We investigated the preliminary mechanisms of dissolved aluminum (Al³⁺) on marine phytoplankton through field and laboratory incubation experiments. Results from in situ experiments indicate that dissolved Al decreased the total abundance of micro-phytoplankton by inhibiting the growth of cyanophyta Trichodesmium sp.; the ratio of diatoms and dinoflagellates to total phytoplankton increased, leading to the change of micro-phytoplankton community structure. Whereas, the growth of Synechococcus was promoted after initial inhibition by Al, which resulted in the increasing of total abundance of pico-phytoplankton. Additionally, the stimulatory effects of Al on Synechococcus was observed under semi-continuous culture condition; especially in 20 μmol · L^-1 Al-treated group, the significant promotion of total pico-phytoplankton abundance and growth of Synechococcus were detected (P < 0.05). The growth of Synechococcus and the maximum quantum efficiency of photosynthesis II after long-term cultivation in dissolved Al were promoted by enhancing photosynthesis due to the increase of four photosynthetic pigments including phycoerythrin, phycocyanin, allophycocyanin and chlorophyll a. The higher Al conditions resulted in higher growth rate in exponential phase and biomass in stationary phases as well as intracellular organic carbon accumulation.

We analyzed the effect of Bacillus cereus (algicidal bacteria CZBC1) on microalgae community in shrimp aquaculture water by method of experimental ecology. According to the algicidal bacteria amount,we set Group J0 (0 CFU · mL^-1),Group J3 (3.0×10³ CFU · mL^-1) and Group J5 (3.0×10⁵ CFU · mL^-1) with three parallels. The initial dominances of Oscillatoria chlorine and Oocystis borgei,the dominant species in water,were 64.14% and 16.42%,respectively. The results show that the dominance of O.chlorine in Group J0 was significantly higher than those in Group J3 and Group J5 after 15-day culture (P<0.01),and their dominances were 81.86%,16.7% and 14.6%,respectively. While the dominance of O.borgei in Group J0 was significantly lower than those in Group J3 and Group J5 (P<0.01),and their dominances were 3.13%,32.42% and 47.14%,respectively. The mortality of shrimp in Group J0 was significantly higher than those in Group J3 and Group J5 on the 6^th day (P<0.01),which were 82.2%,46.7% and 31.1%,respectively. Furthermore,the mortality in Group J0 was also higher than those in Group J3 and Group J5 on the 15^th day. The results indicate that algicidal bacteria CZBC1 can inhibit the growth of O.chlorine (Cyanophyta) effectively,which helps occupy the ecological advantage for O.borgei (Chlorophyta),providing better water environment for the growth of shrimp.

The bacterial community composition in the substrate-biofilm shrimp culture system was monitored and investigated by pcr-denaturing gradient gel electrophoresis (DGGE). Results show that: 1) The water flora structure of substrate group was less diversified than that of the control. 2) The similarity coefficient of substrate group increased with time, while that of the control increased first then decreased. 3) Uncultured Firmicutes (Bacillus spp.), the dominant bacteria at the beginning of culture in the control, were uncultured Proteobacteria and uncultured bacterium, and the dominant bacteria at the end of culture was uncultured Firmicutes (Bacillus spp.). Uncultured Firmicutes (Bacillus spp.) and uncultured bacterium were the dominant bacteria throughout the culturing period. The results provide references for clarifying the function and mechanism of ecological control of microbes in artificial substrate system.

We investigated the weight loss, rate of protein loss and cross-sectional morphology of Stichopus monotuberculatus at different temperatures (50 ℃, 60 ℃, 70 ℃, 80 ℃ and 90 ℃) for 10 min, 20 min and 30 min, respectively. Results show that the water content of fresh body wall was about 93.67 %; with the increase of temperature and time, the weight loss beginning at 50~60 ℃ increased gradually; the loss of protein increased steadily, starting from 70~80 ℃. Then the maximum transition temperature of fresh body wall was observed at 73.5 ℃, consistent with the beginning temperatures of weight and protein loss. At last, the cross-sectional morphology of body wall was observed by scanning electron microscope, where the density of collagen fibers network in body wall had increased significantly since 70 ℃ with hollow generating simultaneously. Thus, the cooking condition should be 70 ℃ for 20~30 min, or 80 ℃ within 10 min.

A preliminary comparative analysis of genetic characteristics between F₂ and F₃ hybrid populations of Oreochromis niloticus♀×Sarotherodon melanotheron♂ was conducted by using microsatellite markers from the second generation genetic linkage map of Nile tilapia. The results show that 22 pairs of primers were amplified and no polyploidy individual was detected in F₂ and F₃ populations, seven different amplified loci were screened out in hybrids F₂ and F₃ populations from 28 loci. In F₂ hybrid population, average allele was 2.71;average polymorphic information content was 0.466;observed heterozygosity was 0.632. In F₃ hybrids, the average allele was 2.14;average polymorphic information content was 0.370;observed heterozygosity was 0.432. The genetic heterozygosity of F₃ population was lower than that of F₂ population. In F₃ population, the allele number at four loci was identical with F₂ population, while the allele numbers at three loci were less than that of F₂ population. Moreover, there were two homozygous loci in F₃ population; the change of alleles in F₃ population showed a homozygous trend. The results provide some fundamental data for inheritance of different generations and tilapia hybridization utilization.

To analyze the genetic rule of allometry between body weight and morphological traits for Japanese flounder (Paralichthys olivaceus), we established 19 full-sib families by artificial insemination to observe their body weights and morphological traits at different days of age. We constructed the optimal joint allometry model by stepwise regression method which was then nested into the fixed and genetic effects of animal model for body weight. Furthermore, we analyzed the genetic rules of allometry for multiple morphological traits. The allometric index between body weight and total length presented positive allometry with maximum value of 1.415 5. The allometric index between residual morphological traits and body weight ranged from 0.061 5 to 0.718 0, showing negative allometry. The maximum positive genetic correlation of allometric index between total length and caudal peduncle depth reached 0.907 8, while the highest negative genetic correlation existed between total length and caudal peduncle length (-0.946 8). Comparing different models by the statistic criteria, Model Ⅰ is the optimal regression model for dynamic allometric analysis.

Three introduced populations of Litopenaeus vannamei were used to establish nine inbred and hybridized populations of F₁ by complete diallel cross, whose hypoxic tolerance and ammonia-N tolerance were compared. The performance for tolerance of each population was evaluated by analyzing combining ability and heterosis of hypoxic tolerance and ammonia-N tolerance. The results reveal that nine groups showed significant difference in tolerance to dissolved oxygen and ammonia nitrogen. Mid-parent heterosis of hybrids for resistance to high ammonia nitrogen and low dissolved oxygen traits were 14.09~42.57 and -52.48~31.39, respectively, while those of heterobeltiosis were 1.860~26.18 and -54.34~24.66, respectively. The general combining ability of parents and special combining ability of hybrid combinations influenced the tolerance performance of phybrid offspring, especially that UH group had higher general combining ability in tolerance traits of high ammonia nitrogen and low dissolved oxygen. The specific combining ability analysis reveals that UM×UH, which had stronger non-additive effect and hybrid superiority, was strong heterosis combination and could be used as candidate materials for further family selection.

We cloned IGF-Ⅲ gene from Protonibea diacanthus by RACE method. The length of cDNA was 1 184 bp. The homologous analysis of deduced protein shows that the identity of IGF-Ⅲ gene and Oreochromis niloticus was 58.0%. Compared with IGF-Ⅱ and two subtypes of IGF-Ⅰof P.diacantus, the identities were 21.9%, 26.2% and 25.2%, respectively. Phylogenetic tree analysis shows that IGF-Ⅲ tended to cluster with IGF-Ⅱ firstly and then cluster with IGF-Ⅰcomposing IGF family, and finally IGF family clustered in the same branch with Insulin. Tissue distribution shows that IGF-Ⅲ was widely expressed in heart, gonad and brain of P.diacanthus, especially highest in gonad. Quantitative real-time PCR analysis reveals that the expression of IGF-Ⅲ in testis was significantly higher in developing phase than that in the others, showing a significant decline. The expression of IGF-Ⅲ in ovary of maturation phase was also remarkably higher than that in other periods. Besides, the expression of IGF-Ⅲ in forebrain, midbrain and hindbrain in female fish in mature phase was higher than that in other periods. However, IGF-Ⅲ expression pattern was different in male fish. It is suggested that IGF-Ⅲ might be important for the development of testis and maturation of ovary, and forebrain might involve in the feedback regulation of IGF-Ⅲ expression in gonad.

Cyclin T is a critical factor that stimulates the process of transcription elongation. We obtained the full-length cDNA sequence of cyclin T from black tiger shrimps (Penaeus monodon)(denoted as Pmcyclin T) by RACE PCR. The cDNA of Pmcyclin T was 3 421 bp, encoding a polypeptide of 1 044 amino acids. Bioinformatics analysis shows that the amino acid sequence contained a CYCLIN conserved region of a periodic protein family as well as N-glycosylation sites and phosphorylation sites. The results of Blast and phylogenetic analyses suggest that Pmcyclin T shared very high homology with other kinds of arthropod such as Diaphorina citri, Acromyrmex echinatior and so on. Besides, we measured the mRNA expression of Pmcyclin T in seven tissues by real-time PCR. Expression was highest in the ovary and moderate in the intestine, brain and so on. While at different stages of ovary, Pmcyclin T was highest expressed at Stage Ⅲ, suggesting that Pmcyclin T might play an important role in ovary development of black tiger shrimp.

We cloned the sialic acid-binding immunoglobulin superfamily lectin Siglec-4b like gene from neutrophilic granulocyte of Oreochromis niloticus, and then analyzed its sequence by bioinformatics approach and detected its mRNA expression levels during embryonic development and in tissues before and after artificial infection of Streptococcus agalactiae (GBS) by qPCR. The analysis shows that Siglec-4b like had specific domains and conservative amino acid residues similar to mammalian Siglec-4. During the embryonic development, a certain amount of Siglec-4b like expressed in eggs, and the expression increased after fertilization. As embryo developed, the expression continued to rise and reached the maximum amount at 7 hpf and then decreased gradually. Siglec-4b like mRNA was ubiquitously expressed in all the tested tissues of tilapia, and the expression levels were relatively high in gill, muscle, skin, head kidneys and intestines but very low in the other tested tissues. After being infected with GBS, the expression of Siglec-4b like in gill, head kidneys, intestines, muscle and skin decreased. The results provide references for further research on immune escape mechanism of GBS and regulation effect of Siglec-4b like on tilapia immune system.

We screened the ubiquitin/ribosomal S27 fusion protein (PmUbS27) from hepatopancreas transcriptome data of Penaeus monodon and cloned the full-length PmUbS27 cDNA sequence by SMART-RACE technology. Besides, we studied the expression of ovaries of PmUbS27 gene at different developmental stages and in different tissues by real-time quantitative detection. The PmUbS27 cDNA was 514 base pairs (bp) long, containing a 3′-UTR of 39 nucleotides and a 465 bp open reading frame (ORF) encoding a 154 amino acid polypeptide. The PmUbS27 protein contained the conserved Ub domain and ribosome structure. The DNA-cloned gene sequence consisted of four exons and three introns. PmUbS27 mRNA was ubiquitously detected in all tested tissues, comparatively high in the ovary, hepatopancreas and lymph. The expression level of PmUbS27 mRNA was significantly higher in ovary at Stage Ⅱ and Stage Ⅴ (P < 0.05). It is showed that PmUbS27 had an important role in oogenesis of P. monodon.

We investigated the effect of dietary graded level of Gracilaria lemaneiformis on the growth performance, fatty acid composition, body composition, immunity and intestinal histology of red drum (Sciaenops ocellatus) [initial weight (9.38±0.06) g].Six isoproteic and isolipidic diets (crude protein: 41%;crude fat: 10%) were formulated containing 0%, 1%, 2%, 3%, 4% and 5% G. lemaneiformis. After eight weeks of feeding, no significant difference was found in survival, weigh gain (WG) and specific growth ratio (SGR) (P>0.05), but weight gains in 1%~4% groups were higher than that in the control whereas 1% group had the highest feed efficiency and SGR among all treatments. The concentrations of docosahexaenoic acid (DHA) were significantly higher in 5% group than that in the control (P < 0.05). Meanwhile, the liver superoxide dismutase (SOD) in 4% group was significantly higher than that in the control (P < 0.05);well-developed intestinal villi was presented in 3% addition group. The results indicate that dietary supplementation of G. lemaneiformis can improve the growth as well as liver and intestinal health, increasing whole fish DHA content.

According to the data collected from four seasonal trawling surveys between 2012 and 2013 in the waters surrounding the Taishan Islands, we made a list of fish species in this area and calculated its taxonomic diversity by PRIMER 5.0. We identified 208 fish species including 2 classes, 20 orders, 81 families and 150 genera in the waters around Taishan Islands, with Perciformes being the major order. According to the survey data from 2012 to 2013, 77 fish species including 2 classes, 11 orders, 40 families and 63 genera were identified. The average taxonomic distinctness (△⁺) and variation in taxonomic distinctness (∧⁺) of fish species listed in that area were 63.14 and 378.4, respectively. The taxonomic diversity (△) and taxonomic distinctness (△^*) were higher in autumn and spring than in summer and winter. It is concluded that the species in spring was more than that in summer and autumn, and was the least in winter. Water temperature and food were the main factors which affect fish species composition.

We applied paraffin section method to investigate the reproductive features for female bigeye tuna (Thunnus obesus) in the southern Pacific Ocean (SPO), using ovarian tissues sampled at sea during 2010~2013. Maturity stage and fecundity were estimated under a microscope. The results show that the development of ovary was divided into five stages: 1 (immature), 2 (maturing α), 3 (maturing β), 4 (ovulating) and 5 (ovulated). Female gonad somatic index (GSI) ranged from 0.26 to 8.58 (average 3.56), increasing with the increase of fork length. Length at 50% maturity was 116.32 cm. Average batch fecundity was 1.09×10⁶ pcs, and average relative fecundity was 20.5 pcs · g^-1. Cluster analysis shows that there were three classes in terms of similarity in catch depth, i.e., Stages 2 and 3, Stages 1 and 4, and Stage 5. It is suggested that bigeye tuna reached first sexual maturity at earlier ages in SPO than in other areas, probably due to overfishing.

Based on the investigation data of gillnets of three different structrues (single wall, double wall, trammel gillnet) of different mesh sizes (40mm, 50mm, 60mm) in the Pearl River Estuary coastal waters in September of 2014, we analyzed the resources community structure of gillnet fishery. The results indicate that the species number, total number and weight of the three kinds of gillnets decreased with increasing mesh size. The species with index of relative importance (IRI) above 1 000 were defined as dominant species, but Nemipterus bathybius was the same dominant species. Since the fish body size varied remarkably, we calculated Margalef richness index, Shannon-Wiener index, Simpson index and Pielou evenness index based on individual number and biomass. T test shows significant difference among diversity indices. The Euclidian distance shows significant difference in community structure of gillnet fishery of different mesh sizes, but no significant difference was found in the same mesh size. Thus, controlling appropriate mesh size is currently the most effective measure to increase fish diversity and resume the stabilization of ecosystem.