克氏原螯虾体表固着类纤毛虫种类调查及硫酸锌对其药效研究

调查克氏原螯虾(Procambarus clarkii)容易感染的固着类纤毛虫种类,并挑选寄生虫种类较单一的寄生部位分割成若干小块,分别放入不同浓度硫酸锌溶液,观察硫酸锌对固着类纤毛虫的药效。结果显示:容易感染克氏原螯虾的种类主要有钟虫、聚缩虫、累枝虫及莲蓬虫。硫酸锌对这几种虫体的24 h和48 h的LC_(50)分别为5.63和2.18 mg/L、5.01和2.44 mg/L、6.28和2.93 mg/L、3.23和1.72 mg/L,对硫酸锌敏感度莲蓬虫钟虫聚缩虫累枝虫。结果表明硫酸锌对克氏原螯虾常见固着类纤毛虫病有效。     

斑点叉尾鮰聚缩虫病防治试验报告

进行斑点叉尾鮰聚缩虫病防治试验,结果表明,用浓度为200mg／l甲醛（化学纯）浸泡30min,病鱼身上的聚缩虫杀灭率只有55％;而当病鱼先用浓度为200mg／l甲醛浸泡15min后,按20mg／l浓度添加高锰酸钾,再浸泡15min后,聚缩虫杀灭率达80％,经治疗后的病鱼平均存活率达82％。     

用双氯苯双胍已烷防治对虾聚缩虫病的研究

<正> 聚缩虫病害是中国对虾养殖明间常见的病害之一,发病率高,危害严重,特别是常与丝状细菌和藻类同时附着,影响对虾鳃丝的气体交换,个体消瘦,甚至发生死亡。该病防治方面的研究引起国内外有关专家的重视,如 Johnson(1973)和 Lightner(1977)曾提出福尔马林能有效地治疗对虾聚缩虫病,国内报道的有用0.5～1 ppm 的新洁尔灭与5～10ppm 的高锰酸钾混合用可杀灭聚缩虫以及用茶粕5ppm 促使对虾脱皮以达到除去聚缩虫之目的等等。我们曾选用福尔马林等药物试验,经多次筛选认为一些药虽     

报刊要闻

<正> 对虾纤毛虫病的防治江苏淡水水产所唐天德等撰文介绍了纤毛虫(聚缩虫、单缩虫、钟型虫、累技虫等)生长繁殖的条件、患病虾的特征和防治方法: 1.加强池水管理、保持水质清新;2.提高饵料质量、增强对虾体质;3.予防与药物治疗相结合,在养虾的中、后期,每周用苏SH—Ⅱ药或添加稀土甲壳素的颗饵连喂3天,每天2次,同时用苏SH-Ⅱ药连续予防;一旦纤毛虫类大发生,治疗方法是先降低虾池水1/3～2/5,用0.5～lppm的苏SH-Ⅱ连续处理3天.也可用碱性品录或新洁尔灭加高锰酸钾混合处理.一般很快能治愈。     

福尔马林防治大黄鱼刺激隐核虫病的研究

为合理使用福尔马林防治大黄鱼刺激隐核虫病,研究福尔马林对体外刺激隐核虫的灭活效果,并评估其对大黄鱼幼鱼的安全质量浓度范围。结果显示,对幼虫分别药浴处理10、30、60、120min,使幼虫全部死亡的福尔马林质量浓度分别为62.5、62.5、31.3、5.6mg/L;对包囊药浴处理1、2、4h,使包囊全部死亡的福尔马林质量浓度分别为150、75、75mg/L;福尔马林对大黄鱼(3.00±0.78)g幼鱼12、24、48、96h的半致死质量浓度分别为394.7、365.3、334.4、322.8mg/L;治疗试验显示,125mg/L福尔马林药浴2h,可有效防治大黄鱼刺激隐核虫病,存活率显著高于75mg/L组和对照组。试验结果表明,每隔3d,125mg/L的福尔马林药浴处理大黄鱼2h,共3次,可安全有效防治大黄鱼刺激隐核虫病。     

高锰酸钾防治对虾幼体聚缩虫病的研究

在对虾育苗期间,以选择施用0.5ppm和1ppm高锰酸钾、换水补药的方式为预防措施,以泼洒2～4ppm高锰酸钾短期药浴为应急治疗方法,连续2年在对虾育苗生产中取得了抑制和杀灭聚缩虫病成功率为100％,每立方水体生产15～25万尾仔虾的良好效果。育苗水体长期施用0.5～1ppm高锰酸钾对对虾幼体、单胞藻、卤虫无毒害作用,对微粒饵料、水质因子亦无不良影响。高锰酸钾施用方便,成本低廉,投入成本只占万尾虾苗售价的万分之一左右,便于在大生产中推广应用。     

河蟹人工育苗期固着类纤毛虫病的防治

河蟹人工育苗期间，受精卵和状幼体用抗真菌药物制霉素药浴，对固着类纤毛虫病的防治效果显著。当药液浓度在３５ｍｇ／Ｌ时浸浴３ｇｍ在６５ｍｇ／Ｌ时浸浴２ｈ，在１２５ｍｇ／Ｌ时浸浴１ｇ，均能杀死固着在蟹卵及幼体上的钟虫Ｖｏｒｔｉｃｅｌｌａｓｐ和聚缩虫Ｚｏｏｔｈａｍｎｉｕｍｓｐ．，并使虫体脱落。蟹卵和状Ｉ期幼体用１２５ｍｇ／Ｌ制霉素药浴６ｈ亦无融作用，受精卵的胚胎发育及幼体的蜕皮变态均正常。     

丁香酚对日本黄姑鱼麻醉效果的研究

为研究丁香酚对日本黄姑鱼的麻醉效果,用体长95 mm的日本黄姑鱼进行了麻醉试验。结果表明,水温25～26℃时,5 mg/L浓度的丁香酚药液对日本黄姑鱼只能起到轻度镇静作用;浓度在10～50mg/L时,浓度与麻醉所需的时间呈负相关,与复苏时间呈正相关;最理想的麻醉浓度为20～40 mg/L。鱼体在浓度20～30 mg/L的丁香酚药液中药浴15 min,能全部复苏;在浓度40 mg/L下药浴9 min,能全部复苏。采用浓度20～30 mg/L的丁香酚药液对鱼体深度麻醉后,鱼体在空气中暴露9 min后能全部复苏,且复苏时间随着药液浓度的升高而变长。     

硫酸铜治疗卵形鲳鲹淀粉卵涡鞭虫病的研究

为更科学地使用硫酸铜治疗淀粉卵涡鞭虫病,该研究以卵形鲳鲹(Trachinotus ovatus)为动物模型,探讨了硫酸铜对眼点淀粉卵涡鞭虫(Amyloodinium ocellatum)生活史各个阶段的有效驱杀浓度和作用时间,并评估其对卵形鲳鲹幼鱼的安全质量浓度范围。结果显示,卵形鲳鲹幼鱼对硫酸铜的耐受性强,安全质量浓度小于43.06mg·L~(-1)。用3.13、0.78、0.20 mg·L~(-1)硫酸铜溶液分别药浴处理10、30、60 min可100%驱杀涡孢子;用2.0、1.0、0.5 mg·L~(-1)硫酸铜溶液分别药浴浸泡鱼体2、4、8 h可100%清除鱼体上的营养体;而包囊对硫酸铜的耐受性强,用100 mg·L~(-1)硫酸铜溶液连续药浴,仍有90%以上的包囊能继续分裂。治疗实验显示,在0.2、0.4mg·L~(-1)硫酸铜溶液中连续药浴10 d,对患病鱼的相对保护率分别为80%和90%,表明使用低浓度硫酸铜溶液连续药浴可有效治疗卵形鲳鲹淀粉卵涡鞭虫病。     

几种常用渔药对三疣梭子蟹Portunus trituberculatus(Miers)稚蟹的急性毒性试验

采用常温静水实验法.对Ⅰ～Ⅱ期梭子蟹稚蟹(平均体长0.2～0.3 cm)进行急性毒性试验,结果表明:在水温26.2～27.8℃F,6种渔用药物对梭子蟹Ⅰ～Ⅱ期稚蟹的96 h半致死浓度(96 h LC50)分别为硫酸铜1.4 mg/L、纤虫清2.5 mg/L、清苔净16 mg/L、二氧化氯3.7 mg/L、强力杀菌消毒剂4.2 mg/L、二溴海因36.8 mg/L;安全浓度(Sc)分别为硫酸铜0.47 mg/L、纤虫清0.62mg/L、清苔净4.1 mg/L、强力杀菌消毒剂1.1 mg/L、二氧化氯1.1 mg/L、二溴海因13 mg/L.梭子蟹对上述药物的敏感性分别为硫酸铜＞纤虫清＞三氯异氰尿酸钠＞二氧化氯＞二溴海因＞清苔净.其中硫酸铜、纤虫清的安全浓度相对较低,在梭子蟹养殖过程当中应谨慎使用.     

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.     

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.     

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.     

Effects of cortisol on hepatic carbohydrate metabolism and responsiveness to hormones in the sea raven,Hemitripterus americanus

The sea raven, Hemitripterus americanus, is a sit-and-wait, low metabolic rate, marine teleost. The objective of this study was to determine i) whether cortisol implantation (50 mg. kg^-1) for 7 days altered hepatocyte metabolism, and hepatocyte responsiveness to epinephrine, glucagon and insulin, and ii) whether 8 weeks of food-deprivation modified the above response. Cortisol implantation significantly increased hepatocyte total glucose production and oxidation from alanine compared to the sham group. There was no cortisol effect on glycogen breakdown, suggesting that the activation of other pathways, including gluconeogenesis, are required to account for the increased glucose production. Epinephrine-mediated (10^-5M) glycogen breakdown and insulin-mediated (10^-8M) total glucose production were enhanced in hepatocytes of cortisol implanted sea ravens, but there were no change in any glucagon (10^-7M) effects. The enhanced glycogen breakdown in the absence of similar increases in total glucose production with epinephrine indicates mobilization of carbohydrate reserves for endogenous use by the liver. Food-deprivation for 8 weeks significantly decreased condition factor, plasma cortisol concentration and liver glycogen content in the sea raven, but had no effect on plasma glucose concentration. Hepatocyte total glucose production and flux rates from alanine increased significantly with food-deprivation. Moreover, food-deprivation increased responsiveness of total hepatocyte glucose production to the actions of glucagon and insulin, but not to epinephrine; none of these effects were modified by cortisol implantation. Our results indicate that cortisol in the sea raven exerts both a direct and an indirect or permissive effect on hepatocyte metabolism by modifying hepatocyte responsiveness to epinephrine and insulin stimulation. Cortisol implantation did not modify the effects of glucagon or food-deprivation in this species.     

Simulation and quantification of enrichment and retention processes in the southern Benguela upwelling ecosystem

Important environmental processes for the survival and recruitment of early life stages of pelagic fishes have been synthesized through Bakun's fundamental triad as enrichment, concentration and retention processes (A. Bakun, 1996, Patterns in the Ocean. Ocean Processes and Marine Population Dynamics. San Diego, CA, USA: University of California Sea Grant). This conceptual framework states that from favourable spawning habitats, eggs and larvae would be transported to and/or retained in places where food originating from enrichment areas would be concentrated. We propose a method for quantifying two of the triad processes, enrichment and retention, based on the Lagrangian tracking of particles transported within water velocity fields generated by a three‐dimensional hydrodynamic model. We apply this method to the southern Benguela upwelling ecosystem, constructing putative maps of enrichment and retention. We comment on these maps regarding main features of the circulation in the region, and investigate seasonal variability of the processes. We finally discuss the results in relation to available knowledge on the reproductive strategies of two pelagic clupeoid species abundant in the southern Benguela, anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax). Our approach is intended to be sufficiently generic so as to allow its application to other upwelling systems.     

Effects of capture,loading density and transport stress on the mortality,physiological responses,bacterial density and growth of rohu <Emphasis Type="Italic">Labeo</Emphasis><Emphasis Type="Italic"> rohita</Emphasis> fingerlings

This study evaluated the effects of three levels of loading density (200, 300 and 400 g L⁻¹) and four levels of duration (1, 3, 6 and 9 h) on the mortality, plasma cortisol and chloride levels and growth of rohu Labeo rohita fingerlings in a transport simulation. While total immediate mortality was low (4–12%), delayed mortality was high (27–49%). Initial capture and handling were found to constitute the most stressful phase as indicated by elevated plasma cortisol. The levels of cortisol continued to rise at 6 and 9 h after transport, with the highest level observed at 9 h after transport. The level of plasma chloride fell after transport across all density levels and treatment durations. Specific growth rate (SGR, %/day) and total bacterial density (cfu/g) were not different between and within treatments, and between treatments and the controls. This study demonstrates that transport has a profound effect on the stress responses of rohu fingerlings. Although the level of immediate mortality was low, the higher level of delayed mortality has serious implications in terms of production inefficiency for grow-out farmers.     

The effects of introduced tilapias on native biodiversity

• 1. The common name ‘tilapia’ refers to a group of tropical freshwater fish in the family Cichlidae (Oreochromis, Tilapia, and Sarotherodon spp.) that are indigenous to Africa and the southwestern Middle East. Since the 1930s, tilapias have been intentionally dispersed worldwide for the biological control of aquatic weeds and insects, as baitfish for certain capture fisheries, for aquaria, and as a food fish. They have most recently been promoted as an important source of protein that could provide food security for developing countries without the environmental problems associated with terrestrial agriculture. In addition, market demand for tilapia in developed countries such as the United States is growing rapidly.
• 2. Tilapias are well‐suited to aquaculture because they are highly prolific and tolerant to a range of environmental conditions. They have come to be known as the ‘aquatic chicken’ because of their potential as an affordable, high‐yield source of protein that can be easily raised in a range of environments — from subsistence or ‘backyard’ units to intensive fish hatcheries. In some countries, particularly in Asia, nearly all of the introduced tilapias produced are consumed domestically; tilapias have contributed to basic food security for such societies.
• 3. This review indicates that tilapia species are highly invasive and exist under feral conditions in every nation in which they have been cultured or introduced. Thus, the authors have concluded that, despite potential or observed benefits to human society, tilapia aquaculture and open‐water introductions cannot continue unchecked without further exacerbating damage to native fish species and biodiversity. Recommendations include restricting tilapia culture to carefully managed, contained ponds, although exclusion is preferred when it is feasible. Research into culture of indigenous species is also recommended.

Copyright © 2005 John Wiley & Sons, Ltd.