达里诺尔湖夏季浮游植物群落结构及分布特征

为了探究达里诺尔湖夏季浮游植物群落结构特征及水质状况,对浮游植物的种类组成、多样性及环境理化因子进行监测。2015年夏季在湖区设置9个采样点进行定期采样,通过Shannon-Wiener多样性指数、Pielou均匀度指数等数据处理,结合Pearson相关分析,研究浮游植物群落结构空间分布特征、多样性及其与环境因子的相关性。结果表明,调查期间共发现浮游植物5门、39属、77种;其中绿藻门29种,占总种数37.66%;蓝藻门和硅藻门均有23种,均占29.87%。达里湖夏季浮游植物优势种为3门、14种,主要优势种为单生卵囊藻(Oocystis solitaria)、湖生卵囊藻(Oocystis lacustris)、不定微囊藻(Microcystis incerta)、小球藻(Chlorella sp.)和细小隐球藻(Aphanocapsa elachista)。浮游植物丰度为4.55×10~4~26.78×10~4个/L,其平均值为:水面下0.5 m(22.46×10~4个/L)1.5 m(20.86×10~4个/L)4.5 m(14.15×10~4个/L)底泥上0.5 m(9.32×10~4个/L);浮游植物生物量为0.682~6.695 mg/L,垂向变化趋势与浮游植物丰度一致。相关分析表明,夏季达里诺尔湖浮游植物丰度与温度、p H值、溶解氧及叶绿素a呈极显著正相关,与盐度相关性不明显。浮游植物群落Shannon-Wiener指数为3.330~4.452,Pielou指数为0.799~0.912,结合浮游植物丰度、优势种及多样性指数分析结果,达里诺尔湖属于绿藻-蓝藻-硅藻型,且水体处于寡污染水平。     

生物絮团对鲤鱼养殖池塘浮游植物群落结构的影响

为了解生物絮团技术在净化池塘水质的同时对池塘初级生产力的影响,干2015年9月10月对陕西团头鲂良种场鲤鱼池塘的浮游植物群落结构进行了调查研究。结果显示:生物絮团池塘共出现浮游植物6门28种,其中绿藻门有17种,占总种类数的65.4%,硅藻门有5种,占总种类数的19.2%,浮游植物群落结构类型属绿藻硅藻型。浮游植物生物密度变化范围为1 372.82×10~4~3 093.71×10~4 ind./L,平均值为2 217.07×10~4 ind./L;生物量变化范围为3.5 3~12.87 mg/L,平均值为7.88 mg/L。浮游植物生物密度和生物量均在9月15日出现峰值,峰值期以后浮游植物密度和生物量在时间和空间上差异性显著(P0.05)。研究表明,生物絮团技术对池塘浮游植物群落结构影响较大,随着絮团的逐渐形成浮游植物群落结构出现明显变化,池塘藻相演替速度加快。     

粉绿狐尾藻（Myriophyllum aquaticum）对景观池浮游植物群落结构的影响

为探究粉绿狐尾藻(Myriophyllum aquaticum)对景观池浮游植物群落结构的影响,选取粉绿狐尾藻在景观池进行培养,对水样中浮游植物进行定性和定量分析。通过多样性指数、均匀度指数以及浮游植物功能群,探究浮游植物群落结构的变化规律。结果显示：种植粉绿狐尾藻后,景观池浮游植物总生物量由最初的1.27×10⁵ mg/L降低到6.0×10⁴ mg/L,总生物量明显降低;种植区Shannon-Wiener多样性指数由0.88增加到1.05,均匀度指数由0.55增加至0.66;浮游植物功能群共10个,分别为：W1、G、X1、J、L0、M、MP、W2、Y、X3,粉绿狐尾藻种植后,浮游植物功能群由代表超富营养型和高富营养型水体的J、M向代表中营养型或富营养型水体的W2、L0转变。     

安海湾浮游植物群落特征

根据2016年5月(春)、8月(夏)、10月(秋)和2017年2月(冬)在安海湾调查所获得的资料,对安海湾浮游植物群落进行研究。结果表明,浮游植物共鉴定6门68属139种,其中蓝藻5属5种,裸藻2属3种,绿藻4属8种,金藻1属1种,甲藻11属17种,硅藻45属105种。浮游植物种类以广布种为主,有较多淡水性种类存在。小环藻(未定种)、中肋骨条藻、菱形藻(未定种)、直链藻(未定种)、簇生布纹藻和聚生角毛藻等是优势的种类,其中小环藻(未定种)和中肋骨条藻在各季度月均为优势种。各季度月浮游植物细胞平均数量分别为22.26×10~4、6.23×10~4、10.61×10~4和54.21×10~4cells/L,四个季度月平均为23.33×10~4cells/L。浮游植物群落多样性指数平均为2.64。晋江经济开发区污水处理厂站位在低潮和高潮时浮游植物数量和多样性指数等变化大,裸藻和栅藻等耐污性种类数量相对较多。安海湾湾顶淡水对部分区域浮游植物有较大影响。浮游植物优势种和多样性指数等的变化表明安海湾浮游植物群落不稳定。     

金普湾秋季浮游植物群落组成

2015年9月在金州-普兰店湾(金普湾)进行网采浮游植物调查,样品共鉴定浮游植物3门31种,其中硅藻门26种,甲藻门4种,金藻门1种。丰度均值为58.00×10^4cells/m^3(11.00×10^4~307.00×10^4cells/m^3),丰富度(D)均值为0.43(0.07~0.71),多样性指数(H')均值2.03(0.20~3.00),均匀度(J')均值0.71(0.20~0.90)。总体而言,金普湾海域浮游植物群落组成属于较典型的北方海域种类组成,藻类细胞数量也基本上处于正常范围。     

天津港附近海域浮游植物群落结构初探

2014年4月、6月、8月、9月和11月对天津港附近海域浮游植物群落结构进行初步调查。结果表明,该调查共鉴定浮游植物2门17科20属共40种,浮游植物丰度0.03×104~10.12×104个/L,生物量0.28~32.50μg/L,浮游植物种类组成为硅藻门占绝对优势,共10科13属28种,占总数的68.3%。5航次调查浮游植物平均多样性指数、丰富度指数和均匀度指数分别为1.2462、0.7539和0.4305,综合分析天津港附近海域浮游植物多样性水平较低,群落组成较为单一。     

荣成近岸养殖海域浮游植物群落结构及与环境因子的关系

基于2016年4个季节的生态调查数据,研究了山东荣成近岸养殖海域浮游植物群落结构,同时,应用典范对应分析(CCA)讨论了环境因子对荣成近岸养殖海域浮游植物群落结构的影响。4个季度共发现浮游植物66种,分隶于硅藻、甲藻及金藻3个植物门、29个属;浮游植物优势种包括中肋骨条藻(Skeletonema costatum)、具槽直链藻(Melosira sulcata)、日本星杆藻(Asterionellopsis glacalis)、扭链角毛藻(Chaetoceros tortissimus)、尖刺菱形藻(Nitzschia pungens)及劳氏角毛藻(Chaetoceros lorenzianus),具有明显的季节演替现象。春季日本星杆藻在荣成湾大量出现使其成为优势种。4个季节浮游植物丰度变化范围为(16.9～251.7)×10~4cells/m~3,平均为119.3×10~4 cells/m~3,以夏季最高,秋季最低;全年浮游植物多样性指数(H￠)、均匀度指数(J)、丰富度指数(d)和优势度指数(D2)的变化范围分别为1.60～2.13、0.40～0.60、0.58～0.79和0.70～0.84,多样性指数以夏季最高,冬季最低,但均处在较好水平;CCA分析结果表明,海水溶解氧(DO)、硅酸盐(SiO_3~)2–)-Si)、铵盐(NH_4~+)、温度和pH等环境因子为影响该海域浮游植物群落结构的主要因子,除了季节影响因素以外,当地多元化的养殖模式可能是导致目前浮游植物群落结构的重要因素。     

淮河流域西淝河浮游植物群落结构特征

为探究淮河流域西淝河浮游植物群落结构特征及其与环境因子的关系,在2016年和2017年冬季(2月)、春季(4月)、夏季(8月)和秋季(11月)对淮河流域西淝河浮游植物群落结构特征进行研究。结果显示,共鉴定出浮游植物236种(含变种和变型),隶属于8门、103属。其中,绿藻门(Chlorophyta)最多,有37属、83种,占浮游植物物种总数的35.17%;其次为硅藻门(Bacillariophyta)28属、78种,占33.05%;蓝藻门(Cyanophyta)20属、40种,占16.95%。浮游植物群落结构组成及变化显示,蓝藻门物种的细胞密度占绝对优势,其次为绿藻门,分别占总细胞密度的57.04%、17.66%。硅藻门物种的相对生物量最大,其次为绿藻门,分别占总生物量的35.69%和28.81%,且浮游植物细胞密度与生物量均在夏季达到最大值。浮游植物细胞密度为(7.24±1.13)×10~7个/L,生物量年均值为(34.08±3.20) mg/L。Shannon-Wiener多样性指数、Margalef丰富度指数和Pielou均匀度指数为3.27～4.66、2.75～6.10和0.73～0.94。Pearson相关性与RDA分析表明,影响浮游植物群落结构的主要因子有溶解氧、水温、水生植被盖度、电导率、营养盐和透明度。研究结果可为揭示淮河流域浮游植物群落结构特征提供基础理论依据。     

三峡水库泄、蓄水过程对小江浮游植物群落结构的影响

为阐述水位升降时三峡水库支流浮游植物生态学特征的变化,分别于2013年6月和10月对小江泄、蓄水过程的浮游植物野外监测数据进行对比分析。结果表明,三峡水库泄、蓄水过程调查期,在小江分别鉴定出浮游植物6门、70属、136种(变种)和7门、70属、136种(变种),以绿藻、硅藻、蓝藻为主,共计占总种类数的87.49%和80.87%,但2个时期种类组成略有差异;浮游植物细胞密度变化范围分别为8.1×104~127.2×104个/L和24.4×104~99.9×104个/L,泄水过程略高于蓄水过程,且随着蓄水过程的推进持续减少,随着泄水过程的推进显著增加;浮游植物数量组成分别以硅藻和蓝藻占优势,占浮游植物总细胞密度的比例均在50%以上;蓄水过程Shannon指数和Margalef指数变化范围分别为1.80~3.68和0.09~0.61,与泄水过程相比,此2项指数明显较高且变化幅度大;泄水过程和蓄水过程的浮游植物群落分别聚在一组内,但各组内变化情况不同;在三峡水库泄、蓄水过程中,水温和营养盐对浮游植物的生长均有很重要的影响,而水文特征变化对浮游植物生长影响作用十分有限。三峡水库泄、蓄水过程中小江浮游植物群落结构特征存在差异,水温、营养盐是主要影响因子,其中泄水后期浮游植物细胞密度会显著增加,且随着水位的进一步降低会持续增加,水华暴发潜在风险增大,需引起关注。     

长江干流安庆段浮游植物群落结构特征

为了解长江干流安庆段浮游植物群落结构特征,分别于2015年4月(春季)、7月(夏季)和9月(秋季)对长江干流安庆段浮游植物进行了调查。结果显示:本次调查共检出浮游植物5门22科33属54种(含变种)。以硅藻门种类最多,占总种数的46.30%;其次是蓝藻门和绿藻门,分别占24.07%和22.22%;黄藻门和甲藻门的种类相对较少,占5.56%和1.85%。优势种为蓝藻门的小颤藻(Oscillatoria tenuis)、极大螺旋藻(Spirulina maxima)、湖沼色球藻(Chroococcus minutus),绿藻门的小球藻(Chlorella vulgaris)、集星藻(Actinastrum hantzschii)以及硅藻门的尖针杆藻(Synedra acus)。浮游植物密度为1.228×10~4~33.002×10~4ind./L,均值为9.453×10~4ind./L;生物量为0.005~0.512 mg/L,均值为0.157 mg/L。密度和生物量最高值均出现在皖河口采样断面(7月)、最低值均出现在杨家套采样断面(4月)。研究结果表明:浮游植物密度和生物量在空间分布上差异均不显著,季节变化上则均表现出显著性差异。利用Shannon-Wiener指数和Pielou均匀度指数分析浮游植物群落结构特征,Shannon-Wiener指数变化范围为0.918~3.147,均值为2.539;Pielou均匀度指数变化范围为0.796~1.000,均值为0.893。Shannon-Wiener指数在空间分布和季节间均无显著性差异;Pielou均匀度指数在空间分布上无显著性差异,但在季节间变化上则表现出显著性差异。浮游植物多样性指数结果表明长江干流安庆段水质状况介于清洁型/β-中污型。     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.