Abstract:Small copepod Paracalanus parvus is the dominant zooplankton species for early larvae of fishes as food in the critical spawning and nursery habitat of Laizhou Bay, Bohai Sea. Annual dynamic distributions of the species in the bay were studied based on the zooplankton samples that were collected from May 2011 to April 2012 by a net with 50 cm diameter and 160 micron mesh size. In this study, stage-specific abundance of P. parvus from the original sorting was transformed before the multiple analysis including cluster analysis and multidimensional scale. Principal component analysis (PCA) and RELATE modules of BIOENV in software Primer 6.0 were used to seek the best matches of environmental factors that affect distribution of P. parvus. As the most common copepod in Laizhou Bay, P. parvus was observed at all stations during the investigated period. The species was more abundant from July to October compared with other seasons and its abundance peaked in August. By cluster analysis based on the copepod stage-specific abundance, three stations groups were recognized. The one was located on outside of Laizhou Bay near the central Bohai Sea; the second was located to the runoff inlet of the west of the bay; the third was appeared in the transition area of the two mentioned groups before. The abundance of P. parvus reached the highest in the transition group and the lowest in the group outside the runoff inlet. According to the results of BIOENV analysis, the surface water temperature and pH co-regulated seasonal distributions of P. parvus, while seawater salinity and depth had stronger effects on the spatial distributions. The significant correlations between seawater pH and Huanghe River runoff suggest that runoff one month earlier may be a possible indirect factor that affects the temporal variations of the P. parvus.

Abstract:The substrate enzyme activity and the spatial distribution of microorganisms are important factors affecting the degradation of pollutants in water treatment system of the constructed wetland. The present study using a laboratory scale constructed wetland system in three different conditions to measure the removal effects of nitrogen, the relationship between the removal efficiency and the spatial distributions of microorganisms and the substrate enzyme activity. Spartina alterniflora was selected as the plant of the constructed wetland, and the density of reed was 64 per square meter. The substrates were filled with fine sand, coral rock and blast furnace slag. In three different conditions, the removal rate of different forms of nitrogen, the quantity and activity of microorganisms, the substrate activity were investigated. The results showed that the average removal rate of TN and NH4-N were (25.02±12.69)% and (82.91±17.51)% in the constructed wetland system during two-month stable operation, respectively. The quantities of microorganisms in different depths were obviously different, and the activities of substrate urease and dehydrogenase were different with depths. The quantities of aerobic microorganisms, the activities of urease and dehydrogenase in the upper and middle layer were significantly higher than those in the lower layer of the system. In the down flow tank of the system, the quantities of nitrifying and nitrite bacteria in the upper and middle layer were higher than those in the lower layer; however, the distribution of denitrifying bacteria was opposite. There were positive correlations between the removal rate of nitrogen and the quantity of bacteria and the enzyme activity (R2=0.50 and 0.61, respectively). There was a significant positive correlation between the total nitrogen removal rate and the activity of urease (R2=0.86). The results contribute to the migration mechanism of nitrogen in the constructed wetland system of treating marine aquaculture waste waters.

Abstract:Red-spotted grouper nervous necrosis virus (RGNNV) is one major pathogen of aquaculture. It mainly affects the larvae and juveniles of groupers. RGNNV is composed of two single stranded RNA (RNA1 and RNA2). Ozone can inactivate RNA virus by degradation of viral genome. So treatment by ozone is a common measure to disinfect RGNNV in farms. But it has no efficient methods to evaluate the disinfection effect of ozone up to now. In this report, a special RT-PCR named as LR RT-PCR (Left reverse transcript Right amplify RT-PCR) was developed and optimized to evaluate degradation effects of RGNNV RNA2 by ozone. Based on the 3 end and 5 end of RGNNV RNA2, a special reverse transcription primer and a set of PCR primers were designed respectively. The concentration of primers, Mg2+, dNTPs as well as annealing temperature of LR RT-PCR was optimized in this study. The sensitivity and specificity of LR RT-PCR also were confirmed. Finally the LR RT-PCR method was used to evaluate degradation effects of RGNNV RNA2 by ozone. With summarizing the results of the experiment, in 25 μl of reaction volume, the optimized parameters of LR RT-PCR were primers 0.2 μmol/L, Mg2+ 4 mmol/L, dNTPs 0.5 nmol, Ex Taq 0.5 U and cDNA template 1 μl. The annealing temperature was 60℃. The sensitivity of LR RT-PCR was 1 pg to RGNNV RNA2 and there were no cross reactions with genomic RNA from healthy groupers, DNA from common bacteria and viruses of aquaculture. Comparative analysis of LR RT-PCR and routine RT-PCR was carried out to evaluate the destructive effects by ozone. As the concentration of ozone increased from 0.3 mg/L to 2 mg/L in solution of RGNNV RNA2, the amplified product of LR RT-PCR decreased and finally was undetected. Former reported routine RT-PCR method for RGNNV detection did not reflect above tendency. This report demonstrated that the LR RT-PCR can quickly and accurately evaluate disinfection effects of RGNNV by ozone and can be widely used in hatcheries of groupers.

Abstract:Roche 454 GS FLX, the second-generation sequencing technique, can read longer fragments accurately and isolate SSR markers, and thus has been widely used in many fields of research. In this study, we applied Roche 454 GS FLX to isolate the microsatellite loci and developed the identification of microsatellites markers in Pleuronectes yokohamae. (AC)12, (AG)12, (AAT)12, (AGG)8, (AGC)8, (AGAT)8 and (ACAG)6 were hybridized with shotgun library of DNA samples. This SSR library was constructed through magnetic beads enrichment, cleaning, elution and purification. The SSR library was then sequenced with Roche 454 GS FLX. MISA was used to search for microsatellite motifs and primer 3 was used to design the primers for P. yokohamae. FAM, HEX, and TAMRA were used to label the microsatellite primers (5′), which were used in the triplex PCR or the nested PCR to identify the genotype of the microsatellite loci. The cluster similarity comparison method was first used to analyze 5641 loci that we obtained, and 247 types of loci with high polymorphism were screened. Among these loci, 52.22% were perfect, 20.24% were imperfect and the rest 27.54% were compound. The percentage of (AC)n and (AG)n was 44% in these loci, and 87.5% of them were more than 10-time repeats. Eleven pairs of fluorescent primers were designed according to the selected loci (more than 10-time repeats) and were applied in 5 individuals. The number of alleles per locus ranged from 3 to 8 with an average value of 5. The average values of Ho, He and PIC were 0.588, 0.788 and 0.670 respectively. Four loci among 11 deviated from Hardy-Weinberg. The results of this research indicated that 454 GS FLX was an intuitive and efficient technique for microsatellite isolating. Our study provides essential information about the population genetic diversity of P. yokohamae, and helps improve the artificial breeding.

Abstract:In this study, we compared the extent of genetic diversity of the triploid and diploid flounders using the microsatellite method. The triploid were induced using cold shock method in 2012, and then they were cultured under the same conditions as their diploid control. Genomic DNAs were isolated using the high salt-extraction method from the muscle tissues of 32 triploid and 32 diploid flounders of 11-month old. The genetic variations of the triploid and diploid flounders were assessed based on the selected 21 microsatellite loci. The PCR products were isolated using 14% PAGE electrophoresis, and the microsatellite alleles were artificially identified and analyzed. The results showed that in the triploid and diploid stocks, the average numbers of alleles per locus (A) were 5.6 and 5.0; the total numbers of genotype were 190 and 142; the average numbers of effective alleles per locus (ae) were 3.7 and 2.8; the values of average observed heterozygosity (HO) were 0.613 and 0.868; and the unbiased expected heterozygosity (HE) were 0.681 and 0.629, respectively. The values of the polymorphism information content (PIC), the power discrimination (DP) and the probability of paternity exclusion (PPE) in the triploid and diploid stocks were 0.642 and 0.589, 0.660 and 0.609, 0.482 and 0.399, respectively. The accumulation of PIC and PPE both achieved 0.999, which indicated that these microsatellite loci were very sensitive and could be used in the parentage and kinship determination in future genetic breeding studies. The genetic distance (D), the genetic similarity (I) and the coefficient of gene differentiation (GST) between the triploid and the diploid stocks were 0.312, 0.732 and 0.971 respectively. The genetic diversity of the triploid stock was moderately reduced compared to the diploid stock. There were also some differences in the genotypes between the triploid and diploid flounders.

Abstract:Activin is a member of the transforming growth factor-β (TGF-β) family and regulates sex hormones. It was originally discovered in pig ovarian follicular fluid. Activin contains two β subunits and plays a vital role in the hypothalamus-pituitary-gonad axis (HPG). It regulates the secretion of pituitary gonadotropin, the production of steroid hormones and the maturation of oocyte in ovary. Paralichthys olivaceus is a type of important commercial fish species that has advantageous traits in aquaculture such as the fast growth rate. Better understanding of its reproduction mechanism is essential for the guidance of the breeding of P. olivaceus. In this study, we analyzed the expression and regulation of Activin gene related to the reproductive endocrinology of P. olivaceus. Our data should provide important information for future studies on biological functions of Activin and for the practice in the culture of P. olivaceus. We used the genome walking method to obtain the partial sequence of promoters located in the upstream of Activin βA and βB genes of P. olivaceus, and predicted the binding sites of transcriptional regulation elements using the bioinformatical method. The promoters of these two genes were 2.7 kb and 2.4 kb in length respectively. The results showed that the TATA box of Activin βB was located at 31 bp in the upstream region of the transcription initiation site, however this structure was not found in Activin βA. We found in the two promoters a number of binding sites of the transcription factors including Sp1, Oct-1, C/EBP, CREB, GATA-1, c-Jun, HNF-3, HNF-1, and USF. Moreover, we also found multiple transcription binding sites of endocrine-related factors such as Pit-1, ER, PR, GR, RAR, and RXR. However, the binding sites of MyoD, myogenin and SRY were only found in Activin βA. In conclusion, the bioinformatical analysis suggested that the basic and hormone-inducing expression of both Activin βA and βB was regulated by a variety of factors; however, the mechanisms of the regulation were different between the two genes.

Abstract:Grey mullet (Mugil cephalus) grazes on plant detritus and microflora and is an omnivorous fish species of ecological importance in both mono- and poly-culture due to its unique feeding habit. However, little is known about the effects of different diets on the growth and body composition of M. cephalus. To address this question we carried out an 8-week feeding experiment on M. cephalus with initial weight of (25.0±1.59) g. The experimental subjects were fed with four groups of diets that were flour (T1), rice bran (T2), shrimp feed (T3) and fish feed (T4). The results showed that the specific growth rate (SGR) and the feed efficiency (FE) in T1 and T2 were significantly lower than those in T3 and T4 (P＜0.05). The SGR and FE in T3 were 1.46 %/d and 48.62% respectively which were 2-fold of those in T4. Fish fed with a single diet of either flour or rice bran barely grew in size but had higher survival rates (＞80%). The weekly average daily food intake (DFI) of T1 and T2 decreased to below 0.80 g/d after 4 weeks, whereas the weekly average DFIs of T3 and T4 were above 0.80 g/d and obviously increased in the 8th week during the experiment. The whole body crude protein was the highest in T2 (18.62%±1.36%), and crude lipid was the highest in T3 (10.52%±0.36%). There was apparent accumulation of crude lipid in T1 (8.01%±0.42%), which indicated that the higher carbohydrates (flour) level could enhance the lipid accumulation in the whole body of the fish. Moreover, the level of whole body crude protein could be well maintained when the formula feeds were replaced with rice bran. Flour or rice bran alone may not be sufficient to support the rapid growth of M. cephalus because of the lack of balanced proteins; however, they might help promote the survival rate at early rearing stage. Therefore a partial diet replacement with flour or rice bran in shrimp ponds could be a useful trial.

Abstract:Epinephelus fuscoguttatus is a new culturing breed with great commercial values and broad market prospects. Frequent invasion of disease restricts the development of E. fuscoguttatus industry. With the characteristics of pollution-free, low-toxic, and low residuals, Chinese herbs as immunostimulants may be candidates for the prevention and control the diseases among E. fuscoguttatus. In this study, Chinese herbal immunostimulants were screened using nitroblue tetrazolium (NBT) reduction method by incubating the isolated white blood cell with water extracts from Chinese herbs. Water extracts from 39 kinds of 100 mg/ml Chinese herbs mixed with or without 5.0 mg/ml zymosan were utilized. Phagocytizing latex beads was employed to determine the effect of water extracts on the respiratory burst activity of the white blood cells on the phagocytic activity. The screened Chinese herbal immunostimulants were mixed with the feedstuff to feed E. fuscoguttatus. The results showed that 10 Chinese herbs extracts significantly increased the respiratory burst of white blood cells more than 15% compared to those in the control group. Three Chinese herbs extracts mixed with zymosan significantly increased the respiratory burst of white blood cells more than 70%. The water extracts from Caulis spatholobi, Cortex phellodendri amurensis and Herba ecliptae prostratae simultaneously elevated the respiratory burst and the phagocytic activity of white blood cell of E. fuscoguttatus. The in vivo experiments also demonstrated that the water extracts from Caulis spatholobi, Cortex phellodendri amurensis and Herba ecliptae prostratae significantly elevated the respiratory burst and the phagocytic activity of white blood cell and head kidney white cells of E. fuscoguttatus. In this study, 3 Chinese herbal immunostimulants were screened, which significantly enhanced the immune responses in E. fuscoguttatus. These results provide evidence to the development and application of new, safe and effective immunostimulants of E. fuscoguttatus.

Abstract:Chinese shrimp (Fenneropenaeus chinensis) is one of the most commonly farmed species in China since the 1970s. However, the pond survival and the total output of F. chinensis have been low because of the deteriorated pond environment and other factors. Ammonia, as undissociated for (NH3), is one of the most toxic substances produced during intensive shrimp farming and may reach concentrations high enough to seriously damage the health and growth of F. chinensis. To address this issue we collected wild samples of conserved “Huanghai No.1” from two geographical populations in the Haizhou bay and the Laizhou bay for the construction of fundamental stock in 2006. Mass selection was applied to obtain the characteristics of fast growth and high resistance to ammonia at concentrations between 3% and 5%. Five generations, namely “Huanghai No.3”, were selected successively and approved by China National Aquaculture Variety Approval Committee. “Huanghai No.3” displayed traits such as stress tolerance and fast growth. Under the same cultivation conditions, the survival rate of Post-larvaeⅠincreased by 21.2%, the survival rate increased by 15.2%, and the average body weight after harvest increased by 11.8%. The proportions of polymorphic loci were 42.28%, 40.64%, 40.32%, 39.95% and 38.05% in the five selective populations respectively, which implied the reduced genetic diversity. However, in later selected generations, there were fewer differences between populations and the genetic structure became more stable. Compared to “Huanghai No.1”, the average body weight and the survival rate of “Huanghai No.3” increased by 2.1% and 13.85% respectively. Compared to the wild seedings, the average body weight and the survival rate increased by 11.85% and 15.1% respectively. These results showed obvious improvement in the production. To the date, the pioneer scale to grow the new strain of “Huanghai No.3” has reached 400 hectares in the coastal areas of northern Jiangsu province since 2009.

Abstract:Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is a kind of common virus in shrimp culture industry in China, influencing prawn breeding all over the world. IHHNV is harmful to Litopenaeus stylirostris and the mortality can be as high as 90%. For Litopenaeus vannamei, the mortality is not high, but can suffer from runt deformity syndrome (RDS). IHHNV infection in Penaeus monodon is usually subclinical, but RDS, reduced growth rates and reduced culture performance have been reported in IHHNV-infected stocks. OIE recommended 5 sets of primer pairs to detect different genotypes of IHHNV. In order to know the detecting types in China, we used four sets of primer pairs in the PCR protocols recommended by the OIE standards to detect penaeid shrimp samples collected in 2011 and 2012 from different provinces. These four sets of primer pairs are 389F/389R, 392F/392R, 77012F/77353R, 309F/309R, respectively. The detection results showed that IHHNV positives were detected in the samples of L. vannamei, P. monodon, Fenneropenaeus chinensis and Melicertus latisulcatus, but not in the sample of Palaemon carincauda. The positive percentage of L. vannamei was the highest, 70.8% (389F/R) in 2011 and 34.3% (389F/R) in 2012, and that of F. chinensis was the lowest, which is 8.3%. The more positive of penaeid shrimp samples in 2011 were detected than that in 2012. The positive percentage of IHHNV in penaeid shrimp samples from East China is higher than that from North China and South China. We got four detecting types from the PCR detection with 4 sets of primer pairs recommended by the OIE standards. For detected typeⅠ, the positive rate is 90% for all the four primer sets. For detected typeⅡ, the positive rate is 4% for primer set 389F/R. For detected type Ⅲ, the positive rate is 4% for primer sets of 389F/389R, 392F/392R and 309F/309R. For detected type Ⅳ, the positive rate is 2% for primer sets of 389F/389R and 309F/309R. The survey provided valuable information for the future study and surveillance on epidemiology of IHHNV.

Abstract:Blepharipoda liberate Shen can clean intertidal sand, which has important ecological significances. In order to study the external characteristics and provide more information for the research and utilization of Anomura, B. liberate Shen were utilized for the dissection and observation under microscope. B. liberate Shen is unisexual; the pleopods and the location of genital pore are different between females and males. Female B. liberate Shen has four pairs of endopodites that are located in the abdomen; however, male B. liberate Shen has no endopodites. The location of genital pores of female B. liberate Shen are on the venter of the basis pereopod II, while the genital pores of male B. liberate Shen are located on the venter of the basis pereopod Ⅳ. The commensal bivalves are attached to body surface and gills. Similar to brachyura, B. liberate Shen have carapaces, but they have no sternum. The abdomen can not attach to the cephalothorax venter because of the lack of the stemal groove. Pleopod Ⅵ is much developed to form tail fan with telson that functions swimming like shrimps. A pair of the pereopod Ⅳ of B. liberate is located in the abdomen that is different from shrimps or crabs.

Abstract:The work of breeding bay scallop seedling has been studied in the past. The breakout of the brown tide in Hebei Area has brought significantly negative effects on the industry of bay scallop. To avoid the outbreak, the breeding of late seedling (parents bay scallop were put into seedling rearing room for breeding at the be beginning of April) and a chain of experiments concerning to bottom sowing culture in pond and longline aquaculture were carried out during 2012−2013. The results showed that the average shell length was 59.7 mm for the late seedling (with shell length 5.0−6.1 mm) after bottom sew into pond in June 2012 for 139 days cultivation. In 2012, after a longline aquaculture, the average wet weight, scallop adductor weight and adductor output rate of the late seedling were 28.7 g, 3.8 g and 13.8%, respectively. In 2013, after a longline aquaculture, the average shell height, wet weight and scallop adductor weight were 50.3 mm, 24.4 g and 3.1 g, respectively. The data suggest that the aquaculture of late seedling may reduce the expenditure of 45.5 t coal and 67.5 thousand Yuan per 1000 m3. These results also suggest that the planned delay may help to efficiently avoid the adverse effects of brown tide and may serve as a reference to the development of the whole bay scallop cultivation industry.

Abstract:Acute viral necrosis virus (AVNV) was reported as the causative agent for summer mass mortality of adult Zhikong scallop (Chlamys farreri) that has been widely cultured along northern China coast. To understand the pathogenesis and the function of IAP-86, a strain of acute viral necrosis virus (AVNV) was isolated from Anadara uropygimelana. RNA was extracted from the mantle of moribund A. uropygimelana that was infected with AVNV, and cDNA was obtained by reverse transcription. Two pairs of nested reverse primer were designed according to the ORF86 sequence of AVNV complete genome sequence that registered in NCBI. The non-coding region of 5' and 3' end of the ORF86 were amplified using the designed primers by rapid amplification of cDNA ends (RACE) technique, and the full-length cDNA sequences were spliced. Blast sequence alignment illustrated that this gene has 100% homology with oyster herpetovirus and 99% with the AVNV. Moreover, overlapping genes were found in the cDNA sequence. Bioinformatics analysis indicated that the protein contains neither a signal peptide nor a transmembrane region. The maximum hydrophobic index was 1.800 and the minimum hydrophobic index was 3.456. There are eight potential phosphorylation sites (including five serine sites, two tyrosine sites and one threonine site), a potential O-glycosylation site, but no potential N-glycosylation site. The epitope were mainly located on the amino acids of 811, 1416, 2839, 7576, 8895, 97100 and 147158. Results suggest that the virus may be a strain of oyster herpetovirus, and gene overlapping may play an important role in the virus evolution.

Abstract:Salinity is an important environmental factor in aquaculture that has significant effects on the growth and digestive physiology of aquatic animals. In the system of an aquatic animal digestive enzymes play a crucial role in the nutrient absorption and growth performance. In this study we investigated the effects of low salinity (16, 18, 20, 22 and 24) on the growth and activities of digestive enzymes in sea cucumbers (Apostichopus japonicus) of three different sizes (28.37±3.21 g, 7.52±1.25 g, and 2.03±0.68 g). The results showed that low salinity had remarkable impacts on the growth and digestive enzyme activities in sea cucumbers. The SGR of all three types of sea cucumber increased along with the increase in salinity, and it reached the lowest value at salinity 16 when the animals failed to stretch normally, crept at the bottom of the tank, and almost stopped the food intake. The lowest SGR was significantly different from the control (P<0.05). We also observed that the SGR reached the highest value at salinity 31. In the salinity range of 16−24, the activities of digestive protease, amylase and lipase all increased as the salinity rose. The protease activity of sea cucumbers reached the highest value at salinity 24, which was not significantly different from the control (P>0.05). Small sea cucumbers (2.03±0.68 g) showed no difference in the protease activity between salinity 20 and 22. Activities of amylase were not different between salinity 20, 22 and 24. For the medium-sized sea cucumbers (7.52±1.25 g), the amylase activity increased when the salinity rose from 22 to 24 (P<0.05). The lipase activity of large sea cucumbers (28.37±3.21 g) significantly increased when the salinity rose from 20 to 22, while it was elevated when the salinity rose from 22 to 24 (P<0.05) in small sea cucumbers (2.03±0.68 g). However, when the salinity was higher than 24, the activities of digestive enzymes increased as the salinity reduced. At the same salinity sea cucumbers of different sizes showed no variation in the activities of digestive enzymes. Our studies on the activities of the three enzymes at low salinity will provide reference for the salinity control in the aquaculture of sea cucumbers.

Abstract:Asterias amurensis is one of the primary predators of bivalves that often cause massive death of cultured bivalves. Better understanding of the feeding ecophysiology of A. amurensis is the key for developing effective control strategies. In this study, we recorded the selective feeding and feeding rhythm of A. amurensis on five species of bivalves including Patinopecten yessoensis, Chlamys farreri, Ostrea plicatula, Mytilus galloprovincialis and Ruditapes philippinarum, and thus identified the characteristics of feeding of A. amurensis. The experimental animals were collected from the sea area of Zhangzi Island and then transported to our seaside laboratory at low temperature. The A. amurensis was acclimated to laboratory conditions for 10 d before the experiment. The experiment was conducted between October 22 and November 12, 2013, at the water temperature of 13−15℃, and at the salinity of 30−31, and at the dissolved oxygen level of 7.8−9.7 mg/L in a concrete tank (L×W×H=5.5 m×2.5 m×1.5m). The results showed that A. amurensis had the highest feeding rate (P<0.05) on R. philippinarum, no matter whether interfering baits, such as Charybdis japonica and Apostichopus japonicus Selenka, were present. The values were 5.7 ind/d, 5.0 ind/d, 5.7 ind/d, 5.3 ind/d and 6.0 ind/d respectively. There was no significant difference in the feeding rate when A. amurensi was fed with different interfering baits. We also observed an active feeding rhythm of A. amurensi in a diurnal cycle by feeding them with C. farreri every four hours. The percentage of food intake between 18:00 and 06:00 was apparently higher than that between 06:00 and 18:00 (60% vs 40%, P<0.05). Furthermore, we found that the feeding frequency of A. amurensis peaked between 18:00 and 22:00 (58%, P<0.05).

Abstract:To study the effects of bioturbation of Sipunculus nudus on the sediment and the pore water, we established a polyculture ecosystem consisting of S. nudus and Mugil cephlus in the laboratory conditions. The experiment was conducted in 20 breeding tanks (diameter 1 m, height 0.8 m, water volumn 550 L). S. nudus [mean weight (1.2±0.1) g] was stocked at four different densities in the sandy sediment at the bottom of the tank: 0 (control), 50, 100 and 150 individuals per tank. In each tank 3 juvenile M. cephlus [mean weight (24.5±0.5) g] were cultured with normal ration supply in a net cage (diameter of 0.8 m, height of 0.6 m). The sediment was prepared in layers: the bottom layer was 6 cm thick medium sand (grain size 0.40–1.10 mm), and the top layer was 1 cm thick fine sand (grain size 0.10–0.28 mm). The results showed that the organic content in the bottom sediment (6–8 cm) in the experimental groups was slightly but insignificantly higher than that in the control group (P>0.05). The contents of nitrate nitrogen (NO3-N), ammonia nitrogen (NH4-N) and soluble reactive phosphorus (SRP) in the pore water increased gradually as the experiment lasted. At the end of the experiment, it was found that the NO3-N content in the bottom pore water was negatively correlated with the density of S. nudus, and it was lower in pore water of the T100 and T150 groups than in the T0 group (P<0.05). The NH4-N content of the pore water in the surface layer was the highest in the T0 group. The TN content in the water column rose along with the increase in the density of S. nudus. During the experiment, the NH4-N content of the bottom pore water in the T100 and T150 groups was significantly higher than that in the T0 group (P<0.05). The lowest NH4-N content was observed in all layers of the pore water in the T50 group. These results suggested that the bioturbation of S. nudus could partly boost the downward transportation of organic content across the sediment, and consequently affect the nutrients content in the pore water.

Abstract:Sea cucumber (Apostichopus japonicus) farming industry has been developing rapidly in North China, but at the meanwhile sea cucumber diseases has become a growing problem. The environmental deterioration was considered one of the main causes. A type of sediment improver studied by our research group has been proved to be effective in adjusting the sediment environment of the sea cucumber culture ponds. In order to detect the responses of the bacterial community to the sediment improver, we conducted experiments using the sediment from the disease-occurring sea cucumber culture ponds. The sample treated with the sediment improver was the trial group and that without the improver was the control group, and we set 3 parallels for each group. The plant counting method and the most probable number method were used to determine the change in the numbers of several bacterial groups in the sediment after the addition of the sediment improver. The bacterial diversity was analyzed using the 16S rRNA gene PCR-DGGE and the sequencing techniques. The results showed that in the trial group the numbers of the heterotrophic bacteria, the nitrifying bacteria and the sulfate- reducing bacteria in sea cucumber pond sediments increased in the first 2 to 4 days, followed by a decrease and then maintained at a low level, and the increase was significantly smaller than that in the control group. The numbers of Vibriols and sulfurizing bacteria sharply declined 1 day after the addition of the sediment improver, which were significantly lower than those in the control group. The sequencing result of DGGE bands showed that the dominant bacteria in the sea cucumber culture environment belonged to chloroflexi, moraxellaceae, Caulobacteraceae, Aeromonadaceae in proteobacteria, bacillaceae, and lactobacillaceaein in firmicutes. The bacterial diversity indexes varied between 2.5 and 3.5. The numbers of 2 species of Aeromonus were observed to decline after the addition of the sediment improver in the trial group. Therefore, we concluded that the sediment improver could adjust the numbers of different bacterial groups in the sediment environment and reduce the quantity of some pathogenic bacteria. The sediment improver may thus improve the quality of the pond sediment environment and protect A. japonicus from diseases.

Abstract:In recent years, the marine aquaculture has been undergoing a rapid development in the quantity and the scale of this industry. The wastewater from marine aquaculture inevitably causes pollution to the adjacent sea water if discharged without proper treatment. In order to meet the criteria of recycling or discharge, currently people have mainly used physical, chemical, and biological methods to remove the suspended solids (SS) and ammonia nitrogen in the wastewater, and to reduce chemical oxygen demand (COD) and biological oxygen demand (BOD). However these traditional methods have certain shortcomings in processing wastewater generated in marine aquaculture. Compared to the traditional treatment, membrane technology has the advantages such as the convenient operation and management and high efficiency, although it brings in membrane pollution during the application. In this study, we coated polysulfone ultrafiltration membrane with dopamine, and examined the properties and the functional performance of the dopamine composite ultrafiltration polysulfone membrane. The preparation of the composite membrane included coating and cleaning. The polysulfone membrane was first immersed in dopamine solution at the concentration of 2 g/L for 12 hours in a concussion incubator. The coated membrane then underwent vibration cleaning with deionized water for 24 hours. Infrared spectroscopy analysis showed that dopamine polymerization formed on the surface of the polysulfone membrane. The contact angle was 63° which was 21° smaller than the basal membrane. The hydrophilism of the composite membrane was significantly increased compared to the basal membrane. The results of separation experiments with aquaculture wastewater showed that under the pressureof 0.10 MPa the removal rates of TSS and COD were 100% and 83.3% respectively, indicating high-quality wastewater treatment.

Abstract:The inshore water areas are the major habitats and fishing grounds of many commercial species. Chinese inshore fisheries accounts for more than 90% of the total marine catches, and is an important resource of high-quality proteins for Chinese people. Currently the inshore fishery resources have been markedly declining due to the combination of overfishing and other excessive human activities (e.g. large-scale reclamation, pollution and mariculture). The sustainable production of many inshore fishery species has been impaired by adverse ecological change, such as the eutrophication-induced red tide and jellyfish bloom, and the fragmentation and defunctionalization of spawning and nursery grounds caused by the loss of wetlands. The recruitment of fishery populations is generally regulated by the interaction between the biological and physical processes in marine ecosystems which can be largely affected by the changes in environmental factors. To better understand the succession of marine ecosystem and sustainable yield of marine fishery populations, it is crucial to investigate how environmental changes affect the habitats and recruitment of fishery populations, especially at their early life stages. In this paper we reviewed literatures regarding these topics and analyzed the current situation of Chinese inshore fishery and the relevant problems of inshore ecosystems. We proposed and discussed four promising topics in future study: 1) fundamental and long-term changes in spawning and nursery grounds of fishery populations; 2) recruitment of fishery populations and the environmental driving forces; 3) adaptive strategies of fishery populations to environmental changes; and 4) evaluation of the effects of environmental changes on fishery population dynamics. These prospective studies are expected to provide essential knowledge that helps with the conservation of fishery habitats and resources as well as the improvement of sustainable development of inshore fisheries in China.

Abstract:Sea urchin embryo and larvae in the early developmental stages is an important model for research on marine ecological toxicology. Sea urchin dopaminergic (DA) nervous system develops earlier than the cholinergic system, and it starts to regulate the morphogenesis and swimming behaviors much earlier than the serotonergic system. Here we used sea urchin in the early developmental stages as a model and reviewed the development and the functions of the dopaminergic nervous system. The synthesis of dopamine and the receptors precedes the development of the dopaminergic nervous system. The dopaminergic neuron precursor cell period starts after the synthesis of DA and the receptors. In this period DA and DA receptor 1 (DRD1) appears in the form of granules of which the diameter is 1-2 μm (DA/DRD1-Gs), and they are also expressed on the surface of the embryo and larvae from the rotational blastula stage to the metamorphosis stage. After the aggregation of DA/DRD1-Gs, dopaminergic cells with the axon contacts begin to develop in the labial ganglion and the base of the back oral arms in the early four-wrist larval stage. The number of dopaminergic cells reached the maximum in the eight-wrist larval stage. Then the dopaminergic nervous system continues to develop until the maturity. The morphogenesis in the early developmental stage is regulated by several neurotransmitter systems together, and the swimming behaviors in different early periods can be regulated by either the dopaminergic nervous system alone or together with other systems. In the end, we assessed the prospective studies on issues, such as the factors affecting the development of the dopaminergic nervous system in the early developmental stages of sea urchin, the functions and the signaling pathway of DA receptors, the primary-secondary relationship and the mechanisms of the up-/down-regulation of the three important neurotransmitter systems in early morphogenesis and swimming behaviors, and the influences of neurotoxic substances on the development of the dopaminergic nervous system.