控制汉江丹江口-王甫洲区间伊乐藻的生态调度及其效果评估

为科学有效控制汉江丹江口至王甫洲区间伊乐藻过度生长繁殖,研究生态调度的实施效果。采用生物量调查法、分布面积统计法、数学模型模拟法分别分析评价生态调度实施前后总生物量的变化情况,分布面积的变化情况,以及对丹江口水库下泄流量的需求。结果表明,连续三年实施生态调度,伊乐藻总生物量由2019年的4.8万t减少至2022年的40.11t,分布面积由11.60 km₂^减少至0.23km2,减幅均达到了95%以上, 伊乐藻生物量占沉水植物总生物的比重从99.99%减少至17%,生态调度效果较好。春季生态调度应重点从增加流量极值比出发进行中度干扰,夏秋季生态调度重点从满足0.14m/s临界流速出发进行大流速冲刷。     

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。     

乌东德水电站库尾栖息地水力生境优化调度

金沙江乌东德水电站库尾河段是乌东德、白鹤滩水电站栖息地保护体系的重要组成部分，该河段受上游观音岩、金沙以及桐子林等水电站非恒定流下泄影响，河段流速、水深等水力条件变化频繁且复杂，河段栖息地保护功能和效果难以保障。为调控栖息地保护河段水位变幅和流速，改善鱼类产卵适宜的水力生境，采用MIKE21进行模拟计算，研究在3―4月裂腹鱼类产卵期对上游梯级下泄流量过程和下游乌东德水库运行水位的控制要求。结果表明，从水深适宜度看，在3―4月特定流量条件下，乌东德水电站运行水位应在974.0～974.5 m；为营造较为适宜的流速，裂腹鱼类产卵繁殖期间，乌东德水电站库水位应维持在974.5 m附近。当上游梯级下泄流量时段内变幅小于1 600 m3/s，下游乌东德水库库水位保持在974.0～974.5 m，可控制河段水深在0.5～1.5 m、流速在1.5～2.5 m/s的适宜阈值区间变动。研究可为进一步提升乌东德库尾栖息地保护河段功能及其保护价值提供技术参考。     

乌东德水电站日调峰对下游裂腹鱼类栖息地的影响研究

日调峰是乌东德水电站日常运行的主要出力约束和调度目标，但调度引起的水库出库流量大幅涨落也可能对下游生态环境产生不利影响。采用河道内流量增量法，通过构建二维水动力模型，研究了乌东德水电站日调峰引起的下游河段水文水动力条件波动对裂腹鱼类繁殖期栖息地适宜性的影响，并分析了2023年电站基荷发电生态调度试验效果。结果表明：当乌东德电站下泄流量低于1160 m3/s时，坝下江段裂腹鱼类潜在产卵场面积相对较大；当流量高于2000 m3/s时，裂腹鱼类潜在产卵场面积显著减少。电站日调峰结束时，出库流量降幅越大，裂腹鱼类潜在产卵场脱水面积及鱼卵脱水风险越大。2023年乌东德电站基荷发电生态调度期间，坝下江段裂腹鱼类潜在产卵场的加权面积有所减少，但潜在产卵场和鱼卵早期的脱水风险有显著降低。为提高繁殖期裂腹鱼类生境适宜性和持续性，电站有必要进一步减少调峰频次、降低出库流量至适宜区间。     

蟹池伊乐藻的控制管理

养蟹池内适量栽种伊乐藻有利于净化水质，创造良好生态环境，为河蟹提供天然饵料，促进河蟹生长发育。但是随着水温升高，伊乐藻容易出现“疯长”现象，从而影响河蟹活动，并且容易造成蟹池缺氧和大面积败草破坏水质。因此，必需加强对伊乐藻的控制与管理。     

水库运行对汉江流域草鱼洄游影响评价研究

水库运行导致河流水文条件发生改变,对鱼类洄游及其性腺发育产生显著负面影响。为了探究丹江口水库运行对汉江草鱼（Ctenopharyngodon idella）洄游的影响,利用三维水动力模型EFDC模拟水库不同运行情景下的库区和下泄口水动力条件,建立带有外源输入的非线性自回归神经网络（NARX）模型预测下游水动力条件;通过室内试验获取草鱼洄游与水文条件响应关系,并建立草鱼洄游适宜度计算公式,评价丹江口水库上游、库区和下游的洄游适宜性。结果表明,时间上,由于4月水温升温较慢,且流速较低,草鱼洄游状况劣于5-7月;空间上,无论是水库下游还是库区,鱼类洄游状况都劣于未受丹江口水库影响的上游区域。库区极低的流速是影响草鱼上溯的限制因素,而下游降低的流速和水温对草鱼上溯和性腺发育都造成了阻碍。在鱼类洄游期间,降低库区水位、增大下泄量有利于提升库区及下游的流速和水温,改善洄游的外部环境条件。根据已有水库下泄方案（初始水位153 m）,如果初始水位降至142 m、下泄增大20%,库区平均洄游适宜度可提高6.5%,下游可提高22.0%。     

3种水草搭配模式对河蟹生长及水环境的影响

为探究水草搭配模式对河蟹的生长性能及水体环境的影响，以河蟹池塘养殖最常用的3种水草为基础，设计了伊乐藻、伊乐藻+轮叶黑藻、伊乐藻+黄丝草3种水草搭配种植模式，进行了河蟹养殖对比试验。试验结果：从养殖河蟹的产量和规格来看，3种模式下河蟹的体质量差异不显著(P>0.05),伊乐藻+黄丝草模式可以获得较高的河蟹产量；从肝胰腺和性腺发育情况来看，单独种植伊乐藻组河蟹的肝胰腺和性腺发育最好，其次为伊乐藻+黄丝草组，伊乐藻+轮叶黑藻组较差；从养殖水质净化效果来看，伊乐藻+黄丝草组效果最好，其次为伊乐藻+轮叶黑藻组，最差的是伊乐藻单独种植模式。结果表明，从经济效益、生态效益等方面综合考虑，3种水草搭配模式中，伊乐藻+黄丝草的搭配模式最佳，其次为伊乐藻+轮叶黑藻，单独种植伊乐藻最差。     

伊乐藻抗椭圆萝卜螺牧食损害能力研究

观测椭圆萝卜螺（Radix swinhoei）对伊乐藻（Elodea nuttallii）植株造成的牧食损害程度,研究伊乐藻的抗牧食损害能力以及受损后的生长特性,进一步了解伊乐藻生态适应性以及入侵能力,为合理利用和控制伊乐藻提供依据。 选取15~20 cm的伊乐藻嫩枝,除去附生生物,用蒸馏水冲洗干净,快速称量鲜重2 g。螺的类型据重量分为大螺（0.17±0.02）g、中螺（0.1±0.01）g和小螺（0.03±0.01）g。玻璃缸水平置于室内靠窗户的位置,加入2 L稀释10倍的Hoaglands培养液。试验组分3组,每组放1种大小的螺4只,螺在培养液中饥饿48h后用于试验;对照组不放螺。每种处理3个重复,试验期15d。螺主要取食伊乐藻茎干和顶芽,取食优先顺序为茎干、顶芽、叶 。中螺危害最甚,该组中伊乐藻的生物量增量约为对照组的40%;大螺危害次之,小螺危害最小,2组中伊乐藻生物量增量分别占对照组的92%和96%。受牧食损害后的伊乐藻仍有较高的成活率,形成的断枝也有较高的萌发率,大螺、中螺、小螺组伊乐藻断枝上腋芽萌发的数量占原枝条数的比例分别为41.7%、22.6%和10%。椭圆萝卜螺可对伊乐藻造成明显的牧食损害,但伊乐藻抗牧食损害能力较强。     

伊乐藻在滨海盐碱地蟹池的利用及耐盐性试验

伊乐藻(Elodea Canadensis)是一种优质、速生、高产、耐低温、营养丰富的沉水植物,是多种鱼虾蟹等水生动物的优良天然饵料,被誉为沉水植物的娇子,上世纪由中科院南京地理与湖泊研究所引进后[1],在我国南方广大地区广泛应用,已成为河蟹、小龙虾(克氏螯虾(Procambarus clarkii)养殖池塘中优选的水草[2].蟹池种植伊乐藻,可以为河蟹提供优质饵料,还可以净化水质,防止水体富营养化,营造蟹池良好的生态环境,提供河蟹活动、隐藏、蜕壳所需的隐蔽环境[3].伊乐藻适应力极强.水温在5℃以上即可生长,冬季在冰下以营养体越冬,当苦草、轮叶黑藻尚未发芽时,该草已大量生长[4],非常适合我国北方地区的池塘引种.     

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。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

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.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

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.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.