Abstract:Based on the phytoplankton net samples from the Yellow Sea collected between 1985 and 2015, the interdecadal variations in the community structure were studied and the composition dissimilarities were analyzed. A total of 1125 samples were checked to establish the phytoplankton community structure, including 220 samples from the Northern Yellow Sea and 905 samples from the Southern Yellow Sea. Phytoplankton samples were preserved in 5% formalin water solution after each towing and were kept in dark until analysis. In the laboratory, sub-samples were analyzed for the identification of the species, which were counted using an optical microscope (Leica Biomed). Phytoplankton diversities were represented by species richness (Margalef index), species diversity (Shannon-Weaver index), and species evenness (Pielou index). The dominance of each taxon was calculated using the Dufrene-Legendre index and SIMPER analysis was performed in Past 3.18 software. A total of 81 genera and 202 species were recorded over the past 30 years, with diatoms and dinoflagellates being the major groups. There were 58 genera and 142 taxa of diatoms, 20 genera and 57 taxa of dinoflagellates, 2 genera and 2 species of silicoflagellates, and one species of . The species number of diatoms accounted for 62.4%, 69.1%, 74.4%, and 62.6% of the total in the 1980s, 1990s, 2000s, and 2010s, respectively. However, this proportion was only 47.5% during the summer seasons; in contrast to the dinoflagellate proportion, which was 52.3%. In 2005-2015, the dominant taxa were Protoperidinium in the Northern Yellow Sea, while in the Southern Yellow Sea, they were . As for the species ecotypes, there were no obvious variations in the eurythermal species, which were 67.4% and 71.8% during 1985-2000 and 2005-2015 century, respectively. However, during 2005-2015, there was an average increase in warm water species of 10.3%. The interdecadal average abundance of total phytoplankton was 76.2×10⁴ ind/m³, of which 80.3% was diatoms, which declined to 67.5% during 1985-2000. During 2005-2015, the average abundances of the total phytoplankton, diatoms, and dinoflagellates were 140×10⁴ ind/m³, 132×10⁴ ind/m³, and 8.4×10⁴ ind/m³, respectively, which had 6.0, 6.1, and 4.7 times increase compared to 1985-2000. In the Northern Yellow Sea, their abundances were 134×10⁴ ind/m³, 121×10⁴ ind/m³, and 12.9×10⁴ ind/m³, while in the Southern Yellow Sea they were 145×10⁴ ind/m³, 140×10⁴ ind/m³, and 5.1×10⁴ ind/m³, respectively. There was a dramatic increase in the dinoflagellate abundance and the ratio of dinoflagellates to diatoms increased by 1.13 times when compared to 1985-2000. In addition, this ratio had marked seasonality, with 7.29 times increase during the summer seasons compared to the other seasons. The average abundances of Noctiluca scintillans were 189×10³ ind/m³, 29.6×10³ ind/m³, 126×10³ ind/m³, 63.3×10³ ind/m³, and 3.19×10³ ind/m³, which had increases 11, 3.24, 11.5, 4.7, and 1.54 times, respectively, during 2005-2015. Similarly, in 2005-2015, the phytoplankton species richness in the Yellow Sea increased by 78.9%. The species diversity was maintained in the Northern Yellow Sea, while it increased by 28.9% in the Southern Yellow Sea, compared to 1985-2000. The long-term variations in the phytoplankton communities determine the variability in the diet composition and food basis of fishery resources. Research found that the fishery community structures had gradually declined with smaller sizes, low commercial value species, and young individuals in the catches. This is in conjunction with human fishing activities, environmental variability, as well as diets for the food base. From the perspective of the phytoplankton diets, this research provides basic data and references for further discussing the effects of phytoplankton changes on the ecosystem food web structure and early recruitment of fishery resources in the crucial habitats of the important fisheries in the Yellow Sea.

Abstract:Fishery stock assessment is a basic component of modern management, required to maintain sustainable fishery development. Traditional methods require a large amount of statistical data assessing yield, abundance index, and age structure. Due to limited funding and data for such surveys, only 1% of fish stocks have systematic assessments conducted. Therefore, it is difficult to assess maximum sustainable yield (MSY) or determine allowable catch for most fishery resources using traditional methods. In recent years, stock assessment using limited available data has become a focus of increasing academic research. A good assessment model based on incomplete data would allow managers to assess the risk of overexploitation, current population biomass, sustainable yield, optimal fishing mortality, and population status relative to reference points such as current total catch limits. These parameters can then be used to determine appropriate fishing limits for the target population. Such models use different assumptions and have different limitations. Therefore, it is necessary to select an appropriate model that will minimize error in the results when evaluating target resources. Where more than one model is available, they can be compared to assess which obtains the best results. In assessment of fishery resources using data-poor methods, more and more attention is being paid to characteristic life history parameters such as intrinsic growth rate, natural mortality coefficient, and so on. Under conditions that combine the yield of the evaluated population with the corresponding life cycle parameters, a more reliable MSY value or sustainable yield can be obtained. In this paper, assessment models based on life-history characteristics are divided into three categories:(1) models that only use life history parameters; (2) models that incorporate catch data and life-history parameters; (3) models that incorporate catch data, life-history parameters, and lifespan or age data. The introductions, data requirements, output results, and limitations of each model is reviewed and systematically analyzed. In addition, several common life-history parameter estimation methods are provided. A simple preliminary assessment of sustainable catch was conducted for North Atlantic blue shark () using Catch-MSY and DCAC models, and results were compared. Results calculated using the DCAC model are similar to those obtained with the Catch-MSY model. Maximum sustainable yield of blue shark was about 3.0×10⁴ tons. This paper also provides suggestions on use of data-limited models and applications to assessment of offshore fishery resources in China. The current survey of Chinese offshore fishery resources started late, and recorded data are relatively few, therefore most fisheries had difficulty estimating by traditional methods. The natural mortality coefficient of fish off China's coasts is generally >0.2; thus, assessment errors using DCAC and DB-SRA models will be large. The catch-MSY model can fit the present resource situation well, and is often used to evaluate fishery resources off China's coasts. In view of the low reliability of the upper limit estimate used by the Catch-MSY model to estimate environmental capacity, the SS model can be compared with it in future resource assessments to provide more theoretical support for protection and scientific assessment of offshore fishery resources.

Abstract:The glucose-6-phosphatase catalytic subunit (G6PC) is an important component of the glucose-6-phosphatase (G6Pase) system, which controls glucose production from glycogenolysis and gluconeogenesis, and plays a key role in blood glucose homeostasis. G6pc can catalyze the hydrolysis of glucose-6-phosphate to glucose and inorganic phosphate in the living body. Despite its importance, little is known about the function of different ). We obtained three gene sequences from the grass carp genome using homologous sequence alignment, which were named through sequence alignment and a phylogenetic tree. Deduced amino acid sequences of cDNA sequences in grass carp shared similarities of 85%-94%, 64%-83%, and 54%-66% with zebrafish (Homo sapiens), respectively. In addition, synteny analyses of were identical with that of zebrafish. This indicates that g6pc mRNA expression was detected in different tissues. The results showed that the mRNA expression level of was highest in the brain, followed by the liver and adipose tissue. Expression of was most strongly observed in the liver, and weakly observed in the midgut and kidney. The mRNA level was highest in the heart, followed by adipose tissue. To explore the role of different g6pc mRNA levels in carps with different diets with normal or high level of carbohydrates. The results revealed that a high carbohydrate diet significantly increased the mRNA expression level of g6pcb2 mRNA levels. Compared with the control group, 15 mmol/L glucose obviously increased the expression of mRNA in L8824, while 30 mmol/L glucose had no remarkable influence, and insulin at a concentration of 1 mmol/L could overcome the stimulatory effect of 15 mmol/L glucose. Our results suggest that the genes of grass carp might have functional differentiation after gene duplication events. In addition, high glucose levels induced the expression of g6pcb1 and , the specific functions of which require further study.

Abstract:Chemokines are small secreted cytokine peptides (8-14 kD), which were initially found to have the ability to recruit a wide range of immune cells to sites of infection and disease in mammals. In this study, we cloned the cDNA is 910 bp, contains an open reading frame of 408 nucleotides encoding 135 amino acid residues. Four conserve cysteine residues at 35, 37, 60, and 77, and the first two cysteines are separated with leucine acid, which is exactly consistent with the features of CXC. Amino acid sequence analysis revealed that the CXCL9 protein of and at 78.5% and 71.0%, respectively. RT-PCR demonstrated that mRNA was expressed highest in the liver and spleen, and high in the skin and gills of healthy mRNA expression was upregulated in the liver after being infected with for 6 h, while in the head kidney and spleen, the peak value of CXCL9 expression was 24 h or 48 h after infection. After being infected with mRNA expression in the liver was upregulated at 6 h, and its expression in the head kidney was upregulated at 24 h. The expression model is different in the spleen, as expression 10-fold after 6 h, then decreased gradually, before upregulating approximately 20-fold at 48 h. These results indicate that genes play an important role in the immune response, and can be a biomarker of bacterial disease in .

Abstract:The largemouth bronze gudgeon () is a dominant species and important economic fish in China, which is distributed in the upstream regions of the Yangtze River. However, it is currently classified as threatened due to a rapid decline in its population. Cryopreservation technology enables germplasm cells to be safely and effectively preserved for a long time, which will help with artificial reproduction (e.g., captive broodstock management and seedling cultivation). In addition, cryopreservation can assist in maintaining original genotypes for the conservation of threatened and endangered species. Many studies have suggested that due to the species specificity of fish sperm, the extender composition, cryoprotectant type, and cryoprotectant concentration are different during cryopreservation. More importantly, there is currently no research on sperm cryopreservation of the largemouth bronze gudgeon. In the present study, to establish a sperm cryopreservation method for the largemouth bronze gudgeon, a computer assisted sperm motion analysis system (CASA) was used to find a suitable sperm cryopreservation method, by comparing the effects of four extenders (D15, D20, L1, and D1) and three cryoprotectants, including dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and methanol (METH), at three concentrations (7.5%, 10%, and 12.5%; ) on sperm motility after thawing. Our procedures followed the two-step method of cooling the mixture and thawing the frozen semen in a 37℃ water bath for 12-15 s. The results showed that D1 and METH are suitable choices for the extender and cryoprotectant, respectively. The motility of the sperm reached (78.11±14.74)%, which showed no significant difference compared to fresh sperm (>0.05). In comparison with the other treatments, the 10% METH group performed better in terms of the average velocity of (50.28±12.46) μm/s, average linear velocity of (35.06±10.82) μm/s, and average path velocity of (39.44±12.46) μm/s, which are significantly different values compared to those of fresh sperm (<0.05). The fastest movement time and lifetime of the sperm were (8.67±1.15) s and (33.33±5.00) s, respectively. In summary, 10% METH as an antifreeze protective agent in D1 was the best cryoprotectant protocol for sperm and could be applied in practice. The results provide a feasible technique for sperm preservation of largemouth bronze gudgeon, which could assist in artificial breeding and species conservation of the species.

Abstract:is an important species in the Chinese economic aquiculture industry. Therefore, it is imperative for us to study the growth regulatory mechanisms of to help improve the growth trait and cultivate new varieties with higher growth rates. To learn more about the molecular mechanisms behind the growth of , the muscle transcriptomes of fish with different weights were sequenced. Despite being cultivated under the same conditions, the from full-sib families showed differences in the growth traits. After three months, 5 overweight and 5 underweight individuals were selected. The weight of the overweight group was 4 times heavier than the that of the underweight group. Muscle transcriptome sequencing was conducted to determine the differences in the gene expression patterns between the overweight and underweight groups. In all, 73353 unigenes were obtained with an average size of 703 bp. Then, 39005 unigenes were annotated by searching against NR, COG, Swissprot, and KEGG. After RPKM comparison, 8942 differentially expressed genes (DEGs) were confirmed, which were mainly found in the underweight group. , and Troponin have a higher gene expression in the underweight group. According to the KEGG pathway, many different expression genes are enriched in pathways concerning protein processing in the endoplasmic reticulum, ubiquitin-mediated proteolysis, and RNA transport. The expression trends of genes relating to protein synthesis and muscle fiber synthesis appear to be consistent. In general, the study showed that with different growing characteristics have different transcriptome expression patterns. The underweight fish are smaller in size and present higher gene expression activities. This data provides rich genetic resources for studies on the growth regulation of .

Abstract:Shen is a small crustacean belonging to the arthropods. It is distributed within the low tide areas of the intertidal zone. It has a delicious taste and high nutritional value. At present, there are very few studies about . Existing researches have focused on the classification, morphology, nutrition, and genetic diversity. There has been no research on the relationship between the morphological traits and weight characteristics. To study the relationship between the morphological characteristics and weight traits of , fourteen biological indicators were measured, including carapace height (), carapace spine length (₁), carapace width (), first abdominal segment length (), pincers length (W_W), and dry weight (). These were studied by means of correlation analysis, path analysis, and regression analysis. The results showed that the female crabs had significantly higher values than the males for the 14 quantitative indicators (0.01). The coefficient of variation for the weight indicators was greater than that for the morphological traits, and the morphological and weight indicators were significantly correlated (0.01). For male individuals, the direct effects and direct determination coefficients of the body length, carapace spine length, and spine width for the wet and dry weights were larger. For female individuals, the direct effects and direct determination coefficients of the body length and carapace width for the wet and dry weights were larger. The regression equations for the morphological traits of the male and female individuals for the wet weight were W₂, respectively. The regression equations for the morphological traits of the male and female individuals for the dry weight were =-2.65 + 0.098 respectively. The indicators for morphological and weight traits of the male and female individuals were significantly different (0.01). The coefficient of variation for the weight index was greater than that for the morphological index. This shows that the selection of weight indicators has great potential, and it is feasible to carry out selective breeding of with weight as the target trait. Stepwise regression analysis showed that the main indicator affecting male wet weight was body length (), while the main indicators affecting female wet weight were body length () and spine width () have a greater decisive effect on dry weight of males, while body length () had a greater role in the dry weight of females. This study provides references for the evaluation of breeding.

Abstract:is one of the most important aquaculture products in China. In this study, Lactobacillus paracasei (M5, X12, and SB27) were added to the feed of juvenile for 4 weeks, to study the effects of lactic acid bacteria on the muscle quality of juvenile . TPA analysis was used to evaluate the texture of the muscle of the shrimp, while the content of fatty acids in the muscle was analyzed using gas chromatography. The results showed that the addition of lactic acid bacteria improved the muscle elasticity and chewiness ([YRL45, QL, and KTP (C-2)] outweighed those of with the elasticity and chewiness of the muscles increasing by 35.14% and 85.71% ( (M5, X12, and SB27) increased the water holding capacity (P<0.05), while the content of saturated fatty acids in the muscle was significantly reduced ( group, the contents of palmitic acid, heptadecanoic acid, and stearic acid were significantly reduced (<0.05), whilst the contents of EPA and DHA increased by 23.22% and 34.40% ( (YRL45, QL, and KTP (C-2)) and (M5, X12, and SB27) caused an improvement in the muscle elasticity, chewiness, and water holding capacity of shrimp, which may be related to the improvement of the muscle antioxidant capacity and protein quality. slightly regulated the basic nutrient content of the shrimp muscle. significantly improved the fatty acid composition of the shrimp muscle, which may be due to the regulation of the nutrition and flora of the shrimp or production of nutrients to improve the fatty acid composition of the shrimp. However, the specific mechanism for this requires further study. In summary, this study showed that [YRL45, QL, and KTP (C-2)] had superior effects on muscle elasticity and chewiness of juvenile (M5, X12, and SB27) improved the fatty acid composition in the shrimp muscle. This indicates that lactic acid bacteria can improve muscle quality and fatty acid composition of juvenile . Furthermore, this provides a theoretical basis for the application of probiotics in the culture of juvenile .

Abstract:Eelgrass () beds, one of the most important coastal ecosystems, are highly ecologically and economically valuable. However, eelgrass beds have been reduced worldwide because of natural and anthropogenic causes. To restore the degraded eelgrass beds, numerous studies have been conducted and various techniques developed. Among them, eelgrass transplantation is the most widely used and intensively studied technology. Some studies have shown that appropriate artificial propagation methods can effectively promote the survival and growth of the transplants, and phosphate-solubilizing microorganisms not only provide phosphate for the growth of the plants, the metabolites also play a major role in promoting plant growth and controlling diseases. However, techniques for promoting the growth of transplanted eelgrass are still absent. Therefore, investigating phosphate-solubilizing bacteria within the eelgrass rhizosphere is necessary. In this study, the growth-promoting activities of the rhizobacteria of eelgrass were investigated, by isolating four phosphate-solubilizing bacteria (P1, P2, P3, and P4) from the rhizosphere sediments of eelgrass using an SRSM medium. Based on the morphological, physiological, and biochemical characteristics, and the sequence analysis of 16S rDNA, we identified P1 as Escherichia coli, and P4 as . The optimal culture conditions and typical growth curves for the four rhizobium strains were established. The optimal temperatures for the growth of the four strains were 34.67℃, 33.95℃, 34.60℃, and 31.19℃, respectively. The optimal salinity for growth was 27.10, 28.29, 29.54, and 26.08, respectively. The optimal pH for growth was 8.26, 7.92, 8.17, and 8.21, respectively. A pot test was conducted to investigate the effects of the four phosphate-solubilizing bacteria strains on eelgrass growth. The results showed that the survival rate, growth, physiological status, and enzyme activity of the rhizosphere soil in the four inoculation treatments increased to some extent. Among the treatments P2 showed the best promoting effect, with the new leaf area, aboveground productivity, and belowground productivity being (54.31±4.79) cm², (3.58±0.36) mg/(shoot·d), and (0.28±0.04) mg/(shoot·d), respectively. Additionally, the contents of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids significantly increased in the P2 treatment with values of 31.35 μg/cm², 12.57 μg/cm², 39.42 μg/cm², and 6.21 μg/cm², respectively. Except for P4, the activity of alkaline phosphatase in all other inoculation treatments was significantly increased (<0.05). However, no significant differences were observed in the soil urease activity between the inoculation and control treatments. A comprehensive analysis indicated that (the P2 strain) could be applied in the future development and application of microbial inoculants and seagrass phosphobacterial fertilizers, thereby benefitting the recovery of eelgrass beds in the future.

Abstract:is a specific small freshwater demersal fish, which is widely distributed in the water systems of the Yangtze River and its northern rivers, as well as the rivers of Henan Province. To assess the current situation of germplasm resources and genetic diversity, 77 samples were collected from the basins of the Yellow River, Yangtze River, Huaihe River, and Haihe River in Henan Province. We analyzed the population genetic diversity and differentiation of the species using the mitochondrial COI gene. In this study, we amplified the partial mitochondrial COI gene sequences of 77 individuals from 10 populations (PH, BSH, HZH, TRQ, MJH, XLSSK, HXC, YH, QH, and WH). The results showed an average haplotype diversity of 0.89088 and average nucleotide diversity of 0.00361 in all populations, with a maximum and minimum in the HXC and NJH populations, respectively. AMOVA analysis showed that the genetic differentiation of mainly occurred within the population variation, with 78.43% genetic variation within populations. The results of phylogenetic tree and network of haplotypes suggested that did not form from a significant geographic cluster. Similarly, the results of SAMOVA support the phylogenetic tree and network of haplotypes when not using grouping in advance. Demographic history analysis showed that the 10 populations experienced rapid population growth and have maintained an upward trend. Fu's value and mismatch nucleotide analysis revealed that a recent population expansion had occurred in populations, the process for which may be related to the climate changing to warm and humid.

Abstract:, an endemic species in China, has been threatened by overfishing, and biological invasion, among other factors. A total of 1126 individuals were collected between August 2008 and August 2009 from Lhaze to Nyemo on the Yarlung Zangbo River, Tibet. The population resources and fishery conversation policies of the fish were studied using per-recruit models. The total instantaneous annual mortality ( was 0.11/a for females and 0.16/afor males. The ranges of natural mortality () for females and males were 0.08/a-0.09/aand 0.10/a-0.12/a, respectively. The range of the current fishing mortality () was 0.02/a-0.03/a for females and 0.04/a-0.06/afor males. The range of the spawning potential ratio of was 61.7%-73.1% for females and 48.5%-63.3% for males, both of which were significantly higher than the target reference point (40%). This indicates that the stock of could be reasonably exploited under the current fishery conversation policy, but special attention should be paid to the stock of in case of over-exploitation in the long-term. To evaluate the protective effects of capture age and seasonal closure, 14 different fishery conversation policies were simulated. The results suggest that the stock of could be effectively conserved by enhancing the capture age to 17 years or above and allocating seasonal closure from at least February to May.

Abstract:The ecological fitness of hatched and released juveniles, during their early post-release period in Xiangshan Bay, was investigated through analyzing their post-release growth performance and feeding over a 3-month period. During the early days following the release, the fish exhibited poor feeding and growth performances. After the first month following the release, approximately 80.95% of the individuals were detected to have empty stomachs. In addition, the dietary niche breadth index was only 63% of that of their wild conspecifics. The hepatopancreas somatic index reduced compared to that prior to release, indicating that the utilization of the energy stored in the liver should be an important route for the juveniles to cope with starvation induced by a low-feeding success. During this period, the growth in length tended to stagnate, with a specific growth rate of only 0.079%/d. Approximately 2 months after release, the empty stomach percentage decreased to 46.15% and the index of dietary niche breadth increased to 2.16 for the released fish. Meanwhile for wild fish, the empty stomach percentage was 38.24% and the index of dietary niche breadth was 2.62. The gaps of the empty stomach percentage and the index of dietary niche breadth between wild fish and released fish were greatly shrinking. Thus, it strongly suggested that the released fish were successfully adapting to the natural feeding conditions. As the feeding ability improved, the hepatopancreas somatic index of the juveniles gradually returned to the level prior to release. Meanwhile, the specific growth rate of the released fish increased sharply. The released fish underwent a period of compensatory growth, a phase of rapid growth following starvation, which gradually returned to the normal growth pattern.

Abstract:The aim of this study was to investigate the effects of sanguinarine on alleviating the immune stress and inflammation induced by lipopolysaccharide (LPS) in the rice field eel (). The control (basal diet) and experimental groups (basal diet+750 μg/kg sanguinarine) were set, with 3 replicates in each group. After 8 weeks, 30 eels with consistent specifications were randomly selected from each repeat for the intraperitoneal injection of LPS. Samples were taken 0 h before injection and 3 h, 6 h, 12 h, 24 h, and 48 h after injection. The results showed that at 0 h, superoxide dismutase (SOD) activity in the liver of the experimental group was significantly higher than that of the control group, and there were no significant differences in the other indices. In the serum, glucose (GLU), cortisol (COR), immunoglobulin M (IgM), complement 4 (C4), alkaline phosphatase (AKP), glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and SOD in the liver all showed a trend of first increasing and then decreasing after the injection of LPS, and reached a peak at 3 h or 6 h, while the malondialdehyde (MDA) in the liver showed the opposite trend. Compared with the control group, the contents of AKP, IgM, C4 in the serum, and SOD activity in the liver of the experimental group increased more after the LPS injection, while the contents of GLU and COR increased more slowly, and the GLU, COR, AKP, IgM, C4, GOT, and GPT recovered to normal levels more quickly. The expression levels of the genes in the intestinal tract first increased and then decreased after the injection of LPS, and reached a peak at 6 h or 12 h. Compared with the control group, the expression levels of were down-regulated in the experimental group, while the expression levels of were up-regulated. Taken together, the findings of the study indicate that under the conditions of this experiment, the injection of LPS induced immune stress and the inflammatory response in the rice field eel, which peaked at 3-6 hours. Furthermore, the addition of 750 μg/kg of sanguinarine into the feed could effectively relieve the immune stress and inflammatory response induced by LPS.