Aquaculture Fisheries
In order to explore the effects of breeding space sizes on the growth, nutrition, and immunity of Procambarus clarkii, and provide theoretical guidance for the development of industrial aquaculture of P. clarkii, an experiment of P. clarkii cultivation was conducted in an indoor circulating water aquaculture system. Four types of individual breeding spaces were set up in this experiment, including sizes of 15 cm×15 cm, 15 cm×20 cm, 15 cm×25 cm and 15 cm×30 cm (referred to as S1, S2, S3 and S4 group), respectively. The experiment lasted for 56 days. In terms of growth performance, the final body weight (20.57 g), weight gain rate (305.18%), and specific growth rate (2.56%/d) of the S1 group were significantly lower than those of the other groups (P<0.05), and the abdominal meat rate of the S1 group (12.13%) was significantly higher than that of the S3 group (P<0.05), and there was no significant difference in the survival rate among all groups. In terms of nutritional performance, with the increase of breeding space, the muscle water content in each group showed a trend of first increasing and then decreasing, reaching the highest level of 79.54% in group S2. The crude ash content showed a gradually increasing trend, with the S4 group having the highest content at 9.37%. There was no significant change in crude protein and crude fat content. The amylase activity in the intestines of each group showed an overall decreasing trend, with the S2 group having the highest activity at 31.34 U/(g·prot) and the S4 group having the lowest activity at 21.91 U/(g·prot). The lipase showed a trend of first decreasing and then increasing, with the S1 group having the highest value at 8.51 U/(g·prot) and the S3 group having the lowest value at 4.96 U/(g·prot). Trypsin showed an increasing trend, with the S4 group being the highest at 220.53 U/(g·prot) and the S1 group being the lowest at 23.97 U/(g·prot). In terms of immune indicators, with the increase of breeding space, the activity of superoxide dismutase, acid phosphatase and alkaline phosphatase in the hemolymph of each group showed a trend of first increasing and then decreasing. Among them, the activities of superoxide dismutase and alkaline phosphatase were the highest in the S2 group, at 31.34 and 362.10 U/(g·prot), respectively. The activity of acid phosphatase was the highest in the S3 group, at 96.72 U/(g·prot). The content of malondialdehyde showed a trend of first decreasing and then increasing, with the lowest level in the S3 group at 2.83 nmol/(g·prot). In summary, under the monoculture mode, the size of the breeding space will have an impact on the growth and physiological and biochemical status of P. clarkii. Overall, when the single breeding space is set at a size of 15 cm×20 cm to 15 cm×25 cm, P. clarkii can exhibit good growth, nutrition, and immune performance.
To clarify the relationship between morphological traits and abdominal meat yield in adult red swamp crayfish (Procambarus clarkii) from Poyang Lake, the abdominal meat yield and nine morphological traits were measured in 310 Procambarus clarkii individuals. The influence of morphological traits on abdominal meat yield was investigated using correlation analysis, path analysis, and stepwise regression analysis. Morphological prediction equations for abdominal meat yield were constructed. The main traits affecting abdominal meat yield in the female and male groups were total length and third abdominal segment length. The main traits affecting abdominal meat yield in the mixed group were total length, first abdominal segment width, and third abdominal segment length. Using the significant traits as independent variables and abdominal meat yield as the dependent variable, multiple regression equations were constructed: female group: yfemale=0.614x1+0.678x2-0.266x3-0.014 (R2=0.735), male group: ymale=0.229x1+0.618x2-3.301x3-0.041 (R2=0.689), mixed group: ymixed=0.718x1+0.496x2+0.480x3-0.086 (R2=0.753). Where x1=total length/body length, x2=first abdominal segment width/body length, x3=third abdominal segment length/body length, and x4=Fulton’s condition factor (K). The best-fitting curve models for the relationship between condition factor (K) and abdominal meat yield were primarily power functions in the female and mixed groups, and primarily binomial in the male group. For selective breeding of Procambarus clarkii from Poyang Lake based on meat yield rate, when breeding female and male groups separately, it is recommended to primarily use condition factor (K) as the main reference trait, with total length/body length and third abdominal segment length/body length as auxiliary reference traits; for the mixed group, it is recommended to primarily use condition factor (K) as the main reference trait, with total length/body length, first abdominal segment width/body length, and third abdominal segment length/body length as auxiliary reference traits. This study provides a reference basis for the genetic breeding of Procambarus clarkii based on abdominal meat yield.
The aims of this study were to investigate the growth performance, coloration, blood biochemical indicators, and nutritional quality differences among the hybrid combinations of four selective lines of Oujiang color common carp (Cyprinus carpio var. color) with different body colors and wild common carp (Cyprinus carpio), and to provide a theoretical foundation for development of the complete set lines breeding in common carp and the further germplasm utilization in Oujiang color common carp. A nested breeding design was employed to construct hybrid combinations by using the four selective lines of Oujiang color common carp with different body colors ("Quanhong," "Mahua," "Fenyu," and "Fenhua") as the female parents and wild common carp as the male parent. The growth performance of the hybrid offspring was evaluated by the same pool polyculture marker, and the countable traits of the external morphology were counted. The number and size of pigment cells were assessed using microscopic observation method, and the expression profiles of the color-related genes were tested using fluorescence quantitative PCR technology. The blood biochemical indices under both normoxic and hypoxic conditions were measured with an automatic biochemical analyzer. The amino acid composition and content in dorsal muscles were measured by an amino acid automatic analyzer, and fatty acid profiles and contents were quantified using gas chromatography-mass spectrometry (GC-MS). The hybrid combination of "Fenyu"♀ × common carp♂ exhibited significant growth advantages, with significantly higher of the final weight, absolute growth rate and specific growth rate than the other combinations (P<0.05) and with the lowest coefficient of variation in body weight and the highest survival rate. No significant differences (P>0.05) were observed in the 12 countable morphological traits across the four hybrid combinations. All hybrids exhibited gray coloration which was similar to the male parent, but the "Fenyu"♀ × common carp♂ combination had the significantly highest number of melanocytes and the fewest number of erythrophore (P<0.05) compared to the other combinations. The expression levels of two melanogenesis-related genes (Tyrp1, Slc24a5) and two carotenoid-related genes (Bco1, Scarb1) did not show significant differences (P>0.05) among the skin tissues of the four hybrid combinations. The obvious fluctuation was observed in relative blood biochemical indices among the four hybrid combinations under both normoxic and hypoxic conditions; however, the "Fenyu"♀ × common carp♂ combination exhibited notably higher survival rates under hypoxic stress than the other combinations. The six key flavor amino acids contributed more than 46% of the total amino acids in the four combinations, and the "Quanhong"♀ × common carp♂ combination showed significantly higher crude fat content and total DHA + EPA levels than the other combinations (P<0.05). The "Fenyu" selective line of Oujiang color common carp exhibits strong compatibility and maternal effects in hybridization, and is a good genetic material for conducting the complete set lines breeding in common carp.
To investigate the characteristics of the plankton community structure in Guangrong Reservoir in Neijiang City, Sichuan Province, and to propose suggestions for improving the fisheries ecology of the reservoir, plankton samples were collected from the reservoir in October 2020 and June 2021, and the collected samples were identified, classified, and counted. The community structure was analyzed by Shannon-Wiener diversity index, Margalef richness index and Pielou evenness index, and the fish productivity was estimated by ecological model. A total of 86 species of phytoplankton belonging to 8 phyla were identified during the two surveys, with an average density of 2.77×108 ind./L and an average biomass of 19.7 mg/L. Among them, cyanobacteria had a higher density, with dominant species including Pseudanabaena, Nitzschia linearis, and Cryptomonas erosa. A total of 39 species of zooplankton were identified, with an average density of 5493.7 ind./L and an average biomass of 5.768 mg/L. Rotifers and protozoa had higher densities, with dominant species being Polyarthra trigla and Trichocerca pusilla. Diversity index analysis results showed that the average Shannon-Wiener diversity index for phytoplankton was 0.98, and was 2.16 for zooplankton. The average Margalef richness index for phytoplankton was 3.09, and was 2.72 for zooplankton. The average Pielou evenness index for phytoplankton was 0.24, and was 0.69 for zooplankton. Based on the density and biomass of plankton, the fish productivity of Guangrong Reservoir was estimated to be approximately 87.52 tons. The study indicated that the water quality of Guangrong Reservoir is generally at the level of medium to heavy pollution. To ensure the survival rate of released fish species, it is recommended to release 47000 Hypophthalmichthys molitrix and 11000 Aristichthys nobilis, along with some benthic and detritus-feeding fish species, thereby effectively slowing down or controlling eutrophication in the water body and providing certain economic benefits.
5-Aminolevulinic acid (5-ALA) is widely present in animals, plants, and microbial cells and serves as a key precursor for tetrapyrrole compounds. It participates in the synthesis of essential metabolites such as heme, vitamin B12, and chlorophyll, exhibiting diverse physiological functions. This paper summarized the biosynthesis pathway of 5-ALA and its transport mechanism across different cell types, analyzed the functions and regulatory mechanisms of important downstream metabolites derived from 5-ALA, and reviewed the current applications of 5-ALA in pharmaceutical and agricultural fields. Furthermore, this paper highlighted existing challenges, including immaturity of biosynthesis technology and lack of standardized application protocols, and provided future research prospects to guide its potential applications in agriculture.
The Pacific spadenose shark (Scoliodon macrorhynchos) is a cartilaginous fish commonly found in China's coastal waters. In recent years, the population resources of this species are continuously declining and it has been listed as Near Threatened on the IUCN Red List. In order to further understand the species and provide a basis for its scientific management and protection, this study investigated and analyzed genomic genetic resources of S. macrorhynchos. In this study, whole-genome resequencing was performed on the genomic DNA of the S. macrorhynchos. Using the resequencing data, preliminary genome assembly was conducted and its quality was evaluated. Genome-wide identification of microsatellite loci was carried out with calculation of their relative abundance. The complete mitochondrial genome sequence was de novo assembled using bioinformatics software. The assembled mitochondrial sequence was comparatively analyzed against published GenBank reference sequences to identify variant sites; variations were annotated by genomic location (protein-coding genes, tRNA genes, and the control region) and analyzed for nonsynonymous substitutions. The results showed that the genome of the S. macrorhynchos exhibited the following characteristics: size= 2991.63 Mb, heterozygosity rate= 0.46%, repetitive sequence proportion= 63.37% and GC content= 44.34%. The preliminary genome assembly yielded a total length of 2482 Mb with a scaffold N50 of 3342 bp. A total of 470542 microsatellite loci were identified genome-wide, with a relative abundance of about 189.58 loci/Mb. The complete mitochondrial genome sequence (16693 bp) was de novo assembled using bioinformatics tools, consistent with published GenBank reference sequences. Comparative analysis revealed 19 variant sites in the mitochondrial genome: 16 in protein-coding genes, 2 in tRNA genes, and 1 in the control region. Among variants in protein-coding genes, 4 were nonsynonymous substitutions located in the COIII, ND4, ND5, and Cyt b genes. The genome of the S. macrorhynchos is likely of a complex type. This study obtained foundational genetic resources including a draft genome assembly, genome-wide microsatellite markers, and mitochondrial genome data. Comparative mitochondrial genome analysis revealed heightened variability in protein-coding regions. Multiple nonsynonymous substitutions detected in key mitochondrial genes (COIII, ND4, ND5, Cyt b) suggest that relaxed purifying selection may be the primary evolutionary driver of the mitochondrial genome in this species. This research aims to provide essential genetic resources for advancing S. macrorhynchos genomics studies, investigations of genetic evolution, and conservation initiatives.
To investigate the effects of fertilization on pond water quality, plankton population structure, and the growth performance of Hypophthalmichthys molitrix and Aristichthys nobilis, H. molitrix and A. nobilis were used as experimental subjects. Four fish fertilizers with different compositions were applied in ponds, namely compound fertilizer (C1), compound fertilizer (C2), organic fertilizer (C3) and inorganic fertilizer (C4). The effects of four fish fertilizers were explored by measuring the physicochemical indicators of pond water, quantitatively analyzing plankton, and measuring growth performance of H. molitrix and A. nobilis. The results showed that the dissolved oxygen content of C2 ponds was significantly higher than C4 ponds (P<0.05), the nitrite content of C1 and C2 ponds were significantly lower than C4 ponds (P<0.05), and the total hardness of C1 and C2 ponds was significantly higher than C3 and C4 ponds (P<0.05). On the 8th day of fertilization, the biomass of phytoplankton and zooplankton of C1 and C2 ponds was significantly higher than C3 and C4 ponds (P<0.05), the biomass of phytoplankton of C3 ponds was significantly lower than C4 ponds (P<0.05). On the 10th day of fertilization, the biomass of phytoplankton and zooplankton of C1 and C2 ponds were significantly higher than C3 and C4 ponds (P<0.05), and the biomass of phytoplankton and zooplankton of C3 ponds was significantly higher than C4 ponds (P<0.05). The growth results showed that the weight gain rate of H. molitrix and A. nobilis of C1 and C2 ponds were significantly higher than C3 and C4 ponds (P<0.05). The fullness of H. molitrix of C1 and C2 ponds were significantly higher than C3 and C4 ponds (P<0.05), the fullness of A. nobilis of C1 ponds were significantly higher than C2, C3 and C4 ponds (P<0.05). In conclusion, compound fertilizer build a positive material cycle from plankton to fish by continuously releasing nutrients, which can maintain stable water quality and improve fish growth performance. The effect of compound fertilizer is better than the single inorganic fertilizer and organic fertilizer. Under the condition of maintaining the best water quality, the ratio of compound fertilizer of C2 is the best.
In order to evaluate the water quality condition of aquaculture ponds in Lianyungang area, this study sampled and analyzed the source water, pond water and tailwater of nine freshwater aquaculture ponds and four seawater aquaculture ponds from May to December 2022, with a focus on the physicochemical indexes of aquaculture ponds and the trend of change. This study adopted the single-factor pollution index method and the Nemerow comprehensive pollution index method to assess the degree of pollution of pond water and tail water in the aquaculture ponds systematically. The monitoring results indicated that the concentration of dissolved inorganic nitrogen (DIN) in the pond water of seawater aquaculture ponds was higher from May to July, while the concentration of dissolved inorganic phosphorus (DIP) reached its peak in August. The concentration of total nitrogen (TN) in pond water from freshwater aquaculture ponds were higher overall, and ammonia nitrogen (NH4+-N) was higher in May, and the concentration of total phosphorus (TP) increased significantly from August to October. The analysis of tailwater quality indicated that the main pollutant in the tailwater of the seawater aquaculture ponds was DIN, and the concentration of DIN in 50.0% of the tail water exceeded the secondary discharge standard of Jiangsu Provincial Discharge Standard of Water from Aquaculture Ponds; the main pollutants in the tailwater of the freshwater aquaculture ponds were NH4+-N and TN, with the proportions of the tailwater exceeding the secondary discharge standard being 25.0% and 37.5% respectively. Based on the Nemerow comprehensive pollution index evalution, 37.5% of the pond water in seawater ponds and 50.0% of the pond water in freshwater ponds were at moderate and severe pollution levels. Overall, 75.0% of the surveyed ponds aquaculture tailwater was relatively clean, with the overall quality condition being good.
Microbial driven nitrogen cycle processes play a crucial role in promoting material cycling within aquaculture systems, purifying aquaculture water environments, and maintaining ecosystem balance. Compared to natural ecosystems, aquaculture systems receive higher anthropogenic inputs of nitrogen, exhibit a rich diversity of nitrogen forms, and have their nitrogen cycling processes and associated microorganisms influenced and regulated by intertwined, complex, and easily fluctuating environmental factors. This article elucidates the ecological characteristics of aquaculture environments and reviews research progress on the major nitrogen cycle processes, including nitrogen fixation, ammonification, nitrification, denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) and their associated microbial communities within aquaculture ecosystems. It summarizes the environmental impact characteristics of nitrogen-cycling functional microorganisms. It discusses other potential ion redox reactions coupled with nitrogen cycling processes in aquaculture environments. Finally, the future research directions for the nitrogen cycle in aquaculture environments are prospected. The aim is to deepen the understanding of nitrogen cycling processes and their functional microorganisms in aquaculture systems, thereby providing a theoretical foundation for the purification of nitrogen in aquaculture environments.
In order to explore the genomic adaptation mechanism and phylogenetic status of Bathyuroconger vicinus to extreme environments, this study carried out whole genome Survey sequencing and systematic analysis for the first time. The Illumina NovaSeq 6000 platform was used for genome sequencing, combined with the SOAPdenovo2 assembly genome sketch, MISA was used to screen microsatellite loci, and a phylogenetic tree was constructed based on the mitochondrial protein-coding gene tandem sequence. K-mer analysis revealed that the genome size of B. vicinus was approximately 1414 Mb, with the heterozygosity rate and repeat sequence proportion of 0.66% and 54.93%, respectively. A total of 1221434 microsatellite loci were identified, with an overall length of 10936848 bp. These microsatellites were randomly distributed across 698950 sequences, with the occurrence frequency, appearance frequency and relative abundance of 19.18%, 33.53%, and 857.57 loci/Mb, respectively. Among the six perfect microsatellite types, the dinucleotide repeat was the most prevalent (804493, 65.86%), with the highest appearance frequency (22.08%) and the greatest relative abundance (564.84 loci/Mb). There were 1484 repeat motifs in all, of which hexanucleotide repeat was the most diverse (668), followed by pentanucleotide repeat (583), tetranucleotide repeat (231), trinucleotide repeat (60), dinucleotide repeat (12), and mononucleotide repeat (4). The dominant repeat motifs were A (128843, 43.40%), CA (239966, 29.83%), AAT (9533, 12.30%), AAAT (2663, 8.16%), CATTA (316, 5.40%), and CACACT (268, 6.56%). The phylogenetic tree based on the concatenated sequences of mitochondrial protein-coding genes was constructed by using the maximum likelihood (ML) method. The topology indicated a close relationship between B. vicinus and the species from genus Uroconger. This study revealed the complex characteristics of B. vicinusis genome and numerous highly polymorphic microsatellite loci, which provided a molecular basis for the study of its deep-sea adaptation mechanism. The selected microsatellite loci can be used for population genetics analysis. The phylogenetic results supported its close relationship with the fish of the genus Uroconger, clarified its evolutionary status in the subfamily Congrinae, and suggested that Congridae may be a polyphyletic group.
In order to study the effects of cultivation models on the growth, nutrition and taste of Chinese soft-shelled turtles (Pelodiscus sinensis), P. sinensis cultured in two different modes (paddy-field cultivation and pond intensive cultivation) were used to evaluate the growth performance, fatty acid nutrition and taste. The results showed that in paddy-field cultivation model, the specific growth rate (SGR) of P. sinensis was significantly higher than that in intensive pond culture by 82% (P<0.05), and the feed coefficient (FCR) was significantly reduced by 8% (P<0.05). The fatty acid nutritional value of P. sinensis was high in both cultivation models. In pond intensive cultivation model, the ratios of SFA/TFA (40.63%), PUFA/SFA (0.777:1), and SFA/MUFA/PUFA (1.28:0.86:1.00), as well as the AI, TI, and HH (0.500, 0.212, 2.087) in muscle were better than those in paddy-field cultivation model. Texture analysis revealed that the hardness, gumminess and chewiness of muscles and calipash of P. sinensis cultured in paddy-field cultivation model were significantly higher than in the pond-intensive model, whereas there were no significant differences in adhesiveness, resilience and springiness. In summary, the growth performance of P. sinensis under paddy field cultivation model was better and the muscle was chewy. And in pond-intensive cultivation model, the fatty acid nutritional value was higher and the muscle was tender and juicy.
In order to conduct a dynamic analysis of the fishery resources in Poyang Lake, a study on the resource status of Coilia nasus and its environmental carrying capacity under extreme low water levels was carried out. Based on the fishery resource survey data, the length-based Bayesian biomass estimation method was used to obtain the relevant parameters of Coilia nasus population, and the Ecopath model was applied to estimate its environmental carrying capacity under extreme low water levels. The results showed that the average L∞ of Coilia nasus in Poyang Lake was 374 (368-381) mm; the resource status index E (F/Z) was 0.067, far less than 0.5; the ratio of current biomass to original biomass (B/B0) was 0.89 (0.225-2.6), which was greater than 0.5; from 2018 to 2022, L∞ and B/B0 showed an upward trend, while the ratio of fishing mortality to natural mortality (F/M) showed a downward trend, indicating that the resources of Coilia nasus showed a recovery trend after the fishing ban. The Ecopath model revealed that environmental carrying capacity of Coilia nasus in Poyang Lake was 5.03 t/km2 (approximately 1136.78 t), while its current biomass was 2.83 t/km2 (approximately 639.58 t). Currently, the overall resources of Coilia nasus in Poyang Lake are in an undeveloped state. The environmental carrying capacity has restricted the population growth of Coilia nasus to a certain extent, but there is still a large growth space for its population. The results of this study provide a scientific basis for the sustainable management of Coilia nasus resources and the protection of the entire lake ecosystem in Poyang Lake.
Enterocytozoon hepatopenaei (EHP) is an intracellular parasite that can infect various shrimp species. To develop an on-site rapid detection method of EHP, recombinant polymerase chain reaction (RPA) and lateral flow strip (LFS) techniques were combined in this study. 3 pairs of primers and probes were designed targeting the highly conserved region of EHP spore wall protein 1(SWP) gene according to primer design principle of RPA. By optimizing reaction conditions and screening the best primers and probes, an RPA with lateral flow dipstick (RPA-LFS) detection method for EHP was developed in this study. Then, detection limit, specificity and reliability were detected. After optimization, the target gene was successfully amplified in reaction temperature of 37℃ for only 15 minutes. With LFS detection, the overall detection time was within 20 minutes. The detection limit of RPA-LFS was 10 copies of EHP DNA. The results of specificity test showed that this method just specifically reacted with the EHP DNA, and had no cross-reaction with other aquatic animal virus such as white spot syndrome virus (WSSV). The clinical samples detection results of the RPA-LFS method were the same as the results of real time PCR method recommended by WOAH. This EHP RPA-LFS detection method established in this study has the advantages of shorter time, visible results, no dependence on expensive instruments, and lower detection costs, compared with qPCR and nested PCR detection methods. This method can achieve on-site rapid detection of EHP and is very suitable for small laboratories, providing a new assay for EHP detection.
The study aims to understand the content of mineral elements in the edible portion of oriental river prawns (Macrobrachium nipponense) from different cultured and wild origins, to further explore the nutritional quality of oriental river prawns from different origins and the possibilities of mineral elements and stable isotopes for determining the origin of oriental river prawns. This paper selected samples from Yixing, Kunshan, and Shezhu culture origins and the Yangtze River wild oriental river prawns population for the study, and analyzed the content of 21 mineral elements using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that each oriental river prawns contained not only the essential macronutrients Ca, Na, Mg and K, but also the essential trace elements Fe, Zn, Mn, Se and Cu. One-way analysis of variance showed that there were significant differences in the contents of various mineral elements in spring and autumn (P<0.05). The results of stepwise discrimination analysis based on mineral elements showed that the discrimination accuracy could reach 100% and 98.3% for spring and autumn oriental river prawns, respectively, while the C and N stable isotope ratios had the potential to differentiate between wild and farmed oriental river prawns. The results effectively confirmed that the oriental river prawns is a healthy aquatic product with high nutritional value, and that the microchemical ‘fingerprints’ have the potential to be used for origin traceability.
To explore the influence of artificial breeding activities on the genetic diversity of natural Procambarus clarkii populations, SNP molecular markers developed via SLAF-Seq sequencing technology were employed to analyze the genetic diversity and genetic structure of seven natural P. clarkii populations in Jiangsu Province. These populations included the main production areas (Weishan Lake, Gaoyou Lake, Hongze Lake, and Luoma Lake) and non-main production areas (Ge Lake, Gucheng Lake, and Yangcheng Lake). In total, 176486 SNPs and 24828 Indels were detected in 210 individuals from these populations. The average Q30 and GC contents were 92.77% and 44.31%, respectively. The average polymorphic information content (PIC) of the seven populations ranged from 0.2070 to 0.2246. The expected heterozygosity (He) was between 0.2388 and 0.2854, while the observed heterozygosity (Ho) ranged from 0.3204 to 0.3387, suggesting a certain degree of heterozygote excess in these populations. The coefficient of genetic differentiation (Fst) among populations varied from 0.033 to 0.124, indicating moderate differentiation. The seven populations could be divided into four lineages. The populations from Hongze Lake, Luoma Lake, Gaoyou Lake, and Ge Lake were classified as one group, and the remaining three populations from Weishan Lake, Gucheng Lake, and Yangcheng Lake formed separate groups respectively. This demonstrated clear geographical distribution patterns among the populations. Linkage disequilibrium (LD) analysis showed that the LD decay distance in the P. clarkii populations was short, with the r2 value decreasing to less than 0.1 within a 100-bp physical distance. Further selection sweep analysis revealed 153 strongly selected genomic regions between the main production area and non-main production area populations. These selected genes were significantly enriched in pathways such as the Cell cycle, AMPK signaling pathway, Meiosis, and other gene pathways closely related to the biological functions of P. clarkii. This study elucidated the genetic diversity characteristics of natural populations in both main and non-main production areas of P. clarkii in Jiangsu Province, thus providing a theoretical basis for the development, utilization and conservation of P. clarkii germplasm resources.
The compound microbial agent can effectively improve the quality of aquaculture water and reduce the harmful factors in the pond water, which is suitable for the ecological regulation of large-scale green aquaculture. At present, the beneficial microorganisms commonly used in aquaculture mainly include Bacillus, photosynthetic bacteria, nitrifying bacteria, denitrobacteria, Lactobacillus, Saccharomyces, Pseudomonas, Bifidobacterium and so on. In order to explore the application status and research progress of compound microbial agents in pond water quality regulation, this paper summarized the factors affecting the water quality, the composition of microbial agents, the function of microbial agents and the application of microbial agents in pond culture. In view of the lack of scientific management, ecological imbalance caused by excessive dependence, the lack of scientific basis, water quality deterioration caused by miscellaneous bacteria pollution, solutions were proposed as follows. (1) Supporting the scientific management technology, to avoid over-dependence; (2) Optimizing the compatibility of bacteria, playing the synergistic effect of multiple bacteria to degrade organic pollutants, and optimizing the microbial community structure of water; (3) Developing highly stable microbial agents and constructing a control scheme to provide technical support for the construction of a healthy and stable water micro-ecosystem.
In the process of fish reproduction, GnRH (Gonadotropin releasing hormone), as a key factor in the hypothalamus-pituitary-gonad (HPG) axis of vertebrates, plays a crucial regulatory role in gonadal development and sex hormone secretion. Its physiological functions are essential for the success of fish reproductive activities. This paper reviews recent domestic and international research progress on GnRH in fish reproduction, including the structural classification, main functions, mechanisms of action, and applications of GnRH analogs in fish reproduction. By analyzing the roles of GnRH in regulating fish gonadal development, sex hormone secretion, and ovulation induction, the core position of GnRH in fish reproduction is revealed. This review aims to provide a theoretical basis for in-depth understanding of fish reproductive mechanisms, while offering references for improving fish reproductive efficiency and developing GnRH-related reproductive regulation technologies. It also lays the foundation for further research on the application potential of GnRH in fish reproduction.
The distribution of nektons in aquaculture areas is the result of the interaction among nektons, environmental loads and hydrological conditions of culture areas. Thus, it is speculated that the corresponding relationship between the distribution of nektons and aquaculture types is diverse and uncertain. To verify this inference, trap nets were used to collect nektons in the aquaculture areas with different types and their adjacent waters in Sansha Bay, Fujian Province. The results showed that the composition of nektons characterized by species number, Chao 1 index, Shannon-Wiener diversity index, Margalef richness index, Pielou evenness index, key species and dominant species did not exhibit specificity to the types of culture areas; the similarity of the communities of nektons in the aquaculture areas with different types characterized by the key species and dominant species was relatively small, but the community similarity based on all the species of nektons was≥0.84; there was no correlation between the composition of nektons and the types of aquaculture area, and the biological community of nektons did not change with aquaculture area. Thus, it is not reasonable to evaluate the biological effects of cage culture by using the commonly used spatial comparison method, and it is suggested to adopt the adaptive management to manage cage culture.
To help the healthy development of Liuzhou snail rice noodle in Guangxi, the shell quality and carbon sequestration effect and benefit of artificially bred snail were studied based on geochemical theory and technology. Using snail and field snail from Liuzhou snail breeding base as test materials, Ca2+, Mg2+, HCO3- and other data were tested to analyze the coupling relationship between shell quality and carbon sink and geological background. The values of Ca2+, Mg2+, HCO3-, pH and fCO2 in water can affect the construction and corrosion of calcite crystals in the shell of snails, making the shell mechanical strength different or eroded. The shell quality of artificially bred snails can be improved by adjusting the contents of Ca2+, Mg2+ and HCO3- in water, with the average content of CaCO3 and CO2 of 92.76% and 40.81% respectively, according to the estimation of 26000 t/a of artificially cultured snails, 3700 t of carbon can be fixed and the carbon sink transaction volume can reach 266800 yuan. The values of Ca2+, pH and fCO2 in water body are directly related to the quality of snails. The carbon sink of cultured snails belongs to the carbon removal technology category of biomass energy carbon capture and storage, and can apply for carbon trading.
As an important economic shrimp species, the Litopenaeus vannamei is frequently affected by bacterial diseases, especially Vibriosis (including Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi, Vibrio cholerae, etc.) during intensive aquaculture. This represents a significant risk to the long-term sustainability of aquaculture. With the widespread use of antibiotics, resistance genes of pathogenic bacteria are prevalent and widespread in the aquatic environment, posing new challenges to the prevention and treatment of Vibriosis. Therefore, it is extremely important to emphasize the maintenance of aquaculture environment and water quality monitoring. This review describes a series of biological control measures, including the use of biofloc technology, probiotics, antimicrobial peptides, quorum sensing inhibitors, and the use of biological control methods such as Bdellovibrio and like organisms and bacteriophage. The combination of biofloc technology and probiotics can improve water quality and enhance immunity. However, it is greatly affected by the environment, making it difficult to control the stability of bacteria flora. Antimicrobial peptides exhibit a broad spectrum of antibacterial activity, and they are safe and not easily resistant to drugs. However, they are difficult to preserve and have a high cost. Quorum-sensing inhibitors provide precise prevention and treatment with minimal environmental impact, but the mechanism research on them is limited. Bdellovibrio are effective at lysing Gram-negative bacteria but have a poor effect on Gram-positive bacteria and grow slowly. Bacteriophages are highly specific but have a narrow host range. Although these biological control measures are less effective than antibiotics, they are environmentally friendly, less prone to drug resistance, and aim to reduce chemical drug dependency, protect the ecosystem, and improve aquaculture efficiency. In the future, innovative and sustainable biological control technologies should be developed to address the challenges posed by pathogenic bacterial resistance and environmental protection.
Aquaculture Fisheries
