金沙江下游中华金沙鳅自然繁殖的生态水文需求研究

为支撑乌东德水电站人造洪峰生态调度方案制定，掌握刺激中华金沙鳅自然繁殖的生态水文指标和水温阈值，2017-2019年5-7月在金沙江下游巧家断面进行鱼类早期资源调查，分析中华金沙鳅卵苗径流量与同期水温、流量日上涨率、涨水持续时间等生态水文指标之间的响应关系，在此基础上提出乌东德水电站生态调度运行要求。结果表明：巧家江段中华金沙鳅产卵高峰期为5月下旬-6月中下旬，产卵高峰期起始水温不低于19.0℃；对应的洪峰过程流量日上涨率平均为358m3/s/d，涨水持续天数平均为 5d，洪峰过程2-3d后开展大规模产卵；偏相关分析表明中华金沙鳅卵苗径流量与起始水位呈负相关关系，结合乌东德水电站3-7月生态基流泄放要求，推荐人造洪峰的起始流量为1160 m3/s，对应的乌东德水文站水位为791.1m，可有效促进中华金沙鳅产卵繁殖。     

汉江中下游产漂流性卵鱼类早期资源现状的初步研究

为了解汉江中下游江段的水文变化特点与鱼类早期资源分布状况,2009年6～8月在沙洋断面开展了汉江中下游产漂流性卵鱼类早期资源现状的调查。结果表明,汉江沙洋站以上可监测到的152.28km干流江段中共有3个产卵场,产卵场总长度为42.12km,占江段总长的27.7%。产卵总量为56601.9万粒,产漂流性卵鱼类约有21种...     

汉江中下游产漂流性卵鱼类早期资源现状的初步研究

为了解汉江中下游江段的水文变化特点与鱼类早期资源分布状况,2009年6～8月在沙洋断面开展了汉江中下游产漂流性卵鱼类早期资源现状的调查。结果表明,汉江沙洋站以上可监测到的152.28km干流江段中共有3个产卵场,产卵场总长度为42.12km,占江段总长的27.7%。产卵总量为56601.9万粒,产漂流性卵鱼类约有21种,其中拟尖头鲌、蛇鮈、双斑副沙鳅、翘嘴鲌、吻鮈、赤眼鳟等为优势种。产漂流性卵鱼类的产卵次数和产卵量与江水的流速、温度、透明度、涨落水持续时间等多个因素都有一定的关联。近5年来,汉江中下游产漂流性卵鱼类的产卵量因为各种因素的影响呈现出逐年下降的趋势,产卵场的位置也有所改变。本研究旨在为水利开发与水生态环境以及鱼类资源保护提供基础资料。     

基于四大家鱼产卵需求的汉江中下游生态流量研究

针对汉江中下游梯级电站开发后水文节律变化造成四大家鱼栖息地生境质量降低的问题,分别通过几种常用水文学法和栖息地模型计算了汉江中下游河道最小生态流量和四大家鱼产卵适宜生态流量,并在最小生态流量的基础上,结合四大家鱼产卵适宜生态流量以及生态水文特征在5-8月进行了脉冲设计,综合确定出了满足四大家鱼产卵需求的生态流量过程。结果表明,Lyon法和7Q10法最适宜汉江中下游最小生态流量的计算,流量为294~863 m3/s;通过栖息地模型计算,彭市和仙桃江段四大家鱼产卵适宜生态流量为1233~3950 m3/s;流量日涨幅在139.1~534.8 m3/s,持续5 d的涨水过程可为四大家鱼产卵提供良好的条件。该研究从考虑四大家鱼产卵需求的角度,为汉江中下游梯级电站的生态调度提供科学参考。     

岷江下游产漂流性卵鱼类的繁殖活动与生态水文因子的关系

2010年5-8月对岷江下游的生态水文数据进行了分析,并对其与产漂流性卵鱼类产卵行为的关系进行了探讨.结果表明,12个水文指标变化趋势基本一致,水位变幅和变化率明显低于流量指标,6个流量指标(日流量、日内最低流量、日内最大流量、日内流量变幅、日间流量变幅、日间流量变化率)和6个水位指标(日水位、日内最低水位、日内最高水位、日内水位变幅、日间水位变幅、日间水位变化率)与鱼卵径流量均呈极显著的相关关系(P＜0.01).产漂流性卵鱼类产卵径流量的波动周期和频率与水文指标较吻合,一般较水文指标波动周期短2～3 d;洪峰过程对鱼类产卵行为的刺激明显,是决定岷江下游产漂流性卵鱼类年产卵量多寡的一个重要环境因子,但第1次洪峰过程对产卵行为的影响明显滞后,2次洪峰过程后,鱼类集中产卵行为的起始时间和持续时间均与水文指标的波动达到高度一致.     

生态调度专刊—鱼类产卵行为与生态水文指标响应关系研究-以长江四大家鱼为例

四大家鱼作为我国重要淡水经济鱼类，近年来产卵规模大幅衰减，水文条件作为影响家鱼自然繁殖的重要因素，确定四大家鱼产卵行为与生态水文指标响应关系对保护四大家鱼早期资源具有重要意义。本文采用ROC曲线、分类回归树、Logistic回归等方法以长江中游宜昌段为研究区域，将生态水文指标对家鱼产卵刺激划分为“无效、低效、高效”多分类问题，应用不同数据挖掘方法，分析家鱼产卵行为与生态水文指标响应关系，并对比研究了不同方法间的性能与优缺点。结果显示，ROC曲线判别准确率、预测准确率、模型鲁棒性均最优，认为ROC曲线是本次研究中判定生态水文指标对四大家鱼产卵规模影响的最优方法。当流量日增量大于1370m3/s且两次洪峰间隔时间大于7.5d时可以引起四大家鱼高效产卵响应。辨识出高效刺激家鱼产卵的生态水文指标及其阈值，将对生态调度的优化改进具有重要的现实意义。     

戴家洲河段航道整治工程对“四大家鱼”产卵场的影响

“四大家鱼”的产卵、繁殖与水文、水力学条件密切相关。以长江黄石段“四大家鱼”产卵场为例,采用河道平面二维数学模型预测分析不同特征流量下戴家洲河段航道整治工程实施后对本江段流态、水位、流速等水文变化的影响,进而研究航道整治工程对“四大家鱼”产卵场的影响。研究表明,航道整治工程实施后,最枯流量下,３道潜丁坝均在水面２．５ｍ以下,不会对鱼类产生阻隔;潜丁坝区域从洪峰开始上涨到最高时,流速最大变化为－０．０３８～－０．０５ｍ／ｓ,占产卵流速４．２％～１５．２％;水位变化３～５ｍｍ。工程运行后基本不改变“四大家鱼”适宜产卵流速,基本不会影响“四大家鱼”现有产卵场所需的产卵水文条件。     

丹江口水利枢纽兴建后汉江中下游四大家鱼等早期资源及其演变

2006～2007年对汉江中下游四大家鱼早期资源进行了调查,并结合1977～1978年、2004年汉江中下游的历史调查资料进行分析.研究表明:汉江中下游四大家鱼卵苗径流量下降明显,从20世纪70年代末的近5×108粒(尾)下降到2004年以后的不足1×108粒(尾),四大家鱼卵苗径流量占鱼类卵苗总径流量的比例也从19.0%下降到了1%以下;产卵场数量减少了1处,产卵场位置也发生了变化.     

长江上游江津段产漂流性卵鱼类早期资源现状及繁殖需求研究

研究长江上游江津段的产漂流性卵鱼类早期资源现状和繁殖水文需求,可为长江上游鱼类资源保护和管理提供数据基础。2019-2022年的鱼类繁殖季节,在长江上游保护区江津断面开展鱼类早期资源调查,以了解该区域鱼类早期资源种类组成、鱼卵密度的时间动态以及与水文、水环境因子的关系。结果表明,采集到67种鱼类卵苗,其中典型产漂流性种类26种;从各种类繁殖规模比例来看,吻鮈、圆筒吻鮈、铜鱼、草鱼等占比较高;长鳍吻鮈繁殖高峰集中在4月,圆筒吻鮈和铜鱼的繁殖高峰集中在5月中下旬至7月上旬,四大家鱼的繁殖高峰集中在6月中旬-7月上旬,吻鮈的繁殖时间较长,高峰期集中在4月下旬至6月中下旬。产漂流性卵鱼类的主要产卵场分布在泸州弥陀镇、重庆朱杨溪-石门和金刚沱-油溪镇江段。相关分析结果表明,日均鱼卵密度与透明度呈显著负相关,与流量呈显著正相关。分类回归树结果表明,涨水过程中的水位涨幅、初始流量和透明度最小值是影响保护区产漂流性卵鱼类类群繁殖规模大小的重要因素,对于不同种类而言,所需的积温、流量条件不尽相同。长江上游保护区江段是多种产漂流性卵鱼类的产卵场,金沙江下游梯级陆续运行后,原产卵场位置和规模均发生了一定的变化,建议实施水文过程生态调度来减缓其影响时,不仅需要考虑水文、积温条件对鱼类性腺的影响,还需要考虑水文过程与产卵场形成之间的联系。     

四大家鱼自然繁殖对水文过程的响应关系研究

为了探究长江中游监利江段四大家鱼繁殖行为对水文过程的响应关系,并了解水文过程刺激四大家鱼自然繁殖的生态水文指标量化范围,于2014—2016年的每年5—7月,在长江中游监利断面进行鱼类早期资源调查,同时,对采集到的四大家鱼卵苗与流量以及水温之间关系进行分析。结果显示:水温在20～24℃,流量日增长率为1 125 m~3s~(-1)d~(-1)及以上,涨水持续时间为3 d及以上的涨水过程情况下,可刺激家鱼发生大规模繁殖。而两次涨水过程间隔仅为1 d时,涨水持续时间和流量日增长率无论高低,持续2次涨水过程对家鱼繁殖行为也有刺激作用。     

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.     

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.     

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).