regulations on the prevention of collisions at sea. In particular, to examine the cause of the accident related to the fishing net damage accident, it was analyzed through the decision of the Maritime Safety Tribunal, and as a result, the cause of the accident was neglect of the boundary, not securing an appropriate distance from the installed fishing gear, and insufficient establishment of the voyage plan. In order to reduce accidents caused by these human factors, it takes a long time and a lot of money, such as constant safety education for seafarers or changes to systems such as ship safety management system. In this paper, measures to reduce the occurrence of accidents by removing other risk factors other than human factors by intuitively discovering fishing gear a little faster are presented in 「Fisheries Act」, 「Rules on the Management of Fishing Licenses, etc.」, 「Aquaculture and fishing grounds」 We will try to find a way to reduce the damage to fishing nets by identifying and improving problems in the “Installation Standards for Marking Facilities” and “Aquaculture Industry Development Act”.

Antibiotic resistance genes and their links with bacteria and environmental factors in three predominant freshwater aquaculture modes

Rapid development of aquaculture industry and increasing demand of various inputs (especially antibiotics), are suspected to promote the occurrence and spread of ARGs in aquaculture related environments. However, the occurrences of ARGs under different freshwater aquaculture practices are rarely known. Here, we investigated the seasonal profiles of the main ARGs, intI1 and bacteria in waters from three kinds of predominant freshwater aquaculture practices around the Honghu Lake (China), as well as their co-occurrences and interrelationships with antibiotics, heavy metals and general water quality. The results indicate that quinolone resistance genes (qnrB), tetracycline resistance genes (tetB and tetX) and sulfonamide resistance genes (sul1 and sul2) were the top five predominant ARGs with seasonal variations of abundance. Fish ponds were of the highest absolute abundances of tested ARGs than the other two modes. Crayfish ponds and their adjacent ditches shared similar ARGs profile. Different subtypes of ARGs belonging to the same class of resistance were varied in abundances. Some bacteria were predicted to carry different ARGs, which indicating multi-antibiotic resistances. Moreover, the combined environmental factors (antibiotics, heavy metals and water quality) partially shaped the profiles of ARGs and bacteria composition. Overall, this study provides new comprehensive understanding on the characterization of ARGs contamination in different freshwater aquaculture practices from the perspectives of environmental chemistry, microbiology and ecology. The results would benefit the optimization of aquaculture practices toward environmental integrity and sustainability.

Bait input altered microbial community structure and increased greenhouse gases production in coastal wetland sediment

Coastal wetland reclamation contributed to development of aquaculture industry, and the residual bait accumulation in aquaculture processes could influence biogeochemical elements cycling, which threaten ecological functions and services in aquaculture and adjacent ecosystems. However, systematic studies for changes in sediment microbial community structure and greenhouse gasses (GHGs) production, as well as environmental parameters following bait input at time scale are still rare. A 90-day incubation experiment was conducted using sediment collected from coastal wetland in Qi'ao Island in southern China, followed by the observations of temporal variations of physicochemical properties, sediment microbial community, and GHGs production in response to different amounts of bait input (0, 20, and 40 mg bait g−1 wet sediment). The results showed that dissolved oxygen of overlying water was profoundly decreased owing to bait input, while dissolved organic carbon of overlying water and several sediment properties (e.g., organic matter, sulfide, and ammonium) varied in reverse patterns. Meanwhile, bait input led to significant loss of microbial community richness and diversity, and strongly altered microbial compositions from aerobic, slow-growing, and oligotrophic (Actinobacteriota, Chloroflexi, and Acidobacteriota) to anaerobic, fast-growing, and copiotrophic (Firmicutes and Bacteroidota). Moreover, both GHGs production and global warming potential were significantly enhanced by bait input, implying that aquaculture ecosystem is an important hotspot for global GHGs emission. Overall, bait input triggered quick responses of physicochemical properties, sediment microbial community, and GHGs production, followed by long-term resilience of the ecosystem. This study could provide new insight into temporal interactive effects of bait input on physicochemical properties, microbial community, and GHGs production, which can enhance the understanding of the temporal dynamics and ecological impacts of coastal aquaculture activities and emphasize the necessity of sustainable assessment and management in aquaculture ecosystems.