欧洲大扇贝人工繁育试验初报

欧洲大扇贝(Pecten maximus)雌雄同体,原产地大西洋欧洲近岸海域。通过引进种贝,在室内7～15℃条件下繁育,成功培育出稚贝80万枚。稚贝入海后生长较快,高温季节死亡率较低。初步认定大扇贝可能适合在北黄海区养殖及底播增殖。     

三沙地区白蝶贝与点篮子鱼混养研究

白蝶贝又称大珠母贝,主要分布于东南亚及澳大利亚北部海域,其栖息环境从具有海草床的浅海一直延伸到具有珊瑚礁的深海区,是4种主要海水珍珠母贝中规格最大的种类,最大个体的壳长超过30厘米,体重达4～5千克.由大珠母贝培育的珍珠称为南洋珠,因珍珠粒径大、珠层厚、品质好,其价值远高于其他珍珠贝所培育的珍珠.至今,已有较多关于大珠...     

不同单细胞藻类对大扇贝幼体的饵料效果初探

<正>大扇贝(Pecten maximus)雌雄同体,原产地大西洋欧洲近岸海域。通过引进种贝,在室内7～15℃条件下繁育,成功培育出稚贝80万枚。稚贝入海后生长较快,高温季节死亡率较低。初步认定大扇贝适合在北黄海区养殖及底播增殖。     

甲藻孢囊在辽东半岛沿岸海域表层沉积物中的分布

孢囊是诸多有毒有害甲藻赤潮暴发的种源,也是底栖贝类毒素积累源之一。近年来,北黄海沿岸海域贝毒呈现明显增加的趋势,为掌握有毒有害甲藻在辽东半岛沿岸海域的种源分布情况,笔者于2013年在辽东半岛普兰店(皮口)、庄河、东港浅海海域的菲律宾蛤仔增养殖区域布设12个站位,利用柱状采泥器采集表层沉积物,通过定性和定量分析,研究甲藻孢囊在辽东半岛沿岸海域的空间分布情况,并通过群落相似性分析,研究3个海域甲藻孢囊群落的相似性情况。研究结果显示,3个调查区域共检测出甲藻孢囊10属15种,其中自养型9种,异养型6种。各区域各站位孢囊丰度相差较大,为87~775孢囊/g,平均丰度为393孢囊/g,东港和庄河海域丰度较低,普兰店海域丰度相对较高。相似性分析结果显示,3个海域孢囊群落组成亲缘关系较远。普兰店海域有毒有害甲藻分布广泛,且临近孢囊种类和丰度较高的长山群岛海域,毒素在贝类体内累积的可能性较高,需引起重视。     

丁字湾莱阳海域渔业资源的保护与开发对策

山东莱阳海域位于黄海丁字湾北部,是半岛南部连接烟台与青岛的节点,海岸线长23．35km,海域面积36．35km^2,5m等深线内滩涂总面积3200hm^2。湾内属泥沙底质,滩平水缓,基础饵料生物丰富,水温、盐度、酸碱度等理化因子适宜。湾外邻接著名的青威渔场,拥有丰富的鱼、虾、贝、蟹、腔肠等渔业生物资源,     

黄渤海贝毒机理及产毒藻类的研究现状

贝类毒素即赤潮藻毒素,贝类通过滤食有毒微藻、细菌等,经过生物累积和放大转化为有机毒素,即贝毒[1]。海洋贝毒主要分为麻痹性贝毒、腹泻性贝毒、神经性贝毒、记忆缺失性贝毒、西加鱼毒素[2-5],此外还有部分溶血毒素。其中麻痹性贝毒是目前分布最广,对人类影响最为严重的一种贝类毒素[6-9]。     

东海区七星底灯鱼数量分布以及与温盐度的关系

本文利用从2000年12月到2001年9月一个周年的渔业资源调查数据,对东海区七星底灯鱼的数量分布及其与温盐度的关系进行了研究。结果表明:东海区的七星底灯鱼可分为东海北部和浙江中南部近海2个群体。以东海北部群体较大,主要分布在30°N以北的海域;浙江中南部近海群体较小,且只有零星分布。七星底灯鱼在东海北部海域从沿岸到外海都有分布,但沿岸数量较少,主要分布在30°30′~32°30′N、124°00′~126°30′E之间的海域;以冬春季节分布面较广,夏秋季节的分布面较窄。东海北部群七星底灯鱼栖息海域的表层温度值变化较大,以春季最低,秋季最高;密集分布区的等温线变化范围在1~2℃左右。浙江中南部近海群的栖息水温变化较小,全年都在20℃以上。各季节浙江中南部近海群的适宜水温均高于东海北部群。各季节东海北部群密集分布区的表层盐度在32.0~34.5之间,以冬春季的盐度值较高,夏秋季的盐度值较低;浙江中南部近海群的栖息海域表层盐度除冬季较高外,其余季节相对较低。     

觉华岛近岸海域浮游动物调查

2018年9月对觉华岛近岸海域的海洋浮游动物进行了调查,并分析了该海域浮游动物种类组成、优势种、生物量和数量分布。结果表明:该海域浮游动物群落生态属性为暖温带广温广盐生态型,以桡足类为主,优势种为中华哲水蚤。调查海域内浮游动物生物量和数量分布不是很均匀,觉华岛南部海域浮游动物生物量最高,北部海域浮游动物总丰度最高,种类数量最大。     

南海北部马面鲀渔获率初步研究

根据2009-2014年在南海北部生产的183艘渔船的渔捞日志,分析了南海北部海域马面鲀渔获率随作业方式、年际分布与季节分布间的变化特征。分析结果表明,渔获马面鲀主要作业类型为双拖、单拖、桁杆拖虾、围网、定置张网和刺网6种,其中单拖、双拖网作业渔获率较高;2009-2014年,南海北部马面鲀渔获率低于南海南部,整体渔获率呈逐年递减趋势,仅2011年渔获率突增,2014年马面鲀渔获率降为最低。马面鲀常年主要分布于珠江口、粤西、海南岛沿岸及北部湾海域,粤东海域偶有分布。海南岛沿岸、粤西及珠江口海域渔获率密度较大,北部湾和粤东海域渔获率密度相对较小。各区域渔获率季节变化明显,渔获率最大值常在夏季出现,春、秋季次之,冬季最小。引起渔获率差异的主要原因为自然条件与捕捞压力。本文通过对马面鲀渔获率变化及原因分析,为南海北部马面鲀合理捕捞提供依据。     

中国沿海贝类腹泻性贝毒的特征分析

<正>腹泻性贝毒是由有毒赤潮藻类鳍藻属(Dinophysis)和原甲藻属(Prorocentrum)中部分藻种所产生的热稳定的脂溶性多环醚类生物活性物质,主要成分为软海绵酸及其衍生物[1]。该毒素可在贝类等滤食性动物体内富集,通过食物链传递至人类,引起腹泻性中毒,危害食用者健康。腹泻性贝毒在全球沿岸海域均有分布,是世界范围内最具威胁的赤潮藻毒素之一。     

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.