Abstract:One of the key problems of the hydraulic design of fish pass structure is the fish first orient to the flow. Obtaining fish behavior parameter in the process of upstreaming is beneficial to the research of target fish physiological characteristics, swimming capability and its response to hydraulic environmental factors. In this paper, taking the Hypopthalmichthys molitrix as the research object, the correlation among flow velocity U, tail-beat frequency f, relative tail-beat amplitude A, absolute swimming speed V and swimming acceleration a was analysed in the state of holding station and moving forward during upstream by behavioral analysis software. Result showed tail-beat frequency and flow velocity were in a positive relationship during holding station; relative tail-beat frequency A was (0.0876 ± 0.0098) BL, while there was no clear relation between tail-beat frequency f and relative tail-beat amplitude A; during moving forward, tail-beat frequency f was greater than that during holding station, while in contrast, little difference lay in relative tail-beat amplitude A; tail-beat frequency f and absolute swimming velocity V were in definite positive relation, while there was no obvious relationship between tail-beat frequency and relative tail-beat amplitude A; in the process of H. molitrix moving forward, swimming acceleration a changed as time went by, and most of swimming acceleration varied from 0.02 g to 0.06 g[55.84%]. In the paper, experiments are conducted in the flume and we had a single flow field, but the flow field is relatively complex in natural environment. The relationship between fish behavior and hydraulic factor requires further research.

Abstract:In a 100 days field trial we examined the growth of sea cucumbers Apostichopus japonicus in bottom culture underneath net pens of tiger puffer Takifugu rubripes at an experimental integrated multi-trophic aquaculture (IMTA) site. We tested the effects of multi-culture on growth in two experimental species. We also compared growth of experimental animals cultured directly with control single species. There was no significant difference in fish growth between polyculture and control group, the average weight of daily weight gain (Md-wg) of T. rubripes was 1.07 g/d and the specific growth rate (SGR) was 4.06%/d in polyculture group. The Md-wg of A. japonicus was (0.11±0.04) g/d and the SGR was (0.67±0.2)%/d in polyculture group. In control single group, the Md-wg of A. japonicus was (0.04±0.02) g/d and the SGR is (0.35±0.19)%/d. Sea cucumbers suspended directly below the tiger puffer net pens grew significantly faster than control individuals. This study demonstrated that A. japonicus is well suited to utilize the heavy fraction of waste from the tiger puffer while providing an additional valuable harvestable product.

Abstract:The aim of this study was to investigate the effects of fish protein hydrolysate on yellow catfish growth, body composition and serum indicators. In practical yellow catfish formulation mode, a control with anchovy fish meal was prepared. ① A control diet containing 305 g commercial fish meal/kg diet (FM) was prepared, and 6% of fish protein hydrolysate partially replaced 20% fishmeal (MPH6) at the same formulation mode. ② With 305 g commercial fish meal/kg diet (FM) as the control, inclusion levels of FPH in 3% (FPH3), 6% (FPH6), 12% (FPH12) were added into non-fishmeal diets directly, and the five experimental diets were isonitrogenous, isolipidic and isoenergetic. The diets were fed triplicate groups of yellow catfish[initial body weight (30.08±0.35) g] for 60 days in outdoor farming system. The results showed that, the SGR, FCR, PRR and FRR of FPH12 have no significant difference with 30% FM, but MPH6, FPH3, FPH6 decreased by 15.45%-24.39%, FCR increased by 32.14%-42.86%. In PRR and FRR, the PRR of MPH6, FPH3, FPH6 decreased by 21.11%-27.78%, FRR of MPH6 decreased by 41.51% compared with FM. The moisture, crude protein, crude fat and ash of fish have no significant difference in all diets, and a variety of free amino acids in fillets of high plant protein dietary is significantly higher than that of FM, and partially the levels of Thr, Val, His in the dietary is significantly associated. There were no significant differences of HSI, CP, VSI, intestinal length/body length, AST, ALT, HDL, LDL, TP, CHOL, TG compared with FM, except the ALB of FPH3. So, there is a certain equivalence between 12% fish protein hydrolysate with FM on yellow catfish growth, feed utilization and indicators; too high plant protein has a significant negative impact on growth performance, and fish protein hydrolysate can elevate the levels of free amino acids in fillets, particularly flavor amino acids.

Abstract:For a long time, the ribosomal RNA gene was thought to conform to the paradigm of strict concerted evolution pattern. In fact, an increasing number of intraindividual and intraspecies variations have been discovered, indicating non-concerted evolution. In order to explore the polymorphism of the first internal transcribed spacer (ITS1) in the species of Soleidae in Pleuronectiformes and whether it is suitable as a marker for species identification, a total of 118 ITS1 sequences were determined from five soles. The results showed that two distinct types were found in Pardachirus pavoninus genome, suggesting a non-concerted evolution pattern, while concerted evolution was confirmed in other four soles because of absence of intraindividual polymorphism. Sequence analysis demonstrated that ITS1 had significant length heterogeneity, ranging from 412 bp in Zebrias quagga to 585 bp in P. pavoninus. The base content of sequences in all five soles was in the same trend with C > G > A > T and GC content (69.5%) was far higher than AT content. Except for one sequence of P. pavoninus, each of five soles clustered into one clade, respectively, suggesting ITS1 sequence was suitable for species identification in the present study. It is worth noting that the sequence of P. pavoninus clustered with Brachiru orientalis, suggesting that ITS1 sequence polymorphism interfered species identification, as a result, it is essential to obtain enough clones before using ITS1 sequence as the molecular marker for species identification in order to avoid incorrect conclusions.

Abstract:A trial was conducted to determine the effects of dietary Vitamin C levels on hypothalamic-pituitary-interrenal axis and physiological indices of juvenile hybrid grouper (Epinephelus lanceolatu♂×Epinephelus fuscoguttatus♀) under acute low temperature stress. A basal diet was used as a control, and four other diets were prepared by supplementing 38, 76, 152, or 304 mg/kg vitamin C. Triplicate groups of fish (initial body weight, 50 g) were fed one of test diets at ratio of 1.5% or 2% body weight for 12 weeks at 27-28℃. Uniform sizes of fish were selected for acute low temperature stress (17℃) at the end of rearing management. Some biochemical indices in their serum and corticotrophin-releasing factor content of brain were examined over 2 hours. Results showed that:Weight gain of the fish fed with D38 group was significantly higher than that of D152 and D304 groups. We found no significant difference in corticotropin releasing factor content (CRF), adrenocorticotropic hormone content (ACTH), epinephrine content (EPI) or cortisol content in juvenile hybrid grouper, among all treatment groups. After acute low temperature stress, CRF content was increased by increasing dietary vitamin C levels. While ACTH and EPI content in serum showed a reverse trend, fish fed diets with vitamin C 304 mg/kg was significantly lower than control diet. Cortisol was reduced significantly in fish fed diets 76 mg/kg to 304 mg/kg diets compared to control diet. Fish fed diets 152 mg/kg to 304 mg/kg dites T3 content were significantly higher than control diet. Whereas, after acute low temperature stress, fish fed diets 38 mg/kg to 304 mg/kg were significantly higher than control diet. There was no significant difference in T4 content in fish among different treatments. Fish fed diet 304 mg/kg diet showed significantly higher than other groups, whereas no difference was found among group D0 to D152. TSH content in D76 group exhibited obviously higher than D0, D38 or D304 groups. After acute low temperature stress, all diets containing vitamin C significantly elevated TSH content in serum. Dietary vitamin C levels had no strong effects on GCK and HK contents of liver. After acute low temperature stress, GCK content was negatively correlated with dietay vitamin C, and reached lowest value in 304 mg/kg diet, and was significantly lower than other groups. HK content reached lowest value in 76 mg/kg diet, and was significantly lower than D0, D152, D304 groups. Significantly higher PEPCK value was found in fish fed 304 mg/kg vitamin C compared to 0 mg/kg diet. After acute low temperature stress, PEPCK concentration was decreased significantly with increasing dietary vitamin C levels. All those data reveal new insights into the funtion of vitamin C that VC can modulate some biochemical indices of hypothalamic-pituitary-interrenal axis, protect and regulate the thyroid of fish, and maintain the dynamic balance of fish body under acute low temperature stress.

Abstract:To guide the subsequent breeding of hypoxia-tolerant population of Megalobrama amblycephala; genetic structures of hypoxia-tolerant (TN), meiotic gynogenesis (TNM), mitotic gynogenesis populations (TNDH) of M. amblycephala were analyzed using twenty microsatellite markers in this study. The mean value of number of alleles (N_a) of M. amblycephala TN, TNM, TNDH and the control TPJ1 was 3.90, 3.55, 3.45 and 2.56, respectively. The mean value of observed heterozygosity (H_o) was 0.7853, 0.3934, 0.2768 and 0.8075, respectively. The mean value of expected heterozygosity (H_e) was 0.6491, 0.5563, 0.4870 and 0.6855, respectively. And the average value of polymorphism information content (PIC) was 0.5695, 0.4796, 0.4181 and 0.6105, respectively. It demonstrated that the genetic diversity of TPJ1 was the highest, and TN population had lower genetic diversity, but there is no significant difference and there was the high genetic heterozygosity. The genetic diversity of TNDH population was significantly lower than TNM population, and the genetic diversity of the gynogenetic (TNM and TNDH) was significantly lower than TPJ1 and TN populations. The mean Hardy-Weinberg index of the TPJ1 and TN had heterozygote excess and the gynogenetic populations (TNM and TNDH) showed heterozygote deficit. Using unweighted pair-group method with arithmetic means method (UPGMA) based on their genetic distances, TPJ1 population and TN population were grouped in one cluster, while TNM population and TNDH population were classified into another cluster, indicating a genetic differentiation between the two clusters. Our results show that the hypoxia-tolerant group in M. amblycephala (TN) in gynogenesis can accelerate homozygosity of genetic material and will have further purification of M. amblycephala hypoxia-tolerant genes.

Abstract:This study aimed to delineate the potentially beneficial effects of choline on the liver histopathology, antioxidative status and innate immunity in blunt snout bream (Megalobrama amblycephala) fed high-fat diet. Fish[weight:(42.20±0.34) g] were fed four experimental diets containing two dietary lipid levels (5% and 15%) and two choline levels (1200 and 2200 mg/kg) in an indoor circulatory system for eight weeks. After the feeding trial, fish were sampled for analysis of plasma and hepatic lipid metabolites, antioxidant enzymes, haemato-immunological parameters and hepatocyte ultrastructural examination. The results showed that high-fat diet significantly increased liver lipid accumulation, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, malondialdehyde (MDA) concentration, activities of total superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX); meanwhile, high-fat diet remarkably reduced blood leucocyte counts, plasma lysozyme activity, total protein and globulin contents and glutathione (GSH). In addition, obvious ultrastructure abnormalities were observed in the hepatocytes of fish fed 15% lipid and 1200 mg/kg choline with apparent alterations involving mitochondrion, endoplasmic reticulum, nucleus and cell membrane. The results indicated that high-fat diet induced significant liver histological alterations, severe oxidative stress and depressed innate immunity of blunt snout bream. However, high dose of choline in high-fat diet significantly decreased liver lipid content, plasma AST and ALT activities, liver MDA concentration, hepatic SOD and CAT activities, and enhanced blood leucocyte counts and globulin protein level; meanwhile, the structures of hepatocyte organelles were normal. In summary, choline could reduce hepatic excess fat deposition, maintain normal structure and function of liver, and enhance anti-oxidative capacity and innate immunity, and hence it could keep the health of the fish.

Abstract:The white shrimp, Litopenaeus vannamei, is one of the most important aquaculture species in China. The broodstocks used in China are mainly introduced from abroad.Recently, several new domestic white shrimp strains have been bred and used as broodstock. To further strengthen the genetic breeding of white shrimp, it is necessary to understand genetic diversity status of different strains. In the present study, the amplified fragment length polymorphism (AFLP) was employed to analyze the population genetic diversity and genetic difference between four introduced populations and three domestic breeding populations. A total of 105 fragments in length of 100~500 bp were identified from 210 individuals using seven AFLP primer combinations, of which 90 of 105 fragments were polymorphic, and the proportion of polymorphic loci was 85.71%. The polymorphic loci within populations varied from 54.17% to 65.63%, with an average of 60.53%, and the mean heterozygosities ranged from 0.164 to 0.236, with an average of 0.202. AMOVA analysis revealed that 51.79% of genetic variations derived from populations, the estimated Φ_ST value over all polymorphic loci across the seven populations was 0.518, indicating significant genetic differences between populations and strong population structure. Furthermore, these results could provide theoretical supports for germplasm improvement of L. Vannamei..

Abstract:Leucine-rich repeats protein is a versatile ligand recognition domain present in receptors, which is involved in many important physiological processes such as development, immune responses and hormone regulation etc. A novel LRRs protein with significant high expression level during embryogenesis was identified in this study. Its function was investigated by various methods including cloning, sequences alignment, in situ hybridization and in vitro treatment with recombined proteins. SMART analysis indicated that an IG-like domain was located in the extracellular region besides the LRRs domain. Thus we designated it as Crassostrea hongkongensis LRRs and IG-like containing receptor (ChLIGR). Sequences alignment revealed that ChLIGR is a new member in the IG-like containing LRR proteins superfamily, and most of its homologous proteins belong to mollusk without any function related description. Consistent with its expression pattern during embryogenesis, the in situ hybridization results showed that ChLIGR was expressed most highly in blastula stage and was distributed to a distinct place in the embryo. Combining with the predicted ETS/AP-1 regulatory site upstream the promoter, we hypothesized that ChLIGR would be involved in gastrulation related epithelial-mesenchymal transition process. Notably, in vitro treatment with recombined extracellular domains of ChLIGR augments the expression of migration related genes, which partly supports our hypothesis. In conclusion, the function of this novel IG-like domain containing LRR receptor is preliminarily unveiled as an activator for gastrulation by promoting the cell migration.

Abstract:Some antioxidant enzymes in hepatopancreas were examined to evaluate the damage of the dietary AFB₁ on antioxidant enzyme in hepatopancreas of juvenile Litopenaeus vannamei. Two kinds of diets (control diet and test diet containing 2000 μg/kg of aflatoxin B₁) were fed to the shrimp[with body weight (0.3±0.02) g] for 4 weeks. 420 shrimps were selected randomly to 6 aquariums (40 cm ×50 cm ×60 cm).The activity of some antioxidant enzymes in hepatopancreas were determined every four days. The results showed that the activity of SOD of test group was significantly lower than that in control group on the 8th day. In two weeks the activity of SOD decreased significantly, and the activity of test group was significantly lower than that in control group. The activity of CAT significantly decreased in each stage. After 8 days, the activity of CAT in test group was lower than control group, especially, the activity of test group was significantly lower than control group on the 8th, 16th and 24th days. Although there was a rising trend after 20 days, the CAT activity showed significant decline from the original value.The activity of GSH-Px was lower than that in the control group, with the ability of repairing themselves decreasing. The content of MDA increased significantly after 16 days and there was a rising trend. Meanwhile, the content of MDA in test group was significantly higher than that in control group. These results indicate that the damage of high concentrations of AFB₁ on antioxidant enzyme in L. vannamei varies with different enzymes, and the damage on hepatopancreas continues to increase, causing severe hepatopancreas damage only in 4 weeks.

Abstract:Reactive oxygen species (ROS) such as superoxide and hydrogen peroxide are continually produced during metabolic processes. ROS generation is normally counterbalanced by the action of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and other redox molecules. However, excessive ROS will attack membrane lipids, proteins and DNA, which were believed to be involved in many health disorders such as diabetes mellitus, cancer, neurodegenerative and inflammatory diseases. On the other hand, food oxidation processes, especially lipid oxidation, lead to the formation of secondary lipid peroxidation products and degradation of food quality. Antioxidants may directly react with and quench reactive oxygen species (ROS). The utilization of synthetic antioxidants is limited because consumers are increasingly demanding additive-free or natural products. Therefore, the application of natural antioxidants as sources of many effective antioxidants is a promising alternative to the use of synthetic antioxidants. More recently, there is growing interest in natural hydrolysed protein antioxidants from many animal and plant sources, including those derived from soybean, zein, Pacific hake, algae, and smooth hound muscle. In our previous study, antioxidative peptides (1-4 ku) obtained from Scomberomorous niphonius skin (FractionⅡ) had a high antioxidant in cooked pork patties because it inhibited both lipid and protein oxidation and stabilized the quality during refrigerated storage. The purpose of the present study is to evaluate protective effects of the S. niphonius skin peptides(1-4 ku)against H₂O₂-induced oxidative stress in Caco-2 cells. There were five treatments in this experiment, including normal control (samples were not treated with H₂O₂ and antioxidant peptide), negative control, H₂O₂+Low-dose of FractionⅡ (10 μg/mL), H₂O₂+Middle-dose of FractionⅡ (50 μg/mL), H₂O₂+High-dose of FractionⅡ (100 μg/mL). The viability of cells, antioxidant enzymes activity including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), lactic dehydrogenase (LDH), and MDA content were determined. Further, the flow cytometry and fluorescence microscopy were also applied to detect the cell apoptosis. The result showed that the contents of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) levels were significantly increased compared with negative control group, while the lactic dehydrogenase (LDH) and MDA contents was sharply decreased treated by middle and high dose of FractionⅡ. Treatment with high dose FractionⅡ(100 μg/mL) could increase the cell viability rate to 47.10%, increase SOD, GSH-Px and CAT activity to 45.50 U/mg protein, 35.10 U/mg protein and 34.13 U/mg protein respectively, and decrease the levels of LDH activity and MDA content to 20.93 U/mg protein and 20.77 nmol/mg protein. Moreover, the flow cytometric analysis and fluorescence microscopy observation confirmed that a certain amount of FractionⅡ have a more effective role in decreasing cells apoptosis caused by oxidative stress. These results demonstrated that preincubated Caco-2 cells with antioxidant peptide (S. niphonius skin hydrolysates) resulted in a significant protection against the toxicity caused by H₂O₂.

Abstract:Skin was the first barrier to protect fish body from the out-environment, and was the main carrier of the body color. For lack of fish skin cell lines, investigation on skin function and color regulatory mechanism reached a plateau. In this paper, Rhodeus sinensis was used to investigate the fish skin cell separation method, with modified enzyme digestion ways. Rhodeus were kept in bacteriostasis and fungistasis solution for about 8-24 hours. After digesting in the 0.25% Trypsin-EDTA for 3-5 min, Rhodeus were killed and stroked off the scales. Peeled fish skin, and removed muscle or other tissue which jointed to the skin in stereo microscope. Then skin was digested by collagenase IV and trypsin jointed digestion method. Later, Rhodeus Skin Derived Cells, RSDCs for short, were collected and cultured at 28℃, 5% CO₂. The growth curve was drawn by hemacytometer counting method. The expression of epithelial markers, Keratin 18 & Vinculin A, and endothelial label gene, collagen I, were tested by RT-PCR method at F₀, F₅ and F₁₀ generation. RSDCs lines were obtained and cultured well with doubling time of 30 h and "S"-growth-curve, which was familiar with the other adherent cells. The RT-PCR results revealed that the expression of Keratin 18 and Vinculin A declined along with cell passage cultivation, while the expression of Collagen I was on the rise. Our researches indicated that modified enzyme digestion method should be ideal method to obtain fish skin cell. The obtained RSDCs growth curve was typical adherent cells "S" type. And the obtained RSDCs were derived from epithelium (ectoderm) and endothelium (mesenchyme). Meanwhile, along with passage cultivation, the proportion of epithelium declined.

Abstract:Thie paper aims to study the activity and mechanism of synthetic Ruditapes philippinarum oligopeptides(RPO) against prostate cancer DU-145 cells. After being incubated with RPO, DU-145 cells' apoptosis rate, changes in mitochondrial membrane potential, cytochrome C expression, changes of caspase3 and caspase9, cell ultrastructure changes were observed with flow cytometry, laser confocal microscope, Western blotting and electron microscope. The results showed that the factor to induce apoptosis of DU-145 cells is concentration and time dependent, when the RPO concentration was 2.5 mg/mL, the DU-145 cells inhibition rate was 49.9%±4.1% for 24 hours, 97.2%±7.3% for 72 hours. Those DU-145cells incubated with RPO were found to exhibit typical characteristics of apoptosis, such as nucleus psychosis, condensed chromatin, and nucleus fragmentation. The apoptosis rate of DU-145 cells rose as the concentration of RPO increased. Western blotting demonstrated that RPO increased the protein levels of Bax, caspase-3, caspase-9, Cyt-C and reduced the protein expression of Bcl-2. RPO can inhibit the proliferation and induce apoptosis of DU-145 cells possibly by up-regulating expression of Bax, down-regulating the expression of Bcl-2, reducing the Bcl-2/Bax ratio, inducing decline of mitochondrial membrane potential, promoting Cyt-C transfer and stimulating the caspase family cascade reaction.

Abstract:In order to explore the effects of inkjetting and stripping on hatching and larval growth of fertilized eggs of Sepia pharaonis, inkjetting and normal eggs hatching rate, incubation periods, hatching periods, and the weight of hatchling cuttlefish were compared by single factor experiment, and comparisons of survival rate and larval growth of four kinds of eggs (inkjetting and peeled eggs, normal and unpeeled eggs, inkjetting and unpeeled eggs, normal and peeled eggs) were also performed. The results showed:the hatching rates of inkjetting eggs and normal eggs of S. pharaonis showed no significant differences, and the hatching rates of inkjetting eggs and normal eggs was 90.1%±1.5% and 87.9%±0.7%, respectively. The statistical analyses of weights of hatchling cuttlefish between inkjetting eggs and normal eggs of S. pharaonis also showed no significant difference, and the mean weight of hatchling cuttlefish of inkjetting eggs and normal eggs were (0.18±0.01) g and (0.17±0.01) g, respectively. Both the incubation periods (d) and the hatching periods(d) between inkjetting eggs and normal eggs of S. pharaonis showed no significant difference, and the incubation periods (d) of inkjeting eggs and normal eggs were (34.67±0.89) d and (35.33±0.44) d, respectively, meanwhile the hatching periods(d) of inkjetting eggs and normal eggs were (14.33±0.44) d and (14.67±0.67) d, respectively. The survival rates of four kinds of eggs showed significant difference, and the survival rates of peeled inkjetting eggs and peeled normal eggs were obviously lower than those of the unpeeled inkjetting eggs and unpeeled normal eggs. However, the survival rates of cuttlefish between peeled inkjetting eggs and peeled normal eggs, unpeeled inkjetting eggs and unpeeled normal eggs all showed no significant difference. The diurnal growth rates of cuttlefish and the average diurnal gain weight of cuttlefish among four kinds of eggs showed significant difference. The diurnal growth rates of cuttlefish and the average diurnal gain weight of cuttlefish of peeled inkjetting eggs and peeled normal eggs were obviously lower than those of unpeeled inkjetting eggs and unpeeled normal eggs. But the diurnal growth rates of cuttlefish and the average diurnal gain weight of cuttlefish between peeled inkjetting eggs and peeled normal eggs, and between unpeeled inkjetting eggs and unpeeled normal eggs showed no significant difference.

Abstract:With the development of aquaculture, it is an important development direction of fishery engineering to design new types of fiber nets. Polyethylene is widely used in fishery because of its high strength, light weight and cost-effectiveness. However, there are also the problems such as easy to damage for ordinary polyethylene fiber net in aquaculture. Middle high molecular weight polyethylene (MHMWPE) monofilaments have greater molecular weight, higher strength and cost-effectiveness than high density polyethylene (HDPE), which can be prepared by melt-spinning and drawing process. To obtain better mechanical property, we should be willing to modify MHMWPE monofilaments. MHMWPE, isotactic polypropylene (iPP) and ethylene propylene diene monomer (EPDM) were melt blended to spin fishery monofilaments. The effect of the iPP and EPDM contents on the dynamic mechanical behavior and tensile strength of the blending monofilaments was studied by thermal property analysis, dynamic mechanical properties analysis and mechanical properties testing. Results showed that T_g was influenced neither by iPP content nor by EPDM content. The degree of crystallinity and the maximum of loss factor (tanδ_α) for MHMWPE decreased while the temperature of α-transition increased with the increase of iPP content. In addition, the degree of crystallinity decreased, α-transition moved to low temperature and the value of tanδ_α increased with the increase of EPDM content. The stretching strength and knot strength increased by increasing iPP content to a certain value. The toughness and knot strength of the fishery blending monofilaments were further raised by blending of EPDM.

Abstract:Salinity is one of the most important factors influencing distribution, abundance and the physiology of aquatic animals. Changes in ambient salinity are directly related to osmoregulation capacity. During acclimation to salinity, the main challenge for aquatic animals is to regulate their osmotic pressure to maintain normal life activities. As the predominant aquatic animal, crustaceans can dwell in seawater and fresh water due to their various osmoregulatory mechanisms. The two forms of osmoregulatory mechanisms are anisosmotic extracellular regulation (AER) and intracellular isosmotic regulation (IIR). AER can mainly control the osmolality of the body fluid through regulation of gills and antennal glands, while IIR maintains intracellular osmolality and maintain the balance between tissues and the hemolymph primarily by regulating amino acids (FAAs) especially non-essential amino acids (NEAA). Under excessive changes in environmental salinity, it's difficult for body fluid osmolality to be maintained at a completely stable level through AER. At that point, it's believed that IIR compensates for AER by accumulating or degrading some particular NEAA as osmolytes, effectivley moderating fluctuations in extracellular osmolality and facilitating volume readjustment. Hemolymph is directly involved in responding to salinity exposure and muscle is the major tissue for protein deposition and possibly represents the main pool of amino acids. Therefore muscle tissue and hemolymph are very important to study FAAs's involvement in osmotic pressure regulation.The experiment analyses the free amino acids content and concentration variation in muscle and hemolymph of Portunus trituberculatus at different salinities. Clarify the composition of FAAs and its function in the salinity adaptation.Enrich the FAAs in the field of salinity adaptation and provide the basis for further study of the molecular mechanism. The contents of FAAs were measured at salinities and the experiment lasted for 5 days.Determination of FAAs extraction solution of muscle and hemolymph with Hitachi 835-50 automatic amino acid analyzer.Results showed that the highest amounts of individual FAA in seawater-adapted P. trituberculatus was exhibited by Tauine, Arg, Gly, Pro and Ala. As salinity increased, the total free amino acids (TOFAA) of the hemolymph and muscle increased significantly. NEAA increased significantly when the salinity varied from 10 to 50 while Essential FAA (EAA) was not affected by external salinity change. The result showed that FAAs played an important role in salinity adaptation, especially Pro, Ala, Gly, Asp and Glu.Because Ala, Gly, Asp, Glu belong to the taste amino acids (TAA), so TAA played an important role in osmoregulation.The content of Pro increased significantly both in muscle and hemolymph, especially from 40 to 50 period. Therefore Pro played the most important role in hyperosmotic stress.

Abstract:The aim of this paper is to study swimming animal composition, dominant species, diversity, niche and community structure in Qixing Islands offshore area, according to taxonomy of ocean swimming animal, IRI formula, Primer, Excel, niche, ABC curve for swimming animal identification and data processing and analysis. The results showed that there are 80 swimming animal species belonging to 3 classes and 14 orders living in the investigated area, including 52 fishes, 13 shrimps, 10 crabs and 5 cephalopods, by the bottom trawl catches in autumn of 2014 and spring of 2015. There were 6 dominant species in autumn, and in spring the dominant species were 4. One common species is Portunus trituberculatus. In the two quarters, the species diversity index H', D, J' was at the middle level. The species of larger niche in the autumn was Polynemus sextarius (10.51), Parapenaeopsis harbwickii (9.47), Muraenesox cinereus (8.84) etc and in the spring was Loligobeka (8.93), Oratosquilla oratoria (8.51), Trichiurus lepturus (7.94) etc. Cluster analysis showed the species among 12 stations of two seasons can be divided into three groups.The result was consistent with the NMDS analysis. The ABC curve analysis showed that the W vaule was 0.052 in the autumn and -0.059 in the spring which were close to zero. The swimming animal community composition was based on fish, followed by shrimp and cephalopods at last. P. harbwickii, M. cinereus and O. oratoria etc., the low value nekon has the high niche and occupied a major competitive position.In the two quarters, the grouping of the species among 12 stations was not affected by the season, because the composition of species and marine environment had a certain degree of similarity in the group of stations. ABC curve analysis showed that the offshore area was in a state of intermediate interference.

Abstract:In this paper, red drum (Sciaenops ocellatus) in deep water aquaculture was used as the research object. By studying the main energy material and the change rule of the metabolite during swimming, the physical distribution model in Red Drum was constructed. Then, combined with the specific law of ocean currents to establish the theory of ocean fisheries location. The results showed that in the swimming of red drum, the blood glucose level was significantly increased, the muscle glycogen was reduced slightly, and the liver glycogen was decreased obviously. When the fish swimming closed to fatigue, the liver glycogen level was nearly exhausted. In the process of high speed swimming, the concentration of blood lactic acid and muscle lactic acid was increased obviously, which indicated that red drum swimming process was accompanied by two kinds of energy metabolism processes (anaerobic respiration and aerobic respiration). This study proposed that liver glycogen concentration was used as an important index to determine the swimming ability of fish, and physical distribution model of red drum swimming based on liver glycogen storage energy consumption was established. Finally, based on the physical distribution model of red drum and the law of ocean currents in aquaculture area, the paper put forward the calculation method of selecting maximum flow velocity in red drum aquaculture area. The research showed that the physical distribution model building method of fish swimming and demonstration method of ocean current selection in aquaculture area could provide a new way for the related research, and provide scientific reference for the ocean current selection of marine aquaculture model (deep water cage, shallow sea fence, ect.).