水体中组织胺对黑褐新糠虾生长与发育的影响

研究了不同浓度组织胺(1 mg/L、3 mg/L和5 mg/L)养殖水体对黑褐新糠虾生长与发育的影响,其中0 mg/L为对照组。结果表明:水体组织胺对黑褐新糠虾生长和存活有显著影响。其中高浓度组(5 mg/L)黑褐新糠虾存活率仅为(83±12.47)%,而对照组为(97±4.71)%,两者存在显著差异(P<0.05)。组织胺对黑褐新糠虾的生长有显著抑制作用,用药17 d后,对照组体长为6.18±0.30 mm,而最高组织胺浓度组(5mg/L)的体长仅约为对照组的87%,即5.35±0.26 mm,两组间有显著性差异(P<0.05);抱卵雌虾的体长各组基本一致,均约为7.58±0.24 mm;组织胺能抑制黑褐新糠虾蜕壳,表现为同一时期内蜕壳比例较低;组织胺能延迟雄性黑褐新糠虾第二性征出现和雌性黑褐新糠虾抱卵的时间,分别延迟约1 d和3 d。     

初始密度对微小亚历山大藻生长及产麻痹性贝类毒素的影响

为研究微小亚历山大藻生长和产麻痹性贝类毒素(PSP)的规律,采用不同初始密度对微小亚历山大藻进行培养,综合采用显微镜计数、小鼠生物检测(MBA)、高效液相色谱—柱后衍生(HPLC-FLD)等方法分析微小亚历山大藻在不同接种密度条件下的生长和产毒特性.结果表明,随着初始密度增加微小亚历山大藻通过静止期的时间缩短,到达最大生长密度的时间提前,但是生长的最大细胞密度和平均比生长率却呈下降趋势,增值模型反应的情况与观测结果相一致,随着初始密度的增加,依赖于初始种群密度的参数(a)减少,环境容量(K)减少,种群瞬时增殖速度(r)下降.4种不同初始密度(0.05×104、0.10×104、0.15×104、0.30×104cells/mL)条件下,微小亚历山大藻细胞的毒性呈现先增大后减小趋势,在初始密度为0.1×104 cells/mL条件下,同一生长期内细胞毒性比其他3个密度条件下高.HPLC检测微小亚历山大藻含有的毒素为GTX1-4,含量分别为2.14、2.08、4.97、5.04 fmol/cell.综合考虑微小亚历山大藻在生长过程中的细胞最大密度、达到最大密度所用时间以及细胞毒性大小等因数,采用(0.10～0.15)×104 cells/mL接种密度培养微小亚历山大藻,能够达到较好的产毒效果.     

黑褐新糠虾血细胞形态及其与日本新糠虾对溶藻弧菌敏感性的比较

实验采用Giemsa与Wright' s两种染色方法对黑褐新糠虾血细胞进行染色,根据血细胞大小,所含颗粒与否,颗粒多少和核质比将其分型,并对各型血细胞所占比例进行统计.结果表明,通过比较Giemsa染色与Wright's染色两种方法的染色时间和效果,Wright's染色更加适合糠虾血细胞.通过染色,将黑褐新糠虾血细胞分为3种类型,它们分别为透明细胞、半颗粒细胞和颗粒细胞.它们的胞体大小依次增大,核质比依次降低.对此3种类型血细胞比例分别统计后发现,颗粒细胞所占比例最多约( 48.38％±0.05％),其次是半颗粒细胞约为(35.22％±0.04％),最少的为透明细胞约为(16.40％±0.01％).对不同浓度溶藻弧菌的感染试验发现,日本新糠虾在较短的时间内出现死亡,即48h,而黑褐新糠虾72 h出现死亡,各浓度组中日本新糠虾死亡率均高于黑褐新糠虾.黑褐新糠虾相对日本新糠虾来说,对溶藻弧菌具有较低的敏感性,可能与其血细胞中颗粒和半颗粒比例较高有关.     

赤潮异弯藻对牙鲆早期发育的影响

就赤潮异弯藻(Heterosigma akashiwo)藻液及各组分对牙鲆(Paralichthys olivaceus)早期发育阶段的影响及敏感性时期作了探讨。实验结果表明，原肠期前的发育卵和初孵仔鱼对赤潮异弯藻较其他发育阶段更为敏感。在同等条件下藻液对牙鲆早期发育各阶段的毒性最大，其次是藻细胞碎片和藻细胞内容物，去藻过滤液的毒性最小。暴露在高浓度80000cells／ml藻液中，96h后仔鱼的存活率为47．6％；而在同浓度的去藻过滤液中，96h后仔鱼的存活率为90％。藻液对牙鲆仔鱼96h LC50为35042cells／ml。     

微小亚历山大藻对近江牡蛎清滤率以及麻痹性贝类毒素(PSP)蓄积的影响

为获知牡蛎对有毒微小亚历山大藻(A. minutum)的滤食以及蓄积PSP毒素的规律性，本实验采用细胞毒性为93.42±2.55×10-6 MU/cell的A. minutum藻投喂牡蛎，以无毒扁藻投喂作对照，首先研究了0.5-3.0×103 cells/mL6个不同浓度的毒藻对牡蛎滤食的影响，然后投喂浓度为1.5×103 cells/mL的毒藻，分别研究15 h短期蓄积和5天长期蓄积对牡蛎体内毒素的影响及规律。结果表明，在0.5~1.5×103 cells/mL毒藻浓度范围内牡蛎清滤率较高，超过1.5×103 cells/mL时牡蛎清滤率显著下降(P<0.01)，由此确定后期投喂毒藻的浓度“阀值”为1.5×103 cells/mL；短期蓄积实验牡蛎在0~6 h内将有毒藻滤食尽，其体内PSP毒素在6~12 h间达到最大值149.6±10.5 MU/100 g，随后开始下降。长期蓄积实验过程中，牡蛎的清滤率没有发生显著变化(P>0.01)，在蓄积实验的第2天牡蛎体内PSP毒素水平超过国家限量标准(400 MU/100g)，在5天实验结束时，牡蛎体内PSP毒素水平高达3069.2±178.2 MU/100 g，高于国家限量标准的7.7倍。实验结果作为PSP在牡蛎中蓄积及代谢的重要基础数据，为研究PSP的脱除及净化提供思路。     

产麻痹性贝毒塔玛亚历山大藻共培养菌群的物种多样性研究

产毒赤潮藻与其共生菌的互作关系是揭示麻痹性贝毒(PSP)产生机制的关键,而其共培养菌群的分离及其多样性解析是开展此研究的必要前提。塔玛亚历山大藻(Alexandrium tamarense)是典型产PSP赤潮原因甲藻,为揭示其共培养菌群的物种多样性信息,本文通过免培养海洋微生物高通量测序技术,解析了东海塔玛亚历山大藻(at3#)共培养菌群的种类、丰度及多样性信息。结果表明,其共培养菌群共有87个种与已有数据库匹配,此外尚有5%的未知种。其包含57个属,其中优势菌属5个,分别为Rhodobacteraceae、Marinobacter、Methylophaga、Nitratireductor及Phycisphaera。研究表明东海产PSP塔玛亚历山大藻(at3#)含有物种丰富的共培养菌群,且具有发掘海洋特殊生境微生物新种属的良好潜力。     

盐度对黑褐新糠虾成活的影响

<正>糠虾是一种小型虾类,对环境因子较为敏感,常被用作重金属、化工污染及环境污染研究的试验生物,美国环保局将巴西拟糠虾(Mysidopsis bahia)作为一种毒性测试的标准试验生物,欧洲把普通新糠虾(Neomysis integer)作为西欧河口系统的毒性试验生物。国内学者将我国的糠虾种类应用于环境监测中,并进行有关糠虾的毒性试验研究,周名江等报道了以黑褐新糠虾为标准试验生物的急性毒性测试方法。糠     

链状亚历山大藻的培养及麻痹性贝类毒素的提取和检测

为了研究麻痹性贝类毒素(paralytic shellfish poisoning toxins,PSP)的来源和检测,对实验室分离培养的产麻痹性贝类毒素的链状亚历山大藻进行了研究。首先通过接种对数生长期藻细胞,培养8 d内就能达到最高细胞密度(2.4×10⁴ cells/mL)左右,再以0.05 mol/L的醋酸超声波破碎藻细胞提取粗毒素,结合小白鼠生物检测法,经高效液相色谱分析,本株藻主要含有C1/2、GTX4、GTX5和NEO,浓度分别为GTX5(0.827 5)>GTX4(0.339 2)>C2(0.252 6)>NEO(0.126 6)>C1(0.045 5)(单位:μmol/L),毒素粗提液经过Sephadex-G15凝胶层析柱处理,用小白鼠生物法和荧光分光光度法联合检测定位,收集到纯度较高的PSP,本论文工作为将来贝类毒素的研究提供资料。     

环境因子对微小亚历山大藻Amtk-9生长与产毒的综合影响

微小亚历山大藻是产生麻痹性贝毒的主要生物之一。产毒藻株在不同培养条件下所产生的毒素总量有差异,因此研究环境因子对微小亚历山大藻生长与产毒的综合影响,找到微小亚历山大藻生长和产毒的适宜条件,对麻痹性贝毒在赤潮中是否造成贝类蓄毒有十分重要意义。本文设计了一个四因素三水平的正交实验,研究温度、盐度、营养盐、光照强度等环境因子对微小亚历山大藻Amtk-9生长与产毒的综合影响。结果表明:在实验范围内,微小亚历山大藻Amtk-9生长最佳条件为温度25℃,盐度30,培养基中氮含量为基础f/2培养液配方中氮磷含量的2倍,光照强度10000 lx。最佳产毒条件除了氮磷含量为基础f/2培养液配方中氮磷含量的3倍外,其它条件与生长的最佳条件相同。盐度、营养盐、光照这三个因素的不同水平对微小亚历山大藻Amtk-9指数生长期细胞比增长率、指数生长末期单位细胞含毒量均有极显著影响(F>F0.01)。温度对微小亚历山大藻Amtk-9的生长和产毒则无显著影响(F相似文献   

塔玛亚历山大藻对中国明对虾肝胰腺和鳃SOD、GST和MDA的影响

本文选择在我国分离得到的一株能典型产生麻痹性贝毒(PSP,Paralytic Shellfish Poison)的有毒赤潮甲藻塔玛亚历山大藻(Alexandrium tamarense,ATHK株),研究其是否能通过引发中国明对虾的脂质过氧化作用, 使机体产生过多活性氧自由基, 导致氧化损伤而发挥其毒性作用。塔玛亚历山大藻粗提液经肌肉注射方式染毒中国明对虾,于染毒后1、3、6、12、24和48 h 测定肝胰腺和鳃SOD,GST活力和MDA含量的影响。结果显示,染毒后 1-6 h, 对虾肝胰腺和鳃组织SOD,GST酶活力均增加,12和48h鳃组织的上述指标受到抑制。对虾肝胰腺MDA含量除1h外未见明显改变,鳃中MDA含量随时间增加呈升高趋势。研究表明：塔玛亚历山大藻粗提液在中国明对虾体内代谢过程中能诱导对虾产生活性氧自由基,塔玛亚历山大藻粗提液能诱导MDA含量增加,降低SOD和GST活力,能够引发鳃的脂质过氧化,对鳃造成氧化损伤。     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

Fertilization by refrigerator stored sperm of the Indian major carp, Labeo calbasu (Hamilton, 1822)

This study reports on the spermatological properties, and on the development of a protocol for refrigerator storage (4°C) of Labeo calbasu (Hamilton, 1822) sperm for artificial breeding. Volume, motility, concentration and pH of the freshly collected sperm were 2.21 ± 0.53 (μL g^?1 of fish weight) (mean ± SD), 95 ± 1 (%), 1.93 ± 0.44 × 10⁹ (cells mL^?1) and 7.56 ± 0.17 respectively. Sperm activation was evaluated at different osmolalities of NaCl solution, and motility ceased completely when osmolality of the extender was ≥287 mOsmol kg^?1. Sperm retained motility for 24, 72 and 108 h, after refrigerator storage when sperm were undiluted, suspended in Alsever's solution and suspended in Alsever's solution containing 5% methanol respectively. Fertilization rate of fresh eggs with sperm stored at 4°C in Alsever's solution and Alsever's solution containing 5% methanol was 77% and 60% with a hatching rate of 60% and 43% respectively. The fertilization and hatching success of the stored sperm suggests potential to use refrigeration for transporting genetic material to hatcheries for artificial breeding of L. calbasu in Bangladesh.     

A novel approach to denitrification processes in a zero-discharge recirculating system for small-scale urban aquaculture

This paper presents an innovative process to solve the nitrate build-up problem in recirculating aquaculture systems (RAS). The novel aspects of the process lie in a denitrification bioreactor system that uses solid cotton wool as the primary carbon source and a unique degassing chamber. In the latter, the water is physically stripped of dissolved gaseous O₂ (by means of a Venturi vacuum tube), and the subsequent denitrification becomes more efficient due to elimination of the problems of oxygen inhibition of denitrification and aerobic consumption of cotton wool. The cotton wool medium also serves as a physical barrier that traps organic particles, which, in turn, act as an additional carbon source for denitrification. Operation in the proposed system gives an extremely low C/N ratio of 0.82 g of cotton wool/g of nitrate N, which contributes to a significant reduction of biofilter volume. The additional advantage of using solid cotton wool as the carbon source is that it does not release organic residuals into the liquid to be recycled. Operation of the system over a long period consistently produced effluents with low nitrate levels (below 10 mg N/l), and there was only a very small need to replace system water. The overall treatment scheme, also incorporating an aerobic nitrification biofilter and a granular filtration device, produced water of excellent quality, i.e., with near-zero levels of nitrite and ammonia, a sufficiently high pH for aquaculture, and low turbidity. The proposed system thus provides a solution for sustainable small-scale, urban aquaculture operation with a very high recovery of water (over 99%) and minimal waste disposal.     

Effects of metomidate anaesthesia or transfer to pur sea water on plasma parameters in ammonia-exposed Atlantic salmon (Salmo salar L) in sea water

Atlantic salmon (Salmo salar L) postsmolts weighing 150 ± 53 g were exposed to 14–15 mg l^–1 TA-N (total ammonia-N) in sea water in 1 m³ tanks for 24h. Blood samples were then taken A) immediately after the fish were netted from the exposure tanks and stunned by a blow to the head; B) 2–20 min after the fish were transferred to 15 l of an anaesthetic solution of metomidate in ammonia-free sea water; or C) 2–20 min after the fish were transferred to 15 l of ammonia-free sea water. Plasma TA-N level was 18% lower in the anaesthetised fish compared to in the fish sampled directly from the exposure tanks (p 0.05), and accordingly 16% lower in the fish transferred to pure sea water although this difference was not significant (p = 0.07). Plasma glucose level was higher in the fish transferred to pure sea water than in the fish receiving the two other treatments (p 0.05), but plasma urea, osmolality, Na^{+, Cl–, Ca2+ or Mg2+} levels did not vary significantly between the different treatments. Plasma TA-N level increased with time in the fish in the metomidate solution (p 0.02).