Abstract:, a common freshwater fish in China, were selected to determine the effects of an aromatase inhibitor on sex differentiation and related gene expression. Two-day-old juvenile were fed different doses of the aromatase inhibitor, letrozole (50, 100, and 200 μg/g diets) for 30 days. The effects of letrozoleon sex ratio, gonad histology, and expression were examined by morphological observation, histology, and real-time fluorescent quantitative PCR during the period of sex differentiation (12−30 d after hatching). The results showed that letrozole doses of 100 μg/g and 200 μg/g produced more males (65.9% and 71.3%, respectively) than did a dose of 50 μg/g (64.7%) (<0.05). However, no significant difference in sex ratio was observed between the 50 μg/L 17α-MT treated group and the control group (51.1%). In addition, letrozole accelerated the occurrence of primary spermatocytes for 2 and 5 days, but deferred that of ovarian cavity and primary oocytes for 3 and 6 days, respectively. Both Cyp19a1 expression prior to and post sex differentiation (12−30 d after hatching). However, In addition, letrozole at dose of 200 μg/g inhibited the expression of both Cyp19a1. Our results suggest that letrozole doses above 100 μg/g could induce involved in the

Abstract:Turbot is an important aquaculture species in the eastern North Atlantic and Mediterranean regions, China, and Korea. Research on the molecular mechanisms of the turbot immune system could contribute to improving the economic performance of turbot aquaculture. In this study, we cloned and characterized the full-length cDNA of ). The full-length cDNAs were obtained by the 5′ and 3′-RACE method. The cDNA was 1 441 bp in length, consisting of a 59 bp 5′ UTR, a 278 bp 3′ UTR, and a 1 104 bp encoding a 367 amino acid polypeptide. The cDNA was 1 451 bp in length and contained a 92 bp 5′ UTR, a 267 bp 3′ UTR, and a 1 083 bp ORF encoding 360 amino acids. The TMHMM (TransMembrane prediction using Hidden Markov Models) analysis confirmed that they were seven-transmembrane-spanning proteins. A phylogenetic tree based on the amino acid sequences was constructed by the neighbor-joining (NJ) method using Mega4. The results of phylogenetic analysis revealed that turbot were more similar to the cDNAs of other teleosts than to each other. The relationships exhibited in the tree are consistent with their evolutionary relationships. The mRNA expression levels in various tissues was measured by quantitative RT-PCR (qRT-PCR). Both gene transcripts were expressed in all of the tissues analyzed, with the highest expression being in the spleen, head kidney, and heart. The expression in spleen and liver was more sensitive than in head kidney or blood. expression levels were both high in immune-related tissues and after induction by LPS. Our results indicate that both genes play a role in the turbot immune system.This work further elucidates the functions of these genes in immune responses, which will help to better understand the important relationship between fish disease resistance and innate immunity.

Abstract:mitochondrial COI gene of five cyprinoid aquaculture varieties were sequenced and their genetic diversity and cluster analysis were compared. Eight haplotypes were detected from 100 individuals,94.06 % belonged to five haplotypes (H1H4H6). Songpu mirror carp had five) was 0.160±0.070 ~ 0.811±0.055, the highest genetic distance between varieties (50.28% ranged from 0.711 4−0.831 2. Compared with the others varieties, exhibited the biggest differences. According to the evolutionary tree based on genetic distance, five varieties could be divided into three groups, the first group included Frigid carp and Red mirror carp, the second included Songpu mirror carp and Songpu carp, and the last included Cyprinus carpio , all varieties shared the same haplotypes (H2H5H6), which may be due to cross breeding. This study also indicated that DNA barcoding is a practical tool for analyzing the hereditary of different varieties. However, some limitations still exist

Abstract:is one of the most commercially important cultured abalone in southern coastal areas in China. However, the frequent occurrence of infectious disease, especially during hot summers, is a major problem that has threatened the abalone aquaculture industry for a long time. As an invertebrate, abalone lacks an adaptive immune system and relies exclusively on innate immunity to defend against bacterial challenge. However, research on gastropod immune responses is limited. Purple acid phosphatase (PAP) belongs to a large family of dinuclear metalloenzymes and is distinguished from other acid phosphatases by its purple color, which is due to a Tyr-to-iron (III) charge transfer transition. PAPs are a group of tartrate resistant, molybdate sensitive, iron containing acid phosphatases with a molecular weight of about 3540 kD and a high activity towards activated phosphoric acid monoesters and anhydrides. They catalyze the hydrolysis of a wide range of phosphate esters. PAPs play important roles in response to different stresses in plants and mammals. However, to date it has not been investigated in molluscs. In this study, the first molluscan PAP gene, , was cloned by combining the expressed sequence tag (EST) and rapid amplification of cDNA end (RACE) methods. Its full length cDNA sequence is 1 215 bp, with a 969 bp open reading frame encoding a protein of 322 amino acids (GenBank: KC337074). The 5′ and 3′ untranslated regions (UTR) of contain 28 bp and 218 bp, respectively. Pairwise analysis results revealed that the has the highest identity, 59%, to the invertebrate HdPAP is 36.8 kD with a theoretical isoelectric point (PI) of 5.27. Multiple sequence alignment of the HdPAP amino acid sequence with other known vertebrate PAPs and invertebrate PAP family proteins revealed that it was conserved, while their lengths varied among species. Predicted three-dimensional modeling (3D) of from Swiss-model identified 7 α-helices and 12 β-sheets. These important secondary structures contribute to the function of this enzyme. expression profiles in various tissues and at different time phases after thermal, hypoxia, or bacteria challenge were determined by real-time quantitative PCR. was detected in all tissues examined, with the highest levels , suggesting that purple acid phosphatase is an important enzyme with a vital function in metabolic stress. expression was suppressed to varying degrees in the gill, hemocytes, and hepatopancreas by thermal stress. Its expression was significantly down-regulated after 4 h and 24 h in the gill, 4 h, 24 h, 96 h, and 192 h in the in the hepatopancreas at 30 expression levels in the hemocytes of the hypoxic group was significantly lower than that of the control group after 4 h of exposure, then rose to the same level as the control group after 24 h. After 96 h the expression level was significantly higher than that of the control group and subsequently dropped to the same level as the control group after 192 h. Expression inhibition was also observed in the hemocytes after ) injection, with the level being significantly lower than that of the control group after 3 h and 6 h. These results suggest that plays an important role in environmental stress and bacterial challenge responses in abalone.

Abstract:by reverse transcriptase-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends(RACE) methods. The full-length cDNA of was 912 bp with a 480 bp open reading frame(ORF) encoding 159 amino acids, which included a signal peptide of 20 amino acids at the N-terminus and a mature peptide of 139 amino acids. The deduced amino acid sequence had a putative size of 17.69 kD and the theoretical isoelectric point was 7.75. The multiple alignments revealed identity of 91.4% between in the i-type LYZ amino acid sequence. The i-type lysozyme conserved sequence DVGSLSCGP(Y)Y(F)QIK was detected in the amino acid sequence. These results indicate that the cDNA sequence cloned from is a member of the i-type lysozyme family. Real-time quantitative PCR was carried out to measure mRNA expression patterns in the mRNA expression levels in peristome membrane were significantly higher than those of , male gonad, and female gonad (after the LPSand reached its maximum level at 8 h post-stimulation, and decreased gradually thereafter. Thirty-six hours after the LPS challenge, LYZ levels in the

Abstract:We studied the retina structure, visual characteristics, and correlated function of Dabry’s sturgeon () ranging from newly hatched larvae to 64-day-old juveniles using paraffin serial sections. The main results are as follows: Larvae exhibited undifferentiated retina at hatching. Single cones appeared after 36 hours and rods appeared after 6 days. After 7 days, the visual system had completely differentiated. The apparent retinomotor responses first occurred on day 13. However, the minimum separable angle (α) decreased from During the developmental period, the density of single cones and ganglion cells decreased while that of the rods correspondingly increased. The ratio of nuclei of the outer nuclear layer to ganglion cells per 100 μm increased, as did the ratio of nuclei of the outer nuclear layer to single cones. Our investigation revealed that the retina structure and visual characteristics changed rapidly from day 6 to 12 to adapt to ecological shifts and changes in photo taxis and feeding behavior.

Abstract:The relationship between oxygen consumption rate, ammonia excretion rate and water temperature, body weight and the respiratory metabolism of wild in South China Sea were investigated with a breather apparatus in closed static seawater system. The experimental results showed that water temperature had apparent effect on oxygen consumption rate and ammonia excretion rate (<0.05),>0.05). Under 16−32, the oxygen consumption rate and ammonia excretion rate first increased and then decreased with increasing temperature; under the same temperature, no significant changes were observed among different body weight. Temperature of 24 respiratory metabolism. Under this temperature, the highest oxygen consumption rate, ammonia excretion rate and fastest metabolic rate were recorded. At 24 oxygen consumption rate and ammonia excretion rate were 0.86 mg/(g∙h) and 36.69 μg/(g∙h) per unit of body mass, respectively. The result of respiratory metabolism substrate analysis showed that under 24−28 the ratio of O: N increased with temperature increasing, which indicated that the proportion of energy provided by protein decreased.

Abstract:are two economically important freshwater aquaculture species in China. Hybrids created by interspecific crossing among several fish exhibit increased growth rate, improved disease resistance, and improved environmental tolerance. In this study, the embryonic development of reciprocal hybrids of Basilewsky (DQ and QD) and F2 of (♂) F1 (F2) were described and compared to each other and their parents. Embryonic development was divided into 6 main periods based on anatomical featureszygote, cleavage, blastula, gastrula, embryonic body formation, and hatching. S. chuatsi, with a mean diameter of (1.197±0.052) mm, were both significantly bigger than that of the F1 ( males) with 1.723±0.0519) mm. Compared with the early development of other fish, e.g., , and zebrafish, we found that chromatogenesis and pigment distribution in , and the three hybrids shared common characteristics: chromatogenesis began on the yolk sac just after the closure of the blastopore. Punctiform melanin gradually spread all over the surface of the yolk sac. A neurocyte-shaped pigment subsequently centralized on the oil globule, and pigmentation later appeared on eyes and head. The features of embryonic development in the three hybrids were similar to their parents. DQ began to hatch 37 h post-fertiliza­tion at 25.5‒27.7 began to hatch 35 h, 34 h, 33 h, 31 h post-fertilization at 25, 26, 27, and 27.5, respectively. The speed of DQ, QD, and F2 embryonic development at 21.6‒28.7. Newly hatched DQ, QD, and F2 larvae were (4.1±0.4) mm3.5±0.2) mm in length, respectively. The similarity in embryonic development of the three hybrids and their parents, and the progeny of males both indicate a very close phylogenetic relationship between , which is consistent with previous studies employing 11 nuclear loci and the cytochrome b gene.

Abstract:from low-salinity water farming ponds were carried out in laboratory. The prawns were reared under different salinities of 1, 8, 15, 23, and 30. Female unilateral eyestalks were sheared to promote maturation. The water temperature for the male shrimps was set at (27±0.5). The sexual development, spawning, fertilization, and hatching rates of the parents were investigated. The female gonads matured in all five salinity conditions; the proportion of mature females in salinity 1 was <10%; in salinities 8 and 15 it was 70%, with low fertilization and no nauplius; and it was >76% in salinities 23 and 30, with low hatching rates. Histological examination revealed that ovarian development did not differ among the 8−30 salinity conditions. The male gonads also matured normally, but the speed of sexual development in salinities 23 and 30 was significantly faster than that in salinities 8 and 15(<0.05). As salinity decreased, the time required for male shrimp maturation increased. The spermatophores were fertilized and nauplius hatched in all salinities.

Abstract:) is a widely cultured marine fish species in China and is highly valued because of its fast growth and good flavor. However, frequent occurrence of disease and subsequent losses limit profitability and aquaculture developmentBreeding a new flounder strain with enhanced disease resistance is an important task in marine fish aquaculture. In the present study, new Japanese flounder families were established based on Japanese stock (JS), Korean stock (KS), and stock with high resistance to (RS) by nested hybrid, cross, and gynogenesis. Forty-three and sixty-five Japanese flounder families were established in 2009 and 2012, respectively. Disease resistance was investigated using 33 families in 2009 and 43 in 2012 through intraperitoneal injection challenged with . The results demonstrate that different families exhibited variable survival rates and 13 families with high disease resistance were obtained. All 13 families exhibited significantly higher survival rates compared with the control, however, some were more significant than others (<0.05 in 10 families). Of these 13 families, three were derived from the F2 family, one from the F3 family, and two belonged to the first and second gynogenesis generations(G1 and G2). In these six families, disease resistance was high in the parents, with the exception of the F2 family; their survival rate variation coefficients were <10%. Analysis of disease resistance in the three successive generations revealed that, 13 of the 16 disease-resistance families which included 13 families mentioned above and 3 resistant families sereened in 2007 were derived from RS. In conclusion, some F2, F3, G1, and G2 families exhibited enhanced disease resistance inherited from their parents, indicating that the establishment of a disease-resistant strain based on these families is possible.

Abstract:A feeding trial was conducted to investigate G) with selenium (Se) and vitamin E (VE) on the growth performance, serum immune, and antioxidant indexes, and disease resistance of with an initial body weight of (0.83±0.02) g were randomly divided into 5 groups and fed one of five diets with added G, 300 mg/kg G+0.2 mg/kg Se+100 mg/kg VE, named G0, G1, G2, G3, and G4, respectively. After 35 d feeding, the shrimps were infected with white spot syndrome virus(WSSV).(WGR) was highest in G2, which was significantly higher than that of G1 by 6.4% (<0.05). Survival rate(SR) in G3 was significantly lower than in G0 and G1 (<0.05). Total hemocyte count (THC) activity increased significantly in G4 (<0.05) compared with G0.<0.05). Acidic phosphatase(ACP) activity in G3 was significantly lower than that in G4(<0.05). Alkaline phosphatase (AKP) activity in G2 was significantly higher than that in the other three treatment groups (<0.05). Glutathione peroxidase (GSH-PX) activity in G4 increased significantly compared with the other four groups (<0.05). There was no significant difference among the five groups in glutathione transferase (GST) activity (>0.05). Catalase (CAT) activity was highest in G1, being significantly higher than that in G2 and G4 (<0.05). The highest value of superoxide dismutase (SOD) activity was observed in G2, followed by G1 and G3. The former was significantly different compared with the other four groups (<0.05), and the latter two were increased significantly in comparison to G0 and G4 (<0.05). Malondialdehyde (MDA) content in G1, G2 and G4 decreased significantly compared with G0 and G3 (<0.05). ) radical activity in G1, G2, and G4 was significantly higher than that in G3 (<0.05). Compared with G1, total antioxidant (T-AOC) capacity in G3 increased significantly (<0.05). After 72 h of WSSV infection, the highest cumulative mortality rate (AMR) was observed in G0, AMR in G1–G4 were lower, with a significant decrease in G2 and G4 (<0.05).The relative percent survival (RPS) in these two groups was 30.8% and 26.9%, respectively. In conclusion, the combined addition of G+Se+VE might improve non-specific immunity, antioxidant capacity, and resistance to the white spot syndrome virus (WSSV) in .

Abstract:k feeding trial was conducted to study the effect of dietary choline chloride supplementation on the growth performance, lipid metabolism, feed utilization, body composition, serum biochemical indices, liver lipid content, and muscle and liver choline content of adult GIFT tilapia()The basal diet contained 27.60% crude protein and 6.45% crude lipid. The basal diet was supplemented with choline chloride (0600food) to formulate six semi-purified diets containing choline of 97.80(control group), 375.04, 565.74, 974.27, 1409.81, and 1 824.35 mg choline per kg food. Each diet was randomly fed to three replicates of GIFT tilapia with an initial average weight of (220.00±8.34) g in 18 pond cages (1.0 m×1.0 m×1.5 m). Compared with the control group, the addition of choline to the diet significantly improved weight gain rate, specific growth rate, and feed utilization(<0.05) in all groups compared with the control. In addition, the liver choline and muscle fat content of all groups increased significantly(<0.05). With increasing dietary choline levels, serum triglyceride and cholesterol content increased in the groups with significantly higher choline chloride than that of the control group(<0.05), the liver triglyceride and cholesterol content decreased significantly(<0.05). Serum aspartate aminotransferase(ALT), alanine aminotransferase (AST), and alkaline phosphatase (ALP) also decreased significantly (<0.05) with increasing dietary choline content. The choline requirement of adult GIFT tilapia was 506.43 mg choline per kg food based on the specific growth rate; however, it was 981.38 mg choline per kg food based on liver choline concentra­tion. Our results suggest that choline chloride supplementation could improve tilapia growth performance, feed efficiency, reduce liver fat content, and promote lipid degradation.

Abstract:The aim of this study was to explore the distribution and composition of integron-gene cassettes in multi-drug resistant (MDR) , and to understand the relationship between integrons and MDR, so that we can accurately evaluate the status of integron-gene cassette systems in the MDR mechanisms of . To determine the distribution and molecular characterization of integron-gene cassettes in 28 multi-drug resistant isolates from fish, the K-B disk diffusion method was employed to determine the antimicrobial susceptibility of the isolates to 18 different antibiotics. PCR amplification was then performed to detect class . The results indicate that isolated from fish exhibited multi-drug resistance, with an antibiotic resistance rate of more than 60% to -lactams, macrolides, chloramphenicols, and tetracycline antibiotics, while it was more sensitive to fluoroquinolones. The drug resistant spectrum also differed greatly among the isolates. The PCR amplification results showed that out of 28 isolates, 15 (53.57%) harbored III was detected in the isolates. Combined with the antimicrobial susceptibility results, the drug resistant rate of the integron positive strains was higher than that of the integron negative ones. In addition, class I integron positive strains exhibited a higher multi-drug resistant rate than those harboring class II integrons, which indicates that the integron-gene cassette system plays an important role in the occurrence of multi-drug resistance in . The main cassettes were those encoding aminoglycoside adenyltransferase A (aadA), dihydrofolatereductase A (dfrA), and chloramphenicol acetyltransferase B (catB). The most prevalent gene cassette array was . In addition, there was an obvious difference in MDR among individuals containing class I integrons, hinting that no direct relationship exists between the MDR phenotype and gene cassettes in the isolates. These findings suggest that the transfer of antibiotic resistance genes can occur through integron-gene cassettes among .

Abstract:Adhesion to the host mucus, which is closely related to the virulence of pathogenic bacteria, is the first crucial step in most infections. In this paper, the adhesion characteristics of ) skin mucus was investigated by indirect ELISA. can be used as an index to reflect the number of adhering bacteria. Second, we confirmed that the iCFU. The number of a saturation kinetics equation =0.986) was obtained by plotting the number of adhering bacteria against cell density. The factors affecting bacterial adhesion were then investigated. The results revealed that the number of adhering increased with incubation time and reached a peak after 150 min. Temperature was one of the major factors affecting bacterial adhesion, with peak adhesion occurring at 20−28. pH also influenced bacterial adhesion. In a weak acid with a pH of 6.2−6.6, the adhesion ability of The optimum concentrations of Na⁺ and adhesion were 1.5−2.5 g/L and 3 g/L, respectively. In summary, the optimum conditions for the adhesion of to eel skin mucuswere 20‒28, and 150 min incubation time. In addition, we found that bacterial adhesion was influenced by carbohydrates. Seven kinds of carbohydrates were investigated and the results indicate that glucosehelp to further elucidate bacterial pathogenicity and help

Abstract:Using tissue homogenate and high performance liquid chromatography(HPLC) methods, the blood-brain barrier permeability and residual tissue characteristics in were examined under different Avermectin (AVM) concentrations. AVM was detected in the 50= 0.127 mg/L, 0.071 mg/L, and 0.039 mg/L)) at 24 h, 48 h, and 96 h, respectively and the safety concentration (SC: 0.003 9 mg/L). Significant differences in the brain AVM contents among the three median lethal concentrations were observed( [() μg/g]. The above results show that AVM can penetrate the blood-brain barrier into the brain under different concentrations. Furthermore, the brain AVM contents were positively correlated with initial drug concentration. In addition, the AVM concentration-time data in the brain, liver, kidney, and muscle were all in line with the non-compartmental method in the DAS 3.0 pharmacokinetics software under the safe concentration (0.0039 mg/L). The main pharmacokinetic parameters were as follows: (1) max: liver>kidney>muscle>brain; (3) : liver>brain>kidney>muscle; (4) AUC: liver>kidney> brain>muscles. The results of this paper provide references for future fish blood-brain barrier research, and AVM nerve toxicity mechanism investigations and its application in aquaculture.

Abstract:Integrating the standardization of abundance indices into stock assessment models to examine the population dynamics of small yellow croaker, was tested through a fisheries mixture matrix constructed with multiple data types. A precautionary approach to fishery control rules was adopted based on the logistic and Fox surplus production models, dependent catch-per-unit-of-effort(CPUE), and regional harvests. A risk-averse control rule, derived from model parameters and associated uncertainty, was developed to manage fisheries for maximum sustainable yield (MSY) and rapid rebuilding of overfished stocks. The proposed control rule consists of relative biomass and relative fishing mortality rate in a deterministic environment and conservative harvest in a fluctuating environment. The results of the Fox model explained 68% of the variance observed for the stock abundance, while the logistic model explained 57%. The parameter estimates were different and the Fox model predicted a much larger decrease in population abundance at the MSY,), and initial exploited levels. We compared the fishing mortality/current stock biomass from 1998 to 2006 with the fishing- and stock-related reference points, respectively. The results in a determined environment revealed that small yellow croaker stock in the East China Sea was overfished in most years, while the population was not always overfished during the entire period, although its biomass has been decreasing since 1999. However, both the Fox and logistic surplus production models indicate that the small yellow croaker fishery has been consistently over harvested in the fluctuating environmentHarvesting at a conservative level with either the Fox or logistic model could increase small yellow croaker abundance substantially with little decrease in harvest. At a conservative harvest level, there is a 24.7% increase in biomass with a 6.1% decrease in yield with the logistic model and a 44.5% increase in biomass with a 9.4% decrease in yield with the Fox model. The MSY assessment results from the Fox surplus production model was more conservative than that of logistic model, which is concordant with precautionary fisheries management strategies.

Abstract:Based on three bottom trawl surveys carried out in spring (June), 2011, crab species composition, weight density and individual density distribution, dominant species, and community characteristics were analyzed by analysis of variance, linear regression, cluster analysis, and non-metric multidimensional scaling. Thirteen crab species, belonging to 7 families of 4 orders in 1 class were sampled. Of these, four were eurythermal and eurysaline, four were hyperthermal and eurysaline, two were hyperthermal and hysaline, and three species were of uncertain ecotypes. Weight density Aprilas did the number abundance density indices) differed significantly betweenhe Margalef richness index (were negatively correlated (<0.05). During spring in the study area, the non-economic mid-minitype crab species occupied the D increased with increase in sea. In addition, most dominant species density in this can be used as a basis for identifying the ecotype function zone and important fisheries waters.

Abstract:into the residue, distribution, and composition of Dichloro-diphenyl-tricgloroethanes (DDTs) in sea water, sediment, and cultured shellfish in Dongshan Bay was carried out in spring(May) and summer(August), 2011. We also evaluated the contamination status and ecological risks. The results were as follows: irst, the DDT content in the sea surface layer varied from non-detectable(ND) to 25.7 ng/L in May and from ND to 36.7 ng/L in August, the average values were (6.08±3.02) ng/L and (16.30±4.78) ng/L, respectively; the DDT content in the bottom layer varied from ND to 30.6 ng/L and from ND to 36.7 ng/L, the average values were (7.75±2.07) ng/L and (13.30±5.12) ng/L in May and August, respectively. In general, the DDT concentration distribution in Dongshan Bay declined from the inner to outer bay and from the near- to far-shore. DDT concentrations in summer were higher than those in spring. Compared with other bays in China, DDTs pollution in Dongshan Bay was at a lower level status; however, it is likely that there has been a recent pollutant input in sites DS03 and DS11. Second, the DDT content in the sediment varied from 5.56−12.8 μg/kg, the average value was (9.00±5.34) μg/kg. The concentration declined from the inner to the outer bay. DDT residue in the sediment may have negative effects on organisms, the toxicity risk index varied from 25% 75%. Third, the DDT content varied among different species of cultured shellfish from 1.68‒26.60 μg/kg and the average was 15.70 μg/kg. The pollution index varied from 0.007 to 2.660, the average was 1.580. This exceeded the standard rate by 71.4% and the highest value was 1.66 fold. These results show that some shellfish have been contaminated by DDTs. This problem requires further attention and must be resolved.

Abstract:Nitrogen assimilation characteristics of strain (Z5) were investigated under both single (organic nitrogen, NH₄-N, or NO₂-N) and mixed nitrogen sources (organic nitrogen and NH₄-N, organic nitrogen and NH₄-N, or NH₄-N, and NO₂-N) Activity of protease, glutamine synthetase, and nitrite reductase, which are all involved in nitrogen metabolism, was also determined. The results showed that both organic and inorganic nitrogen assimilation rates of 2-N assimilation rates under a C/N ratio of 20 were 3.39 and 2.25 times higher, respectively, than those under a C/N ratio of 5. There were no significant differences in the assimilation of NH₄-N and NO₂-N between C/N ratios of 15 and 20 (0.05). -N→bacterial protein, respectively. -N) assimilation rates increased with higher C/N; the protein nitrogen content of the bacteria enriched from NH₄-N and NO₂-N increased from 25.0% and 19.4% under a C/N of 5 to 41.3% and 43.0% under a C/N of 20, respectively. In addition, was significantly regulated by NH₄-N while protease and NiR activity were not regulated significantly by the nitrogen species.

Abstract:Long-term overfishing and environmental pollution has led to a high degree of change in Laizhou Bay fisheries resource structures. Since 1980, small pelagic fish have become the new dominant species in this area. These small pelagic fish play a connecting role in the food chain and are often one of the key groups in marine ecosystems. Research on the trophic level of Engraulidae and Clupeidae fish in Laizhou Bay based on stomach content analysis has provided useful but dated information. More up-to-date research is now necessary. Based on bottom trawl surveys in Laizhou Bay during summer and autumn, 2011, the stable isotope signatures of four Engraulidae and Clupeidae species revealed that the stable carbon isotope ratios ranged from 11.67‰, while stable nitrogen isotope ratios ranged from 8.54‰ to 15.95‰. ANOVA analysis revealed that among the four species (<0.05). Linear regression analysis between fork length and stable isotopic ratios showed that had significant ontogenetic variation in terms of δ¹⁵N ( Thrissa kammalensis did not (trophic level ranged from 2.80 to 4.88, with the average being 3.52±0.46; the trophic level ranged from 2.71 to 4.29, with the average being 3.34±0.33; the trophic level ranged from 3.38 to 4.42, with the average being 3.97±0.28; the trophic level ranged from 3.28 to 4.13, with the average being 3.76±0.23. According to the stable carbon and nitrogen isotope results, we can draw the following conclusions: (1) The stable carbon isotope values showed that trophic level range (-inhabits a wide depth range which is different to that of other pelagic fish; (2) The trophic level decreases with increasing fork length while that of increases with increasing fork length, no such changes were observed in the other two species; (3) The trophic level is about 0.7 times larger than that reported from the traditional stomach content analysis, which may be related to increased feeding on shrimp. The trophic level of the other three species was slightly higher according to the stable isotope results, but not significantly so.

Abstract:Ophiuroids are important components of the macrobenthos and marine ecosystem. However, most previous studies have focused on taxonomy and little is known of their biology or ecology. References on ophiuroids in the Chinese literature are both few and dated. This study focused on the food preference, feeding rate, and feeding behavior of . The objectives were (1) to achieve an understanding of the feeding habits of , (2) to supplement the literature on ophiuroids, and (3) to attract people’s attention on the study of ophiuroids. The results revealed that can only feed on suspended organic particles through differentiating food particles by size. It can feed on particles ranging in diameter from 10Platymonas subcordiformisf. is both polyphagic and a member of microphagous group. When the were The food was collected and formed into a small food ball by the tube feet at the end of the arm. The food ball was then transported to the mouth and became enlarged. When they were not ingesting, the arms were either stationary or cocked at the end. The feeding rate of smaller < 0.05)feeding activity occurred between 8:00‒14:00, but there were some that ingested food at any time. Therefore, no specific feeding rhythm was observed.

Abstract:In recent yearsglobal warming and of green marine algaegreen tide, causes significant harm to the coastal environment. has been used as an edible and medicinal plant since ancient times. It is currently used as a food resource, ingredient, and additive for marine fish, shrimp, and shellfish food. However, there are few reports on its use in aquaculture. The aim of this study is to explore the feasibility using juvenile feed. amino acids and fatty acids contained in E. prolifera and common sea cucumber diets (with an average body weight of (5.26±0.14) g were conducted. The results of the nutrition test revealed that is a good source of protein. Of the amino acidsAsp, Glu, Ala, and Leu contents were highest. The overall fat content was low, but the polyunsaturated fatty acid content was above normal. ) contents were all lower than the The results of the feeding trials revealed that during the experiment, each sea cucumber group fed well. There was no significant difference in survival rate among the groups (>0.05). At the end of the trial, the body weight of fed on each diet had increased significantly (>. The feed efficiency relathunbergiiS. muticum<0.05). There was no significant different between the general feeding effect of is a high-protein, low-fat algae food with lower heavy metal content, so it can be used as an alternative or partial substitute for the most commonly used algal food() for juvenile sea cucumbers. This would not only alleviate the shortage ofutilization rate as part of a new comprehensive management strategy.

Abstract:Recirculating aquaculture systems, i.e. re-using water after purification recycling, are efficient, economic, and environmentally friendly. In addition, they comply with the strategic needs for circular economy, energy conservation and emission reduction, and changing mode of economic growth proposed combined with aquaculture research and industrial development, focused on breeding management and application, water circulation system carrying capacity, water cycle ratio, main breeding animals, breeding effect, perfect breeding density, and other aspects of . The findings are summarized and discussed to provide a corresponding reference for the future establishment of standard breeding management for recirculating aquaculture systems in China.

Abstract:Development of rational management plans and correct management are essential to maintain the sustainability of fisheries resources. Fisheries management plans should be based on stock assessment and so stock assessment models are important tools for this. Over the last thirty years, fishery stock assessment models experienced a golden age and the number of models grew exponentially with improved computer technology and the integration of multidisciplinary research. At the same time, the complexity and diversity of the models makes choosing the correct one increasingly difficult for researchers and abuse of fisheries models may lead to stock collapse. In this paper, we reviewed fisheries stock assessment model structure, type, and estimators, i.e. fixed effect, random effect, and hierarchical Bayes to identify the typical models currently used in fisheries stock assessment and track their evolution and development. Meanwhile, the present paper discusses the problems with these models and presents prospects for their future development.