Volume 76, Issue 1, 2024

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https://hdl.handle.net/10524/74400

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Effects of extreme rainfall events on phytoplankton community in a subtropical eutrophic lake: a mesocosm experiment
(2024) Zhang, Yefei; Li, Tao; Zhang, Lu; Hu, Qin; Liu, Zhangyong; Zhu, Jianqiang; Chai, Yi; Yang, Jun R.
The impact of global climate change has led to an increase in extreme rainfall events, causing fluctuations in terrigenic inputs that significantly affect aquatic communities. Lake Changhu, the third-largest freshwater lake in Hubei Province, plays a crucial role as a reservoir of aquatic germplasm resources in the middle reaches of the Yangtze River. In recent years, the lake has experienced a series of extreme rainfall events. In response to recent extreme rainfall events, a 42-day mesocosm experiment was conducted to understand the effect of terrigenic inputs on various aspects of phytoplankton in Lake Changhu, such as species composition, abundance, biomass, diversity, community turnover rates, resource use efficiency, and stability. The experiment involved the application of different terrigenic treatments, including a control group (CK, using lake water), low terrigenic input (LT), medium terrigenic input (MT), and high terrigenic input (HT). The results showed a noticeable shift in phytoplankton composition from a co-dominated state of Chlorophyta and Cyanobacteria in the CK treatment to a Cyanobacteria-dominated state in the other terrigenic treatments. Furthermore, the terrigenic inputs increased phytoplankton abundance, community turnover rates, diversity, and resistance. Comparatively, the diversity index of phytoplankton increased by 82.61%, 73.83%, and 70.41% in the LT, MT, and HT treatments, respectively, in contrast to the CK treatment. However, phytoplankton abundance decreased by 6.99%, 15.55%, and 14.76% in the LT, MT, and HT treatments. Additionally, the resource use efficiency decreased by 1.94%, 5.16%, and 14.19% in the LT, MT, and HT treatments, respectively, compared to the CK treatment. These findings provide valuable insights into monitoring and managing the water ecology in Lake Changhu, offering a scientific basis for implementing effective management strategies.
Evaluation of genetic parameters of growth traits in G2 selected generation of Penaeus monodon
(2024) Jiang, Song; Wang, Jieyi; Yang, Wanli; Kong, Dewei; Yang, Qibin; Huang, Jianhua; Yang, Lishi; Li, Yundong; Zhou, Falin
Fifteen whole sib families of the second-generation Penaeus monodon were constructed using artificial mating design in 2020. After labeling the families with fluorescent markers, the growth traits and genetic parameters were evaluated in a cement pond for 56 days. The results showed that the coefficient of variation of growth traits was 11.52-47.53%, indicating a high genetic variation. The heritability range of growth traits of the G2 population of P. monodon was 0.25±0.03-0.41±0.13, which belonged to medium and high heritability, and the statistical test results were significant (P<0.01). The heritability of body length and body weight were 0.38±0.11 and 0.41±0.13, respectively. The evaluation results of genetic correlation among growth traits were highly positive, and the statistical test results were significant (P<0.01). The genetic correlation between body weight and body length was the highest (0.99), and the genetic correlation between the width of the first carapace and the height of the first abdominal segment was the lowest (0.71). The phenotypic correlation between body weight and body length was the highest (0.93), and the lowest was head breastplate width and first abdominal segment height (0.53). These results showed that the G2 generation population of P. monodon has high genetic improvement potential, and the combination of family selection and individual selection achieved better genetic gain. The growth traits were highly positively correlated. Body length and body weight could be selected as the key traits for fast growth line selection, while the other growth traits could be indirectly selected through positive genetic correlation.
Morphogenesis of largemouth bass ranavirus (LMBRaV) in the epithelioma papulosum cyprinid cell line
(2024) Zhang, Mengwei; Yang, Tao; Li, Yiqun; Xue, Mingyang; Liu, Wenzhi; Meng, Yan; Xu, Chen; Fan, Yuding; Zhou, Yong; Jiang, Nan
Largemouth bass ranavirus (LMBRaV) belongs to the Ranavirus genus of the Iridoviridae family. It is a highly pathogenic virus that causes mass mortality in largemouth bass. In recent years, outbreaks of LMBRaV have been found in various provinces throughout China. Previous research mainly focused on virus isolation, identification, and detection, while the morphological change of the virus was still unknown. In this study, the ultrastructural morphogenesis of LMBRaV in epithelioma papulosum cyprinid (EPC) cells was observed and studied by using transmission electron microscopy. EPC cells were infected with LMBRaV (MOI=0.1) and then examined at 2 h, 4 h, 6 h, 12 h, 24 h, 48 h, 72 h and 96 h post infection. LMBRaV entered cells through endocytosis or direct penetration of cell membrane. After entering, the virus was observed in vesicles or lysosomes. After capsid uncoating, the virus genomes passed through the nuclear membrane and entered the cell nucleus. Virus genomes completed replication in the nucleus then transferred into the cytoplasm. In the cytoplasm, the progeny virus was assembled in the viromatrix and then aggregated in pseudocrystalline array. Finally, mature virus particles released through budding release from the cell membrane. Mature virus particles had a hexagonal shape and a diameter of approximately 150 nm. This study revealed the process of morphogenesis of LMBRaV in EPC cell line, providing essential information for further research on pathogenic mechanisms and immunological prevention of LMBRaV.
The Molecular Characterization of the Cyprinid herpesvirus 3 (CyHV-3) ORF24 Protein and its effect on the expression of immune genes (in vitro)
(2024) Wang, Jing; Ji, Yan; Zhou, Xuan; Yu, Denghang; Tan, Kianann; Zhang, Chi
Cyprinid herpesvirus 3 (CyHV-3), known as koi herpesvirus (KHV), is highly contagious and lethal. In this study, we aimed to characterize the ORF24-encoding protein of CyHV-3, investigate its sub-cellular localization, and determine its impact on the expression of immune factors through in vitro experiments. The results showed that the CyHV-3 ORF24 protein comprises 579 amino acids. Interestingly, multiple comparisons with homologous proteins from three carp herpesvirus origins showed no significant similarity. The fluorescence localization experiment showed that the green fluorescence signal, representing the protein pEGFP-ORF24, was primarily diffused in the cytoplasm. Notably, the overexpression of ORF24 effectively suppressed the expression of immune factors in both CCO (Channel catfish ovary) and FHM (Fathead minnow muscle cell line) cells. Bioinformatic analysis indicated that the CyHV-3 ORF24 gene exhibited significant differences from the corresponding genes in the other two carp herpesviruses. This suggests its unique functional role in the evolutionary context. Moreover, our findings demonstrated that overexpression of CyHV-3 ORF24 can effectively inhibit the expression of immune factors, underscoring its crucial role as a viral immune escape factor. These results provide further insights into the immune function of the CyHV-3 ORF24 protein and offer a theoretical foundation for developing new vaccines against CyHV-3 virus infections.
The presence of microplastics affects Sepiella maindroni hatching performance and microbiota colonization
(2024) Zhang, Tao; Chen, Xinya; Sun, Ke; Chen, Jiyi; Chen, Xinxin; Xu, Jilin; Shi, Huilai; Ping, Hongling; He, Jie; Li, Bin; Yu, Yebing; Li, Lei; Sui, Yanming
Microplastics (MPs) are a global concern regarding environmental pollution. This study evaluated the impacts of MPs with two sizes (5 µm and 0.5 µm) on hatching performance and microbiota of Sepiella japonica. The presence of MPs increased the hatching rate at some stages of the fertilization process and reduced the oxygen consumption rate at the gastrula stage. No size-dependent impact was observed. The 16S rRNA gene was sequenced to identify the flora. Clustering tags assessed species diversity in the samples with 97% similarity. Proteobacteria was the most abundant phylum in all three groups. MPs publicity appreciably modified flower structure. The most variable genera were Ralstonia, Methylophilus, and Pseudorhodoferax, which can furnish nutrients and modify the host's immune response. MPs exposure appeared to enrich beneficial bacteria in this study. The presence of MPs with a size of 5µm played a greater role in this process, which is supported by presumptive functions. However, since the adsorption of suspended MPs on aquatic eggs can have cascading effects on specific life stages of oviparous animals, regular monitoring of microbial communities is necessary after juvenile S. japonica formation to prevent disease outbreaks.
Plant-based carotenoid supplementation: Growth, feed utilization efficiency, and coloration in false clownfish (Amphiprion ocellaris)
(2024) Tran, Dung Van; Luong, Hau Thi; Pham, Khanh Thi; Dang, Thanh Trung; Hua, Nhan Thai; Pham, Hung Quoc
The false clownfish (Amphiprion ocellaris) is a prominent species in the marine ornamental trade, valued for its vibrant orange-red coloration. However, aquaculture-bred individuals often exhibit less intense coloration than their wild counterparts, presenting a challenge for both breeders and aquarists. This study evaluates the effects of carotenoid-enriched diets, sourced from natural ingredients such as pumpkin, bell pepper, carrot, and gac, as well as a synthetic source like astaxanthin, on the coloration and growth of false clownfish. In a controlled experiment, juvenile fish with an initial average length of 3.21 ± 0.03 cm and weight of 0.61 ± 0.02 g were allocated to 60-liter tanks and fed the experimental diets over a 75-day trial period. Carotenoid supplementation was standardized at 250 mg/kg across diets, with a control group receiving no added carotenoids. The experimental design was completely randomized, involving three replicates per dietary treatment. The results indicated that diets supplemented with gac and bell pepper significantly enhanced growth and feed efficiency (p < 0.05). Notably, the skin redness intensity (a* value) was increased by 75.73% in the gac-supplemented group, 89.20% in the bell pepper group, and 91.99% in the astaxanthin group, relative to the control (p < 0.05). Additionally, carotenoid deposition in the integument was significantly higher in all supplemented groups, with an increase of 83.74% in the astaxanthin group, 89.59% in the gac group, and 98.43% in the bell pepper group, compared to the control (p < 0.05). These findings suggest that natural carotenoids, particularly from gac and bell pepper, can be effective alternatives to synthetic astaxanthin, potentially improving the attractiveness and commercial value of captive-bred false clownfish and alleviating the exploitation of wild populations.
Effect of probiotic feed supplementation on skin ulceration syndrome in Apostichopus japonicus
(2024) Li, Cai-Yun; Li, Xiao-Ai; Tan, Lin-Tao; Zhang, Ning; Li, Yang; Hu, Ming; Xu, Tao
Skin ulceration syndrome is among the most harmful diseases in sea cucumber (Apostichopus japonicus). The annual loss due to this disease is more than 1 billion dollars, which seriously affected the healthy and sustainable development of A. japonicus. In this paper, animals were divided into 4 experimental groups: a control group given basic feed, experimental groups with 1% Lactobacillus, 1% Bacillus, 1% mixture with 0.5% Lactobacillus and 0.5% Bacillus added to the basic feed. After feeding for 60 days, the samples were taken to analyze the growth performance, digestive enzyme activity, and immune indexes of A. japonicus. Furthermore, the resistance to the skin ulceration syndrome of A. japonicus was analyzed. The results showed that the probiotics promoted the growth performance of A. japonicus, the weight gain rate of the control group was 120.08±12.07%, the weight gain rate of the Lactobacillus group was 152.11±10.06%, the weight gain rate of the Bacillus group was 148.03±9.88%, and the weight gain rate of the mixed bacteria group was as high as 210.11±19.41%. The digestive enzyme activities in the intestinal tract of A. japonicus increased significantly in the probiotic-added groups, and the mixed bacteria were more effective in enhancing the digestive enzyme activities than single Bacillus and Lactobacillus. In addition, the probiotics could significantly increase the phagocytosis rate of the body cavity cells of A. japonicus. The phagocytic rate of Lactobacillus and Bacillus subtilis was comparable; the mixed probiotics were significantly higher than those of single probiotics, and this phagocytic rate gradually increased over time. After Vibrio splendidus and Pseudoalteromonas infection, the mortality rate of A. japonicus in the probiotic-added group was reduced, which indicated that probiotics could improve the immunity of A. japonicus, and the ability to resist the infection of Vibrio splendidus and Pseudoalteromonas was enhanced. Bacillus exhibits superior antimicrobial ability compared to Lactobacillus, and the mixed strain displays the most effective antimicrobial properties. This study provided a scientific basis for effectively preventing and controlling skin ulceration syndrome in the aquaculture of A. japonicus.
Molecular Detection and Subtype Distribution of Blastocystis sp. in Cold-water Fish and cultured water
(2024) Wang, Yuwei; Zhang, Chao; Nan, Huizhu; Yin, Shi; Cao, Mengjuan; An, Ruiyong; Ma, Lei
Blastocystis sp. is a eukaryotic protozoan parasite reported in patients with diarrhea and irritable bowel syndrome. So far, it has been determined the parasite occurs in the intestinal tract of humans and animals worldwide. However, few studies have investigated the distribution of Blastocystis sp. in cold-water fish and cultured water. After DNA extraction of tissue and water samples, a polymerase chain reaction (PCR) assay was established to detect Blastocystis sp. The results showed the detection rate of the parasite was 3.70% in the tissue samples and 6.29% in water samples. Only the ST1 subtype was in fish, but five subtypes, ST1, ST2, ST10, ST21, and ST24, were detected in water samples. There were no significant differences in the water distribution rate of Blastocystis sp. The presence of Blastocystis sp. was detected in the intestinal digesta of cold-water fish for the first time in this study, which hinted that Blastocystis sp. may infect cold-water fish. It is speculated that Blastocystis sp. entered the intestinal tract of fish with feeding and water flow. The results will provide data support for ecological prevention and control of cold-water fish diseases and lay a foundation for the formulation of sustainable aquaculture development strategies.
Effect of Inclusion of Fresh or dried black soldier fly larvae in Diets on Snakehead Fish's Growth Performance and Chemical Composition (Channa sp.)
(2024) Manh, Hoang N.; Suong, Tran T.T.; Lan, Pham T.P.; Tram, Nguyen D.Q.
In snakehead fish farming, feeding represents the largest portion (accounting for 50-60%) of production cost. Thus, finding an alternative natural feed that can be replaced as full or partial inclusion in snakehead fish commercial diets is urgently needed. This study was carried out to evaluate the effect of including fresh or dried black soldier fly larvae (BSFL) in diets on the growth performance and chemical composition of snakehead fish cultured in small-scale farms. Fingerlings of snakehead (5.15 ± 0.12 g) were distributed randomly into fifteen net cages (6 m^3^) at a density of 120 fish.net cage^-1^. Including five dietary treatments named: NT1 (100% commercial feed served as a control); NT2 (100% fresh BSFL); NT3 (100% dried BSFL); NT4 (50% fresh BSFL + 50% commercial feed); and NT5 (50% dried BSFL + 50% commercial feed). Each treatment was performed in triplicate. The results showed that the inclusion of fresh BSFL in diets for the snakehead fish did not affect the survival rate (82.22 - 85.56 %), improved feed conversion ratio, increased live weight (70.9 – 103.3 g) and daily weight gain (1.09 – 1.64 g.day^-1^), and fish’s yield (1.16 – 1.73 kg.m^-2^); and did not affect the chemical composition of the fish. These findings suggest that farmers should feed snakehead fish with commercial feed plus fresh black soldier fly larvae to maintain good condition factor and enhance fish growth performance and production.
Transcriptome profiling of the gills to air exposure in mud crab Scylla paramamosain
(2024) Fan, Sigang; Guo, Yihui; Cheng, Changhong; Huang, Xiaolin; Ma, Hongling; Guo, Zhixun; Yang, Qibin; Liu, Guangxin; Gao, Yougen
The mud crab Scylla paramamosain is a valuable commercial mariculture crab worldwide. During the ebb tide or when transported to market, crabs suffer underlying air exposure stress. Gills tissue is the first tissue to cope with this stress. In this study, the transcriptome of S. paramamosain gills from the control group (CG) and experimental group (EG) were sequenced, assembled, and compared. A total of 7,425,620,293 bp and 6,741,616,977 bp clean data were found in EG and CG, respectively. A total of 38,507 unigenes (42.78%) were annotated successfully. 13,626 differentially expressed genes (DEGs) were up-regulated, and 6,502 DEGs were down-regulated. The DEGs related to immunity, apoptosis, metabolism, and ion exchange were detected. DEGs were enriched significantly into the KEGG pathways related to metabolism and immunity. These results proved that more material and energy were required, and immune defense was enhanced when the crab was under air exposure stress. The present study provides the first-gill transcriptomic analysis challenged with air exposure stress in S. paramamosain under air exposure stress, which will be useful to clarify the molecular mechanisms of air exposure adaptation.
The acute toxicity of cypermethrin, emamectin benzoate and imidacloprid on red swamp crayfish (Procambarus clarkia)
(2024) Zhang, Kaixin; Chen, Jiyi; Zhang, Shuxin; Chen, Xinxin; Sun, Ke; Liu, Pujie; Li, Hongshan; Sui, Yanming
Pesticide contamination is commonly found as a mixture of different pesticides rather than individual compounds. However, the regulatory risk evaluation is mostly based on the effects of individual pesticides. In the present study, we aimed to investigate the individual and combined toxicities of cypermethrin (CYP) with emamectin benzoate (EMB) and imidacloprid (IMI) to crayfish using acute indices and various sub-lethal endpoints. Semi-static bioassay procedures were followed in the experiment. The 24, 48, and 72 h LC~50~ values (with 95% confidence limits) of CYP for crayfish were calculated as 0.141, 0.137, and 0.135 ug/ml, respectively, which were higher than those of IMI (75.813, 72.345, 70.568 ug/ml) and EMB (34.581, 27.930, 22.298 ug/ml). Pesticide mixtures of CYP and EMB displayed a synergistic response to crayfish; the LC50 was 0.053, 0.050, and 0.048 ug/ml, which was lower than when only CYP was present. Pesticide mixtures of CYP and EMB were found to be highly toxic to crayfish. At the physiological level, both individuals and mixtures of pesticides caused severe injury to the internal organs of crayfish. Taken together, the synergistic effects indicated that it was highly important to include joint toxicity studies when assessing the risk of pesticides.
Financial Performance Evaluation of Leading Fisheries Enterprises Based on Entropy-Weighted TOPSIS Method
(2024) Gao, Shan; Qingqing, Jiang; Zhao, Zhuming; Biao, Wu
Fishery is a strategic and fundamental core industry in China. Since the 18th National Congress of the Communist Party of China, the central government has attached great importance to the fishery industry and has issued a series of policies to promote its revitalization and vigorous development. In the favorable policy environment, it is crucial for leading fisheries enterprises to pay attention to financial performance evaluation and strive to improve their own operational efficiency. In this study, we selected seven leading fisheries enterprises as research subjects and used the entropy-weighted TOPSIS method to construct a financial performance evaluation system from four dimensions: debt-paying ability, operational capability, profitability, and development potential. We then conducted performance evaluations on the seven sample companies. The research findings indicate that enterprises should focus on their development capabilities to improve their potential for sustained development, enhance the operational efficiency of fisheries enterprises, and promote their continuous and healthy growth.
Price volatility characteristics and policy implications of freshwater fish in China
(2024) Wang, Jing; Zhao, Zhiyuan; Jin, Hongtao; Sun, Chen; Liu, Shen
The fisheries industry in China is experiencing rapid growth, but it is also encountering the challenge of frequent fluctuations in aquatic product prices. Freshwater fish aquaculture plays a crucial role in China's fisheries industry. Analyzing the characteristics of price volatility in freshwater fish is crucial to ensure a stable supply of aquatic products and promote sustainable fisheries industry development. This study focuses on four freshwater fish species, namely crucian carp, grass carp, silver carp, and carp, to analyze the price volatility characteristics of freshwater fish in China from 2006 to 2022. The study uses the price decomposition method and the ARCH model. The results indicate that, from the perspective of dominant characteristics of price volatility, the prices of freshwater fish display periodic volatility with an overall upward trend, as well as significant seasonal and random variations. From the perspective of recessive price volatility characteristics, the price volatility of freshwater fish exhibits clustering and asymmetry. This indicates that the price volatility of freshwater fish is influenced by previous price volatility. Positive news has a greater impact on the price volatility of freshwater fish than negative news. Out of the four freshwater fish species, only the price of crucian carp is characterized by high-risk and high-return volatility.
Otolith morphology and total length relationships in Schizothorax grahami
(2024) Zhou, Yang; Cui, Weijie; He, Zhongtang; Xu, Li; Yang, Feng; Lu, Qun; Liu, Jianhu; He, Tao
Otolith is important for studying fish populations and life histories. In this study, the dominant species of Schizothorax grahami in the source section of the Chishui River was taken to understand the relationships between otolith morphology and total length (TL). Results showed a large difference between the four TL groups (A/B/C/D), except group B is similar to group C. The combined discrimination success rate of linear discriminant analysis was 62.2%. Group A and D's success rate is the highest, at around 75%. Meanwhile, the success rate for Group B and Group C is below 65%. The one-way ANOVA of the Shape Index and the Canonical analysis of Principal Coordinates with two coefficients (Fourier coefficients and Wavelet coefficients) showed that Group B is similar to Group C, with a large difference from the other two groups. When TL was greater than 100 mm (the pearl organs appearing), the otolith growth was lower changing. Otolith morphology still changes with growth after sexual maturity in fish, so the larger fish is more useful for conducting otolith morphology studies for accurate evaluation and management of local fishery resources.
Genetic population structure of the pen shell Atrina pectinata along the coastlines of China revealed by microsatellites
(2024) Zhu, Peican; Wang, Fukai; Wu, Biao; Wang, Feng; Wang, Chunde; Zhang, Xiaotong; Yu, Kai; Liu, Bo
Background
An ecologically and economically important species in East Asia, the natural resources of pen shell Atrina pectinate have suffered severe population declines due to habitat destruction, pollution, and overfishing. Assessing genetic diversity and population structure is the basis for establishing conservation programs for A. pectinate.

Results
Our data indicated that high genetic diversity was found in all six populations, with mean allelic richness (Ar) ranging from 8.255 to 9.734, mean observed heterozygosity (Ho) from 0.574 to 0.680, and mean expected heterozygosity (He) from 0.620 to 0.691. The five A. pectinate populations were divided into two clusters. This clustering result was partly consistent with their geographical origin; the RZ population did not cluster with the northern populations (DL, CD), suggesting that there is no genetic divergence and geographical differentiation between the North China Sea (CD, DL, and RZ) and the Southeast China Sea (HK and ST).
Conclusion
Our results show no significant genetic differentiation between samples from the North China Sea and the Southeast China Sea. High dispersal potential of larvae by passive drift with ocean currents may explain the lack of genetic differentiation between samples. The results suggest a weak level of genetic structure in A. pectinate with a long planktonic larval stage.
Growth, survival and food utilization efficiency of longfin batfish (Platax teira Forsskål, 1775) larvae reared under different salinity levels
(2024) Ngo, Manh Van; Tran, Dung Van; Nguyen, Thuy Thi; Pham, Hung Quoc
Salinity is crucial in fish larval rearing. In longfin batfish (Platax teira), little research has been conducted regarding the specific effects of salinity on growth, survival, deformity, and food utilization efficiency. This study aimed to determine the optimal salinity level for larval rearing of the longfin batfish by testing five different salinity levels (10, 15, 20, 25, and 30‰). Larvae of 1.5 cm in length and 0.2 g/fish in weight were stocked in cylindrical fiberglass tanks (300 L) at a density of 1 fish/L. The fish were fed to meet their dietary requirement and divided into four daily feedings. Each treatment was replicated three times over a 28-day period of rearing. The results revealed that salinity significantly influenced the growth (length, weight, biomass), and food utilization efficiency of the longfin batfish larvae. Overall, larvae reared at salinity levels of 15-20‰ exhibited superior performance compared to those exposed to salinity levels of 10, 25, and 30‰. However, salinity did not affect the coefficient of variation, survival, and deformity. From these findings, it is recommended to rear longfin batfish larvae at a salinity of 15-20‰ to achieve optimal growth and food utilization efficiency. This study provides valuable insights for longfin batfish larval rearing guidance, contributing to the aquaculture development of this economically valuable species.
Effects of estradiol on fatty acid composition and tissue structure of hepatopancreas in Procambarus clarkii
(2024) Zhao, Weihong; Liu, Jintao; Zheng, Xirui; Lv, Linlan; Chen, Jiyi; Wang, Jiamei; Sui, Yanming; Zheng, Liang
The hepatopancreas of Procambarus clarkii provides lipids and other nutrients for ovarian development and contains hormones such as estradiol related to ovarian development. During the development of the P. clarkii ovary, the hepatopancreas' tissue structure and fatty acid content undergo corresponding changes. A controlled indoor experiment was conducted to investigate the effects of exogenous estradiol injection on the tissue structure and fatty acid content in the hepatopancreas of P. clarkii. The experiment consists of three experimental groups and one control group. The P. clarkii in the experimental group were injected with 5, 0.5, and 0.05 μg/(g body weight) of estradiol once every 5 days for 5 times and with normal saline injection as the control. After 25 days, the content of fatty acids and changes in tissue structure in the hepatopancreas were measured. The results showed that the main fatty acids in P. clarkii hepatopancreas were C18:4n, C20:3n, and EPA, and polyunsaturated fatty acid (PUFA) content was 57.17%±4.76%. Injecting estradiol mainly affected the content of C16:0, C16:1n, C18:0, C18:1n9, C18:2n, C18:3n6, C18:3n6, C18:4n, C20:1n, C20:2n, C20:3n, C20:4n3, C20:5n3, C22:n (n=1-4), C22:5n, and C22:6n in the hepatopancreas. Injecting estradiol significantly reduced the total content of PUFA in hepatopancreas with the reduction of C18:3n6, C18:4n, C20:3n, C20:4n3, C20:5n3 C22: n (n=1-4) (P<0.05); Estradiol injection significantly increased the total content of monounsaturated fatty acid (MUFA) in hepatopancreas with the increase of C18:1n9, and C20:1n (P<0.05); Injection of estradiol (0.05 μg/g) significantly increased the total content of saturated fatty acids (SFA) in the hepatopancreas (P<0.05) with the increase of C16:0 and C18:0 (P<0.05). Injecting estradiol can increase the volume and quantity of hepatopancreatic B cells, and the 5 μg/g group had the most obvious changes.
Effects of different feeds and stocking densities on growth and survival rates of mud crab (Scylla paramamosain) at the stage from megalopa to crablet-1
(2024) Ly, Tien Hai; Vu, Le Hoang; Diep, Doan Xuan
Mud crabs (Scylla genus) are luxury foods in high demand internationally. The efficient techniques for mud crab hatcheries are vital for providing breeds for their aquaculture, which is rapidly growing in many countries. This study aims to investigate the effects of different feeds and stocking densities on mud crabs' growth and survival rates (Scylla paramamosain) in the stage from megalopa to crablet-1 stage. Two separate experiments were conducted indoors in the 60-liter round plastic tanks (containing 50 liters of water at a 28‰ salinity). Experiment 1 investigated four feeds: frozen Artemia biomass, pureed shrimp meat, Lansy pellet feed (48% protein), and NRD pellet feed (55% protein). Megalopae (mean weight of 5.8 mg) were stocked at a density of 10/L. In experiment 2, the megalopae (mean weight of 5.4 mg) were stocked at densities of 20, 30, and 40/L and were fed the Lansy pellet feed, which was the best one selected from experiment 1. High survival rates were obtained at all four feeds (82.2–87.5%) and three stocking densities (88.4–90.1%). The growth performances in Lansy feed and frozen Artemia biomass were better than those in pureed shrimp meat and NRD pellet feed, which was seen through higher indicators of daily weight gain (DWG) and specific growth rate in weight (SGRw) (p < 0.05). Despite the survival rate showing no significant difference among the feeds, their highest value (87.5%) was observed in the Lansy pellet feed. On the other hand, the growth performances showed a significant decrease at stocking densities ≥ 30/L, as complemented by a significant decrease in DWG and SGRw at these stocking densities (p < 0.05). Both survival rate and metamorphosis durations did not show significant differences among the feeds or stocking densities (p > 0.05). The investigated feeds and stocking densities suit the nursing mud crab (S. paramamosain) megalopa. In contrast, the Lansy pellet feeds had a stocking density of 20/L, resulting in the highest nursing efficiency.
Analysis of morphological differences in five large yellow croaker (Larimichthys crocea) populations
(2024) Zhang, Yu-Qing; Guo, Hua-Yang; Liu, Bao-Suo; Zhang, Nan; Zhu, Ke-Cheng; Zhang, Dian-chang
To explore the morphological and phenotypic characteristics and differences among different populations of Larimichthys crocea, traditional morphological measurements were carried out on three wild populations from Zhoushan, Xiamen and Zhanjiang and two farmed populations from Ningde and Wenzhou. Seven morphological parameters of five L. crocea populations were compared and analyzed. The results of one-way ANOVA showed significant differences in trunk and caudal stalk among the five populations. The contribution rates of the first five principal components to the total difference among different populations were 29.984%, 18.462%, 17.234%, 12.167%, and 9.904%, respectively, and the cumulative contribution rates were 87.751%. Trunk can be used to distinguish different geographic populations best. The cluster analysis results showed that the distance between wild populations was the closest, while the distance between farmed populations was far. The step discriminant method established the classification discriminant function of 5 populations. The discriminant accuracy P1 was 78.3%-92.7%, the discriminant accuracy P2 was 76.4%-96.5%, and the comprehensive recognition rate was 99.3%. The discriminant accuracy of this method was high, and it could provide a reference for the differentiation of different populations of L. crocea. This study provided basic morphological data for identifying a large yellow croaker population, protecting germplasm resources, and breeding improved varieties.

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