Population Structure and Diversity of Plankton in the Wetland of Qilihai in Tianjin

The population structure and diversity of plankton in the wetland of Qilihai in Tianjin was investigated in May, July and September, 2012 by fi eld investigation and sampling examination. The results showed that there were 44 species of phytoplankton belonged to 6 phyla, including 11 species of Cyanophyta, 18 species of Chlorophyta, 8 species of Bacillariophyta, 4 species of Euglenophyta, 1 species of Pyrrophyta and 2 species of Cryptophyta. There were 13 genus and 22 species of zooplankton, among which 4 genus and 4 species belonged to Cladocera; 2 genus and 2 species belonged to Copepoda; 7 genus and 16 species belonged to Rotifera. The investigation results of density and biomass of plankton in May, July and September showed that the density and biomass of phytoplankton was shown as September>July>May, and that of zooplanktonic was shown as May>September>July. In addition, the diversity of phytoplankton and zooplanktonic were evaluated using Shannon-Wiener index, and the results demonstrated that the phytoplankton species were rich in May, July and September, while the zooplanktonic species were poor in May and general in July and September. There were explicit relationships between the diversity characteristics of plankton and nutrient pollution which caused water eutrophication, and the extent of water eutrophication in the different months was also shown as May>July>September.

Technique for Ecological Pond Breeding of Charybdis japonica

In 2016 and 2017,the ecological pond breeding experiment of Charybdis japonica was carried out,with a total of experimental area up to 4 ha.Through two years of experimental research,it obtained a total of 48950 kg of C.japonica,with an average output of 12237.5 kg/ha.The production output value was 2.3675 million yuan,the total production cost was 831700 yuan,the net profit was 1.5358 million yuan,the average profit was 384000 yuan/ha,and the input-output ratio was 1∶2.85.The average proportion of C.japonica population with a production weight of 150 g or more was 7.9%.The proportion of the group of 120-150 g was relatively large,with an average of 80%in two years,and the proportion of the group below 120 g was relatively small,with an average of 12%in two years.The cumulative harvest of shellfish in two years was 65700 kg,with an average output of 16425 kg/ha,the production output value of 738100 yuan,the production cost of 295500 yuan,the net profit of 442600 yuan,and the average profit of 110700 yuan/ha.

Enzyme responses and lipid peroxidation in gills and hepatopancreas of clam Mactra vereformis, following cadmium exposure

To assess the toxicity of heavy metal pollution to marine intertidal shellfish, enzymatic responses and lipid peroxidation were investigated in the clam Mactra vereformis exposed to cadmium under laboratory conditions. Three antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPx), two immune defense enzymes (acid phosphatase, ACP; alkaline phosphatase, ALP), and one lipid peroxidation product (malondialdehyde, MDA) were measured in the gills and the hepatopancreas of the clam exposed to 0, 25, 75, and 125 μg/L cadmium for 0, 1, 3, 5, and 7 d. The results show that the concentrations of antioxidant enzymes in the organs soared to a peak value on the first day and then decreased afterwards in most cases. CAT and GPx activities in the hepatopancreas were higher than in the gills, but the SOD activity was lower in the hepatopancreas. ACP activity was unchanged until Day 3 in the hepatopancreas and until Day 5 in gills, when it began to increase. ALP activity showed no significant relationship with Cd treatment. MDA concentrations increased in the two tissues after Cd exposure, peaked on Day 3 in gills, and on Day 5 in hepatopancreas. These observations show that changes in the activities of antioxidant enzymes and ACP reflect the time course of oxidative stress in the clam caused by Cd, and could be used as potential biomarkers for ecotoxicological bioassays of heavy metals.

Hematological Changes in White Spot Syndrome Virus-Infected Shrimp,Fenneropenaeus chinensis(Osbeck)

The pathological changes of hemocytes in the haemolymph and hepatopancreas were examined in experimentally and naturally WSSV(white spot syndrome virus) infected Fenneropenaeus chinensis. The results showed that the pathological manifesta-tions of hemocytes were similar among moribund shrimps infected via injection,feeding and by nature. Firstly,the total hemocyte counts(THCs) in WSSV-infected shrimp were significantly lower than those in healthy shrimp. Secondly,necrotic,broken and dis-integrated cells were often observed,and a typical hematolysis was present in the haemolymph smear of WSSV-infected shrimp. Thirdly,necrosis and typical apoptosis of hemocytes were detected with TEM in the peripheral haemolymph of WSSV-infected shrimp. Hyalinocytes and semi-granulocytes with masses of WSSVs in their nuclei often appeared,whereas no granular hemocytes with WSSV were found in the hepatopancreas of moribund infected shrimps. All our results supported that hemocytes were the main target cells of WSSV,and hyalinocytes and semigranular hemocytes seemed to be more favorable for WSSV infection in F. chinensis.

Effects of salinities on the growth and nutrient composition in the muscle of Exopalaemon carinicauda

The effect of salinity on the growth and muscle nutritional quality of theExopalaemon carinicauda was studied through testing the survival rate, specific growthrate, muscle nutrient composition, amino acid composition and content by the culturingin different salinities(0-30).The results showed that the survival rate of salinity (0-30)had no significant difference (P>0.05), and the specific growth rates at salinity 15 andsalinity 20 were significantly higher than others(P>0.05); the muscle moisture contentand the crude fat content significantly decreased(P<0.05), while the muscle crudeprotein content significantly increased with an increase in the environment salinity from0 to 30(P <0.05).The crude ash content with salinity increase had a slight increase; themuscle crude protein content (18.2) at salinity 15 was significantly higher than that atsalinity 0,5, or 10(P <0.05), but there was no significant difference between salinity 15and salinity 20(P>0.05). No significant difference was found in total amino acid contentor total essential amino acid content from salinity 0 to 30(P>0.05). Total delicious aminoacid content at salinity 15-30 was significantly higher than those at salinity 0-10(P<0.05), while there was no significant difference from salinity 15 to 30(P>0.05). Theresults suggest that the suitable salinity for muscle nutritive value ranges from 15 to 30,and the Exopalaemon carinicauda can potentially be cultured above the salinity 15.

Tintinnid community throughout the Bohai Sea during the spring

As one of the important microzooplankton in marine pelagic habitats,tintinnids are classified as neritic genera,oceanic genera and cosmopolitan genera.Until now,we know little about the interaction between neritic and oceanic genera in continental shelves.Low species richness area was found in the mixing area between neritic and oceanic genera in the East China Sea.In this study,we investigated the spatial distribution of tintinnid community throughout the entire Bohai Sea in May(spring)of 2014 to find out:(1)whether the tintinnid assembalges differed in the three major bays bordering this shallow inland sea;(2)whether there was low species richness area in the Bohai Sea.Three genera and 11 species attributed to neritic and cosmopolitan taxa were reported from this region.Tintinnid abundance averaged(81±216)ind./L(0–1234 ind./L).Tintinnid community differed within the three major bays,with each characterized by different tintinnid taxa.Referring to the average abundance of three bays,tintinnids were most abundant in the Laizhou Bay((328±445)ind./L),and least abundant in the Liaodong Bay((34±57)ind./L).A low species richness area occurred in the central Bohai Sea(20–40 m isobaths),in some stations of which no tintinnid was recorded.Our study demonstrates that tintinnid community varied greatly over small spatial scales,and low species richness area was found in the mixing area between neritic and oceanic genera within this inland sea.

Immunogenicity and protective role of antigenic regions from five outer membrane proteins of Flavobacterium columnare in grass carp Ctenopharyngodon idella

Flavobacterium columnare causes columnaris disease in freshwater fi sh. In the present study, the antigenic regions of fi ve outer membrane proteins(OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 k Da, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purifi ed recombinant protein was used to vaccinate the grass carp, C tenopharyngodon idella. Following vaccination of the fi sh their Ig M antibody levels were examined, as was the expression of I g M, Ig D and Ig Z immunoglobulin genes and other genes such as MHC Iα and MHC I I β, which are also involved in adaptive immunity. Interleukin genes( IL), including I L- 1β, IL- 8 and I L- 10, and type I and type II interferon(I FN) genes were also examined. At 3 and 4 weeks post-vaccination(wpv), signifi cant increases in Ig M antibody levels were observed in the fi sh vaccinated with the recombinant fusion protein, and an increase in the expression levels of I g M, Ig D and Ig Z genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fi sh. At four wpv, the fi sh were challenged with F. column a re, and the vaccinated fi sh showed a good level of protection against this pathogen, with 39% relative percent survival(RPS) compared with the control group. It can be concluded, therefore, that the fi ve OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fi sh and protection against F. columnare.

Genetic Differentiation Among Populations of Octopus minor Based on Simple Sequence Repeats Mined from Transcriptome Data

Octopus minor(Sasaki 1920)is an important commercial cephalopod species in China.This species has declined sharply in recent years.Hence,genetic studies of O.minor are imperative to exploit and manage the wild resource.In this study,46192 microsatellite loci were discovered in 70174 unigenes from the transcriptomic data.Among all of the simple sequence repeat(SSR)unit categories,di-nucleotide and tri-nucleotide SSRs accounted for 45.26%and 14.49%,respectively.A total of 108 SSRs were tested,of which 21 were neutral and polymorphic.Seven SSRs were selected for genetics analyses of the O.minor populations in the Bohai Sea,the Yellow Sea,and the southwest coast of the Taiwan Strait region.Significant pairwise F_(st) values were detected among the samples.The UPGMA tree based on genetic distances suggested that the sampling locations could be arranged in three clusters.These markers are evidence that the populations in this region may be structured,with samples from Penghu differing remarkably from those in northern China.The present study characterized genetic markers for population assessment,management,and conservation of O.minor.

High-quality chromosome-level genome assembly of redlip mullet(Planiliza haematocheila)

In the present study,we successfully assembled a high-quality genome of Planiliza haematocheila(redlip mullet)based on Oxford Nanopore long read,single-tube long fragment read(stLFR),and Hi-C chromatin interaction sequencing.The size of the P.haematocheila genome was 652.91 Mb.More than 93.8%of BUSCO genes were detected,and the N50 lengths of contigs and scaffolds reached 7.21 Mb and 28.01 Mb,respectively,thus demonstrating outstanding genome completeness and sequence continuity.A total of 21045 protein-coding genes were predicted in the assembled genome,and 99.77%of those genes were functionally annotated.Comparative genomic and phylogenetic analyses revealed the adaptability of P.haematocheila to complex living environments at the genomic level,highlighting its broad adaptability and resistance to multiple stresses as an important economic fish.The high-quality reference chromosome-level genome of P.haematocheila provides a powerful genomic resource for further systematic study of Mugilidae.

The Effects of Growth Performance and Organosomatic Indices of Atlantic Salmon Juvenile by Using Different Carbohydrate-to-Lipid Ratios in Feeds

The effect of different carbohydrate-to-lipid ratios in feeds on the growth performance and organosomatic indices of Atlantic salmon, Salmon salar, was determined in this experiment. Four iso- energetic feeds were manufactured with increasing carbohydrate level (18%, 21%, 14%, 26%). Lipid level was decreasing from 14% to 11% for each diet for energetic balance. Fish were reared in triplicate tanks for each diet treatment for 49 days. The diet which contained 26% carbohydrate and 11% lipid provided the highest specific growth rate (SGR = 0.66% ± 0.04% per day) to the fish. However, the feed efficiency (FER) ranked from 0.71 to 0.91 had no significant differences between diets. Similarly, the values of condition index (K), relative gut length (RGL) and hepatosomatic index (HSI) had no significant differences between groups. The relationship between liver and carcass weight showed that with the increasing of fish carcass weight, the liver weight increased. According to this experiment, it suggests that based on an optimum level of carbohydrate in diet, the juvenile salmon has a better growth fed by a diet with a higher carbohydrate-to-lipid ratio.

Immunogenic proteins and their vaccine development potential evaluation in outer membrane proteins(OMPs)of Flavobacterium columnare

Flavobacterium columnare is a Gram-negative bacterium that causes columnaris disease in freshwater fish worldwide.Many studies have focused on the identification of protective antigens to aid in the development of novel vaccines against the disease.In this study,an immunoblotting approach was employed to identify immunogenic outer membrane proteins(OMPs)from F.columnare in two-dimensional electrophoresis(2-DE)map gels using antibacterial sera obtained from grass carp(Ctenopharyngodon idella),and anti-grass carp-recombinant Ig(rIg)monoclonal antibodies.Five unique immunogenic proteins,including the gliding motility lipoprotein GldJ(GldJ),hypothetical protein FCOL_13420(Fco1),lipoprotein(Lip),F0F1 ATP synthase subunit beta(F0f1)and outer membrane efflux protein precursor(Omep),were characterized.Over-expression of these proteins in Escherichia coli DE3,and their immunogenicity and protective efficacy were evaluated in grass carp.The relative percent survival(RPS)of the groups immunized separately with recombinant GldJ,Lip and Omep was 72%,64%and 68%,respectively when compared to control fish.Up-regulation of immuno-related genes and specific antibodies were detected in immunized fish and sera of immunized fish inhibited the growth of F.columnare.The results suggest that GldJ,Lip and Omep are major protective antigens and may be considered as novel candidates in the development of vaccines against columnaris disease in fish.

Effects of dietary supplementation of Lactobacillus plantarum and Bacillus subtilis on growth performance,survival,immune response,antioxidant capacity and digestive enzyme activity in olive flounder(Paralichthys olivaceus)

In present study,a 10-month feeding trial was carried out to investigate effects of dietary Lactobacillus plantarum and Bacillus subtilis supplementation singly on growth performance,innate immune response,antioxidant capacity and digestive enzyme activity of olive flounder under a commercial production environment.Two experimental groups fed basal diet with supplementation of L.plantarum(5.0×107 CFU/g diet)and B.subtilis(1.0×108 CFU/g diet)respectively,and control group fed with basal diet without probiotics supplement.At harvest,serum immune parameters,liver antioxidant indices and digestive enzyme activities in liver,stomach and intestines were measured.Fish fed with B.subtilis supplemented diet showed the highest growth rate which was significantly higher than L.plantarum supplemented group(P<0.05)which was also significantly higher than control group(P<0.05).Survival rate were significantly elevated by feeding diet with L.plantarum supplementation(P<0.05),while the improvement was not significant for B.subtilis supplemented diet compared to control group.All the studied immune parameters in serum were substantially enhanced in both experimental groups.Similar results were observed for the antioxidant capacity in liver.Besides,the activities of digestive enzymes increased substantially in both experimental groups compared to control group and the detected improvement in dietary B.subtilis supplemented group were all higher than in L.plantarum supplemented group,though not all the improvements were significant.In summary,the separate supplementation of B.subtilis and L.plantarum in diet is more beneficial for growth performance and healthy status respectively.Hence,in olive flounder aquaculture,favorable effects of compounded supplementation of L.plantarum and B.subtilis are expected.

Effects of low and high levels of nano-selenium on intestinal microbiota of Chinese tongue sole(Cynoglossus semilaevis)

Nano-selenium(Se)has attracted growing attention due to its high bioavailability,low toxicity and its possible applications in the prevention of oxidative damage in animal tissues.Recent research works have conveyed that the use of nano-seleniumas food additive could have positive effects on the nutrition of aquatic animals.In this study,the intestinal bacterial communities associated with low and high concentrations of nano-selenium in the diet of Chinese tongue sole were characterized,through 16S rRNA V3–V4 sequencing.Samples were derived from fish fed with diet containing different nano-selenium level,0 mg/kg for the control group,1.6 mg/kg for low dose group,and 2.4 mg/kg for high dose group The intestinal microbial community structure showed a low overall diversity,among which the vibro genus occupied the most important position with more than 90%relative abundance in all three group.Significant differences in specie diversity occurred between the nanoselenium treated(both low dose[IL]and high dose[LH])groups and the control group(IC).Acinetobacter,Arthrobacter,and Streptophytes were the top three enriched genera after the treatment with nano-selenium compared to IC.Meantime,the weight gain rate of the LH group was 9%higher than control.The results revealed the effect of nano-selenium on microbial community structure of gut and growth performance of C.semilaevis,Future research exploring the interaction mechanism between micronutrients and the microbial communities would increase our understanding of the fish nutrition.