虾池浮激植物初级生产力的研究

用黑白瓶测氧法对辽宁省庄河青堆水产公司虾池整个养殖期间（５－９月）浮游植物初级生产力进行研究。虾池浮游植物的初级生产力为（５．４５±２．３６）ｇＯ２／（ｍ＾２．ｄ），日Ｐ／Ｂ系数为２．３９（０．６７－６．６６），浮游植物对太阳有效辐射的利用率为０．７８（０．２４－２．１８）％，浮游植物毛产量到虾产量的转化效率为７．４１％；回归分析表明，浮游植物生物量和太阳有效辐射量是决定虾池浮游植物初级生产力大小     

报刊要闻

<正> 虾池初级生产力 用黑白瓶测氧法对辽宁省庄河青堆水产公司虾池整个养殖期间(5～9月)浮游植物初级生产力进行研究。虾池浮游植物的初级生产力为(5.45±2.36)gO_2(m~2·d),日P/B系数为2.39(0.67～6.66),浮游植物对太阳有效辐射的利用率为0.78(0.24～2.18)％,浮游植物毛产量     

东港湖浮游植物现存量及生产量

东港湖浮游植物主要有47种，隶属于7门38属。优势种春秋季为绿藻和硅藻，夏季为黄丝藻，冬季为甲藻。浮游植物数量秋季最多（232．45×104个／L）。生物量冬季最高（3．664mg／L．）叶绿素a夏季最高（5．35ug／L）。初级生产力夏季最高（3．13gO2／m2·d）。光和效率夏季最高，种群兴起春季最盛。湖水属中营养型。浮游植物提供的滤食性鱼产潜力为2．966万kg。     

乳山湾6—9月叶绿素a含量的分布及初级生产力的估算

根据1995年6～9月对乳山湾东流区进行的6次综合调查结果，着重阐述了乳山湾东流区叶绿素a含量的分布特．点及其与海洋环境因子的关系，并对初级生产力进行了估算。结果表明，乳山湾东流区对绿素a含量6～9月份平均值为11．16mg／m3，最高值出现在9月中旬，高达45．26mp／m3；估算初级生产力的平均值为432m星C／m2·d；在影响叶绿素a含量分布与变化的环境因子中，与浮游植物细胞数量、温度、径流和营养盐等关系密切；乳山湾东流区叶绿素a含量和初级生产力处于较高的水平。     

轮虫培育池不同粒级藻类对浮游植物生物量和生产量的贡献

研究了流水轮虫培育池(14^#)、静水轮虫培育池(15^#)和轮虫饵料培养池(11^#)中不同粒级浮游植物，特别是超微藻类对浮游植物叶绿素和初级生产力的贡献。结果表明，在14^#池中，超微藻类、微型藻类和小型藻类的叶绿素a含量分别占总叶绿素a含量的3．7％、82．9％和13．4％。各粒级浮游植物初级生产力分别占总生产力的13．6％、66．0％和20．4％。在11^#池中，超微藻类、微型藻类和小型藻类的叶绿素a含量分别占总叶绿素a含量的4．5％、16．1％和79．4％。各粒级浮游植物初级生产力分别占总生产力的9．0％、78．9％和12．1％。在15^#池超微藻类、微型藻类和小型藻类的叶绿素a含量分别占总叶绿素a含量的4．7％、22．3％和73．0％。各粒级浮游植物初级生产力分别占总生产力的12．4％、60．8％和27．8％。水体中的初级生产力主要是由微型藻类提供，占总量的60．8％～78．9％，在轮虫培育池生态系统中微型藻类是主要生产者。     

莺河一库渔业潜力及开发对策

对莺河一库水质的调查分析和饵料生物的定量测定得出：该库属中营养型水库，浮游植物初级生产力平均２３．９６ｋｇＯ＿２／ｈａ·ｄ，其中鱼类生长期内初级生产力３２１．１６ｋｇＯ＿２／ｈａ·ｄ，净生产量２５．７３ｋｇＯ＿２／ｈａ·ｄ，净生产量之和为５４０３．３ｋｇＯ＿２／ｈａ，折合浮游植物鲜重为２８６３７．５ｋｇ／ｈａ；浮游植物、浮游动物和底栖动物的生物量分别为３．２ｍｇ／Ｌ、１．２６ｍｇ／Ｌ和０．８５ｇ／ｍ￣２，水库近期鱼产力为３６３．６ｋｇ／ｈａ，总产量２０．９４万ｋｇ。该库历年平均成鱼单产为８８．４ｋｇ／ｈａ，占估算鱼产力的２４．３％，水库的渔业潜力有待开发利用，因此，提出了今后合理开发水库渔业资源的对策。     

蛤蟆通水库浮游植物初级生产力及能量转化效率的研究

本文论述1991－1993年对蛤蟆通水库游游植物初级生产力和能量转化效率的测定结果。蛤蟆通水库浮游植物初级生产力，日产量达4．420－8．490go2/m^2，水柱年产量达574．6－1103．76go2/m^2。浮游植物初级生产力与浮游植物的现存量、水温、PO4－P等有显著关系。其能量转化效率平均为0．54％，属中等水体。     

南美白对虾高位池浮游生物和初级生产力的研究

4口试验虾池共检出浮游植物32属(种),隶属于7个门,浮游植物生物量变化在2.15～83.24mg/L,平均为30.41mg/L。虾池浮游植物的多样性指数相对较低,平均为0.202。试验虾池共检出浮游动物23种,生物量变化在0.45～6.34mg/L,平均为3.38mg/L。各试验虾池浮游植物和浮游动物生物量平均数相差不大,但各月份的生物量差别较大。浮游植物生物量呈现波动式上升;浮游动物生物量表现为由高到低,再由低到高的变化趋势。试验虾池水柱毛初级生产量变化在2.03～12.54g/m2·d,平均6.58g/m2·d;呼吸量变化在1.24～12.05g/m2·d,平均5.89g/m2·d。试验虾池P/R有很大的波动,变化在0.9～2.21,平均1.27。     

EDTA-Na_2直接滴定乳中总钙及方法的评价

对20份乳样用EDTA－Na2直接滴定Ca含量，结果在1．25mol／lKOH中为1．18±0．19（mg／ml），在1mol／lNaoH中为1．14±0．19（mg／ml）；用食品中钙测定的标准方法测定结果为1．12±0．26（mg／ml），两法之间无显著差异（P＞0．2和P＞0．5）。直接滴定法重复试验结果的CA为3．43％；回收率为102．15％±3．92％（97．44％～107．69％），说明直接滴定法可用于乳中总钙测定。     

养鳗池塘的初级生产力和能量转换效率

报道了养鳗池塘初级生产力的垂直变化和季节变化。养鳗池塘的初级生产量为 3.5 1～ 7.90gO2 /m2 ·day ,高峰通常出现在 7～ 8月。 1米以上水层的光合作用产氧量占水柱总产量的 90 %以上。平均补偿深度为 6 5～ 74cm。池水氧气的消耗 ,池鱼占 2 7.4% ,“水呼吸”占 70 .0 % ,底泥占 3.6 %。浮游植物光合产氧占池塘氧气来源的 6 6 .0 % ,余下的 43.0 %靠空气和加水补给。毛初级生产力对太阳辐射能的利用率为 0 .38%～ 0 .85 % ;鳙产量对浮游植物的利用率为 1 .0 5 %～ 2 .32 % ;太阳能转移为鱼产量的生态学效率为 0 .0 0 9%～ 0 .0 1 0 %。     

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.