侧孢短芽孢杆菌溶藻活性代谢产物对虾池颤藻的溶藻效果

为改善对虾养殖水环境,研究了不同阶段的侧孢短芽孢杆菌无菌滤液和颤藻对溶藻效果的影响.通过测定溶藻过程中藻体干重、叶绿素a含量以及藻蓝蛋白含量,探究了溶藻效果的最佳作用阶段及其作用机理.结果显示,稳定期和衰亡期的无菌滤液对颤藻的溶藻效果极为显著,7d后颤藻干重分别减少了51.77％、47.04％,叶绿素a含量分别降低了67.60％、59.13％,藻蓝蛋白含量分别增加了33.51％、30.97％;溶藻细菌无菌滤液对延滞期颤藻的溶藻效果极显著,7d后颤藻干重减少了63.90％,叶绿素a含量下降了69.72％,藻蓝蛋白含量升高了54.17％.结果表明,侧孢短芽孢杆菌培养至稳定期的无菌滤液对延滞期颤藻的溶藻效果最好.     

Effect of inoculation of the cyanobacteria Oscillatoria sp. on tilapia biofloc culture

Cyanophytes are the most ancient photosynthetic organisms. During its evolution, they have developed various ecophysiological adaptation strategies to survive in extreme conditions. The environment prevailing under biofloc cultures provides various conditions appropriate for cyanobacterial proliferation. An outdoor experiment (7 weeks) was performed with a simple random design consisting of four inoculation levels (by triplicate) of Oscillatoria sp. (0.0, 0.1, 0.5 and 1 mg L^?1) in saltwater biofloc. The objective was to evaluate the effect of the cyanobacteria inoculation on water quality and tilapia production parameters. The results indicated that the amount of Oscillatoria sp. inoculated significantly affected water quality (pH, chlorophyll a, TSS and NO₃‐N) and tilapia parameters (final weight, feed conversion ratio, specific growth rate and survival). No significant effects on dissolved oxygen, total ammonia nitrogen (TAN) or NO₂‐N were observed. We recommend identifying the cyanobacteria species that are able to grow in a biofloc system and their possible adverse effects on the system.     

颤藻对凡纳滨对虾生长和免疫相关酶活力的影响

颤藻(Oscillatoria sp.)是对虾养殖水体中的一种常见蓝藻。通过在凡纳滨对虾养殖水体中投加不同浓度的颤藻,测定凡纳滨对虾的成活率与体长、体重,以及不同颤藻浓度下凡纳滨对虾的免疫相关酶活力,研究颤藻对凡纳滨对虾生长和免疫酶活力的影响。结果表明:颤藻对对虾的成活率、体长和体重有显著影响(P<0.05),随藻浓度增加对虾的成活率、体长和体重呈下降的趋势。颤藻对对虾超氧化物歧化酶(SOD)、过氧化物酶(POD)、酚氧化酶(PO)、碱性磷酸酶(ALP)、谷胱甘肽S-转移酶(GST)、抗菌活力影响显著(P<0.05),低浓度的颤藻诱导酶活力增大,当浓度大于12.5 mg/L时,其酶活力呈下降的趋势。当颤藻浓度为2.5 m g/L和12.5 mg/L时,GST、ALP活力分别达到最大值(39.05 U/mg、73.62 U/g)。以上研究结果说明,颤藻具有一定的毒性,低浓度的颤藻可诱导酶活性增加,高浓度的颤藻能抑制酶的活性和对虾生长。为了保证凡纳滨对虾的健康养殖,养殖水体中的颤藻浓度应该控制在12.5 mg/L以下。     

密斯特黄彩鲶人工繁殖与胚胎发育的研究

从海南省山溪中捕捞收集到野生密斯特黄彩鲶,在池塘养殖条件下培育到性成熟,于2008年4月至10月,3次对其进行了人工繁殖和胚胎发育的系统研究。结果表明,密斯特黄彩鲶受精卵呈圆球形,透明,略带淡黄色。卵径平均1．0mm,沉性,有黏性,属黏性卵。黄彩鲶胚胎发育过程分为7期,包括受精卵阶段、卵裂期、囊胚期、原肠胚期、神经胚期、器官形成期、孵出期,历时约25h,胚胎发育总积温约为693．7h·℃。     

Influence of Nitzschia sp. on release of nitrogen and phosphorus from sediment in pond breeding sea cucumbers

Due to the tonic and nutritive virtues of sea cucumbers, increased commercial aquaculture has resulted in the expansion of breeding ponds, a primary form of sea cucumber production. Expansion of such production methods has led to increased settling of organic wastes onto the seabed, resulting in enriched sediments. Nitzschia sp. serves as an edible sea cucumber feed. Release characteristics of nitrogen (N) and phosphorus (P) from sediments in the presence of different biomass densities of Nitzschia sp. were studied via laboratory static cultures. pH and dissolved oxygen (DO) in the overlying water and biochemical components (i.e., protein, chlorophyll a) of Nitzschia sp. were assessed. When the biomass of Nitzschia sp. was more than (2–5) × 10⁴ ind/cm², the release of N and P nutrients was significantly promoted; additionally, the DO content of the overlying water was relatively high and the pH was relatively stable, which favoured the accumulation of proteins and chlorophyll a in Nitzschia sp. The results indicated that Nitzschia sp. promotes the release of N and P in sediments while absorbing them to maintain their own growth and promote the accumulation of nutrients, such as proteins, for the sea cucumbers. At the same time, the algae release oxygen, increasing the DO of the overlying water, providing a healthy breeding environment for the sea cucumbers. Application of Nitzschia sp. has the potential to reduce environmental harm caused by sea cucumber cultivation and thus achieve sustainable aquaculture.     

Antibacterial activity of immobilized silver nanoparticles on TEPA‐Den‐SiO2 against shrimp pathogen,Vibrio sp. Persian1

In this study, we prepared silver nanoparticles immobilized onto silica sand beads as an antibacterial material against pathogenic luminous Vibrio sp. Persian1. Silica beads were modified with 3‐aminopropyltriethoxysilane (APTES), cyanuric chlorid and tetraethylene pentamine, and silver nanoparticles were generated in various concentrations (0.5, 1, and 2 mM g^?1 of silica beads) of AgNO₃ on the surface using chemical reduction. Ag/TEPA‐Den‐SiO₂ samples were characterized by TEM, FE‐SEM/EDS, FT‐IR and ICP OES and their antibacterial activity assayed by zone of inhibition and test tube tests against pathogenic Vibrio sp. The results of the zone inhibitory test revealed that all the Ag/TEPA‐Den‐SiO₂ samples had an antibacterial effect against luminous Vibrio sp. Persian1. In addition, the tube test results showed 100% killing of bacteria in 2 h contact period. Ag/TEPA‐Den‐SiO₂ samples maintained their antibacterial activity after 14‐day immersion in seawater by slow release of silver ions. These results suggest that Ag/TEPA‐Den‐SiO₂ substrates could be effective antibacterial materials for disinfection of seawater used to culture Penaeid shrimp larvae.     

Effects of dietary Nannochloropsis sp. powder and lipids on the growth performance and fatty acid composition of larval and postlarval kuruma shrimp,Marsupenaeus japonicus

The current study evaluated the effects of fish oil replacement with eicosapentaenoic acid‐enriched single‐cell microalgae in the diets of larval and postlarval kuruma shrimp. Experimental diets containing different level of Nannochloropsis sp. powder (10, 40, 70 g/kg) and lipids (2, 8, 10, 14, 35, 58 g/kg) were evaluated. The substitution of fish oil with algal powder significantly improved shrimp growth compared to that in the control group, with the highest final body weight recorded at 70 g/kg in larvae and 40 g/kg in postlarvae. Larvae fed algal lipids with a dry weight percentage in the diet of greater than 10 g/kg showed significantly lower performance than those in the control group. The neutral lipids in the tissue of the postlarvae that had been fed algal lipids had an improved fatty acid profile, as the content of highly unsaturated fatty acids increased compared to that in the other groups. The content of docosahexaenoic acid increased in the tissue, indicating the possible occurrence of the metabolism and accumulation of Nannochloropsis sp. essential fatty acids. Algal powder could replace FO up to 140 g/kg in shrimp diets without compromising growth and FA profiles.     

理化因子对原绿球藻生长及其色素含量的影响

以COA为基础培养基,进行了光照、温度、盐度等理化因子对原绿球藻生长和色素含量影响的单因子试验。试验结果表明,原绿球藻适宜生长的光照度为500～2500lx,最适光照度为500～1000lx：适宜生长的温度为10～30℃,最适温度为25～30℃;适宜生长的盐度为0～44．9,最适盐度为13．7～33．4;适宜生长的pH5～11,最适pH8～10;最适氮源为NH4-N,其次为（NH2）2CO;适宜生长的氮（NH4Cl）质量浓度为5～25mg／L,最适质量浓度为15～25mg／L。理化因子对该藻色素含量的影响与其生长相吻合。     

Evaluation of growth,feed utilization efficiency and immune parameters in tiger shrimp (Penaeus monodon) fed diets supplemented with or diet fermented with gut bacterium Bacillus sp. DDKRC1. isolated from gut of Asian seabass (Lates calcarifer)

An experiment was conducted to assess the effect of supplementation of cellulolytic gut bacterium with plant protein‐based diet on growth, digestibility and digestive enzyme status of tiger shrimp, Penaeus monodon. Bacillus sp. DDKRC1. (JN641289), a potential cellulolytic bacterium, isolated from the gut of Asian seabass was used as feed supplement in this experiment. The shrimps of group I, II and III were fed with control diet (without bacterial supplement, D1), diet supplemented with live Bacillus sp. DDKRC1. at 2.94 × 10⁷ cfu per 100 g feed (D2) and diet fermented (48 hr) with same bacteria (D3) respectively. At the end of the 42 days experiment, shrimps of group II showed significantly better (p < .01) growth and protein efficiency ratio (PER) and lower (p < .01) feed conversion ratio (FCR) as compared to group I and III. Dry matter, cellulose, hemicellulose and lipid digestibilities were significantly (p < .01) higher in group II than other two groups. Cellulase, amylase and protease activities in the gastrointestinal (GI) tract were significantly (p < .01) higher in group II as compared to other two groups. Total heterotrophic count, amylolytic, cellulolytic and proteolytic bacterial counts in gut were significantly (p < .01) higher in group II as compared to other two groups. Haematological analysis indicated better (p < .05) immune response in groups II and III than control group. Diets D2 and D3 showed better effect on growth, digestibility, FCR, survival and immune response of P. monodon as compared to D1.     

Effects of different diets on larval development in a peppermint shrimp (Lysmata sp. (Risso))

Currently, only a handful of marine ornamental species are commercially produced through aquaculture. In order for the marine aquarium industry to continue to grow, a diverse selection of cultured animals is required to offset wild collections. Long and variable larval durations are the major bottleneck for mass production of marine ornamental shrimp. Improving larval diet may reduce the larval duration and enhance the prospects of commercial aquaculture. A laboratory study was conducted to examine the effect of different diets on larval development and survival of the peppermint shrimp, Lysmata (gulf coast variety), a popular aquarium shrimp. The effect of three feeding regimes [Artemia alone (ART), ArteMac? alone (COMM) and Artemia in combination with ArteMac? (ART/COMM)] on survival and development were tested. Survival to zoea 5 for both ART and ART/COMM treatments was 99%, but only 62.5% for COMM treatment. ArteMac? alone treatment shrimp only survived to zoea 7. Survival to postlarvae for ART treatment (72.5%) was significantly lower (P<0.01) than those of treatment ART/COMM (80.5%). Larvae fed ART/COMM had significantly (P<0.01) shorter larval duration than larvae fed ART. Fourteen days after the first postlarva appeared, the rates of settlement (85.4% and 67.5% respectively) and survival (68.8% and 49.0% respectively) were significantly greater (P<0.01) for larvae fed the ART/COMM than those fed ART.