莱州湾虾池养殖罗非鱼的静水围隔生态系浮游植物的初步研究↑（*）

本文报道了在１９９４年７月至９月间莱州湾海水养罗非鱼围隔生态系浮游植物优势种、叶绿素浓度与理化因子的关系。各浮游植物优势种与理化因子的相关性基本一致，但其相关程度不同，主要优势种卵形隐藻、海洋原甲藻和扁藻与各理化因子的关系最紧密。从总体水平上，各种理化因子对浮游植物影响的相对重要性依次为ＴＮ＞ｐＨ＞ＴＰ＞ＮＯ２－Ｎ＞ＤＯ＞ＣＯＤ＞ＳＤ＞ＮＨ４－Ｎ＞ＰＯ４－Ｐ。氮磷对浮游植物的相对影响取决于氮、磷的比值。在本实验条件下，适宜的 ＴＮ／ＴＰ为 １８左右。施鸡粪和投饵两种养鱼方式中，氮和磷分别是浮游植物生长的限制因子。本文还就浮游植物变动对罗非鱼的影响进行了讨论。     

不同单养及混养海水实验围隔水化学的研究

１９９５年６～１０月和１９９６年６～８月对不同单养和混养海水实验围隔的水化学研究结果表明：围隔中盐度、总氮、总磷和化学耗氧量（ＣＯＤ）在雨季前逐渐升高,进入雨季后降低;投饵养殖时围隔中磷浓度较低氮浓度较高,其中混养中国对虾和台湾红罗非鱼的围隔活性磷（ＰＯ４－Ｐ）浓度相对较高,混养对虾与菲律宾蛤仔的围隔氨氮（ＮＨ３－Ｎ）浓度较高,投铒兼酌情施肥养殖时围隔中氮浓度较低磷浓度较高,其中混养中国对虾与缢蛏     

光合细菌在盐碱地池塘改良水质的研究

研究了光合细菌（ＰＳＢ）在低洼盐碱地池塘围隔中对水化因子和浮游生物的影响。结果表明：ＰＳＢ的施用对水化因子有较大的影响,其中水体中ＤＯ、ＮＯ３－－Ｎ升高,而ＮＨ４－Ｎ、ＮＯ２－－Ｎ、和ＣＯＤ降低,而对ＰＯ４３－－Ｐ影响不明显。当ＰＳＢ浓度高时,可提高水体的ｐＨ值;对浮游生物无明显影响;ＰＳＢ的一次施用量为１０ｐｐｍ,一次效用时间为６天左右,因而ＰＳＢ可达到改良水质,进而改善水质的目的,尤其在水质恶化时,其作用更显重要。     

两种海洋微藻内源醛类对中华哲水蚤繁殖的影响

通过室内实验研究了中肋骨条藻和海洋原甲藻对中华哲水蚤繁殖的影响,并采用顶空固相微萃取-气相色谱质谱法对两种微藻内源醛类进行定性定量分析。结果表明,与海洋原甲藻相比,中肋骨条藻对中华哲水蚤的存活率、产卵率和孵化率都存在负面影响。在微藻内源醛类分析中,检测到中肋骨条藻中含有6种醛类,而在海洋原甲藻中仅检测到两种醛类。不论是从单种醛类的含量上,还是醛类总含量上,中肋骨条藻中醛类含量都明显高于海洋原甲藻,这意味着硅藻释放的醛类物质对中华哲水蚤的繁殖和存活具有潜在的抑制作用。     

水产养殖池塘裸藻水华的特点、危害和调控

水华是水体藻类大量生长或聚集并达到一定浓度的现象,是水体富营养化和特定条件综合作用的结果。能够形成水华的藻类有蓝藻、甲藻、硅藻、隐藻、绿藻、裸藻等,其中,蓝藻、甲藻水华比较常见,     

对虾养殖围隔生态系浮游细菌的数量动态

对５个对虾养殖围隔生态系浮游细菌的数量动态进行了研究。结果表明：浮游细菌数量波动在（０．４１～１０．６３）×１０６ｍｌ－１之间,平均为（４．２９±２．４４）×１０６ｍｌ－１。随着养殖时间的推移,细菌数量逐渐上升,细菌数量昼夜间呈现较大波动。细菌数量与水温、总有机质的化学需氧量（ＴＣＯＤ）、溶解态有机质的化学需氧量（ＤＣＯＤ）呈现显著正相关,与颗粒态有机质的化学需氧量（ＰＣＯＤ）、浮游动、植物生物量无显著相关性。     

中国饲料成分及营养价值表

中国饲料成分及营养价值表ＴＡＢＬＥＳＯＦＦＥＥＤＣＯＭＰＯＳＩＴＩＯＮＡＮＤＮＵＴＲＩＴＩＶＥ表１常规成分ＰＲＯＸＩＭＡＴＥＣＯＭＰＯＳＩＴＩＯＮＧＤ：中华人民共和国国家标准ＮＹ／Ｔ：中华人民共和国农业部推荐标准ＳＣ：中华人民共和国原商业部部颁标准中...     

高产成鱼池蓝绿色裸甲藻水华的研究

由蓝绿色裸甲藻(Gymnodinium,sp．)形成的蓝绿色水华是无锡渔区高产鱼池典型水质之一。本文对该藻的形态特征、生态、池塘培育和控制以及对鱼类的影响进行了研究。蓝绿裸甲藻水华具喜温、喜光、喜有机氮肥,喜红褐色水色(生物因子),且对外界环境的变化十分敏感等生态特点。蓝绿裸甲藻水华池的理化条件较差,特别是藻体繁殖过度,极易恶化水质,造成鱼类泛池。采用增施有机氮肥、合理使用增氧机、加水等综合措施可促进和控制该藻的繁殖。经鱼类消化道镜检表明,蓝绿裸甲藻能被鲢、鳙鱼及鲤、鲫、罗非鱼鱼种大量摄食,并被鱼类消化。对无锡河埒渔业一队成鱼池三年统计,蓝绿裸甲藻水华池的鲢鳙鱼净产量比无水华池高33．4～37．5％。     

无锡市河埒口高产鱼池水质的研究——Ⅱ.浮游生物

无锡河埒口高产鱼池的浮游植物量多在20-100毫克／升之间，以隐藻门为代表的鞭毛藻类占很大优势，绿球藻类和硅藻类次之，蓝藻极少。浮游动物量平均大约为浮游植物量的114-1／3，以轮虫为主。当地养鱼池的水色，主要由膝口藻、隐藻、裸甲藻和绿球藻的水华颜色决定的。膝口藻水华是渔民最欢迎的“肥水”，隐藻水华和绿球藻类水华为一般“肥水”，裸甲藻水华被称为“转水”。文中对“肥、活、嫩、爽”的生物学内容同浮游生物量及鲢、鳙鱼产量的关系进行了分析。     

蓝藻的综合防治技术

由蓝藻形成的“铜绿水”是池塘常见的水质现象。据广大用户反映蓝藻一旦大量繁殖在水面形成翠绿水华层时，用ＣｕＳＯ４·ＦｅＳＯ４合剂（５∶２）０．７ｇ／或者石灰粉进行治疗，效果不理想。为什么“铜绿水”治疗难度较大？笔者认为有以下几个原因。１．蓝藻不能被池...     

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.     

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.