Abstract:Based on Chinese aquaculture (including species and species group) statistics and investigation data during 1950-2014, combined with the estimate on the feeding rate in aquaculture, the percentage of fishmeal and fish oil of compound aquafeed, the trophic level of all kinds of diet (compound aquafeed, trash fish/low-valued molluscs/live fish, natural diet, etc.), the characteristics and changes of species composition, biodiversity, non-fed rate and trophic level in Chinese aquaculture were analyzed. The results were as follows: Chinese aquaculture structure was relatively stable, just less changes during the past decades, and was distinctively characterized by species-rich diversity, dominant species concentration, multi-trophic levels, lower trophic level, high eco-efficiency and more yields. The details were: (1) A total of 439 species and varieties in Chinese aquaculture, including 296 aquaculture species and 143 varieties. Species composition significantly varied with regional differences, and fish were the absolutely dominant species in freshwater aquaculture, e.g. in 2014, the top 6 species (grass carp, silver carp, bighead carp, common carp, crucian carp and tilapia) yields accounted for 69.6% of total yields in freshwater aquaculture, followed by crustaceans, others, molluscs and algae. However, molluscs and algae were the dominant species in mariculture, e.g. the top 6 species (oyster, clam, scallop, kelp, mussel and razor clam) yields accounted for 71.3% of total mariculture yields in 2014, followed by crustaceans, fish and others. (2) Biodiversity was characterized by species-rich diversity, high richness and evenness, not a paralleled aquaculture countries have been found in the world, meanwhile, Chinese aquaculture showed a better development trend. (3) The non-fed rate of Chinese aquaculture showed an obvious decreasing trend, and varied markedly during the different aquaculture development period. The higher non-fed rates were found before the 1990s, were about 96.7%-100%, which was mainly attributed to aquaculture model with natural diet. Meanwhile, with the aquaculture models from natural farm to feeding farm, the non-fed rate greatly decreased from 90.5% in 1995 to 53.8% in 2014 (35.7% for freshwater aquaculture and 83.0% for mariculture in 2014), which still remained the higher level when compared with the average non-fed rate of the other countries in the world. (4) The trophic level of Chinese aquaculture was lower and more stable (range from 2.12 to 2.33). There were three periods in the trophic level changes of Chinese aquaculture: the trophic level decreased from 2.33 to 2.12 during 1950-1980, then showed an increase-decrease- increase changing trend (range from 2.17-2.32) until 2005, and slightly decreased since 2005 for the popularization of compound aquafeed and the percentage decrease of fishmeal and fish oil of compound aquafeed, e.g. the trophic level was 2.32 in 2005, and decreased to 2.25 (2.35 for freshwater aquaculture and 2.10 for mariculture) in 2014. The trophic level pyramid of Chinese aquaculture was composed of 4 levels, and dominated by trophic level 2 (accounted for 70% of total yields in recent years), which means the more yields in Chinese aquaculture ecosystem. In the future, the development of Chinese aquaculture orientates by green, sustainable and environment-friendly development concept, develop the new aquaculture model with suitable and different characteristics, combine with the ecosystem-based aquaculture management based on carrying capacity, and finally realize the environment-friendly aquaculture. Chinese aquaculture is destined to greatly contribute the national food security and ecological civilization construction.

Abstract:Kimura early development of the whole process was investigated. According to the exterior appearance and typical characteristics of the embryo, the process of embryonic development was defined into 25 minor periods and described in detail. The result showed that the total accumulated temperature was 228.31℃·d at an average water temperature 10.2℃ from fertilization to hatching, the fertilized eggs hatching lasted 549 h. The mean total length of newly hatched larvae was (11.62±1.00) mm, the mean body weight of larvae was (0.0254±0.0016) g, the yolk sac volume of larvae was (53.82±1.03) mm³. Primordia dorsal, anal primordia, pelvic primordia, adipose fin primordia appeared respectively on days 2, 4, 9, and 11. The first chamber air bladder was formed on 17 d. Larvae began into the mixing vegetative stage on 18 d. First scales appeared in the larva of abdomen, entered into juvenile stage on 20 d. The yolk sac was completely absorbed, juvenile completely exogenous nutrition on 26 d. All fins completed development on 52 d. Stripes appeared completed development on the body surface on 64 d. The scales fully distributed the body on 73 d, entered the young period. Growth model equations fish larvae period is: TL=0.3766: days of age), the specific growth rate was 0.030. This study aims to provide scientific guidance for the Sichuan taimen artificial breeding and fry cultivation.

Abstract:In our previous study, we compared the transcriptome between Antarctic fish and temperate fish and found that genes were involved in reactive oxygen species (ROS) scavenge and Mitogen-activated protein kinase (MAPK) pathway associated with the cold adaptation in fish. To further study the regulatory network and the reactive oxygen species (ROS) homeostasis under cold stress in fish, we examined the level of ROS and the expression of stress-related proteins in zebrafish-derived ZF4 cells exposed to mildly and severely cold temperatures, 18℃ and 10℃, at various time points (1 d, 3 d, and 5 d). Results showed that (1) DCFH-DA probe method was used to determine the level of ROS in cells. We found that the level of ROS in cell positively correlated with the intensity of cold stress. After 3 days of cold treatment, the level of ROS in cells significantly increased to 1.23±0.04 (0.05) times, respectively, at 18℃ and 10℃, compared with that in cells at 28℃. (2) Western blot showed that the expression of MAPKs (p-JNK p54, p-JNK p46 and p-p38) was induced under cold stress, and reached the highest at 3 d of 10℃. (3) In addition, the expression of γH2A.X reached peak after 3 days both at 18℃ and 10℃. These findings showed that cold temperature could induce the production of ROS in ZF4 cells. The level of ROS in ZF4 cells is dependent on the stress intensity and duration. We observed the markedly induction of ROS in the cells at the first 3 days of cold treatment, while the expression of p-JNK, p-p38, and γH2A.X was markedly induced at the 3 d, indicating that 3 d of cold treatment might be a key time point to determine the protein expression in ZF4 cells.

Abstract:Marine biodiversity is an important indicator of ecosystem health and the material basis for the development and utilization of marine biological resources. Shandong coastal waters are the main breeding grounds for Bohai and Yellow Sea fisheries resources. These waters provide a wealth of biological resources and a superior fisheries habitat for China, Japan, South Korea, and North Korea. However, the Shandong offshore fisheries resources have been trending downward in recent years, and species abundance and diversity have decreased. Therefore, identifying and classifying the fish species in these coastal waters are urgently required to effectively protect and use these resources. In this study, 229 DNA sequences of the cytochrome oxidase subunit I (I) gene from 77 common marine fish species in 13 orders, 50 families, and 73 genera from offshore of Shandong were analyzed to test the efficacy of species identification using a DNA barcode microarray. The results showed that interspecific genetic distance was larger than intraspecific distance. All 77 sequences formed species units in a neighbor-joining dendrogram, indicating that DNA barcodes can be used to identify these 77 species. Sixty-four specific probes were screened to identify the corresponding species among the 77 species based on the I genes and accounted for 83.1%. Thus, the DNA barcode microarray provided technical support and a new way to identify fish species in the coastal waters offshore of Shandong.

Abstract:At normal situation, algae maintain a balance between reactive oxygen species (ROS) production and scavenging states, and a little amount of ROS molecules can be used as intracellular signal transduction molecules involved in biochemical metabolic processes. But under abiotic stress conditions, excessive accumulation of ROS will cause oxidative damage to cell membrane, then resulting in irreparable loss of metabolic function and eventually leading to cell death. Algae evolved a complex antioxidant defense mechanism (including non-enzymatic system of antioxidant enzymes and antioxidant enzymatic systems) to resist the damages of ROS. Glutathione peroxidase (GPX) is an important member of the ROS scavenging enzymatic system, which can clean the lipid peroxide and H₂O₂, its mechanism is to reduce ROS through catalytic the reactions between glutathione (GSH) and lipid peroxides (ROOH) or free H₂O₂, thereby blocking the production of free radicals, inhibiting the peroxidation processes of cells and protecting the enzyme activity of some sulfhydryl. Previous studies have concluded that the level of GPX activity has a positive correlation with the ability of plants to adapt to adversity. So GPX synthesis-related gene has been considered as an important stress resistance-related gene. , naturally growth in coastal intertidal zone, is an important economic macroalgae in Fujian, Zhejiang, Guangdong provinces. With tidal changes, the thallus required to undergo periodic dehydration and rehydration process, therefore it should has a very strong adaptability to adversity. Simultaneously, with global warming, the temperature of sea water increases, which causes damages to seedling of . As for the physiological and molecular response of to high temperature and dehydration stress conditions, our previous studies found GPX plays an important role in stress resistance. In this study, the full-length of was cloned by using rapid amplification of cDNA ends (RACE) technology, which named consists of 1027 bp, including an open reading frame (ORF) of 555 bp, which can be translate into a 184-amino-acid putative peptides with a molecular mass of 19.91 kD and a theoretical PI of 8.76. Multiple sequence alignment and Phylogenetic analysis indicated that the protein belong to the plant GPX enzyme family. Expression patterns analyzed by qPCR revealed that the expression of gene between the thallus phage and conchocelis phage was not significantly different; during high-temperature stress, the expression levels of significantly upregulated firstly and then decreased; However, during desiccation, the expression levels of had no significantly change when the water loss was ≤40%, but as the desiccation continue, the expression levels of were significantly downregulated. These results suggested that the expression of was induced by different stress at different levels.

Abstract:The vitellogenin receptor (VgR) plays an important role in oocyte maturation. VgRs have been studied extensively in various animals from vertebrates to invertebrates, including the chicken, Oreochromis aureus, insects, Macrobrachium rosenbergii and . The aims of this study were to identify and characterize the VgR from , to investigate its expression level during ovarian development, and to describe its interactions with Vg. The full-length cDNA was cloned using degenerated oligonucleotide primers and rapid amplification of cDNA ends technology. Quantitative real-time polymerase chain reaction analysis was used to quantify relative ovarian development. The results showed that the full-length was 5892 bp, containing an open reading frame of 5661 bp, encoding a 1886 amino acid polypeptide. The shrimp VgR contained several conserved domains, such as a ligand-binding domain, an epidermal growth factor-precursor domain, a transmembrane domain, and a cytoplasmic domain; thus, it belongs to the low-density lipoprotein receptor (LDLR) gene family. A phylogenetic analysis revealed that the shrimp VgR was more closely related to VgRs from other crustaceans and insects, rather than to vertebrate VgRs, and was distant from other LDLR members. The VgR was expressed in various tissues, and the highest expression was detected in the ovary. Ovarian mRNA expression level reached the maximum at stage III of ovarian development and was significantly positively correlated with Vg content in hemolymph and expression level in the hepatopancreas before ovarian maturation was completed. The relative Vg expression level in the hepatopancreas reached the maximum. Post-spawning Vg concentration remained high when ovarian expression level reached the maximum. These results indicate that all VgRs from crustaceans were orthologs of insect VgRs. Vg is synthesized rapidly in the hepatopancreas during maturation to supply a nutrient source for the developing ovary. The VgR sequesters Vg in the hemolymph into developing oocytes during ovarian development. Vg was synthesized within and outside the ovary and was transported into the ovary by VgR during the ovarian recovery stage for subsequent ovarian development.

Abstract:The Ras guanyl nucleotide-releasing protein-3() is a guanyl nucleotide exchange protein thatplays important roles in the occurrence of various diseases when differentially expressed. To explore the genetic composition, tissue expression, and immune response characteristics of cDNA was cloned using rapid-amplification of cDNA ends technology based on the partialtranscriptome data. Amino acid sequence alignment and homology analyses were performed based on the sequencing results. The full-length cDNA was 2756 bp, contained a 2244-bp-long open reading frame, and encoded a protein of 747 amino acids. The amino acid sequence ofwas highly homologous with those of other fish species. We applied quantitative real-time polymerase chain reaction (qRT-PCR) analysis to study the expression patterns of the -infected tissues at different time points with lipopolysaccharide, peptidoglycan (PGN), whole glucan particles, and polyinosinic: polycytidylic acid (poly I:C). The qRT-PCR results showed that . The expression level was highest in ovary, followed by liver, brain, and spleen, but low in blood. V. anguillarum-infected tissues. expression was up regulated 3- and 30-fold in liver and gill, respectively, at 6h compared with that at 0h. expression was downregulated in intestine, spleen, headkidney, and blood 6h after infection with RasGRP3 expression was upregulated after PGN and poly(I:C) stimulation. PGN up regulated expression 13-fold after 24 h compared with that at 0 h, and poly I:C up regulated expression eight-fold after 6 h compared with that at 0 h. These results indicate that the immune response and may play an important role in immune regulation.

Abstract:is the largest species of shrimp, with its high economic and natural nutritional value. However, during its breeding process, broodstock breeding technology has been a very important limiting factor. With the development of molecular biology techniques, there are growing concerns about the function of cell cycle genes of crustaceans, especially shrimp. Recently, molecular mechanisms of cell cycle regulatory proteins have been researched. In the study, cell cycle-related protein family genes relating to ovarian development also become a hot topic. Cyclin G2 is a newly discovered cell cycle-related protein that plays an important role during embryonic development, cell cycle progression and development, and disease. Cyclin G2 in some species have been cloned out, but the study of the gene has not been reported in the black tiger shrimp (, mature if the eye stalk is removed. Thus, the full-length cyclin G2 cDNA sequence from ) was cloned by means of rapid amplification of cDNA ends (RACE) approaches to better understand the potential function of cyclin G2 in the regulation of shrimp reproduction. The full-length cDNA sequence was 4075 bp and contained 189 bp 5′untranslated region (UTR) and a 2725 bp 3′UTR. The open reading frame was 1161 bp and coded 386 amino acids (aa) which was highly homology to other species cyclin G2. Bioinformatics analysis showed that the amino acid coding sequence had a conserved cyclin box and the homologous protein box structure domain was 50-150 aa. The predicted molecular weight was about 43.4 kD, and the theoretical isoelectric point was 8.25. The deduced amino acid of cyclin G2 contained 29 phosphorylation sites including 17 Ser, 7 Thr, and 5 Tyr residues. SignalP 4.0 analysis revealed that cyclin G2 did not contain a typical signal peptide sequence. The temporal expression of in different tissues (ovary, heart, intestine, hepatopancreas, brain, muscles, stomach and gills) and different developmental stages of ovary was investigated by Real-time quantitative polymerase chain reaction (QRT-PCR). The lowest expression level of was observed in the hepatopancreas, and the highest in the muscle. During the ovary development stages, was significantly high expressed in stage III ovaries than the other stages. The relative expression of in the ovary was up-regulation after 5-hydroxytryptamine (5-HT) injection, while down-regulation after dopamine (DA) challenge. The study obtained recombinant expression Pmcyclin G2 in prokaryotes and offered theoretical basis for further research on Pmcyclin G2 protein function. Those results offered additional information to understand the development mechanisms of ovaries.

Abstract:Corticotropin-releasing hormone (CRH) and its receptor (CRHR) play important roles in the hormonal response to stress by regulating the release of adrenocorticotropin (ACTH) from the hypothalamic-pituitary-in­terrenal axis and consequent secretion of glucocorticoids. In this report, CRHR1 cDNA was cloned by rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) analysis and characterized by bioinformatics analysis. The expression profile of in different tissues was analyzed by quantitative real-time PCR and changes in expression with stress were detected following a cortisol injection. Serum glucose, cortisol, and ACTH levels were monitored after the injection. The full-length CRHR1 mRNA contained a 1290-bp open reading frame and encoded 429 amino acids. The amino acid sequence alignment showed that Carassius auratus CRHR1. The tissue expression analysis revealed that was expressed at high levels in the pituitary and hypothalamus, but lower levels were detected in liver, kidney, muscle, skin, and heart. Serum glucose plateaued at 2-24 h, serum cortisol peaked at 12 h, and serum ACTH and mRNA expression in different tissues did not change after the cortisol injection. A significant decrease in pituitary CRHR1 expression was detected immediately after the cortisol injection, whereas it increased significantly in the head kidney and heart. The change in hypothalamic CRHR1 followed a unimodal pattern of increasing slowly at the early stage and then decreasing slowly at the end. In conclusion, we cloned the full-length CRHR1 mRNA and detected changes in CRHR1 expression after a cortisol injection.

Abstract:Corticotropin-releasing hormone (CRH) and its receptor (CRHR) play important roles in the hormonal response to stress by regulating the release of adrenocorticotropin (ACTH) from the hypothalamic-pituitary-in­terrenal axis and consequent secretion of glucocorticoids. In this report, CRHR1 cDNA was cloned by rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) analysis and characterized by bioinformatics analysis. The expression profile of in different tissues was analyzed by quantitative real-time PCR and changes in expression with stress were detected following a cortisol injection. Serum glucose, cortisol, and ACTH levels were monitored after the injection. The full-length CRHR1 mRNA contained a 1290-bp open reading frame and encoded 429 amino acids. The amino acid sequence alignment showed that Carassius auratus CRHR1. The tissue expression analysis revealed that was expressed at high levels in the pituitary and hypothalamus, but lower levels were detected in liver, kidney, muscle, skin, and heart. Serum glucose plateaued at 2-24 h, serum cortisol peaked at 12 h, and serum ACTH and mRNA expression in different tissues did not change after the cortisol injection. A significant decrease in pituitary CRHR1 expression was detected immediately after the cortisol injection, whereas it increased significantly in the head kidney and heart. The change in hypothalamic CRHR1 followed a unimodal pattern of increasing slowly at the early stage and then decreasing slowly at the end. In conclusion, we cloned the full-length CRHR1 mRNA and detected changes in CRHR1 expression after a cortisol injection.

Abstract:The white shrimp, (Decapoda, Penaeidae), isomnivorous, grows quickly, and has a low food nutrition demand, which has made it an economically important crustacean species in China. However, the single breed type and high-density culture can result in bacterial and viral disease outbreaks. is the dominant bacteria in shrimp and causes disease when shrimp are immunocompromised. In this study, (initial body length, 7.90 cm±1.15 cm; initial body weight, 7.20 g±1.38 g) were purchased from Qingdao Baorong Aquaculture Co., Ltd. A 3-week feeding experiment and a 2-week infection experiment were performed to evaluate the effects of adding the probiotic to feed on promoting intestinal bacteria, non-specific immune gene expression, and resistance to . The experimental shrimp were divided into control and experimental groups. Control group shrimp were fed commercial feed throughout the experiment, and the experimental group shrimp were fed the same feed supplemented with 1.0×10⁸ CFU/mL and total intestinal bacteria in were checked every 7 days using 22l6E and TCBS media. After 3 weeks of feeding, all shrimp were injected with 1.0×10⁷ CFU/mL (50 μL; dose determined in preliminary experiment).Then, 6 h, 12 h, 18 h, 24 h, 36 h, 48 h, and 72 h, as well as 7 d later, three shrimp from each group were captured randomly to extract RNA from the gill. The RNA was reversed transcribed into cDNA and tested for lysozyme and Toll receptor expression levels. The cumulative mortality rate of the control group was 100%, and the cumulative mortality rate of the experimental group was 22.78% after 14 days. The relative protection ratio was 22.22%. The experimental feed significantly reduced the number of P < 0.05). Relative lysozyme mRNA expression levels in the experimental group 12 h, 18 h, 24 h, 36 h, 48 h, and 72 h after the challenge were significantly higher than thosein the control group( < 0.05). Relative Toll receptor mRNA expression levels in the experimental group 6 h, 12 h, 18 h, 24 h, 36 h, 48 h, and 72 h, as well as 7 d after the challenge were significantly higher than those in the control group (to shrimp feed effectively improved the ability of infection, possibly by reducing the number of in the intestine and improving immune-related gene expression.

Abstract:In order to assess the effect of shell color selection of Pacific oyster () on feeding and respiration, two groups of the forth golden shell color line (G1, G2) and two groups of the normal culture group (C1, C2) were conducted in the experiment. Filtration rate (FR) and oxygen consumption rate (OCR) of 4 groups at different temperatures and salinities were observed. The results of feeding treatments showed that with the increase of temperature, FR began to rise reaching the maximum at 28℃, and then declined. C1 exhibited the maximum FR at salinity of 25 and other three groups exhibited the maximum FR at salinity of 30; Two-way ANOVA showed that temperature, group and salinity, group had a significant influence on FR of . Golden shell color line had significantly larger filtrate rate than the normal culture group ( < 0.05). The results of respiration treatments demonstrated that temperature, group and salinity, group had a significant effect on OCR of 4 groups ( < 0.05). The maximum OCR of G2 occurred at the temperature of 32℃, while other three groups occurred at the temperature of 28℃. OCR of G1 was significantly lower than C1, while OCR of G2 was significantly higher than C2 ( < 0.05). In the set salinity range, all groups exhibited the maximum OCR at salinity of 25; OCR of golden shell color line was significantly higher than the normal culture group ( < 0.05). Oyster of small size filter and consume oxygen more than oyster of large size. The present results indicated that selection for faster growth of golden color line might produce animals that had higher intake of energy by virtue of faster filtrating behavior, and a further selection could be likely meaningful.

Abstract:Oxygen consumption rates (ORs), ammonia excretion rates (NRs), and and oxygen/nitrogen (O/N) ratios of the Haida Golden scallop and Yesso scallop, , were measured seasonally from May 2012 to July 2013 under ambient conditions (5.6℃, 10.5℃, 14.4℃, and 21.2℃) using breathing bottles. The results showed that the variations in OR of and Haida Golden scallop were identical at water temperatures of 5.6-21.2℃. OR increased with temperature when water temperature was < 14.4℃ and decreased with temperature when temperature was > 14.4℃. Maximum ORs of and 1.27 mg/(g·h), respectively. The ORs of Haida Golden scallop were significantly lower than those of < 0.05) but not different at 10.5℃ and 21.2℃( and Haida Golden scallop differed. The NR of increased with temperature and peaked at 14.4℃ (0.063 mg·g^-1·h^-1) and then decreased. NR at 14.4℃ was higher than those at 10.5℃ and 21.2℃( < 0.05). The NR of Haida Golden scallop decreased from 5.6℃ to 10.5℃ and reached the minimum value at 10.5℃[0.029 mg/(g·h)] but then increased with temperature and peaked at 21.2℃. The NR of Haida Golden scallop was higher than those of at14.4℃( > 0.05). The of OR decreased with temperature. The O/N ratio showed that lipids and carbohydrates were the main Haida Golden scallop consumed protein at low temperature, switched to lipid and carbohydrates when the temperature increased, but switched back to protein when the temperature was highest.

Abstract:Morphological variations in , and their reciprocal hybrids were measured and analyzed. The results showed that the ratios of left eye type in the obverse hybrid (K. bicoloratus♀×♂) were 66.9% and 57.3%, respectively, which was between that of (0). The scales on the reciprocal hybrids were distributed similarly to those on and on the equivalent body positions where bony plates occurred on . The reciprocal hybrids had dorsal, anal, and caudal finstripes similar to those of , but they were smaller and more lightly colored. The lateral lines of the obverse hybrid and bent at the end of the pectoral fin, whereas the lateral lines of the inverse hybrid and were approximately linear. The average hybrid meristic character index values of the two hybrids were 20.73 and 20.76, indicating that their meristic characters tended to be more similar to those of their female parents, as shown by the chi-square analysis. Among 11 metric character ratios, most of the metric characters were not different ( > 0.05) between the hybrids and their female parents, and the average hybrid index values of the two hybrids were 27.16 and 26.47, indicating that their metric characters tended to be more similar to those of their female parents, as shown by the cluster analysis. Four discriminant functions were established in the discriminatory analysis. Average discriminant accuracy was 97.50%, indicating that the discriminant effect was ideal. Four principal components were constructed by factor loadings in the principal component analysis, and the cumulative contributing proportion was 82.562%. Scatter plots showed that the morphological differences between the two hybrids were independent of . Therefore, a multivariate analysis of meristic and metric characters could be useful to identify and distinguish the morphological variations among , and their reciprocal hybrids. These results indicate that the reciprocal hybrids between in eye position and scale and fin morphological characteristics and resembled their female parents in the lateral line and meristic and metric characters. The results will help discriminate the morphological characters and determine the genetic relationships between , and their reciprocal hybrids and allow for breeding excellent hybrids.

Abstract:The Kumamoto oyster () is an important wild oyster resource in Southeast Asia, including China, Japan and Korean. They are not only distributed naturally in China, but also live in abundance over a wide geographical distribution, ranging from Jiangsu to Guangxi, and Hainan Island. Traditionally, this species is a wild fishery resource; farmers capture these oysters from the reef or stone on the inter-tidal zone. Although the artificial breeding of this oyster was successfully conducted, but no relative information for genetic improvement was found. Selective breeding is the genetic manipulation of a cultured species for the purpose of improving specific traits of interest to humans. A variety of approaches have been taken in the study of the genetic breeding of mollusks, including Mendelian genetics, quantitative genetics, and cytogenetic and molecular genetic studies. However, not all of these approaches have contributed equally to the immediate development of genetically improved strains. Classically, population selection indicates the method of selection for the offspring bred by free mating among individuals with superior phenotypic traits in the majority from populations of original species according to the selective breeding objective via a comparison and appraisal between the original species and local species. Due to its simple operation and easy promotion, it has been widely used in the improvement of plant and animal species. Through continuous population selection, better cultivated species with rapid growth, strong stress resistance, high meat rate and high yield can be obtained. To improve the growth trait, response to selection and realized heritability for shell height was evaluated using the many radial rib line (Stock M: a number of ribs of left shell≥6) and the non-radial rib line (Stock N: a number of ribs of left shell=0) of the cultchless Kumamoto oyster in southern China. The shell height of Kumamoto oyster was considered to be a growth characteristic due to the positive association between shell height and yield. Truncation selection was conducted by selecting the largest 10% oyster from two stocks as parents for selected groups, while the equal number parents were randomly chosen as control groups before the removal of parents for truncation selection. Progeny from four groups were cultured the identical environmental conditions at larvae, spat and grow-out stage. Genetic index increased with oyster growth, strain M showed slightly higher response to selection and realized heritability than strain N during the whole history life. For strain M, response to selection and realized heritability were 0.33±0.04, 0.19±0.02 for larvae, 0.46±0.03, 0.26±0.02 for spat, and 0.63±0.11, 0.36±0.07 for grow out stage, respectively. The response to selection and realized heritability of Strain N were 0.30±0.04, 0.17±0.02 for larvae, 0.43±0.03, 0.25±0.02 for spat, and 0.58±0.10, 0.33±0.06 for growing out stage, respectively. At the end of 360 day, current genetic gain was 8.41% for Strain M, 7.71% for Strain N, respectively. The relatively high realized heritability has been obtained from the two strains, suggesting that there existed a degree of genetic variation between selective and control lines of this species. Our results clearly demonstrate that population selection can effectively improve growth trait and it is a promising way to Kumamoto oyster aquaculture.

Abstract:Based on the measured data of three important economic traits (body weight, body length and body height) of the hybrids F₁ of individuals at the ages of 0.3 months, 2 months, 7 months and 11 months, the growth rate and heterosis of the hybrids F₁ were analyzed and compared with , using the performance metrics of coefficient of variation, high-parent heterosis, relative and absolute growth rate, relationship curve of body weight and body height, and relative fatness. At age of 7 months, the mean body weight of the hybrids F₁ (300.4 g±118.2 g) was not significantly different with (305.2 g±82.5 g), while the mean monthly relative growth rate of body weight, body length and body height (280.13%, 25.30% and 27.55% ) of the hybrids F₁ were higher than that of (89.62%, 15.90% and 12.72%). The high-parent heterosis of the hybrids F₁ for body length at age of 0.3 months and 11 months was 2.48% and 0.91%, respectively. All growth rate curves of the hybrids F₁ were similar with their female parent (540.88 g±173.66 g) was significantly lower than (624.45 g±154.11 g) at age of 11 months. The coefficient of determination (0.992 and 0.995), condition factor (0.059 and 0.058) and allometric growth factor (2.722 and 2.740) for relationship curve of body weight and body height of the hybrids F₁and were almost identical. These results indicated that the primary growth trend of the hybrids F₁was similar to , the relationship curve of body weight and body height of the hybrids F₁ was consistent with that of , even though their overall growth rate was slightly slower than successfully inherited the fast growth trait from their female parent , with some high-parent heterosis in body length.

Abstract:Domesticated animals provide a unique opportunity to identify genomic targets for artificial selection to a captive environment. Nile tilapia () is a useful model species for studying the genetic basis of recent, ongoing domestication, as reared Nile tilapia strains have experienced intense artificial selection for only a short period of time. In this study, we screened 12 microsatellite loci from 11 independently reared strains (6 used for selective breeding and 5 for ranching) and their wild progenitor population of Nile tilapia to identify recent selection footprints related to domestication and selective breeding. -outlier tests were implemented using three different genetic software programs (LOSITAN, ARLEQUIN, and BAYESCAN) to identify loci under positive selection. All approaches assumed that directional selection increases genetic differentiation between populations and reduces variability at linked loci. However, because all of the tests are based on different assumptions, identifying outlier loci simultaneously using all approaches provides additional support for the candidate status of a particular locus. The LOSITAN program uses coalescent simulations to generate a neutral joint distribution of F_STheterozygosity ratios are candidates for having experienced selection. Coalescent simulations were performed us­ing 12 samples and a sample size of 30, assuming island and stepwise mutation models. The mean value was used with other values close to the mean to obtain half of the data points above and half of those below the median, as suggested in the software manual. The second method to detect selection footprints was based on the hierarchical island model and was implemented in ARLEQUIN software. Coalescent simulations were performed us­ing 12 samples and a sample size of 30, assuming a stepwise mutation model. R-project software was used to generate a neutral joint distribution of and het­erozygosity. The third method to detect selection footprints also identified loci that exhibit extreme differentiation compared with the remainder of the genome using the Bayesian likelihood method implemented via the reversible jump Markov chain Monte Carlo method. This approach was implemented in BayeScan software. was modeled using a logistic regression model and locus and population effects byrelaxing the assumption of the symmetrical island model and allowing for asymmetries in population structure. The estimates of the model parameters were automatically adjusted during short pilot runs (10 pilot runs with 5000 iterations each). We used a burn-in of 50, 000 iterations anda total chain length of 500000 iterations to identify loci under selection. BayeScan estimates the posterior probability that a locus is under selection by calculating the Bayes factor, which is given by the ratio of the posterior model probabilities of two models(selected/neutral), given the data. According to Jeffreys' interpretation, if the Bayes factor BF is > 10[lg(BF) > 1], “strong evidence” favors one model over the other and corresponds to a posterior probability > 0.91.The results showed that two loci (OMO043 and OMO114) provided significant evidence of positive artificial selection in four genetically improved NEW GIFT strain populations. Another two loci (OMO049 and OMO100) showed significant evidence of positive artificial selection in two selective breeding stocks produced by three companies. However, only one loci (OMO013) experienced positive artificial selection in five domesticated populations. The number of loci detected under selection in selective breeding populations was larger than that in domesticated populations. The loci detected under selection varied among the selective breeding and domesticated populations. These results indicate that the Nile tilapia genome has been affected by artificial selection in different directions.

Abstract:The Yangtze Estuary is the largest estuary in the Pacific West Bank and is an important spawning ground, feeding ground, wintering ground, and migration route for fish. has potential economic value, but few studies have been performed on this species. A feeding study is important to understand the biology and ecology of a fish species, as well as the fish community and entire ecosystem structure and function. Domestic and foreign scholars have conducted some studies on feeding of , but no study has been conducted in the Yangtze Estuary. The feeding habits of were investigated in 459 individuals collected bimonthly from the Yangtze Estuary (June 2014 to May 2015) by analyzing their stomach contents. The prey items included 12 groups and 37 prey species dominated by decapods. The prey groups included Mysidacea, fish, and crabs, and the advantage prey species were sp. The prey items were similar to those reported previously from Jiaozhou Bay, Bohai Sea, Laizhou Bay, and the Huanghe Delta; however, the advantage prey species were not the same. Thus, the habitat of the prey determined the dietary composition of . The dietary composition of prey consumed varied seasonally. Decapods were the most important group throughout the year, whereas mysidacea and crabs were predominant in spring, fish were predominant in summer, and mysidacea were eaten mostly during winter. The seasonal variation in prey items was closely related to the life cycle of the fish. Dietary composition also had clear ontogenetic variations; fish < 70 mm standard length (SL) consumed juvenile fish, mysidacea, and euphausiacea, those 70-189 mm SL consumed shrimp and fish, and those > 189 mm SL mainly consumed fish. The species and size of prey items were highly significantly different among body lengths. A cluster analysis for season employing the Euclidean distance index revealed one diet group in autumn, and another for spring, summer, and winter. The cluster analysis for ontogeny revealed a diet group < 70 mm SL and another group ≥ 70 mm SL. Feeding intensity also varied seasonally and during development. The Kruskal-Wallis nonparametric rank test and a contingency table revealed that the mean stomach fullness index of < 0.01). The percentage of empty stomachs did not differ among seasons ( > 0.05), but the mean stomach fullness index and percentage of empty stomachs varied during development ( < 0.01). The feeding intensity of fish was lower during winter than that during autumn, which may be related to the reduced number of prey and temperature. Feeding intensity was higher during summer than that during spring, which may be related to larger fish size. A strong positive correlation was found between body length of prey and that of < 0.01). Predation by increased gradually as mouth parts developed with growth. Moreover, mean prey weight and mean prey number increased with increasing body length, which is consistent with optimal foraging theory.

Abstract:Perfluorooctane sulfonate (PFOS) is a typical perfluorinated compound and a new environmental chemical pollutant found worldwide. PFOS is a potential threat to the environment and public health. Studies on PFOS pollution in China have focused on the aquatic environment and some aquatic marine organisms, but little attention has been given to wild populations of freshwater fish. The upper Yangtze River is inhabited by 112 endemic and several rare fish species. However, the effect of PFOS pollution on fish in this area remains unclear. Brass gudgeon (), the main commercial fish species in this area, was sampled at Baixi, Yibin, Luzhou, and Chongqing cities in April, September, and December 2013, respectively, to clarify the status of PFOS residues in fish inhabiting the upper Yangtze River. A total of 36 brass gudgeon individuals were sampled, and PFOS content in 98 tissue samples, including three different fish tissues, were detected by ultra-performance liquid chromatography-tandem mass spectrometry. A mean value of 2.72 ng/g PFOS (range, 0.33-10.14 ng/g) was detected in all fish samples. The highest mean PFOS concentration was found in liver (5.56 ng/g), followed by muscle (1.39 ng/g), and the lowest concentration was detected in gonad (0.62 ng/g). A highly significant difference in PFOS concentration was observed among different tissues ( < 0.01).These results are consistent with some previous studies on PFOS concentrations in wildlife; that is, PFOS concentrates more easily in the liver than other tissues, which may be explained by the high binding affinity of PFOS for liver fatty-acid proteins. In addition, muscle PFOS concentrations were significantly different among different river reaches (main effects ANOVA, < 0.05). The PFOS concentrations in all detected tissues increased significantly with increasing fish age (main effects ANOVA, ≤0.05), indicating that tissue PFOS concentrations may be related to food items or physiological parameters of different age groups of fish. The PFOS concentrations detected in brass gudgeon were lower compared with levels measured in species worldwide, indicating a relatively low level of PFOS pollution in fish species in the upper Yangtze River.

Abstract:The Chinese giant salamander () is an endangered amphibian in China and the largest salamander in the world. is endemic to rocky, fast-running mountain streams and lakes in China. The wild population is decreasing because of over-hunting and loss of habitat. This endemic species is currently listed in Annex I of CITES and Class II of the Protected Animals in China. Previous studies have reported that this species is carnivorous, and the larvae prey mainly on small aquatic animals, such as shrimp and aquatic insects, whereas adults prey on fish, frogs, and crabs. Macroinvertebrates are important groups in stream and river ecosystems. As most macroinvertebrates have a stationary life mode or a limited migration distance, the species and their numbers are important to access the environmental quality of a habitat. Thus, macroinvertebrate data are commonly used as water quality bioindicators. Field investigations were conducted during January 2013 and 2014 in five natural breeding caves (seven sampling sites) located in the Hunan Zhangjiajie Chinese Giant Salamander State Reserve. The objective was to use macroinvertebrates to assess the health of the habitat. A total of 117 macroinvertebrate taxa were identified in five phyla, eight classes, 16 orders, and 59 families during January 2013. Of them, 107 were aquatic insects, three were mollusks, two were crustaceans, and one each was Hirudinea, Turbellaria, and Nematoda. A mean of 27 macroinvertebrate taxa were collected over the 2 years of sampling. The maximum and minimum numbers collected were 33 and 15 in the water outlet of Qiyanquan Cave (S6) and the water outlet of Luozita Cave (S1), respectively. The density of macroinvertebrates ranged from 872.2 to 3511.1 ind/m² (average, 1747.6 ind/m²). Aquatic insects were the dominant group, and their relative abundance was 97.05%. Serratella sp., sp. were the most dominant taxa, and their relative abundances were 32.27%, 9.15%, 7.13%, 6.61%, 6.52%, and 5.45% of total density, respectively. The water quality bioassessment based on the Shannon-Wiener diversity and biotic index(BI) showed that S1, the water outlet of Wumuyu Cave (S3), and S6 had very good water quality, and that S1 and the water outlet of Bamaoxi Cave (S7) were slightly polluted. The dominant functional feeding groups were collectors-gatherers and predators, and all sites except S1 showed a -dominant macroinvertebrate curve. The macroinvertebrate population had been barely disturbed by humans compared with other sites. In conclusion, higher levels of macroinvertebrate biodiversity were found in most rivers near natural breeding caves during the larval outflow period in Zhangjiajie City, but food shortages were a risk for larvae in some rivers near natural breeding caves. These results suggest that the karst caves and macroinvertebrates should be protected.

Abstract:is an endemic fish in Xinjiang but the population is decreasing because of human activities and natural environmental changes. To understand the population genetic diversity and structureof, 143 specimens from seven populations in the Kumalake, Muzat, Taxkorgan, Karakax, Yurunkax, Kezilesu, and Qarqan Rivers were collected, the mitochondrial DNA control region was sequenced, and 39 haplotypes were detected. The Qarqan River population did not share haplotypes with any other population, and the FST tests were highly significant between the Qarqan and other populations. Analysis of molecular variance showed that most of the variation was apportioned among the populations, whereas the variation within populations was 81.01%, except that of the Qarqan population. Gene flow among populations varied from 0.0464 to 18.2786 and was < 1 between the Qarqan and other populations. A phylogenetic tree constructed using the Bayes method was consistent with the haplotype network, and the tree was divided into two clades. The most recent common ancestor of the two branches was 2.7 Ma. A mismatch analysis showed a bimodal distribution, indicating geographic isolation between the two branches generated by aridification and salinization of Lop Nor at 2.7 Ma, and Lop Nor subsequently recovered because of the cold and wet climate of the Tarim Basin. Secondary contact resulted in the present-day distribution pattern. The results of a population structural analysis suggested the presence of two distinct geographic populations, such as the Tarim River and Qarqan River populations. The former had high haplotype diversity (0.939±0.008) and nucleotide diversity (0.0125±0.0017), whereas the latter had higher haplotype diversity (0.903±0.025) and lower nucleotide diversity (0.0051±0.0012). These results suggest that different management strategies should be adopted for these two groups, and that the Tarim River population should be protected as a priority.

Abstract:An 8-year survey was conducted from 2006 to 2013 at 292 base stations using a bottom trawl to describe the autumnal distribution of cephalopods in the Yellow Sea. The cephalopod catch rate was used as a core quantitative index to analyze species composition, quantitative distribution, inter-annual variability of dominant species, and the spatial distribution pattern in the Yellow Sea. Fourteen cephalopod species, belonging to three orders, six families, and eight genera, were captured during the survey. The number of species captured per year varied (mean, 8±2), and the fewest were captured in 2009. Most of the species were temperate, a number of warm water species were captured, but no cold water species were collected, reflecting the faunal characteristics of a warm temperate zone. The dominant species were Sepioda birostrata, although a slight difference existed between different years. Notably, three new species were recorded from the Yellow Sea during this investigation: . These species were probably present because their habitat ranges may have increased in latitude based on their location, frequency, and quantity. The survey also found that squid and cuttlefish were dominant cephalopods during autumn in the Yellow Sea. The annual catch of different groups of cephalopods fluctuated, and the resource composition structure has changed in the past 10 years. The quantities of cephalopod resources in different regions of the Yellow Sea showed an increasing trend from north to south. Average catch rates in the northern, central, and southern parts of the Yellow Sea were 0.55 kg/h, 0.67 kg/h, and 0.98 kg/h, respectively. These results will provide a theoretical basis for conservation and sustainable utilization of Yellow Sea cephalopod populations.

Abstract:In order to protect the wild population and genetic resources of Chinese shrimp (), stock enhancement activities about Chinese shrimp had been carried out since 1980s in Haizhou Bay. Stock enhancement is an important way of fishery resources conservation, which can increase the high quality fishery resources and improve the fish population structure. However, scientific management of stock enhancement need to understand the carrying capacity of target species. Based on the data of biological resources obtained from an investigation of Haizhou Bay in 2013, a balanced trophic model of the area was constructed using the Ecopath with Ecosim software package. The effects of uncertainty of input parameters and Ecopath analysis sensitivity were explored. Trophic flow and system attributes of the Haizhou Bay ecosystem were analyzed. The ecological carrying capacity for Chinese shrimp were also predicted. The model consisted of 16 functional groups, which covered the main trophic flow in the Haizhou Bay ecosystem. The results showed that the pedigree index of the model was 0.588, indicated that the model input parameters were robust and reliable. The input parameters having the greatest effects on the output parameters were the ecotrophic efficiency (EE). Trophic levels of functional groups varied from 1-4.42. The total system throughput in ecosystem was estimated to be 9335.191 t·km^-2·a^-1, sum of all production was 3892.630 t·km^-2·a^-1, and sum of all consumption was 3838.019 t·km^-2·a^-1, total net system production was 822.042 t·km^-2·a^-1. The total energy transfer efficiency was 7.9%, transfer efficiency from primary producers and detritus was 6.6% and 9.4%, respectively. The proportion of the total flow originating from detritus was 40%, and that from primary producers was 60%, indicating that the energy flow was dominated by grazing food chain. The ratio of TPP/TR was 1.331, the connectivity index was 0.415, the omnivory index was 0.174, the Finn cycling index and the mean path length were 11.4% and 2.8 respectively. This study showed that the ecosystem of Haizhou Bay was still on a relatively low maturity and stability condition, and at a developing stage. The analysis on the keystone species showed that Chinese shrimp was not a keystone species of this ecosystem. The ecological carrying capacity was defined as the level of enhancement that could be introduced without significantly changing the major trophic fluxes or structure of the food web. At present, the biomass of Chinese shrimp in the ecosystem was 0.04 t·km^-2·a^-1, with a greater potential of continued enhancement. The ecological carrying capacity biomass of the Chinese shrimp was 0.846 t·km^-2·a^-1, meaning there is further potential for stock enhancement. Our results will contribute to manage the stock enhancement activities and be a good example for the carrying capacity research of other species.

Abstract:has high economic value and vast market prospects because of its nutritional and delicious flesh and appealing body color. This experiment investigated the effects of light color on growth, skin color, and physiological indices of juvenile in a recirculating aquaculture system (RAS). The trial employed a single factor design of four light colors (red, blue, dark, and day-night) to raise juvenile (body weight, 64.2 g±1.1 g) for 94 d. As a result, the weight gain rate of fish in the day-night group increased by 28.6% and 39.2% compared with that in the dark and red light groups ( < 0.01), but no difference was observed compared with the blue light group ( > 0.05). The weight gain rate in the blue light group increased by 31.2% compared with that in the red light group ( < 0.05). Skin carotene content of fish in the day-night group exceeded that in the blue and dark light groups by 45.7% and 68.5%, respectively ( < 0.05), but no difference was observed compared with the red light group ( < 0.05). Skin carotene and melanin contents of fish increased and decreased at the same time, but by different amounts in the four treatments. Therefore, we defined this phenomenon as “synchronous but different magnitude”. Pepsin activity of fish in the day-night group increased by 48.0%-88.5% ( < 0.05) compared with that in the other groups. Fish in the day-night group had better immunity, assuperoxide dismutase and lysozyme activities were significantly higher than those in the other groups ( < 0.01), whereas malondialdehyde level was lower than that in the dark and red groups (-ATPase activity increased by a mean of 78.1% in the day-night and red light groups ( < 0.01). Trypsin activity was significantly higher in the blue light group than that in the red and day-night light groups by 34.3% and 21.8%, respectively (P. leopardus under day-night light had better growth, skin color, and physiological performance than those held under the other conditions. Blue light improved protein digestive ability and growth, and red light increased carotene content and nutrition absorption by fish. The “synchronous but different magnitude” phenomenon helped regulate and optimize fish skin color. These results suggest that the light color juvenile are exposed to in a RAS should be considered to optimize growth and skin color.

Abstract:Pacific white shrimp, , is the most popular shrimp species cultured worldwide. Previous studies have indicated that high stocking densities negatively affect growth and survival rates, production, water quality, and immune parameters but promote disease outbreaks. Bacteria play a key role in organic contamination. However, little is known about the stress of stocking density on the rearing pond microbial community. Accordingly, the purpose of this investigation was to reveal the effect of shrimp stocking density on microbial community structure in intensive ponds as part of a recirculating aquaculture system. Water samples were collected from a high-density pond (200 ind/m²) and a low-density pond (133 ind/m²) every 15 days during the rearing period and filtered through 0.22-μm polycarbonate filters to collect bacterial cells. Environmental genomic DNA was extracted from the membrane filters. The microbial communities were profiled by high-throughput sequencing of the V4-V5 hypervariable region of 16S rRNA gene using the MiSeq Illumina sequencing platform. The results showed that 1264 operational taxonomic units (OTUs) were obtained via high-throughput sequencing and bioinformatics analyses. The mean number of bacterial OTUs was higher in the high-density pond (549.4) than that in the low-density pond (431.8). Clear differences in relative abundance among bacterial phyla were detected in different samples. Five phylogenetic subgroups were the most dominant in the entire bacterial community, including Proteobacteria, Cyanobacteria, Bacteroidetes, Actinobacteria, and Planctomycetes, accounting for > 98% of all OTUs. The mean Shannon-Wiener diversity index for the high-density pond (4.36) was higher than that for the low-density pond (3.51), and bacterial diversity increased gradually over timein both rearing ponds. This result suggests that new dominant bacterial populations appeared fromthe high nutrient input during the later rearing period, leading to higher bacterial diversity at a higher nutrient level. The relative abundance of Planctomycetes was significantly higher in the high-density pond ( < 0.01) during the initial rearing period than that in the low-density pond, which may have contributed to degradation of more residual feed in the high-density pond. The multidimensional scaling plot and cluster analysis demonstrated that all samples grouped into three clusters, indicating clear differences in the bacterial community structure between the high- and low-density ponds during the initial 50 days of rearing. However, the bacterial communities in the two ponds were more similarduringthe late stage compared with the marked differences during the initial stage, suggesting an initial stage (days 0-50) and a late stage (days 50-80), based on bacterial community structure. The effect of different stocking densities on the bacterial community decreased during the late stage.