甲氰菊酯对黄鳝的急性毒性试验

采用常温静水实验法,进行甲氰菊酯对黄鳝苗种的急性毒性试验,结果表明:甲氰菊酯对黄鳝苗种半致死浓度为59×10-9(96hLc50),安全浓度为5.9×10-9。黄鳝对甲氰菊酯敏感。     

“克虫王”对大口鲶鱼苗的急性毒性试验

为了验证新药“克虫王”在水产养殖中对鱼类的毒性,选用“克虫王”两种剂型渔用杀虫剂对大口鲶鱼苗进行了急性毒性试验。试验结果表明:B_2型“克虫王”对全长4.9cm大口鲶鱼苗的24h、48h、72h半致死浓度(TLm)分别为1.20×10~(-6)、0.88×10~(-6)、048×10~(-6),安全浓度为0.14×10~(-6)。C型“克虫王”对大日鲶鱼苗的24h、48h、72h半致死浓度(TLm)分别为4.65×10~(-6)、3.60×10~(-6)、1.15×10~(-6),安全浓度为0.64×10~(-6)。     

太湖微囊藻对鱼类毒性影响的研究

本文首先通过血凝实验证明太湖的微囊藻具有蓝藻毒素，在此基础上进行鱼类染毒实验，采用全细胞藻体和经冻解的藻液给鱼类染毒，结果发现全细胞输送灌胃染毒对鱼类（乌鳢）的毒性较小，半致死浓度ＬＣ５０×９６ｈ为３５０ｍｇ／ｋｇ；以冻解藻液腹腔注射染毒对鱼类（草鱼）毒性较大，一次染毒４小时的半致死浓度ＬＣ５０×４ｈ为４４０ｍｇ／ｋｇ，二次染毒６小时半致死浓度ＬＣ５０×６ｈ为２５０ｍｇ／ｋｇ，说明太湖微囊藻属于毒藻，毒性级别可定为中等。     

两种药物对脊尾白虾各期(氵蚤）状幼体的毒性试验

采用静水实验法进行甲醛和孔雀石绿对脊尾白虾 (Exopalaemoncarinicauda)各期状幼体 (Z1～Z6)的急性毒性研究。结果表明 :在pH值为 7 9± 0 5、水温 (2 6 0± 0 5 )℃的条件下 ,甲醛对脊尾白虾Z1～Z6的半致死浓度 (48hLC50 )分别为 176× 10 -6,16 7× 10 -6,15 0× 10 -6,16 7× 10 -6,113× 10 -6,5 5× 10 -6,安全浓度 (Cs)分别为 30× 10 -6,17× 10 -6,32× 10 -6,11× 10 -6,4× 10 -6,9× 10 -6;孔雀石绿对脊尾白虾Z1～Z6的 4 8hLC50 分别为 0 4 5 1× 10 -6,0 4 4 8× 10 -6,0 5 91× 10 -6,0 4 4 0× 10 -6,0 380× 10 -6,0 15 8× 10 -6,Cs分别为 0 0 6 9× 10 -6,0 0 5 8× 10 -6,0 10 2× 10 -6,0 0 90× 10 -6,0 0 71× 10 -6,0 0 34× 10 -6。其中Z5和Z6对以上药物的敏感性较高     

在轮虫培养中用敌百虫杀灭桡足类的试验

针对鱼、虾、蟹人工苗种生产中经常遇到的由于轮虫中混杂桡足类导致育苗失败的实际情况,探讨利用轮虫和桡足类对晶体敌百虫忍耐性的差异,在不影响轮虫生长、繁殖的情况下彻底清除桡足类的方法。结果表明:轮虫和桡足类对敌百虫的忍耐性有较大的差异,轮虫和桡足类的96h敌百虫安全浓度分别为2.0mg/L和0.2mg/L;致死浓度分别为3.0mg/L(96h)和0.4 mg/L(72h);在敌百虫添加浓度0.5~2.0mg/L条件下,敌百虫对轮虫繁殖率的影响随添加浓度加大而增加,但这一影响是可逆的,一般在2~3d后即可恢复正常。在苗种生产实际中,将敌百虫处理浓度定为1.0~1.5mg/L较为适宜。     

对中华绒螯蟹生态育苗池中桡足类控制的初步研究

比较了蛛虫速灭、鱼虫恨和强力混杀3种渔药对桡足类和中华绒螯蟹溞状幼体的急性毒性。试验结果表明,蛛虫速灭对桡足类的96h半致死添加量为0.011mL/m3,鱼虫恨为0.036mL/m3,强力混杀精为0.014mL/m3,蛛虫速灭对桡足类的杀灭能力最强;对中华绒螯蟹溞状幼体Ⅰ期的急性毒性鱼虫恨最大,蛛虫速灭最小。蛛虫速灭在0.18～0.20mL/m3的剂量下,对溞状幼体毒性低,幼体能正常变态,可用于蟹苗池桡足类的控制。强力混杀精对桡足类和中华绒螯蟹溞状幼体的毒性很接近,鱼虫恨对中华绒螯蟹溞状幼体的毒性大于对桡足类的毒性,两者均不适宜在中华绒螯蟹生态池控制桡足类。     

江西进贤湖泊浮游动物

1993年-1994年对进贤湖泊浮游动物调查分析.共采到浮游动物85种,隶属于58属.平均生物量0.7112mg/L优势种属群为原生动物的沙壳虫、似铃壳虫、轮虫类的龟甲轮虫,枝角类的秀体、透明、象鼻,桡足类的无节幼体和桡足类幼体.鱼产力2.808×10-3k/m2.     

三种常用化学消毒剂对牙鲆仔稚鱼的急性毒性研究

选用3种化学消毒剂对牙鲆仔稚鱼进行急性毒性试验。结果表明,高锰酸钾对牙鲆仔鱼的24 hLC504、8 h LC50和安全浓度分别为1.678×10-6、1.382×10-6和0.281×10-6,对牙鲆稚鱼的24 h LC50、48 hLC50和安全浓度分别为2.555×10-6、1.789×10-6和0.263×10-6;甲醛对牙鲆仔鱼的24 h LC50、48 h LC50和安全浓度分别为25.821×10-6、10.671×10-6和0.547×10-6,对牙鲆稚鱼的24 h LC50、48 h LC50和安全浓度分别为33.959×10-6、17.046×10-6和1.288×10-6;聚维酮碘对牙鲆仔鱼的24 h LC50、48 h LC50和安全浓度分别为15.744×10-6、8.163×10-6和0.658×10-6,对牙鲆稚鱼的24 h LC504、8 h LC50和安全浓度分别为25.802×10-6、21.286×10-6和4.346×10-6。牙鲆仔稚鱼对3种化学消毒剂的敏感性依次为:高锰酸钾>甲醛>聚维酮碘,并且牙鲆仔鱼分别对3种消毒剂的敏感性均大于牙鲆稚鱼分别对3种消毒剂的敏感性。最后依据本试验结果,作者对牙鲆疾病防治中消毒剂的使用进行了探讨。     

厦门港尖额真猛水蚤室内培养的研究

由厦门港潮间带筛选的小型桡足类——尖额真猛水蚤(Euterpe acutifrons),在鱼、虾育苗中具有明显的应用价值。进行周年室内培养试验,单一雌体生命周期67天,培养两个半月后,个体数达15万个,平均培养密度3689个/升,日增殖率0.149。夏季怀卵10次,间隔3—9天,总怀卵量174个;冬季怀卵3次,间隔12—16天,总怀卵量86个。使用单种饵料——微型黄藻的异胶藻(Heterogroea sp)周年培养该种桡足类是可行的。饵料浓度以100×10~4个/毫升较适,当350×10~4个/毫升时繁殖尚顺利,但在850—1680×10~4个/毫升以上,生长繁殖受抑制,浓度太高甚至死亡。     

孔雀石绿用于防除桡足类的初步研究

在鲍育苗生产中可以用孔雀石绿的草酸盐来替代敌百虫杀灭培育池中的桡足类。使用 １．０×１０－６的孔雀石绿处理３小时与使用１．５～２．０×１０－６的敌百虫处理１５～２０小时的效果基本一致，且对底栖硅藻和鲍无明显副作用     

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.     

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.     

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.     

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).