海马齿对海水养殖系统中氮、磷的移除效果研究

大量的外源性饵料和排泄物使海水养殖水体N、P以及有机物大量增加,导致水质恶化,是制约海水养殖业发展的主要因素。通过构建海马齿面积比为3∶2盐度为15的A、B 2组浮床海水养殖系统,以检验海马齿的N、P移除能力。结果显示,当海马齿处于生长启动期,A组和B组的水质指标与对照组之间无显著性差异（P〉0.05）;但当海马齿生长...     

东山湾海马齿生态浮床原位修复效果研究

针对规模化网箱养殖的自身污染问题,在东山湾八尺门鱼类养殖海区开展海马齿(Sesuvium portulacastrum)生态浮床原位修复研究。经过一年的生长,八尺门修复区海马齿平均茎长1.28 m,平均根须长0.52 m,生物量达152.5×10~3 g/m~2,通过生长吸收对C、N、P的积累量分别为5 214.0、378.5、22.9 g/m~2。经过两年的原位修复,浮床修复区海水的DO比对照区高11.9%;浮床对石油类、悬浮物和COD的去除率分别为42.3%、14.9%和10.0%,对TN的去除率为11.7%,对NH_4-N、NO_3-N和PO_4-P的去除率分别为19.9%、16.4%和9.2%;由于海水的流动性和影响因素的复杂性,浮床对TOC、NO_2-N和TP的去除效果不理想。综上,海马齿生态浮床能够在一定程度上改善修复区海水水质,减轻网箱养殖水体的营养负荷。     

水生植物种类及覆盖率水质净化效果研究

为探究不同水生植物种类及浮床覆盖率对水体的净化效果，将轮叶黑藻、空心菜、鸢尾、生菜、香菇草、香蒲和水芹等7种水生植物100 g固定于长108 cm、宽60 cm、高65 cm塑料桶中的20 cm×30 cm浮床上，轮叶黑藻直接浸泡在水中。试验用水来自水产养殖池塘，盐度4.5。每个水箱均曝气、盖上透光塑料板。另在9个面积约6670 m²的养殖池塘中设置2.0 m×4.0 m的PVC管结构生态浮床，按照2.5%、5.0%和10.0%覆盖率布设空心菜，不同时间分析各水生植物对主要水质指标去除率。试验结果显示：空心菜对总氮、总磷和化学需氧量净化效果最佳，轮叶黑藻对氨氮和硝态氮净化效果最佳。主成分分析结果表明，空心菜对水体的综合净化效果最强，之后依次是鸢尾、香蒲、香菇草、轮叶黑藻、水芹和生菜。30 d后，不同浮床覆盖率总氮、总磷、氨氮、硝态氮和化学需氧量含量均显著低于对照组(P<0.05),其中10.0%覆盖率组含量最低。因此，种植空心菜可显著降低养殖水体富营养化水平，改善水质。空心菜浮床覆盖率越高，水体中总氮、总磷、氨氮、硝态氮和化学需氧量等指标去除率越高，推荐的浮...     

广西工厂化循环水养殖石斑鱼水质处理效果

通过集成海水养鱼、生化处理、设施工程、环境工程、电器自控和水质监控等技术,建立一套适合广西地区应用的工厂化循环水石斑鱼养殖系统。该养殖系统处理流程为:鱼池→沉淀池→蛋白质分离器→生物滤池→海马齿浮床→紫外杀菌,生物滤池包括A、B、C三个通道,A、B通道均由珊瑚石作为一、二级生物过滤和生化球作为三级过滤,C通道由珊瑚石作为一级过滤和椰子壳碎作为二、三级过滤。结果显示:沉淀池处理可以显著降低鱼池的COD,氨氮、亚硝酸盐氮、硝酸盐氮和磷酸盐的质量浓度(P0.05);经海马齿浮床系统处理后,硝酸盐氮质量浓度显著低于沉淀池、蛋白质分离器处理池、生物滤池A、B通道(P0.05);整体上,C通道水质指标略低于A、B通道,但差异不明显(P0.05)。该研究结果可为广西沿海发展循环水养殖技术以及养殖生产方式转变提供可靠的科学数据和技术参考。     

池塘鱼箱集约高效养殖系统水处理模式设计及效果分析

随着淡水养殖集约化程度的提高,水体氨氮和亚硝态氮等有毒物质浓度随之升高,严重危害了养殖对象的生长。因此,水体氨态氮及亚硝态氮的控制成为水质控制的关键。本文针对集约化养殖条件下的养殖水处理在天津市水产研究所淡水试验站进行了生物膜法和生态浮床净化法处理池塘养殖用水的实验。结果表明:生物膜法和生态浮床净化法都能有效去除池塘水体氨态氮及亚硝态氮,如果不使用水生植物,则每生产1t鱼需设置6.76m2的生物包。     

闭合循环水产养殖-植物水栽培综合生产系统的工艺设计及运行效果

闭合循环水产养殖-植物水栽培综合生产系统主要由鱼类养殖池、蔬菜和花卉水培渠、循环水处理系统构成,是一种新型"养殖-种植-水质净化"生产模式。在上海市青浦区的实践表明:①单位水体红罗非鱼(Tilapiamossambica(♀)×Tilapianilotica(♂))和暗纹东方(Fuguobscurus)的产量分别达到58kg·m-3和12.28kg·m-3,养殖期间,氨氮浓度<1.5mg·L-1,亚硝氮浓度<0.8mg·L-1,DO>5.0mg·L-1;②水栽培蔬菜生长良好,对氨氮、亚硝氮、硝氮、总氮、磷酸盐和COD的最大去除率分别为57.46%、51.72%、3.7%、10.67%、9.72%和21.78%,水培蔬菜渠进水和出水的平均N/P分别为6.60∶1和6.53∶1;③生物过滤器对流经水体的NH 4 N、NO-2 N、COD一次性去除率分别为44.79%、20.31%、20.10%;④泡沫分离—臭氧消毒装置对养殖水体中异养细菌的去除率为93.58%,NH 4 N、NO-2 N的去除率为39.00%、38.10%,能明显提高水体中的pH和DO。     

淡水养殖池中亚硝酸盐转化措施

<正>养殖水质的好坏,主要看以下几个水质指标:氨态氮、亚硝态氮、硝态氮、pH值、化学耗氧量、硫化氢等七个指标。水产养殖水体中,如何让含氮有机物进行有效的转化,以确保养殖水质维持良好,是养殖成功的关键之一。养殖水体中的含氮有机物,在水体中先转为氨态氮,再转为亚硝态氮,最后为硝态氮。转化过程中,从含氮有机物到氨氮需要的时间不长,从氨态氮到亚硝酸盐的时间较短,但亚硝酸盐的转化时间比较长,这是养殖水体中亚硝酸盐高的主要原因。     

多级生物净化在封闭循环水养殖系统中的水质调控效果

采用逐月采样的方法研究了多级生物净化措施,即在封闭循环水养殖系统的动力水渠浮床培植多种水生经济植物、构建固定微生物膜和养殖贝类,在沉淀池和净化池放养滤食性鱼类,建立芦苇人工湿地,对养殖系统中无机营养盐和有机质含量与分布的影响。试验结果表明,养殖水体经多级生物净化处理后能够循环使用,水体碱度和硬度轻微降低,除磷酸盐含量上升5.4%外,硝态氮、亚硝态氮、氨氮、总氮和总磷的去除率分别为27.7%、44.0%、26.0%、42.0%和15.7%;浮游植物和浮游动物生物量分别下降31.4%和20.1%;浮游植物生物多样性指数增加,种类组成明显好转,蓝藻生物量和优势度指数明显降低,硅藻和绿藻继而成为优势种群,凡纳滨对虾平均产量达11 250kg/hm~2,最高产量达15 000kg/hm~2,提高了经济效益和生态效益。     

水蕹菜浮床对盐碱地池塘水质与中华绒螯蟹生长的影响

2015年6—9月,在黄河三角洲盐碱地池塘开展了"中华绒螯蟹(Eriocheir sinensis)—水蕹菜"复合种养模式试验。基于水蕹菜浮床的覆盖率,设计3个处理组:0%浮床(对照组)、5%浮床和10%浮床,并定期监测试验池塘水质和中华绒螯蟹生长状况。结果显示:10%浮床组碱度、总氮、总磷、氨氮、硝酸盐氮和高猛酸盐指数明显低于对照组,溶氧、pH和电导率显著高于对照组;5%浮床组浊度显著低于对照组,10%浮床组浊度低于对照组,但与对照组之间无显著性差异。总体而言,10%浮床组的水质状况优于5%浮床组,显著优于对照组。10%浮床组的中华绒螯蟹壳宽和体重增长率明显高于对照组,其特定生长率显著高于5%浮床组,但与对照组无显著性差异;各处理组之间中华绒螯蟹产量和成活率均不存在显著的差异。10%浮床组水蕹菜产量显著高于5%浮床组。结果表明:在黄河三角洲中华绒螯蟹养殖中,应用10%水蕹菜浮床对改善水质、促进中华绒螯蟹生长具有一定的作用。     

水浮莲对水产养殖排放水体净化的初步研究

研究了水浮莲(Pistia stratiotes)在可控条件下对水产养殖排放污水中的氨氮、亚硝酸氮、硝酸氮、总氮、总磷、化学耗氧量等水质指标的去除效果。试验结果表明,水浮莲对水体中的氨氮、亚硝酸氮、硝酸氮、总氮、总磷和COD均有一定的净化效果,各水质指标的含量均有不同程度的降低,其最大去除率分别为42.4%、47.5%、23.2%、5.80%、51.5%和25.9%。     

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.     

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.     

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.     

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.     

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.     

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).