海子湖春季浮游植物群落结构与环境因子相关性分析

2012年春季对长湖海子湖浮游植物群落结构及其主要水环境指标进行调查,同时运用典范对应分析方法 (CCA)对浮游植物与环境因子的关系进行分析。结果表明,海子湖共检测到浮游植物93种(含变种和变型),其中绿藻(Chlorophyta)最多,占46.76%,其次为硅藻(Bacillariophyta)和蓝藻(Cyanophyta),分别为22.65%和15.00%;浮游植物优势种共6种,其中小球藻(Chlorella vulgaris)优势度高达0.36;浮游植物丰度在86.21×105~410.12×105个/L,平均为232.85×105个/L。多样性指数为1.82~3.28,均匀度指数为0.40~0.63。根据浮游植物丰度水平、优势度以及群落多样性指数等生物学指标进行综合评价,海子湖处于重度富营养化状态。CCA分析表明,浮游植物空间分布主要受到硝酸盐氮、化学需氧量、叶绿素以及磷酸盐等环境因子的影响,主要影响因素为海子湖地形、人为干扰因素以及水动力学相关参数。     

桃山水库浮游植物群落结构及水质营养状态评价

2009年的枯水期（5月）和丰水期（7月）,在桃山水库对浮游植物结构群落和水质状况进行了调查研究,结合生物监测和理化监测手段,基于浮游植物优势度、丰度、优势度以及综合指数评价方法,对研究水库进行了生态评价。结果显示：（1）桃山水库浮游植物共有7门46属73种及变种,其中以绿藻为主,分别占44 %;（2）生物量在2.29-10.96 mg﹒L-1之间,丰度变幅在(38.76-124.44)×105 ind.﹒L-1之间;（3）枯水期优势种以硅藻为主,丰水期优势种以以蓝藻、绿藻为主;（4）综合营养指数为42.0-60.1。综合评价结果表明：桃山水库枯水期和丰水期水质营养状态为轻富营养化,化学需氧量是影响桃山水库浮游植物群落结构的主要环境因子。     

高州水库浮游植物群落结构及其与环境因子的关系

摘要：为掌握高州水库浮游植物群落结构变化规律及其与环境因子的关系,2011年4月至2012年3月对高州水库浮游植物群落周年动态进行调查和分析。结果表明：高州水库共鉴定浮游植物7门97种,库区浮游植物细胞密度年变化范围为7.8×105-9.72×106 cells/L;全年主要优势种为铜绿微囊藻（Microcystis aeruginosa）与梅尼小环藻（Cyclotella meneghiniana）。Shannon-Wiener多样性指数和均匀度指数分析结果显示,高州水库各区域属于中污染状态;CCA分析结果表明,氮磷营养盐是影响高州水库浮游植物群落分布的重要因子,温度、pH与CODMn对浮游植物群落分布也有一定程度的影响。     

大连近海水产养殖区中浮游植物群落结构及其与环境因子的关系

为研究大连近海水产养殖区中浮游植物群落结构及其与环境因子的关系,于2020年1月、4月、7月和10月对大连7个区市县沿海裙带菜（Undaria pinnatifida）、仿刺参（Apostichopus japonicus）、菲律宾蛤仔（Ruditapes philippinarum）、扇贝、牡蛎和对虾为主的重点海区设置10个采样点,同步监测调查浮游植物种类组成、生物量及其水质,并对浮游植物群落与水环境因子进行Pearson相关分析和典范排序分析（CCA）。调查结果共发现3门31属78种浮游植物,主要由硅藻组成,还有少量的甲藻和金藻,优势种共14种。浮游植物细胞丰度变化在7.82×104～22.00×104ind./L之间,多样性指数变化在1.51～3.32之间,均匀度指数变化范围在0.378～0.588之间。Pearson相关分析结果表明,浮游植物细胞丰度、硅藻细胞丰度和多样性指数与氨氮浓度呈一定负相关。典范排序分析（CCA）结果表明,水温、p H、溶解氧（DO）、亚硝酸盐、氨氮和硝酸盐含量是影响大连近海水产养殖区浮游植物优势种变化的主要环境因子。     

苏北运东水网区浮游植物群落结构特征及与环境因子关系

为研究苏北运东水网区浮游植物群落结构特征及其与环境因子之间的关系,于2016年3月至12月对苏北运东水网区19个采样点进行了季节性浮游植物群落调查和水质监测。结果表明,浮游植物共计鉴定出142种,隶属于7门、75属,以绿藻门和硅藻门的种类数偏多,其中绿藻门共29属、58种,硅藻门共22属、44种。春、冬季以硅藻门密度最大,分别为2.49×106个/L和 1.67×106个/L;夏、秋季以绿藻门密度最大,为1.57×106个/L和 1.34×106个/L;Margalef丰富度指数（R）、Shannon-Wiener多样性指数（H''）、Simpson多样性指数（D）和Pielou均匀度指数（J）均在夏季最大,分别为1.374、3.198、0.944和0.831,在冬季和春季相对较小;运东河网区内部水流变缓,河网外部水体流动性相对较好,浮游植物密度的监测结果显示,内部河流大于外部河流,但生物多样性指数为外部河流小于内部河流;运东片各季节的主要浮游植物优势物种共有20种,春、冬季主要为硅藻门和隐藻门,而夏、秋季则主要为绿藻门和硅藻门,其中梅尼小环藻（Cyclotella meneghiniana）、尖针杆藻（Synedra acus）和啮蚀隐藻（Cryptomonas erosa）为全年常有的优势种。藻类优势物种与环境因子的CCA分析表明,影响运东片四季浮游植物群落分布的环境影响因子存在差异,其中BOD5、TP、NH3-N和CODMn是关键的环境影响因子。     

黄洲河流域浮游植物的季节变化及其环境影响因子

为了解贵州白云岩喀斯特世界自然遗产地浮游植物群落结构及其与环境因子的关系,于2017年秋季(10月)、2018年冬季（1月）、2018年春季（4月）、2018年夏季（8月）对遗产地境内黄洲河流域的浮游植物群落种类组成、优势种、丰度以及多样性的时空变化进行研究,并应用Pearson相关性分析和冗余分析（RDA）探究环境因子总氮（TN）、氨氮（NH3-N）、总磷（TP）、叶绿素a（Chl-a）、溶解氧（DO）、高锰酸盐指数（CODMn）、水温（WT）对黄洲河浮游植物群落结构的影响。结果表明,调查共鉴定出藻类6门、29科、37属、38种,以硅藻门和绿藻门居多。按季节划分,黄洲河流域优势种共9种,其中硅藻门5种,?绿藻门1种,?蓝藻门3?种;按空间划分,黄洲河流域优势种共19种,其中硅藻门9种,绿藻门4种,蓝藻门6种。浮游植物年均丰度为36.45×104个/L,夏季的丰度最高,达到89.7×104个/L,春秋季次之,冬季最低,仅8.9×104个/L。全年Margalef丰富度指数（D）、Shannon多样性指数（H）及Pielou均匀度指数（J）分别为0.34 ~0.51、1.18~1.4及0.72~0.84。Pearson相关性分析和冗余分析(RDA) 表明,影响遗产地浮游植物丰度和分布的主要环境因子为WT、CODMn、Chl-a。     

汉江上游平水期浮游植物群落特征及水质生物评价

为探究平水期汉江上游浮游植物群落结构特征和水质状况,于2020年4月对汉江汉中段干流以及11条主要支流的浮游植物及水体理化指标进行调查分析。结果显示：汉江汉中段干支流共镜检出浮游植物6门35属51种,物种组成为硅藻—绿藻型,优势种为小环藻（Cyclotella sp.）、舟形藻（Navicula sp.）、尖针杆藻（Synedra acus）、箱型桥弯藻（Cymbella cistula）、棒胶藻（Rhabdogloea sp.）、二角多甲藻（Peridinium bipes）、四尾栅藻（Scenedesmus quadricauda）以及卵形隐藻（Cryptomonas ovata）。浮游植物细胞密度变化范围为0.39×106 cells L-1 ~ 3.59×106 cells L-1,生物量变化为0.39 mg L-1 ~ 3.49 mg L-1。Shannon多样性指数（0.64 ~ 2.15）和Pielou均匀度指数（0.28 ~ 0.81）变化趋势一致,干流略低于支流。结合水体理化指标、营养状态指数、污染指示种以及多样性指数对水质进行综合评价,汉江汉中段干支流处于轻度污染—α-中污染状况,营养状态为轻度富营养。RDA与Spearman相关性分析表明,TN是影响浮游植物群落结构及动态的主要环境因子。     

青岛崂山近岸海域浮游植物群落结构及其与环境因子的关系

2012年5月和8月对崂山近岸和流清河湾网箱增养殖区的浮游植物进行调查。结果显示,5月共检出浮游植物23属36种,细胞丰度变动范围为85.26×103～720.16×103cell/m3,夜光藻为优势种,数量占浮游植物总量的80%以上,受其影响,群落多样性较差,细胞丰度低。8月共检出浮游植物30属54种,细胞丰度变动范围为43.00×103～1 116.27×103cell/m3,群落多样性较好,细胞丰度较低。对浮游植物群落进行聚类分析,5月相似性在60%以上,8月在50%以上。崂山近岸的浮游植物细胞丰度平均值均大于流清河湾网箱增养殖区,而多样性均值前者均小于后者;相关性分析显示,细胞丰度平均值与N/P均值呈显著负相关(r=-0.81,P<0.05),而多样性均值与其呈显著正相关(r=0.98,P<0.05),认为影响浮游植物细胞丰度和多样性的最关键限制因子是无机氮。     

烟台近海贝类养殖区浮游植物群落研究

2018、2019年5—11月海湾扇贝Argopecten irradians养殖期,按照离岸远近在养殖筏架之间设置13个采样站,每月中旬采集表层（2 m）与底层（8 m）浮游植物水样,14个航次调查了烟台近海四个贝类养殖海海域浮游植物的群落组成、Mc-Naughton优势度指数、Shannon-Winner多样性指数、Pielou均匀度指数和丰度的变化,并对浮游植物群落与环境因子进行相关性分析与典范对应分析（canonical correspondence analysis, CCA）,以探究烟台近海贝类养殖区浮游植物的变化规律。结果表明：共检测出5门111种浮游植物,以硅藻门为主,共78种,甲藻门、金藻门、绿藻门以及隐藻门分别为15种、9种、6种和3种;两年的优势种相似度较高,主要以硅藻门和金藻门为主,仅2019年10月以蓝隐藻（Chroomonas sp.）为绝对优势种;两年间,莱州湾各养殖海域浮游植物丰度变化趋势一致,四十里湾有所差别,2018年总体高于2019年。评价指数表明：烟台近海贝类养殖区浮游植物物种多样性较高,群落结构稳定,适宜贝类养殖。相关性分析显示：影响浮游植物丰...     

京杭运河苏北段秋冬季浮游植物群落结构特征及其与 环境因子的关系

在京杭运河苏北段秋冬两季开展水环境监测和浮游植物调查,为京杭运河苏北段的水生态环境保护提供参考。2020 年 10 月（秋季）和 2021 年 1 月（冬季）,对京杭运河苏北段布设的 16 个采样点开展了系统的水环境和浮游植物调查,根据Shannon-Wiener 多样性指数、 Pielou 均匀度指数和浮游植物细胞丰度进行了水质及水体营养状态的评价,利用 Pearson 相关性分析明确了浮游植物与环境因子的关系。结果显示：京杭运河苏北段秋冬季共采集到浮游植物 8 门 101 种,其中秋季 7 门 52 种、冬季 5 门 63 种,秋冬季均是以绿藻门和硅藻门为主,2个门类的种类数在秋冬季浮游植物种类总数的占比分别达到了 73% 和 82%;秋季浮游植物细胞丰度均值为 49.1×104 个/L,生物量均值为 0.344 mg/L,冬季浮游植物细胞丰度均值为 15.0×104 个/L,生物量均值为 0.193 mg/L;秋冬季浮游植物优势种主要以硅藻门（Bacillariophyta）和绿藻门（Chlorophyta）为主;秋季浮游植物的多样性评价结果优于冬季,秋冬季水体营养状态均为中营养型,相关性分析表明氮对京杭运河苏北段浮游植物群落结构的影响大于磷;另外,行船引起的水体扰动也是造成浮游植物群落差异的重要因素。     

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.