Abstract:The CRISPR-Cas13d protein targets RNA substrates through crRNA-mediated sequence-specific binding and achieves precise cleavage via its ribonuclease activity， offering a non-genome-editing strategy for RNA-level gene regulation. In this study， we optimized the Cas13d gene sequence based on the codon preference of medaka （Oryzias latipes）， successfully constructed a prokaryotic expression system， and purified recombinant Cas13d protein with a molecular weight of 115 ku. By microinjecting in vitro-transcribed Cas13d mRNA complexed with crRNA targeting the tyrosinase gene （tyr） into medaka embryos， alongside parallel experiments using Cas13d protein/crRNA ribonucleoprotein （RNP） complexes， we systematically evaluated RNA-editing efficiency. qRT-PCR and sequencing analyses demonstrated that both delivery methods significantly reduced tyr RNA levels in embryos （P<0.01）， while DNA sequencing confirmed the absence of mutations in the target DNA sequences. This study validates the effectiveness and specificity of Cas13d-mediated gene silencing through RNA editing in medaka， not only providing a novel regulatory tool for fish genetic research but also establishing a theoretical foundation for developing RNA-targeted Cas13d antiviral transgenic fish lines.

Abstract:In order to investigate the role of Map2k1 gene in the gonadal development and sex differentiation of Bellamya purificata， gene cloning， quantitative real-time PCR （qRT-PCR）， in situ hybridization， and RNA interference were employed. The results revealed that the full-length ORF of Map2k1 cDNA was 1 191 bp， encoding 396 amino acids. The MAP2K1 protein contained the S-TKc domain， and its amino acid sequence had high homology with mollusks. Map2k1 was detected in tissues of both sexes， showing the highest expression in the female gonads， where expression significantly differed from that in the male gonads（P<0.01）. In situ hybridization analysis demonstrated strong hybridization signals of Map2k1 in the oocytes and ovarian vesicles of female B. purificata. The RNA interference results showed that in female B. purificata， the interference chain G1 of Map2k1 reached the highest interference rate of 73.1% 12 hours after injection， and led to a significant decrease in the expression of other sex-related genes β-catenin， Cyp17a1， and Sox9. Research had shown that Map2k1 may be involved in the gonadal development and sex differentiation of female B. purificata. This study can provide theoretical reference for the gonadal development and monosex breeding of B. purificata.

Abstract:Alosa sapidissima has emerged as a newly imported premium fish species with high value in promoting large-scale aquaculture in China in recent years. Understanding the genetic background of cultured and wild populations of A. sapidissima is crucial for evaluating germplasm resources and breeding new strains. In this study， 20 polymorphic simple sequence repeats （SSRs） were selected to evaluate the genetic diversity and genetic structure of 3 cultured populations and 2 wild populations of A. sapidissima. A total of 201 alleles were detected from 20 polymorphic microsatellite markers average of 10.05 alleles per marker. Among the five populations， the average of the effective alleles （N_e）， the observed heterozygosity （H_O）， expected heterozygosity （H_e） and polymorphism information content （PIC） ranged from 2.675 4 to 4.136 0， from 0.675 0 to 0.775 0， from 0.601 8 to 0.729 8 and from 0.547 3 to 0.698 8， respectively. The analysis of molecular variance （AMOVA） indicated that the genetic variance within individuals accounts for 94.93% and the genetic variance among populations accounts for 5.07%. The result of genetic differentiation index （F_st） analysis showed that the YSF₁ had a moderate level of genetic differentiation from the YZF₄ and YZF₅ （0.05<F_st<0.15）， and the genetic differentiation of the other pairwise populations was weak （F_st<0.05）. The result of the Hardy-Weinberg equilibrium showed that 31% of group loci were found to deviate significantly from the Hardy-Weinberg equilibrium after sequential Bonferroni correction （P<0.05）. The UPGMA cluster tree based on the Nei's genetic distance showed that five populations were divided into two branches and the similar result also obtained from PCoA analysis and Bayesian Structure clustering analysis. Results indicated that the cultured populations of A.sapidissima introduced into Shanghai retain a relatively high level of genetic variation and hold significant genetic breeding potentiality.

Abstract:The family Gastromyzontidae primarily inhabits mountainous streams in Southeast Asia. These fish have a flattened body shape， with broad paired fins， and in some species， the paired fins are specialized into a disc， enabling them to live in fast-flowing environments. To investigate the diversity and structure of the gut microbiota in Gastromyzontidae fish， MiSeq 16S rRNA high-throughput sequencing was conducted on gut samples from 12 species across eight genera， including Plesiomyzon baotingensis， Beaufortia pingi， Beaufortia kweichowensis， Liniparhomaloptera disparis， Erromyzon sinensis， Paraprotomyzon multifasciatus， Labidogastromyzon fangi， Labidogastromyzon changtingensis， Vanmanenia pingchowensis， Vanmanenia stenosoma， Vanmanenia homalocephala， and Formosania stigmata. The analysis focused on the number of operational taxonomic units （OTUs）， microbial community composition， Alpha diversity， and functional predictions. A total of 1，029 OTUs were identified， spanning 31 phyla， 75 classes， 173 orders， 278 families， 465 genera， and 689 species， with an average of 175 OTUs per sample and three shared OTUs. In terms of community composition， the dominant bacterial phyla were Proteobacteria， Fusobacteriota， Actinobacteriota， and Verrucomicrobiota， with Achromobacter，Cetobacterium， Plesiomonas，Mycobacterium being the dominant genera. The shared genera included Rhodococcus， Mycobacterium， and Leifsonia. Alpha diversity analysis revealed significant differences in species richness and diversity among the gut microbial communities of different fish species. Beaufortia pingi exhibited the highest diversity， while Vanmanenia stenosoma showed the lowest diversity. KEGG pathway analysis indicated that most genes encoded by the gut microbiota were related to metabolic processes， with pathways associated with amino acid transport and metabolism being the most abundant， accounting for 11.40%. From the perspective of OTU richness and PCoA analysis at the OTU level， it was difficult to predict associations between microbiotaand phylogeny. Compared with fish inhabiting plains and river-lake systems， the dominant genera in Gastromyzontidae fish included obligate aerobes such as Mycobacterium （9.47%）， as well as some facultative anaerobes that prefer aerobic environments， such as Achromobacter （24.91%）.

Abstract:To investigate the growth and feeding conditions of the juvenile Chinese mitten crab（Eriocheir sinensis） under different diets， traditional （wheat， bran， and soybean meal， Diet 1）， formulated（Diet 2）， and mixed feeds （1：1 mixture of traditional and formulated feeds， Diet 3） were fed in different crab ponds in the study. During the experiment， the stomach contents of juvenile crabs under the different feeding modes were collected in August. The main potential eukaryotic food components were studied using 18S rDNA sequencing. The results showed that the Chao index of food composition under Diet 1 was significantly higher than Diet 3， while the Simpson index was opposite. The phyla with the highest relative abundance in the stomach contents of juvenile crabs for Diet 1 are， in order： Phragmoplastophyta （mainly Chlorophyceae and Trebouxiophyceae）， Ciliophora （mainly Intramacronucleata）， and Ochrophyta （mainly Eustigmatophyceae and Chrysophyceae）. Diet 2 is Phragmoplastophyta， Arthropoda （mainly Malacostraca）， and Ochrophyta. Diet 3 is Phragmoplastophyta， Arthropoda， and Vertebrata （mainly Pisces）. The abundance of Ascomycota in Diet 2 and 3was significantly higher than Diet 1. There was no significant difference in the food composition in the stomach contents between male and female juvenile crabs. There was a total of 207 types of food components in the stomach contents of crabs in three diets. The main components of the stomach content of juvenile crabs in Diet 2 completely encompass the main components found in other diets. In summary， the diversity and abundance of food in the stomach contents were different under different diets. The main contents of the stomach contents in the juvenile crabs were Phragmoplastophyta， which were mainly composed of Chlorophyceae and Trebouxiophyceae. There was no significant difference in the food composition in the stomach contents between male and female juvenile crabs.

Abstract:To investigate the effects of carbonate alkalinity stress on the tissue structure and osmoregulatory gene expression of the oriental river prawn （Macrobrachium nipponense）， juvenile M. nipponense （3.12±0.42）g were subjected to an acute carbonate alkalinity stress experiment to determine the 96-hour lethal concentration （LC₅₀）. Based on this， the control group （1.5 mmol/L） and the carbonate alkalinity treatment group （10 mmol/L） were set up with triplicate to carry out the acute stress test of carbonate alkalinity for 96 h. The results showed that the 96-hour LC₅₀ value for juvenile M. nipponense under carbonate alkalinity stress was 16.89 mmol/L， with a safe concentration at 6.47 mmol/L. In contrast to the control group， with the extension time of carbonate alkalinity stress， the gill epithelial cells and columnar cells in the experimental group were arranged disorderly， and the secondary lamellae began to swell. In hepatopancreas of M. nipponense under carbonate alkalinity stress， the volume of B cell internal running vesicles increased， and the boundary between some hepatopancreas tubules was blurred. Compared to control group， the height of intestinal mucosa and muscle thickness of juvenile prawn obviously decreased in intestine of M. nipponense under carbonate alkalinity stress， and structural integrity of intestinal microvilli in juvenile prawns was deteriorated with the increasing time of carbonate alkalinity stress. It was found that the gene expression of carbonic anhydrase 3 （CA3） and Na⁺-K⁺ exchanging ATPase （NaK-ATP） in the gill tissues of prawn in carbonate alkalinity treatment group were significantly higher （P<0.01） than that of the control group within 96 h. The gene expressions of CA3 and NaK-ATP in the hepatopancreas of prawn in carbonate alkalinity treatment group were significantly higher （P<0.01） than those in the control group within 24 h， but there was no significant difference between the control group and carbonate alkalinity stress group along with coercion time extension. The present study shows that high carbonate alkalinity stress can affects the gill， hepatopancreas and intestinal histology of juvenile prawns， and the osmotic pressure regulating gene expression pattern shows a trend of first increasing and then decreasing. This study can provide reference data for large-scale culture of M. nipponense juveniles in salt-alkali water.

Abstract:The aim of this study was to develop a magnetic bead enrichment-based method for the detection of Mandarin fish ranavirus in culture water. The results showed that the method was effective in enriching Mandarin fish ranavirus in culture water samples， and specific bands could be obtained by conventional PCR amplification. Quantitative analysis showed that the sensitivity of the magnetic bead enrichment method combined with real-time fluorescence quantitative PCR reached the detection limit of 0.01 copies/μL. Feasibility analysis demonstrated that the magnetic bead enrichment method had 90% concordance with qPCR results and was suitable for fully automated nucleic acid detection platforms. Compared with the traditional qPCR method， this method has better anti-interference ability and ease of operation while maintaining high detection consistency. The detection technology developed in this study is characterized by easy operation and high sensitivity， which provides reliable technical support for the monitoring of aquaculture water pathogens and early warning， and is of great practical significance for the prevention and control of aquaculture diseases.

Abstract:Heat shock protein Hsp70 is a molecular chaperone and central regulator in maintenance of cellular homeostasis， which are present within the compartments of almost all organisms and cells and play important roles in promoting protein folding， transport， remodeling， degradation， and other functions. The whole sequence of Hsp70 gene was synthesized in vitro and the prokaryotic expression vector pET28a-Hsp70 was constructed. Using the prokaryotic expression system， the Hsp70-HIS fusion protein was successfully expressed. Peptide sequences that specifically bind to Hsp70 protein by using phage display technology were screened and analyzed by NCBI Blast. SDS-PAGE demonstrated that the Hsp70-HIS fusion protein could be well solubilized in PBS， and the molecular weight of the protein was about 70 kDa. Sequencing of phage spots revealed the presence of two amino acid sequences in the phage display library that can be highly enriched with Hsp70 protein； Dot Blot experiments verified that the two amino acid sequences screened interacted with the Hsp70 protein. In order to uncover the role of screening amino acid sequences， CIK cells were treated with different concentrations of peptides and infected with GCRV virus， and the qPCR results showed that the replication level of GCRV increased significantly after the peptides treatment. Based on the above findings， our homology analysis of the NCBI database revealed the presence of eight groups of proteins in the grass carp genome as well as in the grass carp reovirus genome， and the homology suggests that these proteins may interact with Hsp70. In this study， we screened peptide sequences that could be highly enriched with Hsp70 proteins in phage display libraries using prokaryotic expression system， phage display technology and other technical solutions and verified that， At the same time， homology analysis was performed by NCBI so as to obtain the proteins that may interact with each other， laying a good foundation for the study of the biological effects of Hsp70 involved in the invasion of Hsp70 viruses during heat shock in grass carp.

Abstract:To explore the semi-lethal concentration （LC₅₀） of Vibrio anguillarum infection in Ruditapes philippinarum and its effects on gill tissues and immune related genes. In this study， R. philippinarum was challenged with five different concentrations of V. anguillarum for 168 h. Meanwhile， the LZM activity， bacterial load， pathological analysis and the expression of immune-related genes in the gills were conducted. The results showed that the challenge group injected with V. anguillarum at 5×10⁷ CFU/mL for 168 h corresponded to the semi-lethal concentration （LC₅₀） group， and the semi-lethal concentration （LC₅₀） was 6.08×10⁶ CFU/（mL·g）， with a survival rate of 52.3%. The survival rate was the lowest at 33.6% in the 5×10⁸ CFU/mL group and the highest survival rate of 67.0% was observed in the 5×10⁶ CFU/mL group. The results indicated that the bacterial load peaked at 24 h （7.53 CFU/mg）， and then gradually decreased， reaching 4.26 CFU/mg at 120 h in semi-lethal concentration （LC₅₀） groups. The LZM activity significantly increased in the gills and peaked at 12 h （123.03 U/mg prot/mL）， and then gradually decreased， reaching 77.92 U/mg prot/mL at 120 h. The pathological analysis revealed that the gills filaments showed disordered arrangement， severe shrinkage， and increased gaps at 24 h. Additionally， quantitative real-time PCR （qPCR） analysis revealed that V. anguillarum infection significantly upregulated the expression of several immune related genes， including heat shock protein （Hsp70）， Cytochrome p450 （Cyp1a1）， serine/threonine protein kinase pim3 （Pim3）， Lysozyme， Leukocyte differentiation antigen （Cd109） and tumor necrosis factor receptor associated factor 6 （Traf6） （P<0.05）， revealing their important roles in the immune defense response of R. philippinarum against V. anguillarum. This study preliminarily explored the effects of V. anguillarum on R. philippinarum， providing new insights for the innate immune mechanism of the R. philippinarum against V. anguillarum.

Abstract:From July 2022 to May 2023， 30 sampling sites were established in the south branch， north branch， and dongtan of Chongming Island of the Yangtze River estuary to investigate the seasonal distribution of Coilia nasus，Coilia mystus and their relationships with environmental factors. Field sampling was conducted seasonally using a large larval fish net （mouth diameter： 1.3 m， mesh size： 0.5 mm） for surface horizontal towing， with each tow lasting 10 minutes at a speed of 2 knots. This study aimed to understand the distribution patterns of these two fish species and their responses to seasonal environmental variations in this estuarine ecosystem. The generalized additive model （GAM） was used to analyze the correlation between the abundance of fish larvae and juveniles and environmental factors. The results showed that spring and summer were the main breeding periods for C. nasus and C. mystus in the Yangtze River estuary. C. nasus larvae and juveniles were mainly distributed in the waters near the south branch and the north branch and the dongtan of Chongming Island， In contrast， C. mystus eggs were distributed in the waters from Changxing Island to Jiuduansha in the south branch and in the waters outside the entrance to the north branch， while larvae and juveniles were predominantly found outside the south branch， the north branch， and the dongtan of Chongming Island. GAM analysis revealed significant seasonal patterns in the utilization of the Yangtze River estuary as spawning and nursery grounds by both species. Summer had a significant positive effect on the abundance of C. nasus larvae and juveniles， while both spring and summer positively influenced the abundance of C. mystus larvae and juveniles， with summer showing significantly higher effects than spring （P<0.01）. Salinity had a significant impact on the abundance of C. nasus （P<0.01）. The suitable salinity for C. nasus larvae and juveniles was 0-6 PSU. The distribution of C. mystus larvae and juveniles was mainly affected by temperature， salinity， and pH （P<0.01）. The suitable temperature was 20-32 ℃， the suitable salinity was 2-16 PSU， the suitable pH was 7.3-8.2 and the suitable dissolved oxygen ranged from 6.0 to 9.0 mg/L. The interactive effects of environmental factors， temperature-salinity and temperature-pH exhibited significant impacts on the abundance of C. nasus larvae and juveniles. Overlapping nursery grounds were observed between the two species， with variations in spatial distribution across different developmental stages. The findings contribute to a better understanding of the ecological dynamics in the Yangtze River estuary and offer guidance for the conservation and management of these two species.

Abstract:To understand the reproductive traits of the wild population of Conger myriaster， this study used external morphological characteristics， gonad histological observation， and a morphological index system analysis to investigate the annual changes in the reproductive biology of Conger myriaster in the East China Sea waters near Shengsi， Zhejiang. A total of 235 individuals of Conger myriaster were collected from October 2017 to October 2018. The results showed that Conger myriaster is distributed in the waters near Shengsi， Zhejiang throughout the year. Individuals with a total length of 494-631 mm and a body weight of 140-390 g accounted for 79.1% of the total number. The average body weight， total length， condition factor， and gonadosomatic index （GSI） of Conger myriaster were highest in January 2018 and lowest in April 2018， while the hepatosomatic index （HSI） was highest in April 2018. Among the 235 samples collected over the year， only one male （0.43%） was found， and six juvenile fish without gonads observed could not be sexed. The male was still in the spermatogonial stage， while the oocytes of the females were in the perinucleolar to secondary yolk globule stages. The females in the perinucleolar and oil globule early stages accounted for 21.28% and 61.70% of the total number， respectively. The oocyte diameter was 51.12-167.73 μm， and the nuclear diameter was 26.71-83.42 μm. The analysis showed that the condition factor of female Conger myriaster increased significantly （P<0.05） from the perinucleolar to the secondary yolk globule stage. This study provides detailed basic information for the resource assessment and artificial propagation of Conger myriaster.

Abstract:To compare the synergistic treatment effects of different substrates in constructed wetlands on antibiotics and nutrient pollutants in wastewater， this experiment utilized three types of substrates： bio-ceramic， zeolite， and volcanic rock. These substrates were used to build small constructed wetland， and the removal rates of different pollutants and the bacterial communities structures in different areas were analyzed. The results demonstrated that the removal rates of N₄⁺-N， COD_Mn， and the antibiotic sulfadiazine in the bio-ceramic group were significantly higher （P<0.05） than those of the other two groups， but the removal rates of N₃^--N were significantly lower （P<0.05）. The removal rates of the antibiotic norfloxacin in different substrates are all higher than 98%. The abundance of bacteria collected on the surface of the substrate was relatively high， with Proteobacteria， Actinobacteria， and Chloroflexi being the dominant species. The bacterial communities on the rhizoplane and within root endophytes were dominated by Proteobacteria and Cyanobacteria， respectively. The microbial community structure collected on the substrate surface differed greatly among the different groups of constructed wetlands. The removal of sulfadiazine is primarily achieved through biodegradation. It may not be the diversity of the entire microbial community in the wetland that affects the removal rate of sulfadiazine， but the abundance of these key bacteria. The genus with the highest correlation to the sulfadiazine removal rate was Cyanothece， followed by Craurococcus-Caldovatus. The abundance of these two genera on the surface of bio-ceramic was significantly higher than those on the surfaces of zeolite and volcanic rock. Additionally， the genus Acidibacter showed a significantly positively correlation with the removal of both antibiotics. The removal rate was significantly negatively correlated with the removal of N₃^--N. Studies have revealed that constructed wetlands based on bioceramics exhibit the most comprehensive removal effect on artificial sewage containing sulfadiazine antibiotics and can be widely utilized for the treatment of such sewage.

Abstract:To investigate the effects of chronic hypoxia on testicular development， this study employed histological observation and transcriptome sequencing to compare the microstructural and transcriptomic alterations in zebrafish testicular tissues under normoxic [（6.5±0.2） mg/L] and chronic hypoxic[（1.5±0.2）mg/L] conditions. Key findings revealed that chronic hypoxia induced disorganized arrangement of spermatogonia and significant reduction in sperm quantity under light microscopy. Transcriptome analysis identified 683 significantly downregulated（P<0.05） and 710 upregulated（P<0.05） genes in hypoxic testes. GO（Gene ontology） and KEGG（Kyoto encyclopedia of genes and genomes） enrichment analyses demonstrated predominant involvement of differentially expressed genes in pathways including muscle cell differentiation， response to oxygen-containing compounds， testis development， and amino acid biosynthesis. Notably， upregulated aco2 and downregulated idh3b expression patterns suggested their potential roles in hypoxia-impaired testicular development. The significant upregulation of energy metabolism-related genes （pgam2，aldoaa， aldoab） implied elevated energy demands for spermatogenesis under hypoxia. Furthermore， marked overexpression of muscle cell differentiation genes may represent an adaptive mechanism of male gonadal development to hypoxic stress. This study reveals testicular developmental regression in male zebrafish under chronic hypoxia and provides novel insights into the molecular adaptation of fish testes to prolonged hypoxic conditions through transcriptomic profiling.

Abstract:Biodiversity and the mechanisms of community assembly are research hotspots. Phytoplankton， as primary producers in aquatic ecosystems， have important aquatic ecological functions， and there are few related studies at the level of the Yangtze River basin. In this study， we used environmental DNA macro-barcoding technology to investigate the community composition and construction mechanism of phytoplanktonic diatoms and green algae in the Yangtze River during the dry season.The results showed that a total of 389 operational taxonomic units （OTUs） belonging to 62 families and 101 genera were detected in the whole Yangtze River basin， with more green algae. A total of 378， 322 and 318 OTUs were detected in the upstream， midstream and downstream of the Yangtze River， respectively， and the species diversity in the lower and upper reaches of the Yangtze River was relatively high， with the median value of the Shannon-Wiener index exceeding 2.0. Mantel's test showed that the upper reaches of the Yangtze River were significantly correlated with pH （P<0.05）； the middle reaches of the Yangtze River were highly significant correlated with total organic carbon （P<0.01）， and the middle reaches of the Yangtze River were significantly correlated with electrical conductivity （P<0.05）. downstream diatom communities were highly significantly correlated with dissolved oxygen， permanganate index and fluoride ion （P<0.01）.Redundancy analyses indicated that total nitrogen was the strongest explanation for diatom communities throughout the watershed， followed by conductivity. In addition， neutral and null model analyses indicated that community construction of diatoms and green algae in the Yangtze River was mainly dominated by stochastic processes； the community composition showed an obvious distance decay pattern， and the distance decay phenomenon was increasingly significant from upstream to downstream.

Abstract:To gain a deeper understanding of the recovery status of Larimichthys crocea （large yellow croaker） resources， this study analyzed four seasons of trawl survey data collected from the Dachen Island region at a local scale during 2020-2021. By comparing the body length parameters of captured wild juvenile L. crocea with those of stock-enhanced individuals， we preliminarily identified whether they belonged to wild reproductive populations. Mitochondrial COⅠ gene sequences were determined for wild adult samples （LCA）， wild juvenile samples （LCJ）， and copper-net-cultured samples （LCC） from the Dachen Island waters to preliminarily assess the impact of stock enhancement on the genetic structure and diversity of wild L. crocea populations.The results showed that wild juvenile L. crocea in the study area were predominantly found in spring， with body lengths ranging from 11.24 to 70.00 mm （mean： 33.46 ±12.9 mm）， significantly smaller than the minimum size standard （>5 cm） of stock-enhanced individuals. Wild adults and juveniles exhibited high haplotype diversity and moderate nucleotide diversity （H_d = 0.516-0.879， P_i = 0.001 8-0.003 7）. Genetic differentiation indices revealed minimal divergence among the three populations， with gene flow values ranging from 6.8141 to ∞， indicating no significant genetic structure differences. Phylogenetic and network analyses demonstrated high genetic relatedness between wild and cultured populations. This study suggests that the wild L. crocea population in the Dachen Island waters likely originated from stock enhancement or escapees from net pens， which have successfully reproduced and formed a replenishment population of observable scale. Moreover， these populations exhibit an accumulation of genetic mutations， indicating that the conditions for the recovery of L. crocea resources in the Dachen Island waters are gradually being established.

Abstract:To study the water-sediment distribution and ecological environment changes in the Yellow River Estuary during the 2021 water and sediment regulation period， and to explore the impact mechanisms of water and sediment regulation on the hydrodynamics and ecological environment in the estuarine area， this paper is based on the Finite Volume Community Ocean Model （FVCOM）. A three-dimensional hydrodynamic and ecological model for the Bohai Sea was established， and remote sensing data were used to analyze the spatiotemporal variations of freshwater from the Yellow River， suspended sediment， nutrients， and chlorophyll-a concentration during the water and sediment regulation period. The results show that water and sediment regulation significantly altered the distribution and diffusion characteristics of freshwater and suspended sediment in the Yellow River Estuary. During the regulation period， the concentration of suspended sediment and nutrients in the estuarine area increased significantly， and the diffusion range of suspended sediment remained similar during both the sediment discharge and water discharge periods. However， due to the reduced river inflow， the diffusion range was somewhat limited during the sediment discharge period. Land-based substances were mainly concentrated on the southern and northern sides of the estuary， with the southern side having a wider diffusion range than the northern side. Meanwhile， during the water and sediment regulation period， the nitrogen-to-phosphorus ratio increased， and the input of nutrients promoted phytoplankton growth， leading to a significant increase in chlorophyll-a concentration. However， the increase in suspended sediment concentration caused light limitation， which partly offset the positive effect of increased nutrients on primary production. The study suggests that setting the sediment discharge period after the water diversion period is crucial for reducing light limitation and preventing harmful algal blooms. This research provides scientific guidance for optimizing the water and sediment regulation plan in the Yellow River Estuary， effectively controlling algal blooms， and maintaining the ecological environment.

Abstract:To address the issue that the reliance on a single data source in current sea ice thickness detection limits the further improvement of sea ice thickness inversion accuracy.This paper proposes a sea ice thickness inversion method based on segmented feature fusion of heterogeneous data，the experiment uses Sentinel-1 synthetic aperture radar （SAR） data and ERA5 reanalysis data，by dividing sea ice thickness intervals （e.g.， （0， 1.5） m， （0， 2） m， （0， 3） m）， optimal feature combinations are selected for sea ice in different segmented intervals，a sea ice thickness inversion model based on stacked ensemble learning is constructed， which realizes complementary advantages through the series-parallel cascade of multiple base models and meta-models，this approach fully explores the hidden correlations between heterogeneous features and sea ice thickness to achieve accurate inversion of segmented sea ice thickness.The results show that compared with other traditional machine learning methods， this method achieves better overall inversion performance across different segmented intervals，notably， the interval of （0， 1.5） m exhibits the best performance， with a coefficient of determination （R²） reaching 0.923 and a root mean square error （RMSE） as low as 0.089 m.The study demonstrates that segmented feature optimization and heterogeneous data fusion can effectively improve the inversion accuracy of sea ice thickness， verifying the advantages of the proposed stacked ensemble learning model in heterogeneous data fusion. This research provides a new method for achieving high-precision inversion of sea ice thickness.

Abstract:In the context of frequent global public security incidents and multiple uncertain shocks to urban food systems， improving the resilience of urban fresh agricultural product supply chains has become a key issue to ensure people's livelihood security and maintain the stable operation of urban systems. Fresh agricultural products are characterized by strong perishability， multiple circulation links， high storage difficulty， and high immediate demand， which makes their supply chains more prone to interruption when encountering sudden risk events. This study takes the urban fresh agricultural product supply chain as the research object， focusing on the response capability and operation guarantee capability of the urban fresh agricultural product supply chain in abnormal situations. Based on the PPRR theory， dynamic capability theory and agricultural product supply chain management theory， an analysis framework is constructed to systematically refine the four core dimensions of prediction capability， adaptability， recovery capability and learning capability. On this basis， a resilience evaluation system containing 13 indicators is designed， and the analytic hierarchy process （AHP） is used to assign weights， and the fuzzy comprehensive evaluation method is combined to empirically measure the resilience of the fresh agricultural product supply chain in Shanghai. The results show that Shanghai has a strong foundation in emergency response mechanism and institutional regulation capabilities， but still has obvious shortcomings in risk warning capabilities， organizational training frequency， and information sharing efficiency. Based on the research results， this paper proposes path optimization suggestions focusing on the construction of information perception system， layout of diversified reserve system， optimization of resource allocation mechanism and improvement of organizational learning ability.

Abstract:As an important carrier of Chinese civilization， fishery culture has not only precipitated thousands of years of historical memory， but also renewed its value in contemporary society. This paper focuses on Chinese fishery culture， systematically analyzes its connotation value， resource distribution and extension， and for the first time proposes a quantitative indicator of fishery culture abundance， and uses the propensity matching score method to explore its contribution to the development of leisure fishery. The study shows that the abundance of fishery culture has a significant positive impact on the output value of leisure fishery， with an average quality improvement effect of 4.46 billion yuan， which highlights the value of fishery culture in empowering aquatic industry and promoting local economic growth. The paper also comprehensively examines the current situation of research and inheritance of Chinese fishery culture and the development dilemmas it faces， including the change of inheritance subjects， the impact of urbanization， uneven development and lack of professional talents， etc. The paper further proposes to enhance the value perception and strengthen the resources and resources. The paper further puts forward targeted development suggestions such as enhancing value cognition， strengthening resource investigation， carrying out regional pilot inheritance， expanding publicity and popularization channels， deepening transformation and application， promoting sustainable research and strengthening international cooperation， etc.， aiming at perfecting the protection and inheritance system of fishermen's culture from the theoretical and practical levels， providing new ideas and practical references for the promotion of coordinated development of the cultural industry and the economic and social society， helping realize the creative transformation and innovative development of the fishermen's culture in the new era， and contributing to the construction of a strong cultural country and a strong maritime country.