气候、水文和生态过程对洋河水库富营养化影响研究

为了探索洋河水库富营养化和蓝藻水华暴发的原因,对水库的入库水量、水下地形、温跃层和叶绿素a含量等进行测定,分析了气候、水文和生态过程对洋河水库富营养化和藻华暴发的影响。研究结果表明,全球气候变暖导致洋河水库来水量下降,水库水力停留时间延长,夏季水温上升,为蓝藻水华暴发提供了有利的条件。洋河水库水下地形和坝前较深水位不利于大型水生植被的生长,随着外源营养盐的不断输入,引发藻类异常增殖。当随风飘到库区北部的水华蓝藻密度超过一定数量后,会对该区生长的水生植被产生毒害作用,导致水生植被消亡。洋河水库夏季产生温跃层,下层有机物的厌氧分解和水生态系统食物链的恶化,营养盐滞留时间和水体中浓度增加,同时渔业资源锐减,鲢、鳙数量下降,从而导致蓝藻水华大暴发。洋河水库富营养化和蓝藻水华暴发是自然因素和人为因素综合作用的结果,只有加强外源和内源污染控制,同时进行水生态系统的调控,才能有效改善洋河水库的水环境质量。     

对河口水库营养状况及渔业利用对策的研究

自20世纪90年代开始，对河口水库水质逐年下降，水体富营养化加剧，蓝藻水华时有暴发，但一般持续时间较短，仅3～7d。2000年暴发了严重的蓝藻水华，持续时间近4个月。2001年和2002年蓝藻水华几度暴发，直接影响了水库供水质量和水体功能的正常发挥。为有效保护水质，修复与稳定水生生态系统，控制浮游藻类的过度繁衍，2001年冬恢复放养鲢、鳙鱼种共计17万尾。2002年冬放养鲢、鳙鱼种近30万尾。2003年对河口水库蓝藻水华基本得到控制。为此就蓝藻水华生物控制与水资源保护和渔业利用对策间的相互关系进行了初步的探讨。     

我国内陆水体富营养化的原因及其治理方法

随着城市和工业的不断发展，农业化肥和含磷洗涤剂大量使用，大量未经处理的生活污水和工农业废水流入湖泊和江河中，使湖泊、水库、江河中的氮、磷等营养盐不断积累，促使部分藻类以及其它水生生物异常大量繁殖，造成水体透明度下降，产生异味，水体功能遭到破坏，进而导致水体富营养化。水体严重富营养化可导致合理水生生态结构的破坏，加快湖泊等     

邵克强等揭示蓝藻水华厌氧分解对湖泊微生物群落的影响

细菌是湖泊生态系统中的一个组成部分，在营养盐的生物地球化学过程中起着十分重要的作用。富营养化湖泊中的蓝藻水华在高温、厌氧条件下，死亡分解常会引发“湖泛”，对湖泊生态系统结构产生很大的影响，并可能进一步影响到湖泊的水质安全。因此，认识蓝藻水华降解过程中细菌群落结构的变化对于了解揭示浅水湖泊营养盐的微生物循环机理、蓝藻水华暴发机制具有重要意义。     

龙岩梅花湖水库富营养化评价及分析

梅花湖水库是福建省龙岩市的备用饮用水源，且兼有发电、防洪、养殖、旅游、调节气候等多种功能。但近两年来随着梅花湖水库网箱养鱼的过度发展，水库富营养化日益严重，已影响到备用饮用水源功能和渔业生产。梅花湖水库在2007夏季因蓝藻水华，曾发生死鱼事件。因此对该水库进行富营养化综合评价及成因分析，对今后科学规划库区渔业生产，合理利用生态资源具有重要意义。     

一例蓝藻水华暴发引发草鱼疾病的治疗

<正>当进入夏季,随着气温的升高,草鱼吃食旺盛,饲料投喂量大幅增加,大量的有机质排泄到养殖池塘,导致池塘水质富营养化,很容易暴发蓝藻水华。暴发的蓝藻大量消耗水体中的氧气,影响草鱼生长,严重的导致草鱼缺氧、出血等并发症,继而导致草鱼大量死亡。不过假如在蓝藻暴发时采取相应的措施,可以大幅减少草鱼疾病的发生。笔者就最近治疗的一例蓝藻水华引发草鱼疾病的措施简介如下,为该类疾病的治疗和预     

秦皇岛市水产局认真应对洋河水库水质富营养化问题

洋河水库是秦皇岛市重要饮用水源地之一，近年来，洋河水库水质存在富营养化问题，导致藻类过度繁殖，严重影响到居民的饮用水质。为此。市水产局连续三年在洋河水库投放鲢、鳙等“食藻鱼”苗种400万尾，对于促进库区水质改善发挥了积极作用。但目前洋河水库水质富营养化程度仍然不容乐观，市委书记王三堂同志、市长营瑞亭同志对水库富营养化防治工作非常重视，要求加大洋河水库的富营养化治理力度，尽快放流、禁渔，促进库区水质改善，解决全市人民饮水问题。     

浅析抚宁县洋河水库富营养化原因及建议

洋河水库始建于1959年10月，1961年8月建成并投入使用，总库容达4．2亿m^3，可养殖水面1466．67hm^2。水库建成使用半个多世纪以来，在防洪、农业生产等方面发挥了巨大作用。近年来，洋河流域生态环境受到破坏，导致洋河水库水质下降，富营养化呈加重趋势，蓝藻连年爆发，饮用水出现异味，严重威胁到人民群众的饮水安全。     

水库水生维管束植物的调查方法

水生维管束植物(以下简称水草)是水库水生态系统的组成部分，也是水库的重要资源之一。影响水生植被在水库形成的因素较多，如库水深度、防浪程度、地理位置、水位状况、淹没地区的特征、水土的物理化学性质等。国外对水库水草的研究甚为注重，报道较多。我国拥有八万六千余座水库，对水草作过系统调查者寥寥，实属薄弱环节。水草及其植被的作用概况起来有如下几种：     

洋河水库富营养化评价与防治对策

目前国内外的许多江河、湖泊、水库和海湾已处于富营养化状态,而且富营养化的进程还在加剧,破坏了水生生物的生存环境,引起水体环境生物组成和生物量的改变,严重威胁着人类的健康、生存和发展。就洋河水库微囊藻水华,探讨水体的富营养化问题及防治对策。     

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).