周公宅水库浮游生物种群结构特征研究

周公宅水库是浙江省宁波市2006年新建蓄水的山区性大(二)型水库,目前尚未被开发利用。2008年11月至2009年9月对其浮游生物、水质及鱼类资源现状进行了调查。通过分析浮游生物群落的种类组成、生物量、多样性指数等群落结构特征和水体的理化特性,揭示了周公宅水库水体的营养化水平。同时根据其水生生物的种群结构特点和水体的营养类型,提出了库区发展生态渔业的建议。     

打虎石水库浮游生物群落结构特征及鱼产力评估

为研究打虎石水库浮游生物的种类组成、密度、生物量等群落结构特征,对水体营养状况评价和水库鱼产力进行估算,于2018年5、7、9月对其浮游生物进行调查分析.调查结果显示,打虎石水库浮游植物共57种(属),其中绿藻门种类最多,有22种,占38.60％,浮游植物平均密度为7.5465×106个/L,平均生物量为3.11 mg...     

西泉眼水库浮游生物群落及鲢鳙鱼产力的估算

哈尔滨市西泉眼水库为新建水库,1997年5～9月对其浮游生物状况进行了初步调查。调查结果表明:西泉眼水库浮游植物和浮游动物的平均生物量分别为21.38mg/l和4.95mg/l,属超富营养型水体。据初步估计,浮游生物及细菌、腐屑等可提供的鲢、鳙鱼产力的为1358.62kg/hm~2。此外,本文还讨论了该水库的渔业利用问题。     

龙头桥水库浮游生物与水质状况调查分析

本文作者于2006年12月至2007年lO月对龙头桥水库浮游生物及水质状况进行了初步调查,结果显示：龙头桥水库浮游植物和浮游动物的平均生物量分别为7,350mg／L,属富营养型水体。初步估算,其浮游生物及细菌、腐屑等可提供的鲢、鳙鱼产力为585．24kg／ha。水质条件适合鱼类生长。     

福建街面水库水质现状及浮游生物调查

选择福建省尤溪街面水库两个样点分别于2008年8月-2009年6月对水体石油类、氨氮、总氮、总磷、高锰酸盐指数、大肠菌群进行监测,并在2008年8月对水库浮游生物进行调查。结果显示,目前街面水库水质良好,浮游生物以硅藻为主。     

四明湖水库浮游生物现状调查及评价

2006-2007年分4次对余姚四明湖水库水质理化指标、浮游生物群落结构进行了调查,并进行了多样性指数分析及渔产潜力估算。结果表明,四明湖水库浮游植物种类共计8门、47种（属）,其中以绿藻为最优势类群,占总密度的36.2%;浮游动物共计3大类、30种,其中原生动占40%;浮游植物年均生物量为10.20mg/L,浮游动物年均生物量2.36mg/L。从水体理化指标数据来看,四明湖水库水质属于II～IV类;从浮游植物群落结构和多样性指数分析结果来看,水库属于富营养水平;根据相关公式估算四明湖水库的鱼产潜力为20     

水质的肥度与调控技术

水库水质的肥度，因水库面积大小、地理位置（南北向、各省间差异等）以及季节、气候的差异，会导致施肥肥效、水色及浮游生物种类的差异。大中型水库在同等条件下较小型水库浮游生物的平均密度小．因此水色也偏淡，其基础生产力也就较低。硬度的大小也影响施肥后水体的肥效，硬度大的水体施肥效果较硬度小的水体差。另外，酸碱度偏高或偏低的水域，其施肥效果也差于中性偏弱碱的水域。     

四明湖水库浮游生物现状调查及评价

2006-2007年分4次对余姚四明湖水库水质理化指标、浮游生物群落结构进行了调查,并进行了多样性指数分析及渔产潜力估算。结果表明,四明湖水库浮游植物种类共计8门、47种(属),其中以绿藻为最优势类群,占总密度的36.2%;浮游动物共计3大类、30种,其中原生动占40%;浮游植物年均生物量为10.20mg/L,浮游动物年均生物量2.36mg/L。从水体理化指标数据来看,四明湖水库水质属于II～IV类;从浮游植物群落结构和多样性指数分析结果来看,水库属于富营养水平;根据相关公式估算四明湖水库的鱼产潜力为2076kg/hm2。     

龙头桥水库浮游生物状况调查

2006年12月-2007年10月,我们对龙头桥水库浮游生物状况进行了初步调查。调查结果表明：龙头桥水库浮游植物和浮游动物测定的平均生物量分别为7．3507mg／L、1、6423mg／L,属富营养型水体。据初步估计,浮游生物及细菌、腐屑等可提供的鲢、鳙鱼产力为585．24kg／ha。     

黄颡鱼苗种培育中浮游动物种类丰度变化规律及其影响因素

<正>浮游生物是大部分鱼类的天然适口饵料,是养殖水体生态系统中能量流动和物质循环的重要环节,其群落结构及其动态变化一直是研究热点。目前,针对黄颡鱼人工繁育及苗种培育研究有较多报道,但其培育过程中的浮游生物及水质变化未深入研究,本文自2013年6月中旬清塘至7月11日鱼苗长至夏花规格,每天对黄颡鱼苗种培育池水质及浮游生物进行了连续取样调查,以期能够量化黄颡鱼夏花培育水体中浮游生物种类、丰度及分析探讨其动态变化,为科学培育提供可靠的生物学依据。     

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).     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

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.     

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.