糖蜜添加对凡纳滨对虾养殖水体菌群结构的影响

为探索糖蜜对凡纳对虾(Penaeus vannamei)生长及其水体菌群的影响，本研究利用16S rDNA扩增子高通量测序技术，比较了添加糖蜜调节水体碳氮比的处理组 (C/N = 16.0)与无添加的对照组(C/N = 8.5)两种模式下第4、13和34 d时水体菌群结构差异，并通过PICRUSt2对菌群功能进行预测。结果显示，糖蜜添加对对虾体长和体重无显著性影响，但可显著提高对虾存活率；第4 d时水体菌群香农多样性与均匀度均显著上升，但第13与34 d时均显著下降(P<0.05)。添加糖蜜后，处理组α-变形菌纲(α-proteobacteria)和放线菌门(Actinobacteria)丰度均极显著高于对照组(P<0.01)，蓝细菌门(Cyanobacteria)和γ-变形菌纲(γ-proteobacteria)丰度则显著低于对照组，β-变形菌纲(β-proteobacteria)丰度在第4和34 d时也显著低于对照组，拟杆菌门(Bacteroidetes)丰度在第4和13 d时分别显著高于和低于对照组。科水平上，处理组第4、13和34 d时微杆菌科(Microbacteriaceae)相对丰度均显著高于对照组，第4 d时红杆菌科(Rhodobacteraceae)、黄杆菌科(Flavobacteriaceae)和海仙菌科(Halieaceae)丰度均极显著高于对照组，而德沃斯氏菌科(Devosiaceae)、产碱菌科(Alcaligenaceae)和束缚杆菌科(Haliscomenobacteraceae)丰度均极显著低于对照组，第13 d时海仙菌科和环杆菌科(Cyclobacteriaceae)丰度分别极显著高于和低于对照组，脱醌菌科(Demequinaceae)丰度在第34 d时显著高于对照组。添加糖蜜后处理组芽殖杆菌属(Gemmobacter)和脱醌菌属(Demequina)等优势属的丰度显著高于对照组，而海仙菌属(Haliea)等丰度则显著下降。菌群功能预测结果显示，第34 d时，处理组丰度前20的代谢功能富集项均极显著高于对照组，糖酵解/糖异生等8项属于碳水化合物代谢或能量代谢的功能均高度富集。以上结果表明，糖蜜添加可显著影响凡纳对虾养殖水体优势菌群相对丰度，优化水体菌群结构，并增强其碳水化合物和能量代谢通路功能，从而提高对虾存活率。本研究为糖蜜作为有机碳源应用于对虾生物絮团养殖提供了理论依据。     

健康与患病凡纳滨对虾肠道菌群结构及功能差异研究

为探究病害发生后健康与患病凡纳滨对虾肠道菌群结构和功能的差异,并筛选肠道指示菌群来评估宿主健康状况,评价凡纳滨对虾肠道菌落的功能冗余性。实验采集健康和患病凡纳滨对虾样品,通过Illumina高通量测序技术测定肠道菌群组成,并利用PICRUSt进行功能预测,以此比较健康与患病凡纳滨对虾肠道微生物的群落结构和功能差异,并预测功能与群落组成的相关性。结果显示,病害的发生伴随着肠道菌群结构的显著变化,而多样性无显著差异。与健康凡纳滨对虾肠道细菌组成相比,患病凡纳滨对虾肠道中放线菌门(Actinobacteria)、浮霉菌门(Planctomycetes)和疣微菌门(Verrucomicrobia)相对丰度降低,而γ-变形菌纲(Gammaproteobacteria)和拟杆菌门(Bacteroidetes)增加。同时,筛选出16个指示细菌科,能够很好地指示宿主健康状况。与健康组相比,患病凡纳滨对虾中参与弧菌侵染的过程显著增加,而溶酶体和过氧化物酶等免疫功能代谢过程显著减弱。此外,肠道微生物群落结构与功能组成呈显著正相关,表明凡纳滨对虾肠道菌群组成具有较低的功能冗余性。研究表明,健康与患病凡纳滨对虾肠道菌群结构存在显著差异,并且由细菌介导的功能随之发生改变,能够用指示微生物评估宿主健康状况。     

凡纳滨对虾不同养殖密度高位池水体细菌群落动态

通过对养殖水体环境基因组DNA中细菌16S rRNA基因V4–V5区的高通量测序和生物信息学分析,研究了两种养殖密度的凡纳滨对虾(Litopenaeus vannamei)高位池水体中细菌群落在养殖过程中的动态。结果显示,养殖过程中各菌群相对丰度变化明显,细菌多样性随时间逐渐提高,优势菌群为变形菌门(Proteobacteria)、蓝藻门(Cyanobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)和浮霉菌门(Planctomycetes)。随着养殖时间增长,蓝藻丰度所占比例逐渐减少,而变形菌、拟杆菌和浮霉菌丰度逐渐增大,同时养殖前期高密度池浮霉菌丰度显著高于低密度池(P0.01),而其他菌群无显著差异。结果表明,养殖期前50 d不同养殖密度水体细菌群落差异较大,而后30 d内细菌群落的时间异质性大于空间异质性,这意味着高位池水体菌相被划分为两类,到养殖后期菌相快速转变,养殖密度所带来的影响被减弱。     

凡纳滨对虾工厂化循环水养殖系统水质指标及微生物菌群结构的分析

为探究凡纳滨对虾(Litopenaeus vannamei)工厂化循环水养殖系统的养殖水体水质情况以及微生物菌群的组成结构,本研究利用高通量测序技术和生物信息学分析手段,测定凡纳滨对虾工厂化循环水养殖过程一级移动床生物净化、二级固定床生物净化、养殖水体的水质指标、水体和生物净化载体以及对虾肠道微生物菌群的组成。结果显示,水体的氨氮(NH4+-N)和亚硝态氮(NO2–-N)质量浓度显著降低,分别为0.85和0.21 mg/L。养殖系统水体、生物净化载体和虾肠道样品中共有的优势菌为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes),此外,一级、二级生物净化系统水体中的放线菌门(Actinobacteria)为优势菌,生物净化载体中浮霉菌门(Planctomycetes)和硝化螺旋菌门(Nitrospirae)为优势菌;对虾肠道中的厚壁菌门(Firmicutes)为优势菌。另外,对虾养殖循环水系统中生物净化载体上的细菌物种含量比水样中的细菌物种少,但微生物多样性高于养殖水体,生物净化载体中微生物具有低丰度和高多样性的特点。综上所述,生物净化系统可有效地增加水体中促进氮、磷代谢的微生物菌群,调控养殖水体的水质指标,研究结果为凡纳滨对虾工厂化循环水养殖系统构建及水质调控提供理论依据。     

溶藻弧菌VZ5株在凡纳滨对虾育苗中应用的研究

在凡纳滨对虾育苗涵状幼体期以不同频次添加溶藻弧菌VZ5株,并在糠虾幼体后搭配添加芽孢杆菌Bz5株,测定育苗过程中水质、水体中弧菌密度变动以及对虾幼体生长和存活状况,研究溶藻弧菌VZ5株在凡纳滨对虾育苗中应用的效果。结果表明,添加溶藻弧菌的3个处理组仔虾期氨氮浓度显著低于对照组;仔虾期幼体干重分别为0．0463±0．0009、0．0420±0．0006、0．0407±0．0009g／尾,显著高于对照组（0．0253±0．0003g／尾）。滏状幼体期每天添加溶藻弧菌的处理组幼体成活率显著高于其他处理组（P〈0．05）。溶藻弧菌VZ5株能够有效降低水体中氨氮的积累和促进对虾幼体生长。     

高通量测序法分析两株益生菌对凡纳滨对虾肠道菌群结构的影响

为分析荚膜红细菌和蜡样芽孢杆菌2株益生菌对凡纳滨对虾肠道菌群结构的影响,本实验对凡纳滨对虾进行为期30 d的养殖饲喂实验,饲喂后期利用高通量测序凡纳滨对虾肠道微生物的16S rDNA V4区,来分析不同益生菌饲喂后凡纳滨对虾肠道菌群的结构特征,并结合对虾体质量增加率和攻毒后累计死亡率的宏观指标来进行分析。结果显示：①空白组（CK）、荚膜红细菌组（Rc）和蜡样芽孢杆菌组（Bc）样品OTU范围为374~506,其中CK组对虾肠道菌群OTU数量最低,饲喂益生菌后的2组对虾肠道菌群中OTU数量相对较高;②在门分类水平上,3组的变形菌门数均为最多,CK组主要为变形菌门和少量拟杆菌门,Bc组主要有变形菌门、拟杆菌门、无壁细菌门、厚壁细菌门和假单胞菌,Rc组主要是变形菌门、拟杆菌门、厚壁菌门、酸杆菌门、放线细菌、梭杆菌门和蓝细菌;③稀释曲线和Shannon指数结果可见,CK组样品物种丰度和复杂度最低,且Bc组样品丰度和复杂度相对较高;④PCA分析发现,Rc组和CK组样品微生物组成较为接近,结合宏观对虾体质量增加率和攻毒后累计死亡率的结果分析,可见相较于荚膜红细菌,蜡样芽孢杆菌对凡纳滨对虾肠道微生物菌群影响更显著,且益生效果更佳。研究表明,饲喂益生菌可以扩增对虾肠道微生物菌群丰度,并能抑制弧菌属等有害菌群的生长,提高对虾体质量增加率并降低死亡率,从而达到益生效果,其中以饲喂蜡样芽孢杆菌菌株效果更佳。     

不同消毒剂对凡纳滨对虾育苗水质和菌群结构的影响

该研究使用碘(I₂)、二氧化氯(ClO₂)、甲醛溶液(HCHO)和漂白粉[Ca(ClO)2]4种常用消毒剂对凡纳滨对虾(Litopenaeus vannamei)育苗海水处理后,研究了不同发育期育苗水体总菌和弧菌数量、氨氮和亚硝酸氮含量、幼体成活率以及水体和幼体菌群的变化。结果显示:1)甲醛组水体的总菌数较低,且弧菌数量最低;2)4种消毒剂组水体氨氮和亚硝酸盐浓度均低于对照组,其中漂白粉组最低;3)甲醛组幼体成活率显著高于其他各组(P<0.05);4)消毒剂改变了育苗水体和幼体的菌群结构和优势菌丰度,育苗水体菌群组成比幼体更为复杂,且早期阶段比后期复杂。其中,无节幼体(N₆)—溞状幼体(Z₁)阶段水体优势菌属主要为OM43_clade、食烷菌属(Alcanivorax)、赤杆菌属(Erythrobacter)、交替赤杆菌属(Altererythrobacter)、黄杆菌属(Tenacibaculum)、水栖菌属(Enhydrobacter)、泥滩微菌属(Gilvibacter)等,糠虾幼体(M1)—仔虾(P1)阶段水体中优势菌属有东吉科拉属(Donghicola)、黏着杆菌属(Cohaesibacter)、Phaeodactylibacter、念珠菌属(Candidatus-Cquiluna)和鲁杰氏菌属(Ruegeria),而幼体中的优势菌属有弧菌属(Vibrio)、动性杆菌属(Planomicrobium)、微杆菌属(Exiguobacterium)、嗜冷杆菌属(Psychrobacter)、不动杆菌属(Acinetobacter)、芽孢杆菌属(Bacillus)、嗜甲基菌属(Methylophaga)和盐单胞菌属(Halomonas)。     

健康和患病凡纳滨对虾幼虾消化道菌群结构的比较

凡纳滨对虾养殖过程中,早期阶段是病害易感阶段,而消化道菌群结构与对虾健康关系密切。因此,探讨幼虾的消化道菌群尤其是弧菌类细菌与对虾发病的关系对病害有效防治具有重要意义。本实验采用Illumina测序研究了凡纳滨对虾健康和患病幼虾的消化道细菌群落结构,并基于纯培养和16S r DNA,rec A和pyr H基因序列比对,分析了幼虾消化道中弧菌的主要种类组成。结果发现,健康幼虾消化道中α-变形菌纲和厚壁菌门丰度较高,而患病幼虾中γ-变形菌纲、拟杆菌门、放线菌门和β-变形菌纲较高,其中放线菌门丰度差异显著。基于科水平的响应比分析,发现患病幼虾消化道中动性球菌科和噬菌弧菌科的丰度显著降低,而弧菌科的丰度显著升高。相似度分析发现,驱动群落变异的OTU主要来源于弧菌属、海洋杆状菌属、冷杆菌属、假交替单胞菌属以及未分类至属的红杆菌科和微杆菌科。健康幼虾消化道弧菌组成以锡那罗亚州弧菌为主,而患病幼虾消化道弧菌组成以坎氏弧菌为主。尽管健康和患病幼虾消化道内细菌群落结构整体差异不显著,但一些重要类群丰度变化显著,其特征与已知的生态功能一致。     

四种糖作为碳源对凡纳滨对虾生长、肠道消化酶及肠道菌群的影响

为研究4种常见的糖源对凡纳滨对虾生长、肠道消化酶及肠道菌群的影响,选取初始体质量为(0.36±0.02) g的凡纳滨对虾为研究对象,从多种糖类中选择常见的4种糖(葡萄糖、果糖、淀粉、蔗糖)作为糖源配制饲料,实验共计4个处理,每个处理3个重复,每个重复40尾虾,养殖周期为56 d,每种糖源的添加量为20%。结果显示,(1)凡纳滨对虾的特定生长率和蛋白质效率均存在显著性差异,淀粉组显著高于其他3组,但各组间的肝体比和含肉率无显著差异。全虾体成分,蔗糖组的粗脂肪显著低于其他3组,葡萄糖组的灰分显著高于其他3组,粗蛋白与水分各组间无显著差异。(2)各组间对虾肠道的脂肪酶活性,淀粉组与蔗糖组显著高于葡萄糖组及果糖组,胃蛋白酶活性方面,淀粉组显著高于其他3组。(3)各组间凡纳滨对虾肠道的OTU、Ace指数及Chao指数无显著差异,Shannon指数淀粉组及蔗糖组显著高于葡萄糖组,Simpson指数淀粉组显著低于蔗糖组,而蔗糖组又显著低于葡萄糖组。门水平上,变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)与放线菌门(Actinobacteria)的相对丰度差异显著,但疣微菌门(Verrucomicrobia)相对丰度各组间无明显差异;在纲水平上,各处理组间的对虾肠道菌群的差异性较显著,淀粉组对虾肠道中黄杆菌纲(Flavobacteriia)、γ变形菌纲(Gammaproteobacteria)、放线菌纲(Actinobacteria)及噬纤维菌纲(Cytophagia)是明显高于蔗糖组与葡萄糖组。研究表明,凡纳滨对虾对淀粉和蔗糖的吸收利用优于葡萄糖和果糖,同时,淀粉和蔗糖对凡纳滨对虾肠道菌群多样性存在一定的影响,淀粉和蔗糖为凡纳滨对虾饲料中的适宜糖源。     

蜡样芽孢杆菌对凡纳滨对虾幼体变态的影响

研究了1株蜡样芽孢杆菌zou8对数期细胞对凡纳滨对虾无节幼体Ⅲ期到溞状幼体Ⅱ期幼体变态的影响;并通过zou8与弧菌的平板拮抗、共培养试验探讨其促进幼体变态的机制是否与拮抗病原弧菌有关。结果表明:高数量zou8细胞对凡纳滨对虾无节幼体Ⅲ期到溞状幼体Ⅱ期幼体的变态具有极显著(P<0.01)促进作用,尤其是多次加菌;zou8促进幼体变态作用的发挥并非通过产生拮抗物质直接抑制病原弧菌,而是通过其他可能机制。     

Structural characteristics and succession of intestinal microbiota for Paralichthys olivaceus during the early life stage

The research of intestinal microflora structures for Paralichthys olivaceus larvae and juveniles will help us to master the ontogeny and developmental colonization of microflora during the larval rearing stage. In this study, we sequenced the total bacterial genomic DNA in larval and juvenile guts with an Illumina MiSeq PE300 system, and analysed the structural characteristics of these microbiota, feed and rearing water in live and formulated feeding periods. The structure of gut microbiota was gradually similar to those in wild P. olivaceus at the phylum level and the newly hatched ones with the growth, according to the distribution and abundance of intestinal microbiota. And the colonized rule of main microbial species in guts was decreased initially and then increased during the larvae and juveniles stage. Meantime, the core microflora of this study were obtained through the analysis of shared and dominant species, which included Bacteroides, Bacillus, Enterococcus, Lactobacillus, Lactococcus, Escherichia_Shigella, Acinetobacter, Pseudomonas, Vibrio, Nitrosomonas, and Glaciecola. The correlation analysis of microbiota between intestines and environmental factors suggested that microflora in feed and water could affect the distribution of larval and juvenile gut microbiota. Moreover, many species of Acinetobacter, Pseudomonas and Vibrio are treated as important potential pathogens in aquaculture. These all pointed out the microbial quality of feed and rearing water should be strictly controlled in fish breeding and farming, and supply theoretical bases for screening the native probiotics to artificially regulate the gut microbiota.     

病例研究：未知病因的凡纳滨对虾溞状幼体的病原和微生物组分析

从某对虾育苗场2个育苗池中分别采集了发生摄食下降、活力降低及死亡率增高等症状的未知疾病的凡纳滨对虾(Litopenaeus vannamei)溞状幼体3期(Z3)和1期(Z1)的样品。用PCR检测白斑综合征病毒(WSSV)、传染性皮下及造血组织坏死病病毒(IHHNV)、急性肝胰腺坏死病副溶血弧菌(VpAHPND)、桃拉综合征病毒(TSV)、传染性肌坏死病毒(IMNV)、黄头病毒(YHV)、虾肝肠胞虫(EHP)、偷死野田村病毒(CMNV)和虾血细胞虹彩病毒(SHIV)等9种已知病原为阴性。组织病理学诊断观察到肝胰腺小管上皮细胞内存在不明褐色团块。使用2216E培养基对致病菌分离鉴定，得到2株溶藻弧菌(Vibrio alginolyticus)，浸浴感染悉生卤虫(Artemia franciscana)幼体后的平均存活率分别为58%和83%。采用Illumina HiSeq高通量测序方法对这2个溞状幼体样品中细菌16S rRNA基因的2个高变区(V3~V4)进行总细菌菌群的测序，分析揭示了未知病因病虾中细菌菌群的多样性和相对丰度，门水平上2个样品的优势菌群均包括变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)，但相对丰度有显著差异；在属水平上相对丰度最高的均为弧菌属(Vibrio)，在2个样品中的丰度分别为74.3%和60.5%，此外，Z1样品相对高丰度(21.9%)的属为黏着杆菌属(Tenacibaculum)。育苗管理信息及上述病例分析结果提示，该疾病可能是由于在过期存放的幼体饲料质量下降所致的营养障碍情况下，有一定致病性的溶藻弧菌条件性感染所引起的疾病。     

Complete Larval Development of the Fresh Water Prawn Macrobrachium vollenhovenii in Cameroon

The African River prawn Macrobrachium vollenhovenii is the largest of the local Palaemonidae prawns along the Cameroonian coast and an important target species for fisheries and aquaculture. A preliminary study on larviculture of this species was carried out at the IRAD-AQUASOL hatchery in Kribi, Cameroon. Berried females M. vollenhovenii were obtained from the Lobe and Lokoundje Rivers in the Southern Region, typical Lower Guinea rainforest streams. The larval rearing system consisted of a single recirculation system of four 65 L cylindrical plastic containers connected to a submerged biological filter container (65 L). Experiments were conducted three times in the same condition, with two batches of larvae reared separately in duplicate per experiment, at a density of 40/L, temperature 26°C, and salinity 16%. Larvae were fed from 1 day after hatching until metamorphosis to postlarvae (PL) with newly hatched Artemia nauplii, three times daily at the rate of 5 nauplii per mL water. The number of newly hatched larvae per female body weight unit was not affected by the female size and ranged between 531 to 1349 larvae g^?1. The six batches succeeded from hatching to metamorphosis, and the 11 distinct larval stages described for M. rosenbergii were found. Larvae in all the batches developed more or less at the same pace up to stage V. However, a clear difference in the timing of appearance of the developmental stages was observed between batches and individuals of the same batch during the subsequent stages. The transition from stage V to stage VI and from stage IX to stage X was longer than the passage to other stages and seems to be the critical rearing period of M. vollenhovenii. From day 20 onward to sampling, the larval stage index (LSI) showed that larval development of the batch 1 was significantly faster than for all other batches. The time for first appearance of postlarvae was variable between batches (41–74 days), and batch 1 larvae passed through metamorphosis within a shorter span of time (41 days). Survival up to postlarvae was variable among batches, ranging between 3%–9%, and was better in batch 1 (9.31 ± 1.09). The general poor performance in terms of survival and metamorphosis rates of larvae seems to be related to the wild condition of broodstock. To improve performance of larvae, domestication of stock may be necessary. This result is the first recorded success in larviculture of M. vollenhovenii in Cameroon.     

Feeding and digestion in the caridean shrimp larva of Palaemon elegans Rathke and Macrobrachium rosenbergii (De Man) (Crustacea: Palaemonidae) on live and artificial diets

Larvae of two caridean shrimp species, Macrobrachium rosenbergii (De Man) and Palaemon elegans Rathke, were fed live and artificial diets. P. elegans larvae fed exclusively live Artemia salina (15 nauplii mL^?1) developed into first postlarval stage (PL1) within 12 days at a temperature of 25°C and salinity 32.5 g L^?1. Their survival and mean total length at this stage were 88.5% and 6.7 mm respectively. M. rosenbergii larvae fed on 15 Artemia mL^?1 started to metamorphose into PLl within 24 days at 29–30°C and 12 g L^?1. Attempts to completely replace live Artemia for rearing P. elegans during early stages failed, and only a partial replacement was achieved for the larvae of both species. P. elegans larvae survived (49%) solely on a microgranulated diet (Frippak PL diet) from stage zoea (Z) 4–5 to PL1. Similarly, a microencapsulated diet (Frippak CD3) also sustained M. rosenbergii larvae from Z5–6 to PL1 with a 28% survival. Development of the larvae of both species was retarded by 2–3 days and their survivals were lower than those fed on the live diet. The inability of the early larvae of these caridean species to survive on artificial diets is attributed to their undeveloped guts and limited enzymatic capabilities. Trypsin activity in the larvae was determined for all larval stages. It was found that the highest trypsin activity, at stage Z4–5 in P. elegans and at stage Z5–6 in M. rosenbergii, coincides with a rapid increase in the volume of the hepatopancreas and the formation of the filter apparatus. These morphological changes in the gut structure appear to enable the larvae to utilize artificial diets after stage Z5–6. Low larval trypsin activities may be compensated by the easily digestible content of their live prey during early larval stages (Z1–Z4/5) and by longer gastroevacuation time (GET) and almost fully developed guts during later stages.     

Efficiency of stagnant water larviculture using disinfected amictic eggs of the rotifer <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> in Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>

There is a need to develop low-cost methods for larviculture that emphasize disease prevention. We evaluated stagnant water larviculture in flounder Paralichthys olivaceus using rotifer amictic eggs treated with glutaraldehyde. Growth and survival of the larvae were similar to in larvae reared by standard running water larviculture with daily feeding of rotifers (control). In the experimental group, the n-3 highly unsaturated fatty acid content of rotifers in the rearing water was higher than in the enriched rotifers fed to the control group. We also observed a similar pattern for the fatty acid composition of flounder larvae. The viable bacterial counts associated with rotifers in stagnant water were lower than those associated with enriched rotifers, and there were fewer bacterial genera. However, the viable bacterial count was the same or higher in the experimental rearing water compared with that in the control group. The α-Proteobacteria and Cytophaga–Flavobacterium–Bacteroidetes group dominated the bacterial community structure after larval hatching. To our knowledge, this is the first time that stagnant water larviculture, using only disinfected amictic eggs, has been successfully demonstrated on a mass production scale. This method appears to offer benefits including improved nutrition, more favorable bacterial communities, and lower cost.     

Improved techniques for rearing mud crab Scylla paramamosain (Estampador 1949) larvae

A series of rearing trials in small 1 L cones and large tanks of 30–100 L were carried out to develop optimal rearing techniques for mud crab (Scylla paramamosain) larvae. Using water exchange (discontinuous partial water renewal or continuous treatment through biofiltration) and micro‐algae (Chlorella or Chaetoceros) supplementation (daily supplementation at 0.1–0.2 million cells mL⁻¹ or maintenance at 1–2 millions cells mL⁻¹), six different types of rearing systems were tried. The combination of a green‐water batch system for early stages and a recirculating system with micro‐algae supplementation for later stages resulted in the best overall performance of the crab larvae. No clear effects of crab stocking density (50–200 larvae L⁻¹) and rotifer (30–60 rotifers mL⁻¹) and Artemia density (10–20 L⁻¹) were observed. A stocking density of 100–150 zoea 1 (Z1) L⁻¹, combined with rotifer of 30–45 mL⁻¹ for early stages and Artemia feeding at 10–15 nauplii mL⁻¹ for Z3–Z5 seemed to produce the best performance of S. paramamosain larvae. Optimal rations for crab larvae should, however, be adjusted depending on the species, larval stage, larval status, prey size, rearing system and techniques. A practical feeding schedule could be to increase live food density from 30 to 45 rotifers mL⁻¹ from Z1 to Z2 and increase the number of Artemia nauplii mL⁻¹ from 10 to 15 from Z3 to Z5. Bacterial disease remains one of the key factors underlying the high mortality in the zoea stages. Further research to develop safe prophylactic treatments is therefore warranted. Combined with proper live food enrichment techniques, application of these findings has sustained a survival rate from Z1 to crab 1–2 stages in large rearing tanks of 10–15% (maximum 30%).     

基于微卫星分子标记的凡纳滨对虾商业苗种遗传多样性分析

为研究我国凡纳滨对虾(Litopenaeus vannamei)商业苗种的遗传多样性特征，于河北、山东、广东、海南等地采集了6个有代表性的凡纳滨对虾品牌苗种，分别命名为黄骅R、东营M、广州P、广州Z、海南S和海南Z，以8个微卫星标记检测其遗传多样性。结果显示，6个品牌的凡纳滨对虾在8个位点呈现不同程度的多态性，其平均等位基因数(Na)、期望杂合度(He)、观测杂合度(Ho)和多态信息含量(PIC)分别为4.5~9.5、0.516~0.733、0.346~0.550和0.472~0.700，各品牌遗传多样性丰富程度从高到低分别为黄骅R>广州Z>广州P>海南Z>东营M>海南S。哈迪–温伯格平衡(HWE)检验显示，4.17% (2/48)的检测结果表现为显著的偏离(0.01相似文献   

The effect of live feeds bathed with the red seaweed <Emphasis Type="Italic">Asparagopsis armata</Emphasis> on the survival,growth and physiology status of <Emphasis Type="Italic">Sparus aurata</Emphasis> larvae

Larval rearing is affected by a wide range of microorganisms that thrive in larviculture systems. Some seaweed species have metabolites capable of reducing the bacterial load. However, no studies have yet tested whether including seaweed metabolites on larval rearing systems has any effects on the larvae development. This work assessed the development of Sparus aurata larvae fed preys treated with an Asparagopsis armata product. Live prey, Brachionus spp. and Artemia sp., were immersed in a solution containing 0.5% of a commercial extract of A. armata (Ysaline 100, YSA) for 30 min, before being fed to seabream larvae (n = 4 each). In the control, the live feed was immersed in clear water. Larval parameters such as growth, survival, digestive capacity (structural-histology and functional-enzymatic activity), stress level (cortisol content), non-specific immune response (lysozyme activity), anti-bacterial activity (disc-diffusion assay) and microbiota quantification (fish larvae gut and rearing water) were monitored. Fish larvae digestive capacity, stress level and non-specific immune response were not affected by the use of YSA. The number of Vibrionaceae was significantly reduced both in water and larval gut when using YSA. Growth was enhanced for YSA treatment, but higher mortality was also observed, especially until 10 days after hatching (DAH). The mortality peak observed at 8 DAH for both treatments, but higher for YSA, indicates larval higher susceptibility at this development stage, suggesting that lower concentrations of YSA should be used until 10 DAH. The application of YSA after 10 DAH onwards promotes a safer rearing environment.