温度与盐度对方斑东风螺胚胎发育及幼虫生长的影响

在水温14～33℃（盐度34）、盐度18-40（水温25．5-26℃）范围内各设12个梯度，采用突变法进行温、盐度对方斑东风螺[Babylonia areolata（Link）]卵囊孵化及幼虫生长实验。结果显示：（1）方斑东风螺胚胎发育适宜水温为23～31℃，最适水温为25-30℃；适宜盐度为28-38，最适盐度为30～38。在适宜水温和盐度范围内，孵化速度随水温和盐度升高而加快，但以水温的影响效应最明显；温度或盐度超过其适宜范围时，孵化率明显下降或幼虫畸形率明显增大。（2）幼虫适宜水温及最适水温与胚胎发育的基本一致；适宜盐度和最适盐度存在向高盐度延伸的现象，其适宜和最适盐度下限分别为30和32。温盐度超过适宜范围时，死亡率明显增大，生长受到抑制。     

鳗鲡（Anguilla japonica）胚胎发育与水温和盐度的关系

实验结果表明，鳗鲡胚胎发育与水温和盐度关系密切，在一定的水温范围内，胚胎发育所需时间与水温呈负相关关系，ｙ＝２４６．７７５ｅ＾－０．０８２ｘ。其合适水温范围是２０－２６℃，临界水温上限３０℃，下限１６℃；胚胎发育的合适盐度范围是１５－３５‰，临界盐度上限４０－４５‰，下限５－１０‰。胚胎孵化率与盐度呈二次曲线相关关系，ｙ＝３６．９３＋０．２３ｘ－０．１９ｘ＾２。     

温度和盐度对宝石鲈胚胎发育的影响

宝石鲈(Scortum barcoo)是原产于澳大利亚的一种杂食性、中型经济淡水鱼类,对饵料要求不高,生长速度较快,肌肉的Omega-3不饱和脂肪酸含量很高,具有较高的食用价值。2001年首次被引进中国,2004年人工繁殖获得成功。为了让人们充分了解该物种的繁殖生物学特性,同时为宝石鲈的开发利用提供基本数据,本研究对宝石鲈的胚胎发育时序及不同水温和盐度对胚胎发育的影响做了较为祥细的观察与研究。采用人工催产、授精获得受精卵,在水温(27.0±0.5)℃孵化,观察胚胎发育情况。成熟卵圆形、透明、漂浮性,卵径0.87~0.92 mm,吸水后卵膜膨胀直径为2.10 mm左右;胚胎明显特征是有一个直径为0.50 mm左右的大油球。出膜仔鱼全长2.00 mm左右,出膜4 d后卵黄完全吸收,并开始摄食,此时仔鱼全长3.5~3.7 mm。胚胎发育的最低和最高临界水温分别是21℃和31℃,最适水温范围是24~27℃,胚胎发育所需时间与水温成负相关关系。胚胎发育的最适盐度范围为0~8,盐度8时,各个发育时期的胚胎和仔鱼的存活率最高,12为临界盐度。因此在生产实践中要掌握好温度和盐度,以获得最佳的种苗生产效果。     

温度、盐度对褐牙鲆（♀）×犬齿牙鲆（♂）杂交子一代胚胎发育和仔鱼存活的影响

探讨了温度、盐度对褐牙鲆（♀）×犬齿牙鲆（♂）杂交子一代（杂交F1）胚胎和初孵仔鱼发育的影响。结果表明，杂交F1受精卵孵化适宜温度范围和最适温度分别为15～21℃和18℃，在适宜温度范围内胚胎发育时间随温度的升高而缩短，二者符合乘幂函数关系式N=115．99T^-0.768.8（R^2=0．9769）。胚胎发育的生物学零度和有效积温分别是7．54℃和540．1℃·h，积算温度（A）与试验水温间呈乘幂函数相关，表达式：A=1328．1T^-0.3149。（R^2=0．9624）。胚胎发育的最低盐度界限为10，孵化的适宜盐度范围和最适盐度范围分别为10～45、25～35；初孵仔鱼生存发育的适宜盐度范围、最适盐唐范围分别为10～40和10～20。     

温度、盐度对条斑星鲽胚胎发育的影响

就温度、盐度对条斑星鲽胚胎发育的影响作了初步探讨。实验表明,胚胎发育的适宜温度为6～12℃,最适水温为8～10℃,在适温范围内胚胎孵化速度与温度呈正相关关系（N=65.925T^-0.9672）。盐度低于27,受精卵下沉,27～30之间悬浮于水体中,盐度高于35,受精卵浮于水面。胚胎孵化的适宜盐度范围、最适盐度范围分别为25～40和28～36;盐度低于25或高于40,孵化率都降低。研究表明,条斑星鲽胚胎发育的生物学零度（阈温度）为-0.1℃,有效积温值为1726.48℃.h。另外,根据其Q10值推算的胚胎发育的适宜水温与实验结果相似。     

温度、盐度对条石鲷胚胎发育影响及初孵仔鱼饥饿耐受力

研究了盐度、温度对条石鲷胚胎发育的影响和初孵仔鱼对饥饿的耐受力。结果表明，胚胎发育的适宜盐度范围为20～35，最适盐度范围为25～30，孵化率都在89%以上，盐度低于20或高于35，孵化率都降低。盐度对孵化时间有一定影响，盐度高于35或者低于15条件下孵化时间都延长。胚胎发育的适宜温度范围为21～27℃，孵化率都在77%以上，最适温度范围为23～25℃，孵化率达89%以上，低于19℃或者高于27℃时孵化率降低且初孵仔鱼畸形率升高。胚胎孵化时间与温度成负相关关系，胚胎发育速率与温度成正相关关系。条石鲷胚胎发育的生物学零度（阈温度）为10.06℃，有效积温值为405.3℃·h。对胚胎发育的Q10值进行了计算。饥饿条件下，条石鲷初孵仔鱼8日龄全部死亡，半数死亡时间出现在第6天，饥饿对初孵仔鱼生长具有明显的抑制作用。     

温度、盐度对褐牙鲆(♀)×犬齿牙鲆(♂)杂交子一代胚胎发育和仔鱼存活的影响

探讨了温度、盐度对褐牙鲆(♀)×犬齿牙鲆(♂)杂交子一代(杂交F1)胚胎和初孵仔鱼发育的影响。结果表明,杂交F1受精卵孵化适宜温度范围和最适温度分别为15～21℃和18℃,在适宜温度范围内胚胎发育时间随温度的升高而缩短,二者符合乘幂函数关系式N=115.99T-0.7668(R2=0.9769)。胚胎发育的生物学零度和有效积温分别是7.54℃和540.1℃.h,积算温度(A)与试验水温间呈乘幂函数相关,表达式:A=1328.1T-0.3149(R2=0.9624)。胚胎发育的最低盐度界限为10,孵化的适宜盐度范围和最适盐度范围分别为10～45、25～35;初孵仔鱼生存发育的适宜盐度范围、最适盐度范围分别为10～40和10～20。     

温度、盐度对似刺鳊鮈胚胎发育过程的影响

设置10℃、15℃、20℃、24℃、27℃、30℃6个温度组和0‰、2.5‰、5‰、10‰、15‰、太湖湖水组6个盐度组,探讨了温度和盐度对似刺鳊鮈(Paracanthobrama guichenoti)胚胎发育的影响。温度实验结果表明:似刺鳊鮈胚胎发育的起始温度(生物学零度)为9.5℃,适宜的发育水温为20～24℃。水温10℃时胚胎卵裂异常,未能进入原肠期;水温升至30℃时胚胎在发育至原肠期前后死亡。水温度为24℃时孵化时间仅为73.5 h,孵化率高达80%,畸形率为0,为最适孵化水温;水温对胚胎发育速率的影响后期较前期大。盐度实验表明:似刺鳊鮈胚胎对盐度有一定的耐受力,各盐度梯度下的胚胎发育速率差异不大,但孵化率的差异极显著。在水温18℃、盐度为2.5‰的水体中胚胎的孵化率为81.67%,高于太湖湖水组的孵化率,此盐度应为似刺鳊鮈胚胎发育较适盐度。     

温度对乌鳢（Ophiolephalus argus Cantor）胚胎发育的影响

将人工催产自然产出的乌鳢受精卵置于不同水温条件下进行胚胎发育观察，结果表明，在一定范围范围内，乌鳢胚胎发育所需的时间与水温呈负相关关系，表达式为：ｙ＝２７３．４２ｅ＾－０．０７ｘ。胚胎发育适宜温度范围为２３－２８℃，最适温度为２５℃。     

盐度对九孔鲍胚胎发育的影响

本文采用单因素试验方法研究了盐度对九孔鲍胚胎发育的影响.结果表明九孔鲍胚胎发育的最低和最高临界盐度分别是20和38,适宜盐度范围为26～36,最适盐度范围为30～32.实验说明,在适宜盐度范围内,盐度对九孔鲍胚胎发育的影响是十分显著的.     

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).