Abstract:Perinereis aibuhitensis Grube is an important feed for fish, shrimp, and crabs in the shores of China, and there have been extensive studies in biology, culturing technology and ecophysiology of this species. Although much less is known about their habitat environment, knowledge about this is important for us to better understand the biology of polychaete. In this experiment, we investigated various features of the sediments in different depths and tidal zones in a typical natural habitat of P. aibuhitensis, including hydrogen sulfide, organic matters, carbon, nitrogen, the moisture content, and the particle size. The results showed that the hydrogen sulfide concentration in the high tidal zone was significantly lower than those in the other two tidal zones (P<0.05). The hydrogen sulfide concentration was significantly higher in the depth of 25 cm than those in others (P<0.05). There was no difference in the hydrogen sulfide concentration and the moisture content of the pore water among three different tidal zones (P>0.05). There was also no difference in different depths (P>0.05). The contents of organic matters and nitrogen in the low tidal zone were significantly lower than those in the high and mid tidal zones (P<0.05). The levels of carbon were similar among different tidal zones (P>0.05). As the depth increased, the contents of organic matters and nitrogen in the sediment went up. The proportion of silt was the highest in all three tidal zones and in different depths of the same tidal zone, while the proportion of sand was the lowest. The median particle size in the low tide was higher than those in other two tidal zones (P<0.05). The median particle size remained unchanged in different depths (P>0.05). These results suggested that the hydrogen sulfide concentration was high in the sediment of the selected habitat of P. aibuhitensis. It became higher as the depth increased. There was a significant correlation between the contents of organic matters and carbon, and so were the contents of carbon and nitrogen. The dominant ingredient of the sediment was clayey silt. Compared to the low tidal zone, the high tidal zone had higher contents of organic matters and the moisture, which was probably caused by the smaller particles in this zone.

Abstract:American shad (Alosa sapidissima) is an abundant anadromous clupeid that is found along both coasts of the United States and part of South Canada. This fish species has high economical and ecological values. Because of its size, market demand and high economic value, the amount of American shad has quickly increased since it was introduced into China. At present, the species has become an important candidate for aquaculture. However, the study about the embryonic development of A. sapidissima is still lacking. Here we observed the morphological and histological characteristics of the embryonic development using microscope and paraffin sectioning. The results showed that at (21.0±0.5)℃, the hatching occurred at 71 h 15 min after fertilization. The embryogenesis of A. sapidissima was divided into six main stages. The longitudinal fissure was observed from the first to the fifth cleavage; after that the horizontal cleavage was visible at the sixth cleavage (64-cell stage); and then the blastoderm differentiated into the enveloping layer at periphery and the deep cells in the center. At 6 h 2 min after fertilization, the internal syncytium and external syncytium were visible at high stage. At 7 h 40 min, the blastocoel was obvious in the blastula stage. At 10 h 39 min, the embryonic shield formed at 30%-epiboly stage. At 14 h 50 min, the three germ layers differentiated at 50%-epiboly stage. At 17 h 33 min, the neural plate was formed at 75%-epiboly stage. At 21 h 13 min, the brain rudiment, optic capsule, notochord and somite formed at 90%-epiboly period. At 24 h 15 min, the neurula, otic vesicle, forebrain, midbrain and hindbrain were visible at 100%-epiboly period. At 24 h 55 min, Kupffer’s vesicle appeared. At 35 h 44 min, the heart and digestive tube appeared. Pronephric tubule was formed at 42 h 50 min, and Kupffer’s vesicle degenerated at 47 h 35 min after fertilization. The cornea was formed at 42 h 50 min after fertilization. A large number of larvae were spawned from the membrane at 70 h 15 min. The hatching larvae had a large and homogeneous yolk sac with pigment cluster. In conclusion, the embryonic development of A. sapidissima has a similar general pattern but different timing compared to other teleosts.

Abstract:Percocypris pingi is one of the endemic fishes in the upper reach of the Yangtze River and is one of the protected fish species in Sichuan Province. In this study, we investigated the ploidy and other cytogenetical characteristics of P. pingi. The karyotype of the renal tissue of P. pingi was examined using PHA injection with air-dry method. The C-band of P. pingi was displayed with modified BSG method. The results showed that the number of chromosomes of P. pingi was 98, and the formula could be expressed as 4n=98=42m+30sm＋10st＋16t, and the arm number (NF) was 170. Sixteen telocentric chromosome of P. pingi was found in this study although unreported in previous studies. Neither small chromosomes nor other heteromorphic chromosomes were found. All the karyotype had the size of the C-band appeared. The types of C-bands of P. pingi were diverse, including centromeric band, telomere band and intermediate band. Multiple C-bands were found in some chromosomes, for example, all types of C-bands were found in m2 and st4. The level of the heterochromatin was 58.824%±0.034%. We confirmed once again that P. pingi was a tetraploid fish. Its chromosomes were ‘plastic’ to some extent based on the karyotype and C-bands, indicating that P. pingi might be adaptable to specific habitats in different regions.

Abstract:Sablefish (Anoplopoma fimbria), also known as black cod, is a sleek, black-skinned and valuable cold water benthic fish species that lives in the north Pacific Ocean. They possess high content of unsaturated fatty acids. Sablefish have been cultured in British Columbia of Canada, and in recent years, they were introduced into the aquaculture industry in Shandong Province in north China. In this study, we reported the observation of furunculosis found in cultured sablefish in China. AF-1, a strain of bacterial pathogen was isolated from the diseased sablefish. Sablefish infected with this bacterium showed typical symptoms of furunculosis such as subcutaneous hemorrhage in the abdomen and the fin, abscess, ulcer and liver congestion. AF-1 was confirmed to be the pathogen of sablefish furunculosis through the artificial injection experiment, in which the injected fish showed the same symptoms. A series of methods including biochemical and biophysical tests and phylogenetic analysis of 16S rRNA and gyrB genes were used to identify the pathogen. The API ID32E results showed that AF-1 belonged to Aeromonas sp. The 16S rRNA and gyrB genes were amplified and sequenced, and the submission numbers were KU359246 and KU362567. Phylogenetic analysis of gene sequences showed that AF-1 was Aeromonas salmonicida. The chemotherapeutant sensitivity test showed that AF-1 was resistant to 13 antibiotics such as penicillin, amoxicillin and cephalothin, but was sensitive to another 16 antibiotics such as fumequine and florfenicol. According to the antibiotics sensitivity test result, florfenicol was added into diets to control furunculosis in sablefish. Our study indicated that A. salmonicida could infect cultured sablefish in our country, and provided information on the disease control in cultured sablefish.

Abstract:A strain of bacterial pathogen was isolated from eyeballs of cultured Centropristis striata with the symptoms such as white chaotic, hyperaemia and paraplasm in the eyeballs. The strain grew quickly in the TCBS culture medium, and the colonies were protruding, yellow, and tackiness. The strain named CJG01 was Gram-negative, bacillus and monotricha. The intramuscular injection experiment revealed that CJG01 was virulent to C. striata with LD50 value of 2.67×105 CFU/ml. CJG01 could cause symptoms including larval exophthalmos, eyeball fall off, muscle ulceration, and fishbone exposure. Anatomical observation showed liver inflammation, splenic organ enlargement, kidney inflammation and yellow liquid in the intestine. The results of API 20NE rapid identification and related physiological and biochemical experiments showed that the growth temperature for CJG01 was 28℃–37℃, and the optimum temperature was 28℃. CJG01 could grow in TSB culture medium with 0–5% salinity. It was sensitive to vibrio inhibitors O/129, was oxidase and ornithine decarboxylase positive, and was V-P negative. CJG01 could assimilate mannitol, maltose and malic acid, but not glucose, arabinose, mannose, decanoic acid, acetic acid, citric acid, benzene, etc. The strain shared similarities with Vibrio harveyi in biochemical and biophysical properties. Analysis of the 16S rDNA sequence and the phylogenetic tree suggested that CJG01 was highly similar to V. harveyi. Based on the results above, CJG01 was identified as V. harveyi. The chemotherapyeutant sensitivity test showed that CJG01 was insensitive to ampicillin, cephalosporins ammonia benzyl, cephalosporins, norfloxacin, penicillin, azithromycin, polymyxin B, etc. It was moderately sensitive to cefazolin, streptomycin, erythromycin, clarithromycin, etc. Novobiocin, neomycin, cefoperazone, ceftriaxone, gentamicin, cefoperazone, kanamycin, ofloxacin, ciprofloxacin, fleroxacin, furazolidone, rifampicin, ciprofloxacin, tetracycline, chloroamphenicol and minocycline could effectively inhibit the growth of CJG01.

Abstract:To characterize the traits of the cuttlebone of Sepia esculenta at the early developmental stages, we collected data at different stages including the red-bead and black-bead stage, the heart-beating stage, the hatching stage, the newly-hatched larvae stage, the 5-day-old stage and the 10-day-old stage. The principal component analysis was performed to evaluate seven growth traits including the dorsal mantle length, the mantle breadth, the body weight, the cuttlebone length, the cuttlebone breadth, the cuttlebone weight and the lamella number. The results showed that there were significant correlations between any two traits at the red-bead and black-bead stage, the hatching stage and the 10-day-old stage. However, some traits showed no correlation at the heart-beating stage, the newly-hatched larvae stage and the 5-day-old stage. The first principal component was the weight factor at the first two stages, and it became the length factor at other four stages. The second principal component was the length factor and width factor. The third principal component was mostly the width factor. At only two stages there was the fourth principal component that was the lamella factor and the width factor. The growth rate of these traits varied at different stages. From the red-bead and black-bead stage to the heart-beating stage, the morphometric traits outgrew the body weight, and this pattern was reversed from the hatching stage to the 10-day-old stage.

Abstract:Accumulation of macroalgae fouled on the net of marine cage during hot seasons is one of the major problems of the cage culture in Northern China. Biological clearance is an effective way to solve this problem. In this study, Siganus oramin was used as the potential “cleaner” fish to control the fouling macroalgae. From June to November in 2015, a series of laboratory experiments and field observations were carried out in the cage culture area around Chudao in the Sanggou Bay. We investigated the monthly variation of the biomass and diversity of fouling macroalgae in different layers, the feeding activity of S. oramin on the dominant specie of fouling macroalgae, and the cleaning effect of S. oramin on the fouling macroalgae. The results showed that in the same month, the growth rates of fouling macroalgae varied according to their layers; from 7th August to 14th September, the growth rate of fouling macroalgae was significantly higher than in other months in different layers (P<0.01). Plocamium telfairiae was the dominant species in this area. A carbon budget equation for the S. oramin feeding on Plocamium telfairiae (100C=11.69G+10.82F+6.06U+71.43R) was constructed under the appropriate seawater temperature. The initial average wet weight of S. oramin was (1.44±0.61) g and it reached (45.38±4.22) g after a 152-day cultural period; the growth rate was 0.26 g/d. The removal rate for fouling macroalgae varied between 80.28% and 90.15% in the cage culture area. These results suggested that the removal of fouling macroalgae was more efficient using this method and thus it could be used to control the fouling macroalgae on the net of marine cages.

Abstract:In order to study organism attachment on artificial reefs made of different cements, we hanged the artificial reefs constructed with five different cements including Composite Portland cement (P.C), slag Portland cement (P.S), pozzolana Portland cement (P.P), fly ash Portland cement (P.F) and aluminate cement (CA). The artificial reefs were exposed to the marine environment near the Xuejia Island in September 2015. In November 2015, we collected the first water samples to analyze different reef materials on organism attachment. We found that the biomass of fouling organisms on different artificial reefs followed the order P.P > P.S > CA > P.F > P.C, and the values were 888.29 g/m2, 755.43 g/m2, 752.07 g/m2, 620.11 g/m2 and 402.01 g/m2 respectively. The number of organism species on P.S was 7, and it was 5 on P.F, P.P and CA. We collected the second samples in March 2016 and found that CA still had the largest biomass that was 1956.94 g/m2, followed by P.P, P.F, P.C and P.S on which the biomass was 1601.44 g/m2, 1453.06 g/m2, 1254.63 g/m2 and 1072.43 g/m2 respectively. The number of species on P.F, CA, P.S, P.P and P.C was 17, 15, 12, 11 and 8. In the first sampling, the Pielou evenness index (J) followed the order CA > P.P > P.F > P.C > P.S; in the second sampling, the order was P.S > P.F > P.P > CA > P.C. In the first sampling, the Shannon-Wiener diversity index (H´) of fouling organisms followed the order CA > P.P > P.F > P.C > P.S; in the second sampling, the order was P.S > P.F > P.P > CA > P.C. Our study showed that the aluminate cement and fly ash cement artificial reefs were most suitable for organism attachment, whereas the composite Portland cement had poor biological adhesion capability.

Abstract:The microalga community in 6 industrial aquaculture ponds of Pacific white shrimp (Litopenaeus vannamei) was analyzed at Baorong Aquatic Science and Technology Limited Corporation in Qingdao from June to September in 2015. The composition of species, abundance, biodiversity and characteristics of dominant species succession were investigated and discussed based on the situation of shrimp culture. A total of 49 species of microalgae were identified that belonged to 28 genera and 5 phylums (including 14 dominant species). The population density of microalgae was 5.2×105–9.4×108 cell/L, the biomass was 1.23–208.00 mg/L, and the biodiversity index was 0.42–2.44. The stability of the ecosystem was weak and the shrimps were prone to outbreaks of diseases when the biodiversity index was below 0.9. The dominant species in the early stage of cultivation were green algae, diatoms and some species of dinoflagellates. Microcystis incerta and Oscillatoria willei belonging to Cyanophyta gradually became the dominant species in the middle to late stages. The culture density of shrimp had significant effects on the succession of microalga dominant species. The shrimp grew well in a stable community of microalgae where the culture density was 300 ind/m2 (pond A1) and the dominant species were mainly green algae and diatoms. The harmful Oscillatorias tended to become the dominant species in the middle to late stages as the culture density was 400–500 ind/m2 (in pond B1, C1 and C2), which easily led to the outbreak of shrimp diseases. Our study provided important information on the tuning of the environment of industrial aquaculture ponds.

Abstract:In order to study the biodiversity of microbial community structure and explore the water quality purification mechanism of bio-filter in the recirculating aquaculture system for Litopenaeus vannamei, microorganism samples were collected from 5 different positions which were the outer and inner surfaces of the upper part of nano-membrane, the outer and inner surfaces of the lower part of the nano-membrane, and the collecting tray. Microbial diversity, functional microorganisms and purifying capacity among different samples were analyzed according to molecular biological methods and 16S rRNA gene pyro sequencing. The results showed that 10 phyla were identified in 5 different positions, in which Proteobacteria was the dominant group. Nitrospirae was detected in the nano-membrane (4.3%), while with low abundance in the collecting tray (0.33%). Ammonia oxidizing bacteria and nitrite oxidizing bacteria in nano-membrane were the primary microorganisms to remove nitrogen and the proportions were 1.70% and 6.99%, respectively. There were 41 dominant species identified in total. Among which, Pedobacter was absolutely dominant, Parvularcula was the second dominant species, and both abundance ratios were above 10%. Nitrospira was the third dominant species, whose average abundance on membrane (4.31%) was significantly higher than that in the collecting tray (0.28%). Rich biodiversity of microorganism and stable microorganism ecosystem in the biological filter had a crucial role in buffering water quality. The analysis of effective biomass indicated that nitrification happened mostly in the upper part of the biological filter, and the nitrification effect was weakened in the lower part, while almost disappeared in the collecting tray. Therefore, in order to improve efficiency of nitrification, the hanging membrane density and length should be scientifically designed and rationally distributed.

Abstract:Aquaculture provides human beings with steady sources of high-quality proteins and has been an ever-growing industry thanks to the recirculating aquatic system (RAS). RAS allows aquaculture to be less dependent on natural resources. However, RAS is prone to the accumulation of hazardous substances such as flocculation, non-ionic ammonia and heavy metals, so the safety of produces raised in RAS needs to be carefully evaluated. In this study, we analyzed the safety and the distribution of eight heavy metals in Dicentrarchus labrax cultured in a closed RAS in Tianjin. The contents of arsenic, cadmium, chromium, copper, nickel, lead and zinc were measured with Inductively Coupled Plasma (ICP), and the level of mercury was measured with Atomic Fluorescence (AFS) during the three growth stages including juvenile, mid-term and adult. It was found that the distribution of heavy metals varied at different growth stages. In the muscle, the content of arsenic increased over time with the maximum value of 1.93 mg/kg. The contents of copper and mercury changed in an opposite pattern and the maximum values were 0.354 mg/kg and 0.021 mg/kg respectively. In the liver, the contents of arsenic, cadmium and copper increased over time with the maximum value of 1.47 mg/kg, 1.09 mg/kg and 143.00 mg/kg respectively. In the gill, the content of arsenic increased over time with the maximum value of 0.321 mg/kg. The contents of chromium, copper, arsenic and mercury first rose and then dropped, and the maximum values were 0.356 mg/kg, 45.8 mg/kg, 19.2 mg/kg and 0.0137 mg/kg respectively. The distribution of arsenic in different tissues followed the order of muscle>liver>gill; the distribution of cadmium, copper and zinc followed the order of liver>gill>muscle; mercury followed the order of muscle>liver>gill; and chromium followed the order of gill>liver>muscle. In general, the contents of all elements in the muscle complied with the national food safety standard (GB 2762-2012). All the samples were unpolluted according to the grading of heavy metal residues in fishes. Contents of all heavy metal elements were under the limits of the water quality standard for fisheries (GB 11607-89) except for Pb and Cd. In conclusion, the heavy metal contents in the tested RAS were in a safe range.

Abstract:The effects of illumination (5000 lx illumination and darkness) and size [shell length: (63.53±1.22) mm as “small” group, (75.87±1.50) mm as “medium”, and (92.75±3.02) mm as “large”] on the metabolism of dissolved oxygen, ammonia nitrogen and active phosphate in the giant clam Tridacna crocea were studied under laboratory conditions at 24–26℃. The results showed that under illumination, T. crocea released oxygen and absorbed ammonia nitrogen and active phosphate; the metabolism of T. crocea was similar to other bivalve mollusks in the dark. The metabolism rate of individual T. crocea was closely related to the size. Under illumination, the oxygen-production rate and the ammonia nitrogen/active phosphate absorption rate had a highly positive correlation with the size; in the dark, on the contrary, there was a negative correlation between the size and the oxygen production rate and the ammonia nitrogen/active phosphate absorption rate. Under illumination, the metabolic rate of symbiotic zooxanthellae (per gram of dry weight) of T. crocea was negatively correlated with the individual size. In this study, the metabolism of oxygen, ammonia nitrogen and active phosphate of T. crocea was quantitatively correlated with the size and light conditions for the first time. Our results provided basic information on the role of T. crocea in coral reef ecosystems and on the artificial breeding of giant clams.

Abstract:The probiotic has various beneficial effects on fish such as improvements in nutrition, immunity and balance of intestinal micro-ecology. The combination of multiple probiotics is thought to be even more beneficial than single probiotic. Lactobacillus, Bacillus and yeast are the most widely used probiotic species in aquaculture. The effects of lactobacillus combined with bacillus have been extensively studied, whereas little is known about the combined effects of bacillus and yeast. In this study we investigated the effects of the compound preparation fermented by bacillus and yeast on the growth performance, digestive enzyme activities and the nonspecific immune indices of Atlantic salmon (Salmo salar). Four hundred and twenty Atlantic salmons with an average body weight of (180±28) g were randomly designated into 4 groups including one control group and three test groups. In each group there were 3 replicates of 35 fish. The control group was fed with the basal diet and test groups were fed with basal diet complemented with 1%, 3% or 5% complex-probiotic-preparation (BSCP) for 42 days. Compared to the control group, there was a higher weight gain and a lower feed conversion ratio and mortality (P<0.05) in the test groups. The digestibility of protein rose along with the increase of BSCP. In the 5% group, there was a difference in protein digestibility (P<0.05) and a reduction in lipid digestibility (P<0.05). BSCP up-regulated the digestive enzyme activities in varied degrees, except that it down-regulated the liver lipase activity in the 5% group (P<0.05). The liver immune indices were improved in test groups, however in the serum, BSCP induced little change except for the decrease of SOD activity in the 3% and 5% groups (P<0.05). The results indicated that the BSCP could improve the growth performance of Atlantic salmon, enhance the activities of some digestive enzymes and protein digestibility, and promote the nonspecific immunity to some extent. The optimal dietary level of BSCP was determined to be 3%.

Abstract:An 8-week feeding trial was conducted to evaluate the effects of dietary skimmed krill meal (SKM) on the growth performance, serum biochemical parameters and non-specific immunity of juvenile spotted halibut (Verasper variegatus). The basal diet was formulated with fishmeal and SKM as the protein resource, and fish oil as the lipid resource. The control diet (R0) did not contain SKM, and 6 other diets were supplemented with SKM at 6.33% (R10, 10% replacement of the fishmeal protein. The same were as follows, 12.66%(R20), 18.99%(R30), 25.32%(R40), 31.66%(R50) and 63.31%(R100). These diets were then fed to seven groups of juvenile spotted halibut with initial weight of (60.11±0.13) g. Results showed that the specific growth rate, survival rate and feed efficiency of R10–R50 groups were not significantly different from those of R0 (P>0.05), but it displayed a decreasing trend from R30. The hepatosomatic index and viscerosomatic index of R10–R30 groups were not significantly different from those of R0 (P>0.05). The serum acid phosphatase in R10 and R20 was significantly higher than that in R0 (P<0.05). The serum acid phosphatase of R30 was not different from that of R0 (P>0.05). The serum alkaline phosphatase in R30–R100 groups was significantly higher than that in R0 (P<0.05). The serum SOD of R10 was not different from that of R0 (P>0.05). The liver acid phosphatase in R10 was significantly higher than that in R0 (P<0.05). The liver alkaline phosphatase of R30 and R40 was not significantly different from that of R0 (P>0.05). The liver SOD of R10–R40 groups was not significantly different from that of R0 (P>0.05). The serum total protein of R10–R50 groups was significantly higher than that of R0 (P<0.05). There was no difference in the viscerosomatic index and glutamate dehydrogenase among groups (P>0.05). The results above showed that 10%–30% of SKM replacement might have the same effects on the growth performance, feed efficiency ratio and non-specific immunity of juvenile spotted halibut.

Abstract:Heritability is the most basic parameter for estimation of selection effect, breeding value and comprehensive selection index. It is widely applied in the determination of the selection method and artificial breeding practice. In this study, the heritability of body length, body weight and the number of pallet were estimated in 9-month-old sea cucumber (Apostichopus japonicus), with the goal of providing heritability reference for breeding practice. A total of 29 mature sea cucumbers from five different populations were selected as parents. Six dams and twenty-three sires were mated by unbalanced nested design using artificial insemination. Each dam was mated with 2 to 5 sires, producing 6 half-sib families and 23 full-sib families. Full-sib families were reared separately under identical environmental conditions. Thirty to fifty individuals from each full-sib family were randomly selected for assessment of three economic traits: body length, body weight and the number of pallet in 9-month-old sea cucumber. The heritability of body length, weight and the number of pallet was compared statistically using GLM (General Linear Model) procedure of the SPSS software. The results indicated that the heritability of body length in full-sibs, maternal half-sibs and paternal half-sibs was estimated to be 0.86, 0.87 and 0.85, respectively. The heritability of body weight in full-sibs, maternal half-sibs and paternal half-sibs was estimated to be 0.46, 0.20 and 0.73, respectively. The heritability of the number of pallet in full-sibs, maternal half-sibs and paternal half-sibs was estimated to be 0.37, 0.43 and 0.32, respectively. Results obtained from t test showed that the heritability of body length and body weight in paternal half-sibs was significant (P<0.05), and the heritability of body length and body weight in full-sibs was highly significant (P<0.01). By contrast, the heritability of the number of papilla in full-sibs, maternal half-sibs and paternal half-sibs was not significant. The estimation of heritability of the three economic traits in the large-scale seeding program could provide theoretical basis and technical reference for future artificial breeding of A. japonicus.

Abstract:In this study, the diets for sea cucumbers (Apostichopus japonicus Selenka) were formulated with Enteromorpha prolifera, Ulva lactuca, soybean meal, glucose, scallop side, shell powder, vitamins premix and mineral premix, and processed in four ways using Brewer’s yeast and alkaline protease. The final products were 5 groups of experimental diets including the control group, the fermented group, the hydrolyzed group, the composite group and the fresh-group. Each diet was randomly given to 3 replicates of 30 sea cucumbers of which the average body weight was (1.92±0.02) g. The results were described as follows. E. prolifera-diets had significant different effects on the survival rate (SR), the weight gain rate (WGR), the specific growth rate (SGR) and the feed coefficient (FC) (P<0.05). The SR in the composite group and the fresh group was higher than that in the hydrolyzed group (P<0.05), but was not significantly different from other groups (P>0.05). The WGR in the fresh group was higher than that in other groups (P<0.05). The FC in the fresh group was lower than in all other groups except for the composite group. Over the feeding time, the intestinal amylase activity (AMS) showed an increasing-decreasing-stabilized pattern in the control group, the fermented group, the composite group and the fresh group; however, AMS had been constantly declining in the hydrolyzed group. The intestinal cellulase activity in the hydrolyzed group tended to decrease over time, and in other groups, it was higher than the initial values and had been fluctuating. Except for the hydrolyzed group, the trypsin activity in all other groups showed no significant change. E. prolifera-diets also affected the activities of acid phosphatase (ACP), alkaline phosphatase (AKP) and superoxide dismutase (SOD) in the coelomic fluid to different extents (P<0.05). ACP in the fresh group was the highest and was significantly higher than all other groups (P<0.05) except for the composite group (P>0.05). SOD in the composite group was the highest and was significantly higher than the hydrolyzed group and the fermented group. These results suggested that juvenile sea cucumbers could benefit from the diets of the composite group and the fresh group in terms of the growth performance, the intestinal digestion and immunity. Our study also provided information on solving the shortage in raw dietary materials for sea cucumbers and making good use of E.prolifera.

Abstract:In recent years, the fast development of sea cucumber (Apostichopus japonicus) farming overwhelmed the supply of algae powder as the feed. In this study, we investigated whether fermented soybean meal (FSBM) could be an effective replacement of algae powder. The algae powder and the mixture of fishmeal and algae powder (2∶15) were replaced with FSBM in this study. The growth performance and body composition were tested in A. japonicus with initial body weight of 17.7 g. In the 10-week feeding trial, nine isonitrogen experimental diets were formulated. D1 was the control group; D2–D5 were algae powder-replaced groups; and D6–D9 were mixture-replaced groups. Each diet was assigned randomly to three tanks each of which contained 30 sea cucumber juveniles. The results showed that: As the proportion of replacement of algae powder increased, the weight gain rate (WGR) and the specific growth rate (SGR) first increased and then decreased. D2 showed the highest WGR and SGR, which were significantly higher than those of D4 and D5 (P<0.05). As the proportion of replacement of the mixture increased, WGR and SGR decreased significantly (P<0.05). Replacement of algae powder caused decrease in the crude lipid, Gly, Met, and Cys, and it increased the contents of Phe and His; while replacement of mixture led to decrease in crude ash of the body wall and contents of Ser, Thr, Gly, Met, Lys, and His, and it increased the contents of Arg, Pro, Phe and Cys. Replacement of powder caused decrease in contents of Ca, Mg, Fe, Zn, Cu, Cr, Mn and Pb; Replacement of mixture led to decrease in contents of Ca, Mg, Zn, Cu, Cr and Pb, and it increased contents of Fe and Mn. Using WGR as the indictor, SAS REG analysis showed that the optimum proportion of replacement of algae powder with FSBM was 29.75%. NLIN analysis showed that the optimum replacement proportion of the mixture was 46.46%.

Abstract:The abuse of antimicrobial has raised more and more attention in recent years because of its severe harm on environments and human health caused by the drug residues. In this study, we investigated the effects of florfenicol on immune and antioxidant activities of the Exopalaemon carinicauda by measuring the concentration of HEM and the activities of ACP, AKP, T-SOD, CAT and T-AOC in the plasma of E. carinicauda in the presence of florfenicol at different concentrations. At 3 h, the HEM concentration of the samples treated with low/medium dose of florfenicol (10 or 20 mg/kg·BW) was significantly higher than that of the control group (P<0.05); from 3 h to 48 h, high dose of florfenicol (40 mg/kg·BW) had the same effect (P<0.05). At 3 h and 6 h, the ACP activity in the presence of low/medium dose of florfenicol was higher than that of the control group (P<0.05); from 3 h to 168 h, high dose of florfenicol reduced the ACP activity (P<0.05). In the presence of low/medium dose of florfenicol, the activity of AKP was higher than the control at 3 h (P<0.05), from 6 h to 48 h, however, it decreased to a lower level than the control (P<0.05). At the end of the three experiments described above, all the values of the experimental groups returned to the control level. When treated with low/medium dose of florfenicol, the activity of T-SOD was higher than the control and peaked at 6 h and 24 h; in the contrast, the T-SOD activity was lower than the control at 24 h and 48 h when treated with high dose of florfenicol (P<0.05). Regardless of the florfenicol concentration, the activity of CAT was higher than the control at 3 h and 6 h (P<0.05), but was lower than the control group from 12 h to 96 h (P<0.05), and then recovered to the control level at the end of the experiment. Florfenicol at all three concentrations caused a decrease in the T-AOC activity up to 96 h (P<0.05) in a dose-dependent manner. Our results suggested that these parameters discussed above could serve as potential biomarkers to evaluate the safe use of florfenicol in the culture of E. carinicauda.

Abstract:In this study, we investigated the effect of pathogenic Enterococcus faecalis challenge on the non-specific immunity-related gene expression of Exopalaemon carinicauda. The expression levels of prophenoloxidase (proPO), C-type lectin (CTL), superoxide dismutase (SOD), cathepsin D (Cat D) and cathepsin L (Cat L) in hemocytes and hepatopancreas were measured with quantitative real-time PCR at different sampling time points after healthy E. carinicauda were injected with 0.86% sterile saline (control) or pathogenic E. faecalis. Compared to the control group, after infected with E. faecalis, the relative expression levels of proPO gene in hemocytes and hepatopancreas both increased to the highest at 6 h (P<0.05), and then decreased gradually back to normal. The relative expression levels of CTL gene in hemocytes and hepatopancreas increased to the peak value at 12 h and 6 h respectively (P<0.05), and then decreased gradually. Although the relative expression levels of CTL gene in hemocytes decreased at 72 h, it was still significantly higher than the control (P<0.05). The relative expression levels of SOD gene in hemocytes and hepatopancreas both increased to the highest at 6 h and 3 h respectively (P<0.05), then decreased gradually back to normal at 72 h. The dynamic expression of Cat D gene in hemocytes and hepatopancreas was consistent, which was a significant decreased in the beginning followed by an increase. After the decrease of expression at 12 h, it was increased significantly again. The Cat L gene expression in hemocytes and hepatopancreas both decreased significantly at 6 h and 3 h respectively (P<0.05), then it increased to the highest and recovered to the control level at 72 h. The results indicated that pathogenic E. faecalis challenge affected the immune status of E. carinicauda probably by changing the immunity-related gene expression, and that proPO, CTL, SOD, Cat D and Cat L were all sensitive to E. faecalis infection.

Abstract:Desiccation is the main abiotic stress for Pyropia yezoensis. In this study we investigated the photosynthetic and antioxidant physiological responses of a wild P. yezoensis thallus to desiccation stress, including the optimal chlorophyll fluorescence quantum yields of photosystem Ⅱ (Fv/Fm), the contents of photosynthetic pigments [chlorophyll a (Chl a), carotenoid (Car), R-phycoerythrin (R-PE), R-phycocyanin (R-PC)], soluble proteins (SPs), malondialdehyde (MDA), and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). The results revealed that as the water loss increased, Fv/Fm decreased linearly and reached the lowest when the water loss was 60%; Fv/Fm returned to the normal level after the blades were rehydrated for 1 h. The contents of Chl a, Car, and SPs decreased gradually. The contents of R-PE and R-PC decreased when the water loss was <30% and then increased as the water loss was ≥30%. The change of phycobiliproteins/soluble proteins was similar to that of phycobiliproteins. This ratio increased to the control level when the water loss was 40% and was significantly higher than the control when the water loss was 80%. There was no significant difference in the content of MDA between the control and the blades when the water loss was ≤30%. The content of MDA increased significantly when the water loss was ≥40%. However, there was no significant difference between the blades when the water loss ranged from 40% to 80%. There was no significant change in the activities of SOD and CAT when the water loss was ≤20%. The activity of POD was significantly increased when the water loss was ≤20%. When the water loss increased to 30%, the activities of SOD, CAT and POD decreased significantly. There was no significant difference between the blades when the water loss ranged from 50% to 80%. The results above suggested that during the early stage of water loss, the antioxidant enzymes POD, CAT and SOD played key roles in scavenging the reactive oxygen species, which inhibited the yield of excessive MDA; as water loss increased, the water condition became disadvantageous for the antioxidant enzymes, and MDA was accumulated as a result. Based on the change of phycolibiprotein/SP, we speculated that the function of phycobiliproteins became more and more significant in protecting the blades against desiccation stress when the water loss was ≥30%, which could help with the rapid recovery of photosynthesis (Fv/Fm) during rehydration.

Abstract:Cadmium is among the most toxic metals in the aquatic environment. It particularly affects shellfish because the latter can accumulate large amounts of cadmium from the water. To reduce the potential risk on the health of public consumers, it is necessary to measure and monitor the level of cadmium in shellfish. Conventional analysis methods are usually time-consuming due to the prolonged sample digestion and pretreatments. A direct solid sampling technology without digestion treatment has been applied in the fast determination of cadmium concentration in agricultural produces such as grains and vegetables. Here, we tried to employ this method in the rapid measurement of cadmium concentration in shellfish. Solid sampling (SS) device was coupled with atomic fluorescence spectrometry (AFS), and the SS-AFS instrument was assembled with a tungsten coil trap (TCT) and porous carbon ETV. Meanwhile, electrothermal vaporization atomic fluorescence spectrometry (ETV-AFS) with a tungsten coil trap was optimized, and SS-ETV-AFS was established as a novel direct sampling method of detecting cadmium in shellfish. The results showed that a tungsten coil could work as a cadmium trap and eliminate most of the matrix interferences. Samples were homogenized and diluted with different acids, and 1% HNO3 was determined to be the optimal acid reagent. Under the optimized conditions, the fitting with both the standard addition method and the standard curve method showed good linearity with regression coefficient (R2) larger than 0.995. The relative standard deviation (RSD) of the standard addition method and the standard curve method were 6.5%–7.7% and 3.3%–8.6% respectively; the spiked recoveries of them were 96.4%–105.5% and 98.1%–110.6%; the limit of detection (LOD) were 0.6 pg and 3 pg. Moreover, the time elapsed (including sample pretreatments) was within 5 min. The standard addition method generated data with similar accuracy to those measured with graphite furnace atomic absorption spectrophotometry (GFAAS) or certified reference materials (CRMs) (P﹥0.05) . Therefore, the standard addition method could be suitable to the field analysis and monitoring of cadmium in shellfish.