青肯泡浮游生物及鱼产潜力

青肯泡浮游生物共计1 1 3个种属,其中浮游植物63个种属,浮游动物5 0个种属,浮游植物数量2 37 .2 8×1 0 4 ind /L ,生物量2 5 0 0mg/L ,浮游动物数量5 5 0 5 .4ind /L ,生物量6 .692mg/L ,全库总鱼产潜力5 2 7760kg ,总放养量2 80 4 80 0尾。     

昆承湖浮游生物调查与生态渔业研究

2002～2003年对昆承湖水中浮游生物进行调查分析，共检测到浮游植物7门52个种属，年平均数量为161．10万个／L，生物量为2．47mg／L；浮游动物4门56个种属，年平均数量为582、36个／L，生物量为3．40mg／L。通过对湖泊鱼类结构调整，恢复水生植物，力求昆承湖渔业朝生态渔业方向发展。     

鲟亲鱼培育池塘中浮游生物的组成与变化特点的研究

研究了2009年5-9月鲟亲鱼养殖池塘中浮游生物的种类组成,细胞数量、优势种组成和随季节的变化。结果显示：鲟亲鱼的活动导致养殖池塘沉积物再悬浮,水体透明度较低。浮游植物的种类组成以绿藻门（Chlorophyta）的月牙藻（Selenastrum spp．）和小球藻（Chlorella spp．）等小型个体为主,浮游植物密度1．0883×lO^7ind．／L—1．5662×lO^7ind．／L,生物量14．6438～19．2535mg/L。浮游动物以轮虫（Rotifera）和桡足类（Copepoda）为优势种群,浮游动物密度162．0000ind／L～560．0000ind／L,生物量0．3795～1．5482mg／L。研究显示,鲟亲鱼的活动是决定池塘浮游生物的群落结构变化的重要过程之一。     

大力加湖鲟鱼放养场浮游动物及鱼产潜力

2004年5、7、9、12月对大力加湖浮游动物的种类组成结构特征进行了研究。结果表明：大力加湖鲟鱼放养场浮游动物59个种属,密度16475 ind．/L,生物量0．3923mg/ L。浮游动物季节变化比较明显,密度春季最高为44200．0ind/L,生物量变化不明显。浮游动物鱼产潜力3666kg,放养量18330尾。     

西泉眼水库冰下浮游动物种群结构的观察

2006年3月对西泉眼水库冰下浮游动物种群结构进行了初步的观察。结果表明,冰下浮游动物共32个种属。其中优势种有偏孔砂壳虫、普通表壳虫、表壳虫、镖水蚤、剑水蚤。浮游动物中原生动物的数量最大为1600.0 ind/L,占总数的92.6%;桡足类的生物量最大为0.3851,占76.1%。水平分布Ⅱ采样点数量最高为2661.0 ind/L,Ⅲ采样点生物量的总量最高为0.5378 mg/L。垂直分布在同一断面,上层的浮游动物大于下层浮游动物的数量;深水区浮游动物的生物量大于浅水区。     

大力加湖鲟鱼放养场浮游植物及鱼产潜力

2004年5、7、9、12月对大力加湖浮游植物的种类组成结构特征进行了研究。结果表明：大力加湖鲟鱼放养场浮游植物96个种属,密度255.54×10~4 ind．/L,生物量14.166 mg/L。浮游植物季节变化比较明显,密度秋季最高为456.160×10~4 ind．/L,生物量以秋季最高30.105 mg/L。多样性指数变化是夏季＞秋季＞冬季＞春季;均匀度指数变化是冬季＞夏季＞秋季＞春季。全库总鱼产潜力527760 kg,总放养量2804800尾。     

蛤蟆通水库浮游生物的研究

1991－1994年对蛤蟆通水库浮游生物进行了调查。浮游植物8门96种属，浮游动物86种属；浮游植物生物量平均为4．624mg/l，浮游动物生物量年平均为2．631mg/l；浮游植物生物量中以硅藻为主，占48．30％，浮游动物生物量中轮虫类最高，占67．0％；鱼类生长期（5－9月）浮游植物生物量10．992mg/l，浮游动物生物量为3．315mg/l；冰封期冰下浮游植物的种类组成、生物量等明显与越冬池冰下游浮植不同。浮游生物可提供的鱼产潜力为540．9吨。     

安邦河湿地浮游植物春季初步调查

2006年5月对安邦河湿地浮游植物进行调查,共采到浮游植物37种,其中绿藻9种,蓝藻5种,硅藻14种,其他9种。浮游植物数量年平均为95．26×10^4ind．／L（个／L）．生物量为2．22mg／L。浮游植物数量和生物量变化为上游高于下游,边缘区高于核心区,与地理位置相关。     

迎龙湖水库水质调查

于2020年春、夏、秋、冬，对重庆迎龙湖水库水质进行调查，分析了浮游生物与水体理化因子间的关系。结果表明，共检测到浮游植物7门35科125属种，其中绿藻门(46个种属)和硅藻门(41个种属)种类最多；共监测到浮游动物4门33科84属种，原生动物(30个种属)和轮虫(34个种属)种类最多。浮游植物平均密度为660.893 1×10⁴ cells/L，平均生物量为3.611 4 mg/L；浮游动物平均密度为14 039.79 ind./L，平均生物量为4.120 7 mg/L。迎龙湖水库水体为中-富营养，透明度最高为1.65 m,pH值平均值为7.6，水中溶解氧丰富，氮磷含量较高，水体呈富营养化趋势。指出，透明度、叶绿素a以及pH值，是影响浮游生物群落结构的主要因子。     

纯化水库渔业资源现状及利用对策

库水总盐量约为0.6mg／L,属一般淡水,平均总碱度、总硬度均有利于水生生物的生长发育。浮游植物平均数量474．23万个／L,生物量4．608mg／L,作为滤食性鱼类优质饵料的硅藻门在数量和生物量上占绝对优势。浮游动物平均生物量0．828mg／L,平均数量2498 ／L,属一般营养水平。底栖动物生物量0．663g／m^2,种类组成简单,数量较少,生物量较小,所能提供的鱼产力较低。针对该水库的渔业资源现状,提出了合理的利用方式。     

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.