Abstract:Cadmium is ubiquitous in the human environment and has been recognized as one of the most deleterious heavy metal pollutants. Pollution of sea by cadmium as a component of industrial wastes leads to a considerable increase in its concentration in aquatic animals. But, considerable difference in the sensitivity to cadmium among shellfish has been reported. This work was an attempt to investigate cadmium bioaccumulation in various tissues of bay scallop Argopecten irradians and the factors influencing cadmium bi oaccumulation during simulated pollution. Cadmium in the seawater entered the gill of bay scallop by passive pervasion. The Langmuir isotherms were employed to describe the gill surface binding activity of cadmium. The binding capabilities were 2.12 μmol·g^-1 dry wt. The cadmium exposure results indicated: the bioaccumulation amount in tissues increased with the addition of cadmium concentration in seawater. When the cadmium concentration in the seawater was 2 μmol·L^-1, after 4 days, the bioaccumulation amount in the gill was (1.5±0.52) μmol·g^-1 dry wt and the accumulation velocity was (0.375±0.13) μmol·（g·d）^-1. At the same time, the bioaccumulation amount in the viscera was (7.19±0.83) μmol·g^-1 dry wt and the accumulation velocity was (1.79±0.21) μmol·（g·d）^-1. But the accumulation number in the muscle was the least ［(0.005±0.0009) μmol·g^-1 dry wt］. During of 19 days exposure in seawater containing 2 μmol·L^-1 cadmium, the bioaccumulation in the gill, viscera and muscle increased with the extension of feeding time. After 14（336 h）days, the cadmium accumulation in the gill, viscera was close to saturation. But the cadmium in the muscle was far from saturation. In fact, when the storage capacity limits of the liver and kidney are reached, cadmium accumulation in muscle is stimulated. The reported results show that salinity affects cadmium accumulation in various tissues of the tropical fiddler crab Uca rapax. In the present study, we found that there was not significant effects of salinity on cadmium accumulation in various tissues of Argopecten irradians（P>0.05）. When the bay scallop was bred in unchlorinated, aerated well water, the cadmium accumulated in the body was eliminated significantly. The excretion rate in the gill was 38.3%.

Abstract:The purification of serum immunoglobulin (Ig) of European eel（Anguilla anguilla）was carried out by affinity chromatography. The structure and the antigenicity of eel’s serum Ig were analyzed by electrophoresis and Western-blotting. The results showed that after separating by the affinity column, the amount of eluted protein of serum Ig was showed as a sharp curve on plotting paper. And the protein curve was highly correlated with the antigenic activity curve when analyzing the sample by ELISA. SDSPAGE dem onstrated that the heavy chain of the serum Ig was 68 kD in size, there were three light chains with the molecular weight of 21 kD, 23 kD and 26 kD respectively. Under nonreduced and nondenatured conditions, the serum Ig appeared as two protein bands with the molecular weight 790 kD and 350 kD, and showed 790 kD, 593 kD and 350 kD three protein bands under denatured and nonreduced conditions. Western-blotting revealed that the rabbit antiserum could recognize various polymers, heavy chain of the serum Ig, but could not react with the light chains. In combination with the above results, the natural form of the serum Ig could be presented as tetramer and dimer, which was different from other serum Ig of teleost. The disulfide linkage between the heavy chains of the Ig was incomplete. Under the reaction of the SDS the Ig had come apart into various smaller polymers. There were three distinct light chains found in the Ig of European eel for the first time.

Abstract:Detection of tetrodotoxin（TTX）in aquatic products is a hot topic of research in food security field. Although the mouse bioassay is the current standard method with high sensitivity, its quality and quantification are poor. Detecting TTX by high performance liquid chromatography (HPLC) can improve quality and quantification. In China, the detector of the popular HPLC method is UV detector, its sensitivity and quality can’t satisfy the food security standard. This article is researching determination of TTX in aquatic products by post column derivation HPLC. The separation characteristic of HPLC and fluorescence detector with selectivity and high sensitivity effectively improve sensitivity, quality and quantification, which make this method satisfy the food security standard. Takifugu and Nassarius were selected as the main research objects. Sample was extracted with 0.1% acetic acid, and then purified with C18 solidphase extraction cartridge. TTX was separa ted by reverse phase ionpair liquid chromatography, of which ionpair reagent was heptanesulfonic acid sodium salt, then heated with 4 mol·L^-1 NaOH at 110 ℃ in online derivation system. It was converted to C9base with fluorescence characteristic, quantified by fluorescence detector. Good linearity was observed: the linear range was 5-1 600 ng and linear relationship r=0.9997. For the 1, 2, 8 μg·g^-1 spiked samples, withinday and daytoday recoveries were 80.9%-91.2%, RSDs were 1.93%-5.57%, and the limitation of quantification were 1 μg·g^-1. This method was good quality because of no interference peak near the TTX target peak in the chromatogram of spiked sample. When a poisonous Takifugu was detected by post column derivatization HPLC and mouse bioassay simultaneously, the results of the two methods were consistent. From the results of above, detection of TTX in aquatic products by post column derivation HPLC is feasible.

Abstract:In this trial, effect of extrusion process parameters on the physical properties of extruded fish protein using a twin screw extruder was studied employing Response Surface Methodology. As input variables, twinextrusion cooking running parameters examined were barrel temperature in the last zone,screw speed and feed moisture, each at 5 levels. Meanwhile, as output v ariables, physical properties of the resultant extrudates included water content and bulk density. Results showed that moisture content of extrudates were affected intensely by feed moisture, and bulk density was effectively controlled by controlling the feed moisture, barrel temperature and screw rotation speed. Polynomial regression equations of process variables with two physical properties were obtained with R²=1.000, and R²=0.926, respectively. Both of two regression equations were highly credible. It is the first domestic study on the effects of thermoplastic extrusion cooking conditions on physical properties of extruda tes for the case of wet fish protein extrusion cooking. From the results discussed above, it is evident that for the extrusion of products with specific characteristics from wet fish protein, operating conditions can be defined fairly accurately. Variation of barrel temperature, screw speed and feed moisture enables extrudates with specific physical properties to be made for various applications. Moreover, response surface analysis can be seen to provide a quite effective means for the study and optimization of operating conditions in extrusion technology. By extrusion cooking, it is possible to produce products with attractive textures such as textured products with meat structure. Extrusion of proteinrich materials can be used to create various “fabricated\" foods, most commonly meat analogues or extenders. Experience has proven that it must be delivered in forms that fall within the organoleptic limits established by traditional human eating habits. So, by converting low value fish into protein food ingredients, the products should have a functional value in the food systems already familiar to a populace. Texturized fish protein products from low value fish protein by extrusion cooking can be used as meatlike products or meat extenders after rehydration with water or flavored liquids. The investigation of the relationships between chewy properties or eating quality and physical parameters for extrusion texturized fish protein are still unexplored. The work on these issues will be continued.

Abstract:Sea perch embryonic stem cells (LJES1) are undifferentiated cell lines derived from midblastula of sea perch (Lateolabrax japonicus), and retained luripotency in vitro, which provide a unique tool for introducing random or targeted genetic alterations. For improving the transformation efficiency of exogenous gene into LJES1 cells, a simple and effective method of gene ransfer was established with several lipsomes transfection reagents. pCMVEGFP plasmids were transformed by three lipsomes reagents (genejammer, genejuice and metafectene) into LJES1 cells. Expression of green fluorescent protein(GFP) in the cells was detected by fluorescence microscope equipped with mercury burner. For evaluating transformation efficiency, cells expressing GFP in 12well plates were counted under fluorescent microscope. ransformation efficiencies of three lipsomesmediated LJES1 cells were compared, and effects of various factors were examined, such as incubation time of cells, initial incubation density, the doses of DNA and lipsomes, and ratio of DNA and lipsomes, etc. It was demonstrated that the highest transformation efficiency was acquired by genejammermediated GFP into LJES1, which was suitable for transformation of this cell line. For the same kind of lipsome, the ratio of DNA and lipsome for transformation of LJES1 is very important. It was found that 3 μL genejammer and 0.5 μg DNA gave rise to the optimal transfor mation efficiency of 27.3% for cells in 12 well plates with a ration of DNA and genejammer of 1∶6; 4 μL genejuice and 1 μg DNA gave rise to the optimal transformation efficiency of 12.1% with a ration of DNA and genejuice of 1∶4; and 6 μL metafectene and 2 μg DNA gave rise to the optimal transformation efficiency of 5.3% with a ration of DNA and genejuice of 1∶3. The efficiency of transformation increases slightly as the increase of the DNA and lipsomes amount, but decreases after reaching a definite amount. Otherwise, initial incubation density and incubation time of cells affected the efficiency of transformation. 20×104·mL-1 cells in 12 well plates are optimum, which should be 70%-90% confluence. The higher efficiency of transformation arrived in 12 and 30 h after incubation, and cells should be rapid growth. ES cellmediated gene transfer technique will be the most promising approach for producing sitemutated transgenic fishes with enhanced growth rate or disease resistance and in analyzing functions of fish genes. Optimization of onditions for lipsomemediated gene transfer with high efficiency would provide a technical foundation for genetic modifications in vitro.

Abstract:Bacterial flora and identification of dominated spoilage organisms on cultured Pseudosciaena crocea at the end of shelf life during storage at 0 ℃ and 5 ℃ were qualitatively and quantitatively investigated, based on the colony and cellular morphology, biochemical and physiological characteristics as well as wholecell fatty acid composition, and applied with Sensititre，BioFosun，MIDI bacteria identification systems. The dominated bacteria of Shewanella putrefaciens were 75.5% and 59.6% at the end of shelf life at 0 ℃ and 5 ℃,and its colonies on nutrition agar and trypticase soy broth agar were global apophysis, trim side, smooth clarity, achromatism to pink. The cells were gram negative rod［(0.6-0.9) μm×(1.5-3.3) μm］ and motile by means of polar flagellum, the optimum growth occurred at 25-35 ℃ and pH 7-9. Strains were positive for oxidation，H2S，TMAO，gelatin and Tween 40. Strains utilized NacetylD-glucosamine, ect. The dominant fatty acids were 16∶1ω8c, iso15∶0，17∶1ω8c，16∶0, mean contents were 21.31%，13.63%，9. 82%，9.76%， respectively. Results from tested strains were compared with database values in the bacterial identification systems, indicating the dominated spoilage organisms were Shewanella putrefaciens.

Abstract:The changes of 3,5,3'triiodo-L-thyronine (T3) levels during the early developmental stages of orangespotted grouper (Epinephelus coioides) were examined by radioimmunoassay, and the effects of T3 on grouper yolk-sac larvae were studied. The fertilized eggs contained a substantial amount of T3. The levels of T3 in eggs gradually decreased during embryonic and yolksac larval development, and T3 could not be found at first feeding. The decrease of T3 levels in fertilized eggs during development suggests that TH could be utilized to act on the embryonic development and the yolksac larval development of orangespotted grouper. The effect of T3 on larval development was not obvious within 24 hours posthatching(hph), however, the advancement in development of gut was induced by T3 treatment after 24 hph. Compared to the control, the diameter of larval rectum in 0.01 mg·L-1T3 groups was significantly longer but the differences in both the diameter of intestine and the total length of larvae was not significant at 72 hph. Both the diameters of larval intestine and return the rectum in 0.1 mg·L-1 and 1 mg·L-1T3 groups were obviously longer than those in the control, but the total length of larvae was obviously shorter than that in the control at 72 hph. The resorption of yolk sac was accelerated by 1 mg·L-1 of T3 treatment, but that of oil globule was not. The rate of survival in 0.01 mg·L-1T3 groups was obviously higher than that in the control in 8 dph. The results indicated that the action of T3 on development of gut was closely related to developmental stages. The development of larval gut was susceptible to T3 treatment after 24 hph but that was not within 24 hph. The rate of larval survival could be promoted by lower concentration of 0.01 mg·L-1T3 treatment.

Abstract:In recent years, piscine nodaviruses have emerged as major pathogens of a wide range of larval and juvenile marine finfish resulting in high mortality in aquaculture worldwide. Affected fish exhibit a range of neurological signs, such as erratic swimming behaviour with the associated microscopic lesions of necrosis and vacuolation of the central nervous tissues and retina. Numerous roundshaped, unenveloped and 25-30 nm in diameter virus particles were found in the cytoplasm of affected retinal and nerve cells. Nodaviruses have a bipartite genome of positivesense RNA,with RNA1 encoding the RNAdependent RNA polymerase and RNA2 encoding the capsid protein. Both RNA are capped, but not polyadenylated. The family Nodaviridae comprises two genera: Alphanodavirus and Betanodavirus, members of which primarily infect insects and fish, respectively. Therefore, betanodavirus is also named piscine nodavirus. At present, piscine nodaviruses are divided into four genotypes based on partial sequences of the coat protein gene. ELISA and RT-PCR amplification have been developed as specific diagnostic methods for the d etection of the virus. Antibodies to striped jack (Pseudocaranx dentex) nervous necrosis (SJNNV) were found in 65% of plasma samples collected from wild and domestic brood stocks of striped jack, suggesting that the virus is very prevalent. Viral antigens were detected in eggs, larvae, and ovaries of hatcheryreared and wild spawner fish, suggesting both horizontal and vertical modes of transmission of the virus. Selection of nodavirusfree spawners using ELISA for detection of antigens and RT-PCR techniques have successfully reduced incidences of the virus infections in juvenile sea bass (Dicentrarchus labrax),striped jack and barfin flounder (Verasper moseri). The SSN1 and GF cell lines have been successfully used in isolating piscinenodaviruses.Although there are many papers describing the molecular characteristics of betanodavirus, our knowledge of the genomic attributes of these viruses is still limited. Vaccination studies are being undertaken by a number of researchers and need to be fostered. In particular, the use of passive immunization of broodfish with homologous and heterologous, high titre antisera are worthy of investigation.

Abstract:The mudskipper Boleophthalmus pectinirostris is a commercially important fish in China. At present, this species is widely farmed in the southeastern coastal waters of China. Studies have been focused on early development and larval rearing. Early larval feeding habits have been documented. However, little is known about the digestive enzymes at the e arly stage of Boleophthalmus pectinirostris. The purpose of this study was to investigate the digestive enzyme activities of this species in ord er to know its nutritional requirements and establish the feeding protocols for optimizing larval mass rearing production. Changes of pancreatic, intestinal enzymes and pepsin activities in prelarva, postlarva, juvenile and early young fish of Boleophthalmus pectinirostris were investigated by means of enzyme analyses. In order to obtain pancreatic segment (PS) and intestinal segment (IS), juvenile and early young fish were cut into four parts: head, PS, IS and tail. The intestinal segments were homogenized to purify intestinal brush border membranes (BBM). The secretion levels of pancreatic enzymes were expressed as percentages of the segmental activity in the IS related to total activity (PS + IS). The establishment of an efficient intestinal BBM digestion represents the adult mode of digestion by enterocytes. And the degree of purified intestinal BBM was estimated by the enrichment factors and the activities of the intestinal enzymes. The results of this study show that the specific activities of four pancreatic enzymes (amylase，trypsin, chymotrypsin and carboxypeptidaseA) and eight intestinal enzymes (maltase, sucrase, luctase, trehalase, cellobiase, alkaline phosphatase, aminopeptidase and γ-glutamyltranspeptidase) are higher in the larval stage, decrease to the lowest levels in the juvenile stage, and increase rapidly in the early young stage. However, the total enzyme activit ies of individual increase with the development of larvae. Pepsin is initially detected in the postlarval stage, and then it continuously increases rapidly. The percentages of four pancreatic enzymes activities accounting for the total activities are significantly higher in the early young fish than in the juvenile in the intestinal segment. Only three enzymes (maltase, cellobiase and γ-glutamyltranspeptidase) are highly enriched in the intestinal brush bord er membranes in the juvenile. However, enrichment factors of seven intestinal enzymes in intestinal brush border membranes of the early young fish are all above 5.1 except for sucrase. In conclusion, in the larval stage, protein digestion depends on pancreatic enzymes; and when the larvae develope into the juvenile stage, pepsin plays an important role in protein digestion. The complete achievement of the secretion mechanisms of pancreas and maturation of enterocytes in the early young fish indicate the formation of an adult fish mode of digestion.

Abstract:The Hu-IFN-α gene, which was transducted into downstream promoter of β-actin gene of common carp (Cyprinus carpio), was recombined by DNA recombination technology. These recombined genes were injected into 1-2 cell fertilized eggs of grass carp (Ctenophatyngodon idellus) by microinjection technology, we gained transgenetic fish by molecular detection methods. In order to analyse the genetic expression of tranHu-IFN-α gene gynogensis F₁, which male individualization were gained by raising methyltestosterone, molecular genetic marker technology was used. In our research, 30 random primers were picked out from 48 and were used into RAPD-PCR, the result indicated that 1 169 clear, steady and repeated DNA finger printing bands were achieved. On the basis of gentic distance matrix among tranHu-IFN-α gene gynogenesis F₁ group, the genetic relationship of gynogenesis F₁ were analysed by UPGMA, the results showed the genetic patterns are close between the 3# male gynogenesis F₁ and the the 23# female of gynogenesis F₁, 5# and 27#, 2# and 28#, 2# and 30#. The data indicated that these group could be served as parent of tranHu-IFN-α grass carp (Ctenophatyngodon idellus) pure line.

Abstract:Recombinant silkworm (Bombyx mori) nuclear polyhedrosis viruses were applied to express recombinant grass carp growth hormone (r-gGH), which shows similar immunoactivity and bioactivity as natural grass carp growth hormone (GH). To save lots of effort in the downstream work, especially to get rid of the complicated purification of r-gGH, the silkworms expressing r-gGH we used as a foodstuff additive with aims to stimulate growth of juvenile grass carp (Ctenopharyngodon idellus) and to optimize administration conditions for further economic and practical applications in largescaled aquaculture. Silkworms expressing r-gGH were freezedried, ground into powder, mixed with basic foodstuff, and then orally administered to cultured juvenile grass carps in Zhongshan University,Guangzhou. The dietary delivery experiments proved that r-gGH can be absorbed into the circulation and transported to target organs to play its physiological roles. Short-term feeding of r-gGH silkwormcontaining foodstuff (r-gGH scf), compared with feeding of normal silkwormcontaining foodstuff or basic foodstuff, significantly elevated serum GH levels in juvenile fish at 2 h and 6 h post-feeding. Feeding everyday or every 3 days also increased fish serum GH levels, and remarkably improved fish growth. Applying different doses of r-gGH silkworms, 10 or 20 mg·g^-1 diet, caused significant elevation of fish serum GH levels during short (3 days) and long (42 days) treatments. Longterm feeding (for 42 days) of r-gGH scf demonstrated remarkable stimulation on fish growth, with significant increases in relative size growth rate, relative length growth rate, food change efficiency and condition factor. In a word, our studies demonstrated that dietary delivery of r-gGH in r-gGH scf showed GH immunoactivity and bioactivity in cultured juvenile fish; and subsequently resulted in dosedependent increase in fish serum GH level, and stimulation on fish growth. Our work suggests that oral administration of recombinant GHcontaining silkworms in diet is a promising way to accelerate growth rate of cultured fishes in future aquaculture.

Abstract:The growth and reproduction of Daphnia magna fed with Microcystis viridis and Chlorella spp respectively and 20% fish oil + 80% yeast and yeast were studied. The intrinsic rate of natural increase of Daphnia magna (rm) was 0.243 fed with Microcystis viridis, 0.301 with Chlorella spp., 0.244 with 20% fish oil + 80% yeast and 0.193 with yeast. The result showed that：Daphnia magna fed with Microcystis viridis had lower growth rates than that fed with Chlorella spp. an d 20% fish oil + 80% yeast which both had full fatty acids. And the Daphnia magna fed with yeast was the lowest. So the fatty acids composition of diet may affect the growth of Daphnia magna. This paper further examined total lipids and main HUFA (EPA and DHA) compositions of the continuous three generations of Daphnia magna (in order to get rid of t he effects of former diet) fed with different of above diets (except the yeast). The result showed that:the three generations of the D. magna fed with Microcystis viridis had the lowest total lipids and the percentages of the HUFA (EPA, and no DHA) have a significant decrease and get the lowest EPA in the final experiment because of the very low HUFA especially EPA and DHA in Microcystis viridis. So the results indicate that Microcystis viridis with low HUFA made the lower growth rate, spawn ing rate and hatching rate of Daphnia magna.

Abstract:Partial sequences of the mitochondrial cytochrome oxidase unit Ⅱ (COⅡ) gene of 23 species of Cyprinidae amplified by Polymerase Chain Reaction (PCR), and other two species of Cyprinidae from GenBank were treated by Clustal X and analyzed by PAUP 4.0，while selected outgroup was Crossostoma lacustre. 600 bp gene fragment from these species were obtained, in which 250 variable sites were identified, without insertions or deletions. The two types of molecular phylogenetic trees based on the sequences of 25 species with neighborjoining method(NJ) and maximum likelihood method(ML), respectively. The genetic distances among 25 species of Cyprinidae, measured by the kimura2 parameter model, were from 0.018 5 to 0.237 5. The least genetic distance was 0.018 5 between Hemiculter leucisculus and Toxabramis swinhonis, whereas the largest was 0.237 5 between Paracanthobrama guichenoti and Acheilognathus macropterus. Leuciscinae, Culterinae, Cyprininae, Gobioninae, and Acheilognathinae did not form monphyletic group respectively. Leuciscinae was divided into southern group and east Asian group. The southern group of Leuciscinae was monphyletic, while east Asian group of Leuciscinae, Culterinae, Xenocyprinae and Hypophthalmichthyinae formed a monphyletic group. Tinca tinca, Leuciscus leuciscus baicalensis, Abramis bramaorientalis and Rutilus rutilus lacustris formed a monphyletic group, which supported that tinca tinca should be kept in leuciscinae.

Abstract:Hemifusus ternatanus(Gmelin), a gastropoda living in the deep water areas of undertide,as well as a delicious seafood, was distributed mainly in Chinese southeast seas and Japanese seas near the coast. In this experiment Hemifusus ternatanus' breeding ecological conditions and its propagation habit were studied in order to provide an experimental foundation for the artificial breeding. The brood stocks of test animals collected from the waters in Taiwan Strait, and then were examinated their growing temperature， salinity, feeding and propagation habit in the laboratory. The re sults showed that the growing temperature for Hemifusus ternatanus ranges from 16 ℃ to 32 ℃, with an optimum temperature between 20 ℃ to 28 ℃ and between 23 ℃ and 28 ℃ for breeding. The optimum growth salinity was 18.3-32.3 though it much adapts to salinity from 13 to 35. They prefer to feed on bivalves particularly those with thin shells and byssusless. Hemifusus ternatanus is dioecious and fertilization finishes inside the body. It was called as egg vesicle procreation that the whole stages of embryo growth were developed within egg vesicle. Larva forms as soon as it leaves egg vesicle, which is called direct occurrence type. The larva became the juvenile after metamorphosis during 20-25 days development. It was first to obtained 233 juveniles with shell height 32-45 mm by an artificial breeding method.

Abstract:On the basis of purifying effect of single strain probiotic bacteria on water of intensive turbot breeding, the purifying effect of multistrain bacteria product was studied. The results of experiments showed that the free multistrain mixed bacteria had better purifying effect on turbot breeding water than that of any singlestrain bacteria. this phenomenon can be explained with the principle of “ biopump”. The immobilized multistrain probiotics product, biofilm, also showed excellent purifying effect on wate r of turbot breeding. The removal rates of COD and ammonia in 5 days were up to 73.1% and 80.0%, respectively. The concentration of nitrite kept low, which indicated most ammonia had been transformed into nitrate and accumulation of harmful intermediate productnitrite was decreased. This paper supplied theoretical and technical foundation for saving sea water through biopurification of wastewater from marine fish culture.

Abstract:The reproductive biology of marine pulmonate Onchidium sp., such as the copulation and spawning season, reproductive mode, fecundity, hatching and development of fertilized eggs, the effects of water temperature and salinity on embryonic development, the diapause of embryonic development, larval development and premetamophosis etc., were systematically investigated through either laboratory experiment, or field observation in both mollusk hatchery and culture ponds from 2004 to 2005. The results indicated that the marine pulmonate Onchidium sp., was protandrous hemaphrodite, and copulated with one another although the animal was often a functional male before the female organs developed. The main reproductive stocks were thos e of over 10 g in body weight while the smallest individual was the one with 3.1 cm long and 3.5 g in body weight. The reproductive season was usually during a period from the mid May to late September with the water temperature above 22 ℃. The period from June to August was the mating fastigium. The fertilized eggs were laid out in 15 days after courtship and mating, which usually occurred at night in 3 to 5 days during a high tide to low tide. There were often 6 obvious peaks of egg laying. Each egg mass usually contained 44 000 to 80 000 zygotes with a surface area of 15 to 30 cm². The hatching rate of the egg mass were insignificantly different no matter the egg mass were kept in water or in the moist air. It would take 10 to 14 days for hatching under the temperature between 26 ℃ and 35 ℃. The embryo ceased development under 23 ℃. The suitable salinities for embryonic development were between 6 ppt and 20 ppt. The veliger began to feed on microalgae 2-3 days after hatching. The free swimming veliger developed its periostracum of the body after a 23 day pelagic period. There might exist a process for the postmetamorphic larvae to periodically shed a cuticlelike structure from the dorsal body surface. More work still needs to be done to ascertain the condition and process of metamorphosis for pelagic veliger.

Abstract:Since the end of the 20th century, jellyfish Cyanea nozakii Kishinouye bloomed in Northeastern China Sea, the Yellow Sea and the Bohai Sea, and there was tendency for increasing intensity. They have led to the broken net and influenced the fishing season of the East China Sea, the Yellow Sea and the Bohai Sea. The main purpose of this study was to provide taxonomic evidence when investigations of Cyanea nozakii in natural fields were carried out for the forecast of jellyfish blooming. In this paper, morphology of different developmental stages of the scyphozoan Cyanea nozakii was described particularly from fertilizedegg to adult medusa stages. The fertilized eggs develop into a ciliated planulae which form into planoconvex cysts (planulocysis) on attachment prior to forming a polyp. Elongation of the barrowing stalk occurs in the early excystment, flaskshaped in outline gradually becomes newly metamorphosed scyphistoma with four tentacles. They reproduce asexually by two ways including podocyst and stolon. Strobilation is typically monodiscous. Newly liberated ephyra have 8 marginal lobes, 8 rhopalia and 8 pairs of bluntshaped lappets, aberrant specimens with maximum 12 and minimum 6 marginal lobes. In the mean time, morphological difference between ephyra of Cyanea nozakii and ephyra of Rhopilema esculentum are compared. Adult medusa of Cyanea nozakii are about 200-300 mm, maximum size of over 500 mm. Middle of smooth exumbrella is marked by a lot of scattered nematocyst batteries. They have 8 marginal lobes, 8 rhopalia, strong oral canalis carpi, and a lot of long tentacles. By the c haracters of tentacular pouches is connected with sense gastric pouches on the fringe of the umbrella by transverse tube, and peripheral canals with numerous anastomoses, Cyanea nozakii would be distinguished from Cyanea capil lata, Cyanea ferruginea and Cyanea purpurea.

Abstract:The feeding selectivity of Sagitta crassa, some ecological factors effect to the feeding rate and their diurnal feeding rhythm were experimentally studied in this paper. From the results, Sagitta crassa choose Moina mongolica first, second is Calanida, third comes Harpacticoide and never feed on Brachionus plicatilis. There were significant effects of food density. temperature and salinity on the feeding rate of Sagitta crassa. The relational formulas respectively are（1）Y=-0.0394X²+1.5861X-4.0500(R²=0.9235)（2）Y=-0.0514X²+1.3238X+7.3833(R²=0.9510)，（3）Y=-0.0275X²+1.3992X-6.3571(R^2=0.9041).The optimum food dencity for feeding was 100 ind·L^-1 Moina(15～20　mg·L^-1 biomass) In which the feeding rate was 11.9 ind·d^-1 Moina. The optimum temperature of water for feeding was 12.9 ℃ in which the feeding rate was 15.9 ind·d^-1 Moina. The optimum salinity for feeding was 25.4S in which the feeing rate was 11.4 ind·d^-1 Moina. There was more intense grazing behaviors of Sagitta crassa at night or slight light .The feeding rate of Sagitta crassa were minimum 8:00-12:00 and maximum 16:00-20:00.