Abstract:To study the impact of different aquaculture activities on the air-sea carbon dioxide flux (F), a cruise research was carried out in May, 2014 in Sanggou Bay, the most representative area of integrated multi-trophic aquaculture in northern China. During the study, the partial pressure (pCO2) of the surface sea water was measured using the pCO2 underway system (OceanPack, SubCtech Co., German). The CO2 flux of the Sanggou Bay was evaluated through following parameters. Twenty-four hours monitoring was set up and performed in the caging culture area, bivalves culture area and kelp culture areas. Furthermore, the in situ hydrodynamic, chemical, biological and culture conditions, the impact factor of the air-sea CO2 flux in Sanggou Bay in spring were discussed. The results showed that the pCO2 in cage culture areas was much higher than the other culture areas. The F value was (–1.02±0.83) mmol/(m2·d) in bivalves culture area, (–15.40±1.28) mmol/(m2·d)in kelp culture area, (–4.32±1.41) mmol/(m2·d) in bivalves-kelp culture area, and 8.14 mmol/(m2·d) in cage culture area. The continuous 24 h observation showed that the average values of pCO2 in kelp, bivalves and cage culture area were (320±14) μatm, (330±10) μatm, (413± 37) μatm, respectively. The results showed that the Chl-a value was one of the key factors for the air-sea carbon-dioxide flux F, with significant differences in F value among different culture areas. The F value was negative in the bivalves, kelp and bivalves-kelp multi-culture areas, which means these areas 'sank' or absorbed the atmospheric CO2. By contrast, F value in cage culture area was positive, which indicated that it was a 'source' or producer of the atmospheric CO2.

Abstract:Based on the survey data at the Yellow River estuary in June 2012, the characteristics of macrobenthos were analyzed using canonical correspondence analysis and other methods. Sixty-seven species of macrobenthos were identified, which belonged to 6 phylums and 53 families. Among them, 28 species were crustacea; 17 were arthropods; 16 were mollusca; 3 were echinodermata; 3 belonged to other benthic groups. There were three dominant species including Leucon sp., Heteromastus filiforms and Glycinde gurjanovae. The average biomass and the habitat density were 2.03 g/m2 and 358 ind./m2, respectively. The ranges of Margalef species richness index, Shannon-Wiener diversity index and Pielou’s evenness index were 0.775–4.052, 1.825–3.976, and 0.637–0.924, respectively. The results of MDS and CCA indicated that 18 stations could be divided into three groups. The community of GroupⅠ(C4, D4) was composed of Apseudes sp.-Ophiophragmus japonicus-Gammaridea sp., and their distribution were positively correlated with the water depth, water temperature and salinity. Group Ⅲ(C1, B1) had H. filiforms-Notomastus latericeus, of which the distribution were positively correlated with ammonia, nitrate, total nitrogen and dissolved oxygen. GroupⅡincluded all other stations, and it had G. gurjanovae-Moerella jedoensis-Leucon sp., and their distribution had no obvious relationship with environmental factors. ABC curving analysis showed that the macrobenthic community tend to be disturbed moderately. The depth and ammonia were the most and second most relevant factors in the distribution of abundance.

Abstract:Japanese flounder Paralichthys olivaceus is the major species of released fish in the coastal area of Qinhuangdao. In recent years, the ecological and genetic risks caused by releasing a large number of hatchery-reared fish to the sea have attracted more and more attention. In this study, we used 12 microsatellite markers to analyze the genetic variability of the captured population of P. olivaceus from the coastal releasing area of Qinhuangdao. We also compared parameters of genetic diversity among the brood stock, the pre-releasing population and the captured population. The mean number of alleles was between 11.917 and 22.167, and the maximum and minimum values were found in the captured population and the pre-releasing population respectively. The mean observed heterozygosity (Ho) ranged from 0.800 to 0.836, and the mean expected heterozygosity (He) was between 0.814 and 0.845. The brood stock had the highest He value, and the pre-releasing population had the lowest value. The mean polymorphism information content (PIC) ranged from 0.775 to 0.818. Twenty-three out of 36 group-loci combinations were significantly deviated from the Hardy-Weinberg equilibrium (P<0.05). The Gst values among the five populations varied from 0.005 to 0.043, indicating a low level of differentiation. Results of this study suggested the high genetic diversity of these three populations. Moreover, no obvious genetic risk was caused by the large-scale releasing of hatchery-reared fish in the coastal releasing area of Qinhuangdao.

Abstract:In order to analyze the genetic diversity of Protosalanx hyalocranius in the Hongze Lake, the mitochondrial cytochrome b (Cytb) and cytochrome c oxidase subunitⅠ(COⅠ) gene sequences were investigated in this study. Using PCR amplification and sequencing, 1141 bp of Cytb and 630 bp of COⅠ sequences were identified. For the Cytb sequence, the contents of A, T, G and C accounted for 21.7%, 29.3%, 16.7%, and 32.3% respectively. Six polymorphic sites and 7 haplotypes were obtained from 40 individuals. The haplotype diversity and nucleotide diversity were 0.775 and 0.00129 respectively. The average nucleotide difference was 1.469. For the COⅠsequence, the contents of A, T, G and C accounted for 21.6%, 26.0%, 19.2% and 33.2% respectively. Five polymorphic sites and 6 haplotypes were obtained from 40 individuals. The haplotype diversity and nucleotide diversity were 0.700 and 0.00207 respectively. The average nucleotide difference was 1.303. The kimura-two-parameters analysis showed that the genetic distances of the haplotypes varied between 0.001 and 0.004 for Cytb, and between 0.002 and 0.005 for COⅠ. Furthermore, the phylogenetic tree constructed with the neighbor-joining (NJ) method indicated that the haplotypes of P. hyalocranius formed one clade, which suggested that there was no genetic differentiation in the haplotypes of Cytb and COⅠof P. hyalocranius. Fu’s Fs values (–0.32836 for Ctyb and –0.52548 for COⅠ) in the neutrality test was negative, but there was no significant difference. The mismatched bases distribution analysis showed a peak type, which indicated that P. hyalocranius in the Hongze Lake had experienced a population expansion.

Abstract:Turbot (Scophthalmus maximus) is an economically important species extensively cultured in China. In this study, we exerted acute salinity stress on turbot to identify their response in the expression of certain genes including prolactin (PRL) and Na+-K+-ATPase a1 in the intestine and gill. Relative mRNA expression of PRL and Na+-K+-ATPase a1 in four salinity groups (salinity 5, 10, 40, 50) and a control group (salinity 30) were tested using quantitative real-time PCR. Sampling of the control group conducted at 5 h, 12 h, 24 h, 53 h, and 102 h. Data analysis demonstrated that the two genes expressed in all tissues in a spatio and time specific pattern. Over the time, the relative mRNA expression of intestinal PRL and Na+-K+-ATPase a1 firstly increased and then decreased under the stress of salinity 5 and 50. The expression of PRL mRNA in the gill firstly increased and then decreased under salinity 50; under the same salinity, the expression of Na+-K+-ATPase a1 mRNA showed a reversed pattern which was a decrease followed by an increase. Compared to the control group, the mRNA expression of Na+-K+-ATPase a1 in the gill did not change significantly under salinity 5. In the intestine, the mRNA expression of the two genes were highly synergic, and they both firstly increased and decreased along with the increase of salinity, and the correlation coefficient was close to 1. However, there was an obvious antagonistic effect between the two genes in the gill under salinities 10 to 40. When the expression of PRL rose/fell, the expression of Na+-K+-ATPase a1 declined/rose, and the correlation coefficient was negative. This confirmed that PRL could inhibit the Na+-K+-ATPase activity. Our study provided theoretical information in the turbot gene regulation mechanism in response to salinity stress.

Abstract:Temperature is one of the key environmental factors affecting the growth and physiological functions of fish. Both the physical activity and the feeding behavior of fish can be significantly reduced or even stopped at low temperature. In this case, fish may consume stored nutrients to stay alive. Rice field eel Monopterus albus is a subtropical freshwater fish with great commercial values. They are prone to diseases and have a high mortality rate in winter. Previous studies suggested that overwintering could significantly affect the intestinal digestive enzymes, the immune and antioxidant functions (serum catalase and lysozyme), muscles and the liver lipid content of M. albus. However, changes in nutrients and physiological adaption during overwintering have been unclear. In this study, we conducted a 124-day experiment to investigate effects of overwintering on the body biochemical composition and partial serum biochemical indices of M. albus with the initial average body weight of (118.42±4.38) g. Results showed that after overwintering: 1) The compositions of the whole body, the liver and muscles of M. albus were significantly affected. The body crude lipid decreased compared to that before overwintering (P<0.05), whereas the body moisture and body crude ash were increased (P<0.05). The hepatosomatic ratio and the content of the liver glycogen were dramatically reduced (P<0.01), but the liver crude lipid was significantly increased (P<0.05). In muscles, the level of saturated fatty acids dropped (P<0.01), the content of polyunsaturated fatty acids rose (P<0.05), and the total amino acids and essential amino acids were markedly increased (P<0.01). 2) The serum triglycerides, glucose, total amino acids and essential amino acids became lower than those before overwintering (P<0.05), and the level of total serum proteins was greatly increased (P<0.01). However, there were no differences in the total cholesterol, the blood urea nitrogen, the aspartate transaminase and the alanine aminotransferase before and after overwintering (P>0.05). In conclusion, M. albus may consume the liver glycogen and body lipids to maintain life activities during overwintering, which consequently changes the compositions of amino acids and fatty acids in the muscle.

Abstract:Eleutheronema tetradactylum is subordinate to Mugiliformes, Polynemida, Eleutheronema in taxonomy. As a new aquaculture species, it has gained popularity in most farmers in recent years because of the delicious meat, the fast growth, the high market value and other advantages. However, this species is prone to stress from the pulling capture and the transport due to its weak anti-stress ability. In order to understand the effects of acute off-water handling stress on the tissue structure and oxidative stress of juvenile E. tetradactylum, we stocked the juvenile fish in the outdoor water tank and stressed them by simulating the pulling capture. The samples were collected at 2 h, 6 h, 12 h and 24 h after the off-water handling stress, and fixed separately with poly formaldehyde and liquid nitrogen. The samples fixed with poly formaldehyde were used in tissue sectioning and we observed the changes in the micro- structure of gills and muscles. The samples fixed with liquid nitrogen were used to examine the activities of antioxidant enzymes in muscles and the Na+-K+-ATPase in gills. Results showed that varying degrees of damages were induced in the gill lamella, the squamous epithelium cells and mitochondrion-rich cells (MRC) in 2 h after stress. Firstly, the muscle fiber necrosis appeared and then the gap of muscle fiber became widened, followed by vacuolation and even muscle fiber loss. Superoxide dismutase (SOD) and glutathione (GSH) had the same changing pattern, which was a significant drop (P<0.05) in 2 h after stress, followed by the rise to the highest level 12 h later. Then they began to decline slightly lower than the control level at 24 h. Catalase (CAT) and total antioxidant capacity (T-AOC) did not change significantly (P>0.05) at the beginning of 2 h, but then it rose to a highest value at 12 h and subsequently recovered to the normal level at 24 h. The content of malondialdehyde (MDA) did not have a marked change (P>0.05), and it reached the highest value at 6 h, and then fell back to the normal value at 24 h. The activity of Na+-K+-ATPase was elevated (P<0.05) at 2 h, stayed stable, and rose again until 12 h when it reached the highest value, then it went back to the normal value at 24 h. In conclusion, muscles and gills of E. tetradactylum will be damaged by acute off-water handling stress; besides, the damage will deteriorate as the off-water time goes over. The muscle antioxidant enzyme system will only be activated at 2 h after the handling stress. The synergy may exist between SOD and GSH when the organism was stressed by external factors. At 24 h after the stress, the activities of SOD and CAT will be in a state of equilibrium and the values will be significantly lower (P<0.05) than the control level, and this explains that antioxidant enzymes were affected to certain extent by off-water handling stress. In addition, MDA, the degrading product of peroxide lipid, can be used as a biological marker of rapid stress response in E. tetradactylum. Na+-K+-ATPase in gills can provide energy support during this process to improve the anti-stress ability of E. tetradactylum.

Abstract:A feeding trial was conducted to investigate the effects of dietary curcumin at different levels on the growth performance, digestive enzyme activities and antioxidant ability of yellow catfish (Pelteobagrus fulvidraco). Juvenile yellow catfish with an initial body weight of (13.17±0.68) g were fed with 6 different experimental diets containing curcumin at the concentration of 0 (control), 50, 100, 200, 400, and 800 mg/kg (namely T1, T2, T3, T4, T5 and T6 respectively) for 60 days. There were 3 replicates per group of 40 yellow catfish. The results were described as follows. The specific growth rate (SGR) and the survival rate (SR) of fish fed in the control group were significantly lower than those of all treatment groups (P<0.05), and the feed conversion ratio (FCR) was higher in T3 and T4 than the control group (P<0.05). The lipase activity in the foregut of fish from T3, T4 and T5 was significantly higher than the control group (P<0.05). The amylase activity in the foregut of fish from T4 was significantly higher than the control group (P<0.05). The level of superoxide dismutase (SOD) was higher in the hepatopancreas of fish from T6, in the brain of fish from T5 and in the head kidney of fish from T4 (P<0.05). A significantly lower content of malondialdehyde (MDA) was observed in the brain of fish from all treatment groups (P<0.05). In T5 and T6, there was a significant increase in the catalase (CAT) activity in the spleen and hepatopancreas (P<0.05). The glutathione peroxidase (GSH-PX) activity was enhanced (P<0.05) in the fish from T4, in the spleen of fish from T5 and in the mid-kidney of fish from T5, furthermore, it was also higher in the serum of fish from all treatment groups compared to the control group (P<0.05). The GSH activity in the hepatopancreas of fish from all treatment groups was higher than that in the control group (P<0.05). A significantly higher level of nitric oxide was found in the hepatopancreas of fish from T5 and in the spleen and serum of fish from T4, compared to all other treatment groups (P<0.05). The results indicated that 200 mg/kg curcumin supplemented into the diets could effectively boost the growth performance, and enhance the intestinal digestive enzyme activities and the antioxidant ability of juvenile yellow catfish.

Abstract:In order to protect the germplasm resources of pomfret (Pampus argenteus) and provide some theoretical basis for its genetic breeding, this research was carried out by thermal titration method for preparing chromosome specimens of pomfret in living state and analyzed its chromosome karyotype. Finally, the evolutionary taxonomy of pomfret had been preliminary discussed. The pomfret involved in this experiment were juveniles 70-80 days old and their sizes ranged in 7.0–9.0 cm. They were divided into three groups, each group of three fishes, and kept in seawater containing 0.005% colchicine for 4 hours. Then, each group took three individuals, and a part of the gill tissues were sheared for preparing the chromosome specimens. The methods in this experiment prevented the pomfret from the physical damage caused by the operations off the water and ensured the experimental materials were obtained from pomfret with normal vitality. The analysis of chromosome karyotype showed that there were 48 telocentric chromosomes in the diploid and their karyotype formulae is 2n = 2SM + 10ST + 36T, namely, there were one pair of submetacentric chromosomes (SM) and 5 pairs of acrocentric chromosomes (ST) and 18 pairs of telocentric chromosomes (T), and their fundamental number (NF) was 50. There was no visible evidence of polyploidy chromosome and sex chromosome. and the karyotype was in accordance with the typical characters of karyotype in the higher group of fish evolutionary taxonomy. As the research objects were juveniles which had the immature sexual gland, and were unable to distinguish between male and female, it is uncertain whether there is a sexual chromosome in pomfret, and it needs to be further studied when the gonads are ready.

Abstract:The morphological character is an important external indicator of the value of a large yellow croaker (Larimichthys crocea). Therefore, it has become a hotspot how to improve the morphology of the cultured large yellow croaker in the fishery industry. In this paper, we analyzed the morphological differences among the large yellow croakers cultivated in different environments and fed with different diets. We collected the morphological data of three groups of large yellow croakers, and then applied methods such as cluster analysis, principal component analysis and discriminant analysis to analyze the data. The results showed that there were significant differences in the body height, the caudal peduncle length, the caudal peduncle width and the trunk width between the groups. The environment and the diets also had effects on the frame morphology of D3–4, D3–6, D4–6 and D5–6. The morphological differences primarily existed in anterior trunk of the fish, which indicated that the morphological changes caused by the environment might be associated with the flow velocity. We also speculated that the diet might affect the fish morphology due to different nutrition compositions and accumulation. The cluster analysis showed that the formula diet group and the net-cage group clustered closer than the fresh diet group. Three principal components were extracted by principal component analysis, and it showed that the formula diet group and the net-cage group shared similarity in principal component 1, but were different in principal component 3. The fresh diet group was discrete on each principal component. This finding suggested that the large yellow croaker cultured in the small net cage and fed with fresh diet were more diverse in morphology. We also applied discriminant analysis and established the discriminant functions of the large yellow croaker under different conditions. The cross validation analysis showed that there was no significant difference between the discriminant functions and the expectation, which indicated that the discriminant functions could be used in the morphological identification of the large yellow croaker cultured in different patterns. Our study suggested that the morphological improvement of the large yellow croaker would be achieved to some extent by altering the flow velocity, the size of the cultural space and diets.

Abstract:In the present study, we applied the quantitative feeding method to compare the sensitivity to WSSV infection of shrimp species including Wild Fenneropenaeus chinensis (W-Fc), Selected Fenneropenaeus chinensis (S-Fc) and Commercial Litopenaeus vannamei (C-Lv). We found that the average survival time after being fed with equal amount of WSSV-loaded baits was (124.11±39.49) h, (166.79±51.54) h and (136.90±41.99) h for W-Fc, S-Fc and C-Lv respectively, which were significantly different among the three groups (P<0.05). The death peak of W-Fc appeared at 96 h after infection and continued to 216 h, and the death peaks of C-Lv and S-Fc occurred at 144 h after infection. The quantity of virus in muscles of living shrimp samples was examined with absolute quantitative PCR at eight time points (3 h, 6 h, 12 h, 24 h, 36 h, 48 h, 72 h, and 144 h). The virus loads in W-Fc, S-Fc, and C-Lv at 48 h were (1.22×106±6.14×105), (7.10×103±7.26×102), and (1.50×104± 4.19×103) copies/ng DNA respectively. At 144 h, the virus loads in the three groups of shrimps were (8.44×106±1.25×106), (3.21×106±8.21×105), and (1.49×106±6.59×105) copies/ng DNA respectively. These results indicated that W-Fc was more sensitive to WSSV, and that S-Fc had higher resistance to WSSV. It suggested that S-Fc and C-Lv had different sensitivity to WSSV infection and thus might have distinct immune mechanisms against WSSV. S-Fc showed higher resistance to WSSV, implying that the resistance to WSSV was well improved in “Huanghai No.2” through long-term artificial selection. Therefore, an effective way to prevent and treat WSSV is selective breeding, which could greatly reduce the damage of WSSV disease.

Abstract:In this study we investigated effects of low-molecular-weight fish hydrosate (LWFH) on nonspecific immune and antioxidant capacity in the hepatopancreas and the expression of some immunity-related genes in the digestive tract of Pacific white shrimp (Litopenaeus vannamei). A diet containing 30% of fishmeal was regarded as a high fishmeal diet (HFM), and a diet containing soybean meal that substitutes 50% of the fishmeal in HFM was considered as a low fishmeal basal diet (LFM). Five LFM diets were formulated by adding LWFH at incremental levels (0, 0.5%, 1.0%, 1.5% and 2.0%) to LFM, which were designated as LFM0, LFM0.5, LFM1.0, LFM1.5, and LFM2.0, respectively. The experimental diets were fed to L. vannamei of (0.44±0.02) g in a water recirculation system for 48 days. The nonspecific immunity and antioxidant indices, and the activities of acid phosphatase (ACP), alkaline phosphatase (AKP), total superoxide dismutase (T-SOD) and the content of malonaldehyde (MDA) in the hepatopancreas were measured to determine the effects of dietary LWFH. We studied the expression of immunity-related genes including IMD, Penaiedin 3a, LZM and Crustin using qRT-PCR. The results suggested that a certain amount of LWFH could significantly improve the activities of ACP, AKP and T-SOD while reducing the content of MDA in the hepatopancreas. Moreover, the relative expression of IMD, Penaiedin 3a, LZM and Crustin were up-regulated in the LFM1.5 group. Therefore, the plant proteins may not be an ideal substitute because they may reduce the nonspecific immunity and antioxidant capacity of L. vannamei. Our results also suggested that 1.0%–1.5% LWFH added in LFM might increase the expression of the disease resistance related genes and enhance nonspecific immunity and antioxidant capacity．

Abstract:In this study we applied PCR to amplify and analyze partial sequences of mitochondrial COⅠ, 12S rRNA and ribosome 18S rRNA, 28S rRNA of five groups of Scapharca broughtonii (Jiaonan, Rongcheng, Changdao, Penglai in Shandong Province of China, and Tongyeong of Korea). In spite of the apparent genetic variation in COⅠ, 12S, 18S and 28S, the base compositions of these genes were stable. The genetic diversity of the five populations indicated the good condition of the germplasm resource of these species. Sixty-seven sequences of COⅠ, 73 sequences of 12S, 75 sequences of 18S rRNA and 75 sequences of 28S rRNA were obtained, and their lengths were 776 bp, 443 bp, 909 bp and 894 bp respectively. Sequence analysis showed that the polymorphic sites, haplotype, Hd dversity and nucleotide diversity index of COⅠ were 466, 32, 0.925 and 0.086, respectively. While that of 12S were 292, 43, 0.928, 0.0856, and 18S were 909, 74, 1.0, 0.717, and 28S were 27, 18, 0.778, 0.289. In addition, the Jiaonan population and Penglai population showed the highest diversity in 18S and 28S. Genetic distance data revealed the Korea population has bigger genetic distance with China population than that of within populations from China. Clustering analysis based on the partial sequences of COⅠ gene showed that the China S. broughtonii individuals from same population China clustered generally together, however, the Korea individuals clustered more than one group.

Abstract:Amphioctopus fangsiao (d’Orbigny, 1839–1841), aka Octopus ocellatus (Gray, 1849), is widely distributed in coastal areas of West Pacific Ocean. A. fangsiao has high market value because of the delicate meat texture and enriched nutrition. Hence it has been one of the most important economic species in the north coast of China, and the development of the culture industry is promising. In this study we used new hatchlings to study the food requirement of A. fangsiao at different developmental stages. We first observed the feeding behavior under different conditions, and then investigated the growth process of A. fangsiao fed on different diets at different developmental stages. As the density of Artemia nauplii (the food) increased from 0.1 ind./ml to 1 ind./ml, the highest food intake rate of the hatchlings occurred when the density was 0.1 ind./ml. Because the feeding behavior of hatchlings aged Day 1–2 and Day 2–3 was highly active, the diet should be carefully prepared starting from Day 2 after hatching. The food intake of new hatchlings was usually active in the nighttime, and was especially intense in the shimmer and dark environment. A mixed diet helped improve the growth and lower the mortality rate. Artemia nauplii was the key diet at the para-larvae stage (0.03 g). A switch of diet was needed at the benthic stage (0.1 g), and shrimp and fresh shellfish meat was the optimal combination for the benthic hatchlings. Results of this study may provide important information for the large-scale culture of A. fangsiao.

Abstract:Cultellus attenuatus is a commercially valuable species that is widely distributed in the north and south coastal waters of China. In this study, we applied histological sectioning and experimental ecology methods to study the reproductive biology of C. attenuatus including the reproductive cycle, gonadal development, breeding season, embryonic development and larval development. Experimental subjects were collected from the Laizhou Bay of Shandong Province in the North China. C. attenuatus were sampled three times per month from May to July, and was sampled once a month in the rest months from April 2013 to March 2014. The results showed that C. attenuatus was dioecious, and that the sex could be identified with the colors of mature gonads that were white and yellow for the female and the male gonads respectively. The reproductive cycle of C. attenuatus was one year. The gonad of C. attenuatus was composed of the follicle, gonaduct and gonadial tube. The gonadal development could be divided into five stages, which were the proliferation stage in March, the increasing stage in April, the mature stage from May to early June, the breeding stage from mid-June to early July, and the suspension stage from mid-July to February of the next year. Its breeding season was between mid-June and early July when the water temperature was 22.0–26.6℃. The diameters of fertilized eggs were 50–55 μm. Hatching and the larval culture were conducted with aeration at a stable temperature and salinity. At 26℃ and salinity 28, the D-shaped larvae were hatched in 24 hours to the size of 90 μm×60 μm. Since Day 10, the larvae began to settle down and developed into the post larvae, and metamorphosis was completed. It was found that the C. attenuatus had high tolerance to air exposure. No mortality occurred when the razor shells were exposed to air at 20℃ for 12 h. Our study provided useful information for the artificial breeding of C. attenuatus.

Abstract:Grateloupia livida (Harv) Yamad is a red seaweed that has high economic value. In recent years, research on the seed production of G. livida has gained more and more attention. To further understand the progress of seed production, we studied the effects of water velocity and light on the growth and development of G. livida carpospores under the laboratory conditions. G. livida carpospores that attached for 1 d and 15 d were incubated in the water with different velocities (0, 1, 1.5, 4, 7, 10, 14 cm/s) for 20 d. The 0 cm/s group was the control group (without any water flow or under non-aerated condition). Except that the 1.5 cm/s group was controlled by aeration, all other groups were controlled by the water flow equipment. G. livida carpospores that attached for 1 d were incubated with different light intensity (35, 85, 135 µmol photons/m2·s) at different photo periods (6L:18D, 8L:16D, 10L:14D, 12L:12D, 14L:10D and 16L:8D) for 70 d. The results were described as follows: G. livida carpospores that attached for 1 d developed faster in the 0 cm/s group than in the other water velocity groups (P<0.05). The carpospores that attached for 15 d had grew and developed more slowly in the 0 cm/s group than in any other water velocity groups, and the optimum water velocity was 1.5 cm/s (P<0.05). The photo period and light intensity had a significant effect on the growth and development of G. livida carpospores and had interactive effects on the growth of the disc and plantlet (P<0.05). The optimum light condition for G. livida carpospores was 8L:16D and 10L:14D as the photo period and 35 µmol photons/m2·s as the light intensity. We recommended that the released carpospores of G. livida should be incubated in the still water for 15 d and then in the water with a velocity of 1.5 cm/s (by aeration) under the light intensity of 35 µmol photons/m2·s and photo period of 8L:16D or 10L:14D.

Abstract:In this study, we explored how the nutritional and culture conditions affected the growth of a Bacillus sp. strain A4 and identified the growth characteristics of this strain during the multi-factor interaction. We first applied the single factor test to study the effects of different carbon and nitrogen sources, and then employed Plackett-Burman (PB) test to evaluate the effects of seven factors including carbon source, nitrogen source, pH value, inoculation amount, temperature, rotation speed and liquid volume in the flask. The results showed that the absorption efficiencies of strain A4 for different carbon and nitrogen sources were different. We found that the corn steep liquor was the best carbon source for strain A4, and that the soybean protein was the best nitrogen source. When cultured with the corn steep liquor or the soybean protein for 24 h, the amounts of bacteria reached 3.58×108 CFU/ml and 3.19×108 CFU/ml respectively. The results of Plackett-Burman (PB) test showed that the order of factors affecting the growth of strain A4 as soybean protein> temperature>corn steep liquor>rotation speed>inoculation amount>pH value>liquid volume in the flask. Moreover, the soybean protein as the nutritional factor and the temperature as the culture condition both had significant effects on the growth of strain A4 (P<0.05). Temperature had a greater effect on the growth of strain A4 than the corn liquid factor. The results above indicated that the culture conditions played a vital role in the growth regulation of the bacteria. We also recommend that it should be essential to associate the nutritional factors with the culture conditions when evaluating the effects of related factors on the growth or ecological function of bacteria.

Abstract:In this study, we developed a method to determine 17 kinds of quinolones residues in aquaculture seawater by using solid-phase extraction and liquid chromatography tandem mass spectrometry (SPE-LC/MS/MS). The target antibiotics in water samples were enriched and cleaned-up by solid-phase extraction cartridges after the acidification with hydrochloric acid. We compared the sample recovery under different conditions to find the optimal pH of the loading buffer and the most suitable type and volume of the eluent. The elute was collected and concentrated under a gentle stream of nitrogen gas, and then dissolved into 1 ml liquid by the mobile phase. All antibiotics were separated by gradient elution with the mobile phase of 0.1% formic acid in water and acetonitrile. The targets were then analyzed by LC-MS/MS under the positive electrospray ionization condition in the multiple-reaction-monitoring (MRM) mode. Seventeen kinds of antibiotics can be separated successfully within 10 minutes. Calibration curves for antibiotics exhibited good linearity in the concentration range from 1 to 200 ng/ml and the correlation coefficients were larger than 0.999. The limits of detection (LOD) were 2-10 ng/L and the limits of quantification (LOQ) were 5-20 ng/L. The average recoveries of 17 quinolones at the spiked concentrations of 20 ng/L, 100 ng/L and 200 ng/L were 71.3% to 125.0% with a relative standard deviation (RSD, n=5) of 2.44% to 12.27%. This new method was applied to the analysis of four mariculture farms located in the Lingshan Bay of Qingdao in China. The results showed that four kinds of quinolones were detected including enrofloxacin, ofloxacin, norfloxacin and ciprofloxacin, and the highest concentration was 6880.05 ng/L. These results suggested that the new method was efficient and reliable, which was suitable for the detection of quinolones in seawater samples.

Abstract:The acute toxicity and bioaccumulation of deltamethrin was studied in four species of mariculture organisms including the crustaceans Portunus pelagicus and Marsupenaeus japonicus, and the bivalve Meretrix meretrix and Ruditapes philippinarum. The results indicated that there were significant positive correlations between the mortality rate of the mariculture organisms and the concentration and exposure time of deltamethrin. The LC50 values at 24 h, 48 h and 96 h for the crustacean P. pelagicus were 2.07×10-4, 1.70×10-4 and 1.10×10-4 mg/L respectively, and the values for M. japonicas were 7.32×10-4, 3.90×10-4 and 1.43×10-4 mg/L. The safe concentrations for these two species were 3.44×10-5 mg/L and 3.32×10-5 mg/L respectively. The LC50 values at the 3 time points for the bivalves M. meretrix were 1.52, 0.30 and 0.27 mg/L respectively, and for R. philippinarum they were 0.67, 0.11 and 0.06 mg/L respectively. The safe concentrations for these two species were 3.51× 10-3 mg/L and 9.50×10-4 mg/L respectively. Obviously the two crustacean species were more sensitive to deltamethrin than the bivalves. Next, the bivalves M. meretrix and R. philippinarum were exposed to the seawater containing deltamethrin at average concentrations of 0.86–0.05 mg/L and 0.37–0.03 mg/L respectively for 24–96 h, and we found that the accumulation coefficients of deltamethrin in these two species were 2.57–12.40 and 3.03–27.85 respectively. The accumulation rate of deltamethrin in the two bivalve species was positively corelated with the exposure time of deltamethrin, but negatively correlated with the concentration of deltamethrin. There were significant differences in sensitivity and accumulation rate of deltamethrin between different species of marine aquaculture organisms.

Abstract:High-mobility group box protein (HMG) is a novel cytokine that takes part in inflammation, cell migration, and tissue damage and regeneration. Regeneration usually involves the regrowth of cells, tissues and organs, and plays an essential role in the survival and adaptation of a species. Sea cucumbers Apostichopus japonicus (Echinodermata, Holothuroidea), which are phylogenetically related to invertebrates, are capable of regenerating damaged organs and body parts, such as the intestine, the respiratory tree, the gonads and the body wall. Sea cucumbers can eviscerate intestines and other organs through the cloaca in response to external stimulations. Within a few weeks after losing an organ or an appendage, the sea cucumber is able to regenerate the missing parts. These animals are thus excellent candidate models for research on organ regeneration. In this study, we analyzed the expression of mRNA and proteins of HMG during the intestine regeneration in sea cucumber using qRT-PCR and immunofluorescence techniques, respectively. The results showed that compared to the control group, there was no significant rise in the expression of either mRNA or proteins of HMG from 30-minute to 6-hour post-evisceration. HMG mRNA expression was significantly upregulated from 1-day to 7-day post-evisceration. The protein expression was higher as well compared to the control group. These results suggested that HMG was involved in the intestine regeneration of A. japonicus and could participate in the activation of the innate immune system in response to tissue damages, and hence was required in the processes such as repair, remolding of extracellular matrix (ECM), and the induction of stem cell migration and differentiation.