Abstract:The growth of the phytoplankton greatly depends on the productivity of the water, and the changes in the water environment can directly determine the community structure of the phytoplankton. Therefore the community structure can serve as an indicator of the productivity and the environment of the water. The recent seawall closing the Funing Bay reclamation project (Fujian Province, China) may have caused lots of changes in the environment and the productivity of the water, however, the reports are lacking. In this study, we collected data about the phytoplankton in the Funing Bay in December of 2011 and in May and August of 2012, and analyzed the seasonal variations in the species composition, the dominant species, the biodiversity and the related factors. There were 149 species identified which belonged to 7 Phylum and 61 Genus. The Phylum including most species was Bacillariophyta followed by Pyrrophyta. The number of observed phytoplankton species was the largest in winter, and the second largest was in spring and followed by summer. There was an obvious seasonal variation in the dominant species. Skeletonema costatum, Cerataulina bergonii, Tribonema affine, Coscinodiscus jonesianus, and Rhizosolenia setigera were the dominant species in winter. In spring, Noctiluca scintillans, Ceratium trichoceros, Nitzschia lorenziana and Pleurosigma aestuarii were the dominant species. Cyclotella striata and Skeletonema costatum were the dominant species in summer. The abundance of the phytoplankton was 0.51×104−1298.73×104 ind/m3, and the average abundance was 137.90×104 ind/m3. The average diversity index was 1.988. The average evenness index was 0.473. The highest diversity index and evenness index were both observed in spring, followed by summer and winter. There was a positive correlation (P<0.05) between active phosphate and the biomass of phytoplankton in winter and summer, but the correlation was negative (P<0.05) in spring. There was also a highly positive correlation between the abundance of the phytoplankton and the chemical oxygen demand (P<0.01). These results suggested that after the seawall was closed, there had been obvious changes in the biomass and the community structure of the phytoplankton in the Funing Bay, and active phosphate was the limiting factor.

Abstract:According to the catch data of I. argentinus from Chinese squid jigging fishery in the Southwest Atlantic Ocean from January to May of 2003−2007 and the combination of sea surface temperature (SST) and sea surface height (SSH), fishing times-based Suitability Index (SI) Models were estimated by using the method of Data Envelopment Analysis. Using Arithmetic Mean Model (AMM) and Geometric Mean Model (GMM), the integrated habitat suitability index (HSI) was established based on SST and SSH. HSI values were compared with the actual catch and fishing times from January to May of 2003−2007. The results showed that both AMM and GMM were fitted well. When HSI is more than 0.6, AMM results indicated that the percentage of catch and fishing effort were 86.75% and 89.82% respectively, and GMM results revealed that the percentage of catch and fishing times were 84.30% and 85.80% respectively. AMM was slightly better than GMM to analyze the actual fishing data from 2003−2007. The HSI value in 2008 by AMM was further verified by the catch data. When HSI is bigger than 0.6, the percentage of catch and fishing times reached 64% and 68% respectively. Thus, AMM-based HSI model can be used to predict the real-time dynamic fishing ground of I. argentinus in the Southwest Atlantic Ocean, which would provide scientific guidance for its efficient exploitation.

Abstract:Anthocidaris crassispina, which possesses high pharmaceutical and nutritive value, is one of the most important fishery species in the southeast China Sea. Because of continued over-fishing, the population of A. crassispina has been decreased sharply in last several years. Thus, it is urgent to take some actions to improve this situation. In order to study the growth rate and survival state of juvenile A. crassispina, we designed several experimental facilities, and threw them in Dayawan Bay to simulate the natural growing environment in the sea from September 2013 to May 2014. The superficial area of specially made experimental facilities was 0.473 m2. The diameter of shells was between 3 mm and 9 mm, and the density was between 3 ind and 25 ind per experimental facility (6 ind/m2 and 52 ind/m2), while the weight range was between 1.48 g/m2 and 13.32 g/m2. Fourty-five experimental facilities of Juvenile A. crassispina had been divided into 15 groups according to 3 different diameter of shells and 5 various densities (each group has three parallel facilities). The result indicates that the diameter of shells and density affected the death rate significantly. The highest death rate was in the group of smallest diameter of shells and lowest density. At the early stage of the culture, there is a significant negative correlation between 3 growth rates, Growth rate of Shell Diameter (GSD), Special Growth Rate of Shell Diameter (SGR) and Net Yield of Shell Diameter (NY), with density in groups whose diameter of shells is 5−7 mm or 7−9 mm. Two months after the culture, these differences disappeared. There is also a significant difference in production between different weight ranges. The highest production is in the group of the weight of 10 g/m2. From November to March in the next year, the juvenile A. crassispina grew more slowly and the GSD was lower.

Abstract:Albacore (Thunnus alalunga) is an important economic fish species in the long-line tuna fisheries in western and central Pacific Ocean, and it is also one of the major species that the Chinese long-line fleets target in this area. To explore the spatio–temporal changes in the fishing grounds of albacore and provide guidance to the long-line fishery practice, we studied the relationship between the catch per unit effort (CPUE), the monthly catch and the sea surface temperature (SST), and analyzed the geographical changes in the fishing grounds using the frequentness accumulation method. The statistical analysis was based on the data collected from 10 albacore long-line fishing vessels of China National Fisheries Corporation (CNFC) from Feb. 2011 to Jan. 2012, combined with the environmental factors such as the SST. The results showed that in western and central Pacific Ocean, the temperature at the depth of 200 m and 150 m remained stable in a year but SST fluctuated dramatically and thus had great effects on the distribution of fishing grounds and CPUE. In a year (Feb. 2011 to Jan. 2012) the fishing ground moved periodically from 14S to 26S then back to 14S. To the north of 20S the fishing ground existed all year long, and the high catch and high CPUE were present in the area where SST was 28–29℃. To the south of 23S the fishing ground only existed from May to August because the adverse weather conditions in other months imperiled the fishing vessels, and the high catch and high CPUE were present in the area where SST was 22–24℃. In this time window the catch accounted for 27.6% of the yearly total catch while the fishing vessels worked for only 14.4% of the yearly total fishing days. Given the enhanced anti-wind and anti-wave features of fishing vessels and gears, a new sustainable fishing ground of albacore could be explored and exploited to the south of 25S.

Abstract:The half-smooth tongue sole (Cynoglossus semilaevis) is a mariculture fish species in China that has high economic values. The growth of this fish is sexually dimorphic, and females grow 23 times faster than males. The tongue sole exhibits the phenomenon of sex reversal during the growth and has a ZZ-ZW sex-determining system, thus it is a valuable animal model in the study of the mechanisms of fish sexual growth dimorphism. Several sex-specific genes have been cloned from half-smooth tongue sole, but the functions of these genes remain unknown. This research aimed to preliminarily study the function of the female-related gene CSW3. CSW3 was one of the female specific genes in half-smooth tongue sole which was identified from the screening in the whole genome sequencing project of half-smooth tongue sole. The full length of CSW3 cDNA was 1677 bp and contained a 414 bp open reading frame which coded 137 amino acids. The sequence also included a 173 bp 5 noncoding region and a 1090 bp 3 noncoding region that possessed a polyadenylation signal and a poly A tail. We constructed a recombinant expression vector for CSW3 and the plasmid was transformed into E. coli. IPTG was used to induce the expression of CSW3 protein. The proteins were isolated and purified with His-tag purification of affinity chromatography. The western-blot analysis showed that the recombinant protein was 33 kDa, which was consistent with the bioinformatics prediction. We then investigated the function of CSW3 protein using protein transfection. The liposomes encapsulating CSW3 protein were injected into the gonad of male half-smooth tongue sole. The experimental group was injected with bioactive CSW3 protein, and the control group was injected with heat-inactivated CSW3 protein. Real time quantitative PCR analysis showed that there were changes in the expression of three sex-related genes including one female-related gene and two male-related genes. The results suggested that the female specific CSW3 protein may cause the up-regulation of the female-related gene foxl2, and the down-regulation of the male-related genes sox9a and amh.

Abstract:Enzyme-linked immuno sorbent assay was used to measure the serum L-thyroxine (T4), 3,5,3'-triiodo-L-thyronine(T3), growth hormone (GH), and insulin-like growth factor-I (IGF-I) in Japanese flounder (Paralichthys olivaceus) of three ponds. The seasonal variations of body weight and body length were found in present study. Body weight and body length increased constantly as time grows, which were higher in late summer and early autumn compared with other seasons. The average weight of three aquaculture ponds were 1341.77 g, 1198.20 g and 958.93 g and the average length were 54.22 cm, 45.33 cm and 39.40 cm after cultivation for 12 months. The seasonal variations of serum T4, T3, GH and IGF-I were observed. The highest level of the serum T4 was in late summer and the peak of the serum T3 level appeared in early autumn. The highest GH level existed in early summer. The peak level of IGF-I appeared in early autumn. These results revealed the close relationship among the water temperature, body length and body weight growth rate and the serum level of T4 and T3 and T4/T3 increased rapidly, however the potential mechanism need further study.

Abstract:To study the effects of artificial farming conditions on the growth parameters such as the body length, body weight, growth index, and condition factor, the F1 hybrid of E. moara (♀)  E. septemfasciatus(♂) and its parents at 10 to 14 months old were used for the current study. The optimal growth equations of three groups based on the growth model were established. The results showed that the order of body length and body length growth index from high to low was E. moara (♀)  E. septemfasciatus(♂), E. moara, and E. septemfasciatus, and the hybrid F1 had obvious heterosis in body length. The order of cumulative growth of body weight among 10−11 months and 13 months from high to low was E. moara (♀)  E. septemfasciatus(♂), E. septemfasciatus, and E. moara. The order of body weight and body weight growth index from high to low was E. moara, E. septemfasciatus, and E. moara (♀)  E. septemfasciatus(♂). E. moara had the fastest increment in body weight, and had faster weight growth rate than others after 10 months. The best condition factor was observed in E. septemfasciatus among 10−14 months, and hybrid F1 was the second. E. moara had the lowest degree in the coefficient of variation and the heredity was stable. The current study indicated that the hybrid F1 grew fastest in body length among three groups and grew fastest in body weight before 11 months old, and that the growth of body weight of E. moara was faster than others after 11 months old. Hybrid F1 had a significant heterosis in growth among 14 months. The growth of E. moara was isometric and the growth of E. septemfasciatus was allometric.

Abstract:In the current study, 4022 individuals composed of 37 families at 4-month-old age were identified and counted based on haematoxylin-eosin staining of histology section of the gonads and macroscopic examination. The statistical analysis showed that the number of male and female were 2426 and 1596, respectively, which reflected a highly significant difference (P<0.01) in sex ratio to the hypothesis of a balanced sex ratio (50% males/50% females). At family level, there were 19 families among 37 families exhibited significant male-deviation from a balanced sex ratio (1:1) (P<0.05). Although the other 18 families showed no significant deviation (P>0.05), 13 of them were male-biased. The significant male-deviation in sex ratio has been confirmed in culture stock of turbot juvenile at 4 months age, which was observed in many families. Meanwhile, 2254 individuals composed of 20 families were randomly selected and weighted. The results demonstrated that no significant difference of body weight has been observed between female and male individuals within population and families for 4 months old juvenile fish, indicating that the selection of weight traits in juvenile stage in selective breeding project did not affect the sex ratio among selective breeding stock. Our study supplied useful information for the mechanism of turbot sex deviation and selective breeding project.

Abstract:Brood stock was collected from Israel strains red tilapia, GIFT strain of Nile tilapia (Oreo¬chromis niloticus), Blue tilapia (O. aureus), and Nile tilapia (O. niloticus) to form a base population of tilapia with broad genetic variation. Using artificial oriented mating, we obtained 15 full-sib families by inbreeding within the Israel strain red tilapia population and 65 full-sib families from crossing filial generation between Israel strain red tilapia and other tilapia populations. The subjects were tagged when the mean body weight in a family was 58 g. Forty tagged individuals were randomly selected from each family and cultured in sea water with the salinity gradually increased to 28. After 150 days we measured the body length and the body weight of the subjects, and estimated the crossbreeding and genetic parameters of tilapia. Offspring of Israel strains red tilapia and Egyptian strain of Nile tilapia (R×N) showed the highest growth rate. The average body length, the average body weight and the absolute growth rate (AGR) of the first selected generation of R×N were 24.44 cm, 385.23 g and 4.94 g/d respectively. ANOVA analysis showed that there were significant differences (P<0.05) in the body length and the body weight. The multiple comparisons of LSD test in the body length and the body weight indicated that R×N were significantly different (P<0.05) from other three intercross populations (A×R, R×A, and R×J) and the self-reproducing population (RT), except for J×R. Based on the data of 2496 subjects from 80 full-sib groups of tilapia, we estimated the heritability of the body weight. The model was composed of different factors including the average body weight in the tagged family (covariate), tanks and sex effects, etc. The estimated heritability of the body weight was medium (0.46±0.07). Our results suggested that there was a great potential in the genetic improvement of tilapia through the selective breeding. This should provide the theoretical guidance for the mariculture and breeding of salt-tolerant strains of tilapia.

Abstract:To investigate the optimal temperature and salinity for the Fenneropenaeus meiguiensisi, Central Composite Design (CCD) and Response Surface Method (RSM) were used to study the combined effects of temperature (16−35℃) and salinity (5−29) on the growth and survival of the F. meiguiensis, which will provide theoretical basis for the industrial culture of F. meiguiensis. The results showed that the linear and quadratic effects of temperature on the specific growth rate (SGR) and the survival rate (SR) of F. meiguiensis were significant (P<0.05). The linear effect of salinity on the SGR was not significant (P>0.05), but the effect on SR was significant (P<0.05). The quadratic effect of salinity on the SGR and SR were significant (P<0.01). The interactive effect of temperature and salinity on the SGR and SR of F. meiguiensis were not significant (P<0.05). Based on the response surface methodology analysis, a model equation about the relationship of the specific growth rate and survival rate to the two factors were established, which the R2 were 0.9014 and 0.9631, respectively, and the Adj. R2 were 0.8310 and 0.9367, respectively, suggesting that the model was satisfactory, and it could be practicably applied for predicting the variety of SGR and SR. Based on the established model, the SGR and SR reached the maximum (1.296%, 98.34%) at the 2-factor combination of 26.6℃/15.5, which had desirability value of 0.970. These results suggest that the optimization of temperature and salinity of F. meiguiensis were 26.6℃/15.5, which could offer theoretical reference for the production of the F. meiguiensis.

Abstract:Hag, a Flagellin coding gene, has conserved domains on the ends and a central domain that is highly variable in the length and the sequence, and hence has been used as a molecular marker in bacterial classification and identification. In this study, the hag gene was amplified from Bacillus firmus with the primer set Bhag, which was designed based on the conserved regions of the hag gene of B. subtilis and other bacteria. Two primer sets, Bfho and Bfhi, were designed based on the obtained sequence of hag of B. firmus and were used in the nested PCR for the species-specific detection of B. firmus. Furthermore we developed another specific detection method using fluorescent quantification PCR based on the inner primer set Bfhi, and tested the detection limit. Some simulated samples were tested with this FQ-PCR method and in the positive samples the concentrations of B. firmus were determined with the same method. The sequence of hag cloned from B. firmus had 1213 bp and was only 13%15% similar to that of B. subtilis according to NCBI BLAST, and most differences existed in the variable region. The detection limits of the FQ-PCR method were 17.3×103 CFU/ml and 19.7×103 CFU/ml for B. firmus strains PC004 and PC024 respectively. In 15 simulated samples, 7 were detected positive with the FQ-PCR method, and the concentrations of B. firmus in the samples were determined as well. The detection methods developed in our study have technical advantages such as high specificity, time-saving, and high sensitivity, and thus may become valuable tools in the practical application.

Abstract:Along with the rapid expansion of the culture of Portunus trituberculatus, various problems, such as diseases, larval degeneration, and natural resource depletion, have largely led to economic losses. Salinity is an osmotic pressure-related environmental and water quality factor which has great impact on the growth, the respiratory metabolism, the immune defense, and the survival of P. trituberculatus. In this study, we estimated the heritability of the body weight of P. trituberculatus with the intra-group correlation of full-sibs. A total of 400 mature crabs were taken from the culture, and 100 sires and 300 dams were mated in 1♂×3♀, and 9 half-sib families and 32 full-sib families were generated. We divided 450 individuals equally into 9 groups from each family at Ⅱ stage, and 270 individuals were divided equally into 9 groups from each family at the 80-day stage. The subjects were stressed under salinity 11 and then the survival rates were measured. Causal components of phenotypic variance were calculated with the GLM procedure of SPSS software. The heritability of Ⅱ stage and 80-day stage was 0.120.24 and 0.130.26 respectively. No significant difference was found in the heritability between the maternal and the paternal genetic variances. However, there was a significant difference in the components variance of full-sibs within sires and dams. The values from components of variance of full-sibs within sires and dams were 0.18 and 0.20 for Ⅱ stage and 80-day stage respectively, and they were precise and unbiased. These results suggested that the heritability of the tolerance to low salinity was low in P. trituberculatus.

Abstract:Portunus triuberbuculatus is an important economical species in China with fast development in the past decades. In recent years, the wild stocks of P. triuberbuculatus along the coast of China have suffered from the overfishing and environmental pollution. To investigate effects of the body color diversity of P. triuberbuculatus in resource conservation, 50 individuals were collected in March 2007 from four wild geographic populations distributed in the Yalujiang Estuary, Laizhou Gulf, Zhoushan, and Haizhou Gulf. Families were established by group hybridization. Discriminant analysis and One-Way ANOVA analysis were adopted during the analytical process. Cluster analysis and discriminant analysis were conducted on spots characters of P. trituberculatus from four populations. The results indicated that the total accuracy rate of discriminant on female crabs from four gulfs was 53.3%. The lowest accuracy rate of discriminant of 30.0% was observed in Laizhou Gulf population and the highest of 83.3% was in Haizhou gulf population. Results showed that carapace color and spots were significantly different among four populations. There was a tendency for the association between less carapace color and spots with the decrease in culturing in the same environment at four populations. These results supported that body color of P. triuberbuculatus is decided mainly by environment, and that genetic also is an impact factor.

Abstract:Fish meal is a major protein source in aquafeeds especially for carnivous fish species. Increasing demand, unstable supply and high price of fish meal with expansion of aquaculture made it necessary to search for alternative protein source. Fermented silkworm pupae is a compound protein of both silkworm pupae and some plant proteins and was a promising substitute for fish meal. To evaluate fermented silkworm pupae as an alternative for fish meal, a 56-day feeding trial in an in-door seawater recirculating system was conducted to investigate the effects of fishmeal replacement by fermented silkworm pupae (FSP) on growth performance, feed utilization blood physiology and enzymatic activities of juvenile turbot with initial average weight of (19.84±0.04 g). Six isonitrogenous and isocaloric practical diets were formulated to replace fishmeal at 0%, 15%, 30%, 45%, 60%, and 75% levels with FSP. Each diet was randomly fed to quadruplicate groups of fish. With the increasing FSP level, the specific growth rate (SGR) and feed efficiency (FE) decreased and was significantly different at over 30% replacement levels (P<0.05). Whole body protein and lipid content decreased with the increasing FSP substitution level, and was significantly different at 75% and 30% replacement level respectively (P<0.05). However, whole body moisture and ash content increased with the increasing fishmeal replacement level, and significant difference was shown at 75% and 30% replacement level respectively (P<0.05). ADC of dry matter (42.53%−54.36%) was significantly lower than the control at 75% replacement level (P<0.05); while ADC of protein (71.67%−86.89%) decreased significantly only when 45% or 75% fish meal was replaced by FSP (P<0.05). Hepatic SOD activity in all treatments was higher than the control and was significantly different at 45% and 60% replacement levels (P<0.05). Results of the present study indicated that FSP could replace 15% fish meal in the diets of juvenile turbot without compromising growth performance, feed utilization, blood parameters and enzymatic activities.

Abstract:In this study we conducted a 10-week feeding trial to evaluate the effects of dietary selenium on the growth, the physiological status and the body composition of Japanese seabass with initial average weight of (214.5±1.0) g. Six semi-purified diets were supplemented with NaSeO3•H2O and the concentrations of Se were 0.12, 0.36, 0.42, 0.60, 0.78 and 1.10 mg/kg．In seawater floating net cages (1.5 m×1.5 m×2 m), a group of 18 fish was fed with these six diets twice daily and every 3 fish had one type of diet. The survival rate and the feed efficiency were not significantly affected by the increased level of dietary Se (P>0.05). The weight gain and the whole body crude protein were the highest in Japanese seabass fed with 0.60 mg Se/kg (diet) (P<0.05). Hepatopancreas and the level of the whole body selenium were positively correlated to the dietary Se level. The activities of both serum and heaptopancreas glutathione peroxidases (GSH-Px) were increased along with the elevated dietary Se level, and peaked at 0.60 mg Se/kg (diet) (P<0.05). When the dietary Se increased to 0.78 mg/kg, the activity of the serum GSH-Px decreased significantly (P<0.05). The activities of both serum and hepatopancreas glutathione S-tramsferase (GST) initially decreased and then increased along with the elevated dietary Se level. The activity of serum GST was significantly higher in the 0.78 mg/kg group than in the 0.12 mg/kg group (P<0.05). The activity of serum glutathione reductase (GR) was also significantly affected by the dietary selenium level, and was significantly higher in the 0.78 mg/kg group than in the 0.12 mg/kg group (P<0.05). The activity of serum superoxide dismutase (SOD) increased along with the elevated dietary Se level up to 0.60 mg/kg, and then declined (P<0.05). The activity of serum SOD was significantly decreased in the 0.78 mg/kg group compared to the 0.12 mg/kg group (P<0.05). The level of malonaldehyde (MDA) was initially decreased and then increased along with the elevated dietary Se level. Japanese seabass in the 0.60 mg/kg group showed the lowest level of MDA, which was distinct from the control group and the 1.0 mg/kg group (P<0.05). These results indicated that 0.60 mg Se/kg (diet) might promote the growth and the anti-oxidative ability of Japanese seabass. Quadrate broken-line analysis with specific qrowth rate (SGR) showed that 0.63 mg Se/kg (diet) could be optimal for the growth of Japanese seabass.

Abstract:Tongue sole Cynoglossus semilaevis has high economic values and is extensively exploited in northern China. However, there have been few reports on the broodstock nutritional requirements of this species. In this study we investigated the effects of dietary taurine on the reproductive performance, the antioxidant function, and the egg and larval qualities of tongue sole C. semilaevis. Three experimental diets containing different levels of taurine (control T-0, T-0.5 and T-1.5%) were formulated and randomly distributed into three 3 m×2.5 m×1.2 m cement ponds with 15 females and 20 males in each for 9 weeks. Dietary taurine (0.5%) improved the relative fecundity and boosted the secretion of testosterone and estradiol in tongue sole broodstock (P<0.05). Moreover, compared to T-0, the T-0.5 diet significantly elevated the buoyant egg rate, the fertilization rate, the hatching rate, the egg diameter, the oil droplet diameter, and the larval length at 3 DPH and 7 DPH (P<0.05). The broodstock fed with the control (T-0) diet exhibited higher abnormal rate than the other two groups (P<0.05), and there was no significant difference in larval survival activity index (SAI) among the different dietary treatments (P>0.05). The concentrations of taurine in the liver and the gonad were increased and the activity of cysteamine dioxygenase was decreased along with the increase in dietary taurine. Compared to the control group, the activity of superoxide dismutase (SOD) in the liver, the serum, the testis, and the semen was also significantly higher in broodstock fed with T-0.5 diet (P<0.05), and the level of malondialdehyde (MDA) in the gonad and the eggs were significantly lower (P<0.05). In conclusion, these results suggested that dietary taurine may have considerable effects on the reproductive performance, the antioxidant function, and the egg and larval quality of C. semilaevis, and that the optimal concentration of taurine in the diet should be 0.5%.

Abstract:To study the impact of Bacillus subtilis on sea cucumber Apostichopus japonicus, the functions of the different densities of B. subtilis in the culture of sea cucumber were examined by focusing on various parameters, such as water quality, specific growth rate (SGR), activity of non-specific immune enzymes, and digestive enzymes. The results showed that B. subtilis significantly reduced the content of nitrate and nitrite in the culture water, and the highest removal rates of nitrate and nitrite were 42.28% and 22.33%, respectively. B. subtilis obviously improved the SGR of sea cucumber and the activity of non-specific immune enzymes. The density of B. subtilis did not impact on ammonia nitrogen and COD content in the culture water. At the density of 6×106, the SGR and the activity of amylase in sea cucumber tissues compared with the control group were increased by 40.74% and 30.27%, respectively. Additionally, the increasing value of the activity of peroxidase, alkaline phosphatase, lysozyme, and superoxide dismutase were 135%, 27%, 396%, and 192%, respectively. When the density of B. subtilis was 5×106, the activity of protease in sea cucumber was improved by 53.93%. These findings suggest that the appropriate density of B. subtilis in sea cucumber culture water not only improved the quality of water but also increased the activity of digestive enzymes and nonspecific immune enzymes, resulting in better growth of sea cucumber.

Abstract:The accumulation and elimination of heavy metals in shellfish are greatly affected by many factors including the type of the heavy metal, the size, tissue, and organ of the shellfish. External environmental factors are also involved such as the temperature, pH, and the concentrations of the heavy metal. Here we investigated the accumulation and elimination of two heavy metals (Pb and Cd) in Patinopecten yessoensis in a semi-static system. We measured the concentrations of Pb and Cd in different organs of P. yessoensis with different sizes. Using the two-compartment model with non-linear curve fitting, we obtained kinetic parameters such as bioconcentration factor (BCF), uptake rate constant (k1), elimination rate constant (k2) and biological half-life (B1/2). P. yessoensis had high capacity of the bioaccumulation and elimination of Cd and Pb. BCF for Pb in large-size scallops and small-size scallops were 1671 and 896 respectively, and the values for Cd were 7433 and 1123 respectively. This indicated that the size of P. yessoensis had impact on the accumulation of heavy metals, and that large-size scallops had higher capacity. Given the same size, BCF for Cd was higher than Pb, which implied a preference in the bioaccumulation of Cd. The accumulation of Pb in different organs showed the order gill> visceral mass> adductor muscle, and the order for Cd was visceral mass> gill> adductor muscle. The B1/2 for both Pb and Cd was higher in large-size P. yessoensis, which suggested that large-size scallops were more capable of eliminating Pb and Cd. The elimination rate of Cd in the visceral mass was the highest among the organs, and there was no difference between the gill and the adductor muscle. Our study provided insights into the toxic effects of heavy metals in shellfish.

Abstract:To determine the appropriate farming capacity and the density of sea cucumbers and Sargassum thunbergii in certain volume of water, we analyzed the growth of sea cucumbers and S. thunbergii and the changes in the condition of the water from April to May, 2014. The results showed that the mean daily weight gain rate (Mdwg) and the specific growth rate (SGR) of sea cucumbers and S. thunbergii were significantly affected by their densities (P<0.05). In the absence of S. thunbergii, sea cucumbers showed poor growth performance when the density was 750, 500 and 250 g/m3. The growth was much improved when the sea cucumber density was 250 g/m3 and the S. thunbergii density was 1000 g/m3 and 1500 g/m3 respectively. The highest SGR of S. thunbergii appeared when the densities of sea cucumbers and S. thunbergii were 750 g/m3 and 500 g/m3 respectively, and the lowest SGR of S. thunbergii appeared when the densities of sea cucumber and S. thunbergii were 250 g/m3 and 1500 g/m3 respectively. The levels of NH4+-N, NO3–-N, NO2–-N and PO4–-P were significantly affected by the density of sea cucumbers and S. thunbergii (P<0.05). The levels of NH4+-N, NO3–-N, NO2–-N and PO4–-P in the experimental group was relatively high when the sea cucumber densities were 750, 500 and 250 g/m3, and reached the highest when the density was 750 g/m3. The levels of NH4+-N, NO3–-N, NO2–-N and PO4–-P in the experimental group were relatively low when the sea cucumber density was 250 g/m3 and the S. thunbergii density was 1000 g/m3 and 1500 g/m3. In conclusion, the growth of sea cucumbers was significantly affected by the density of S. thunbergii, and S. thunbergii had high absorption capacity to the trophic factors in water. Under the experimental conditions, the appropriate density of sea cucumbers should be 250 g/m3 and the density of S. thunbergii should be 1000 g/m3 or 1500 g/m3.

Abstract:To investigate the pharmacokinetics of difloxacin in Scophthalmus maximus after intravenous and oral administration at 14−17℃ water temperature, several tissues and plasmas were collected at various time points to calculate the dosage regimen of difloxacin. Five fish were randomly selected from the tank and sampled at 15, 30 min and 1, 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h after intravenous and oral administration, respectively. The concentration of difloxacin was determined by the High Performance Liquid Chromatography. The data were analyzed with the pharmacokinetic program DAS 2.0. The results showed that the plasma concentration of difloxacin at each time point was best described as a two-compartment open model. The elimination half-life (t1/2β) was 30.02 h for intravenous administration, and the area under concentration-time curve (AUC0-t) was 440.37 h•μg/ml. The peak concentration (Cmax) by oral administration was 6.32 μg/ml at 4 h, and t1/2β was 94.72 h, and AUC0-t was 246.66 h•μg/ml. The concentration in muscle and kidney was higher than that in liver by oral administration. According to the difloxacin pharmacokinetics and the minimal inhibitory concentration of most fish bacterial pathogens, the recommended dosage of difloxacin was 11.94 mg/kg once per day by oral administration.

Abstract:In this study we used major aquatic products in china (Penaeus chinensis, turbot, carp, river eels, crabs and turtles) as the experimental materials to explore the simultaneous detection of multiple residues of chloramphenicol drugs [Chloramphenicol (CAP), Thiamphenicol (TAP), Florfenicol (FF) and its metabolites-Florfenicol amine (FFA)] in the muscle tissues of aquatic products, and the method of Gas chromatography-Mass spectrometry was established. Samples were extracted with ethyl acetate and ammonium hydroxide (v : v = 98 : 2), degreased with n-hexane, and further defatted with the Oasis MCX solid phase extraction cartridge. Then the samples were derivatized with the silanization reagent and negative chemical ionization (NCI). The selected ion monitoring mode (SIM) was applied in the experiments. The selected ions of the four drugs were as below: CAP m/z 376, 378, 466*, 468; TAP m/z 409*, 411, 499, 411; FF m/z 339*, 341, 429, 341; FFA m/z 209*, 194, 210, 194 (*quantitative ion). The matrix spiked calibration curve was established. There was a clear linear relationship in the ranges of 2−200 ng/ml for CAP and 5−200 ng/ml for TAP, FF and FFA, and the correlation coefficients were more than 0.990. The recovery was 75%−110%, and the relative standard deviation was 5.7%−13.9%. The detection limit was 0.2 μg/kg for CAP, and 1.0 μg/kg for TAP, FF and FFA. These results indicated that the GC/MS method could be accurate, efficient, sensitive and highly specific. Therefore it may satisfy the simultaneous determination of the four target compounds in aquatic products.