Effects of dietary protein and lipid levels on growth performance,fatty acid composition and antioxidant‐related gene expressions in juvenile loach Misgurnus anguillicaudatus

Dojo loach (Misgurnus anguillicaudatus) is one of the most important cultured freshwater fish in several East Asian countries. However, a little information is available in its nutritional requirements. Thus, this study was conducted to evaluate the effects of feeding varying levels of dietary protein and lipid on growth, fatty acid composition and antioxidant‐related gene expressions in juvenile loach. Six practical diets at three levels of protein (30%, 40% and 50%) and two levels of lipid (6% and 12%) were fed to loach juveniles (initial weight 0.40 g) in triplicated groups (20 fish per replicated) for a period of 8 weeks. Results showed that regardless of lipid level, body weight gain of fish was significantly increased with incremental dietary protein level. Meanwhile, feed conversion ratio was significantly decreased by dietary protein levels, and the lowest value was observed in fish fed dietary protein levels of 50%, regardless of dietary lipid level. Moreover, the percentage of 22:6n‐3 in viscera was significantly increased by different protein levels. The expression level of catalase was significantly increased with incremental dietary protein level with both lipid levels. Meanwhile, the expression level of hepatic nuclear factor erythroid 2‐related factor 2 (Nrf2) was downregulated with incremental dietary protein level with 6% of lipid level, but the expression was upregulated with incremental dietary protein level with 12% of lipid level. In conclusion, these data suggested that 6% lipid and 50% protein in diet was optimal for loach during early development stage.     

夏季杭州湾南岸慈溪滩涂泥螺种群空间分布格局

2004年7月对杭州湾南岸慈溪自然滩涂的泥螺种群进行了取样调查,分别采用Taylor幂法则、Iwao聚集格局回归分析法及Morisita指数公式计算和统计分析。结果表明:杭州湾南岸7个样地间泥螺种群密度差异极显著,种群空间格局在局域斑块尺度属于聚集型负二项分布。造成样地间密度差异的主要原因是人为干扰,泥螺种群的空间分布格局主要与滩涂上积水区域呈斑块状分布有关。     

Replacement of fish meal with two fermented soybean meals in diets for rainbow trout (Oncorhynchus mykiss)

The present study investigated the effect of fish meal (FM) replacement with fermented soybean meal (FSM) on growth and feed utilization of rainbow trout. Two FSM products, FSM1 (more fermentation with more small peptide and acid than FSM2) and FSM2 were used to replace 20%, 40% and 60% of FM in control diet (250 g/kg FM), respectively (FSM1‐20, FSM1‐40, FSM1‐60, FSM2‐20, FSM2‐40 and FSM2‐60). Then the seven diets were fed to rainbow trout (18.1 g) for 8 weeks. Weight gain (WG), feed conversion ratio (FCR) and digestibility of crude protein and dry matter showed no significant difference among the groups of FSM1‐20, FSM1‐40, FSM2‐20, FSM2‐40 and the control, but WG significantly decreased and FCR increased when 60% FM was replaced by both FSMs (p < .05). The replacement of 40%, 60% FM resulted in lower villus height than the control (p < .05), and intestinal protease activity was lower in FSM2‐40, FSM2‐60 and FSM1‐60 groups than the control group (p < .05). In addition, the activity of alkaline phosphatase and superoxide dismutase increased with increasing levels of FSM (p < .05). In conclusion, dietary fish meal could be replaced by 40% with both FSMs without adverse effects on growth and feed utilization of rainbow trout based on an eight weeks feeding trial.     

Replacement of Fishmeal by a Mixture of Soybean Meal and Chlorella Meal in Practical Diets for Juvenile Crucian Carp,Carassius auratus

A growth trial was conducted to evaluate the effect of a mixture of soybean meal and Chlorella meal (SCM) as a dietary fishmeal (FM) substitute on growth performance, apparent digestibility coefficients (ADCs), digestive enzymatic activities, and histology of juvenile crucian carp, Carassius auratus. Five isonitrogenous and isoenergetic diets were formulated to replace 0 (SCM0), 25 (SCM25), 50 (SCM50), 75 (SCM75), and 100% (SCM100) of protein from FM with SCM, respectively. The diets were fed to triplicate groups of juvenile crucian carp for 6 wk. Weight gain, specific growth rate, feed intake, protein efficiency ratio, and intestinal digestive enzymatic activities (amylase, trypsin, and lipase) tended to decline with increasing FM replacement levels (P > 0.05). Dietary SCM substitution significantly influenced dry matter content in muscle, and crude protein and lipid contents in liver (P < 0.05). ADCs for dry matter, protein, lipid, energy, and most amino acids showed no significant differences between the control and SCM25 group, but tended to decline with replacement levels over 25%. Higher SCM substitution (50–100%) caused karyopyknosis and necrosis in liver, but intestinal histology did not show noticeable pathological changes. The present study indicated that FM could be replaced by 25% of SCM, without significant adverse growth performance, feed utilization, and histology of crucian carp.     

鱼池不同水层细菌的密度、昼夜波动及其与主要环境因子的关系

鱼池细菌的密度为表层高于底层,表、底层细菌密度的差异以夏季最大,冬季次之,春秋两季最小。各季节池塘表层和底层的细菌密度在24h内均呈现一定程度的波动,但经昼夜波动后又大致回到原来水平。细菌密度与水温、COD、浮游动物生物量呈正相关,与浮游植物生物量无直接相关。     

流域系统径流侵蚀链内泥沙输移的空间尺度效应

尺度问题在地貌过程及水文模拟研究中具有重要意义,以黄土高原丘陵沟壑区岔巴沟小流域为例,基于毛沟-支沟-干沟尺度序列典型水文站的实测径流泥沙数据,分析流域系统基于事件的径流侵蚀链内泥沙输移的空间尺度效应。结果表明:1)基于侵蚀链毛沟-支沟-干沟不同空间尺度的平均输沙模数、平均含沙量、最大含沙量分别依次为3 912、3 285、3 522 t/km2,497、524、679 kg/m3,639、634、800 kg/m3,且在流域系统中均保持空间上的不变性;2)与单一力学指标相比,引入洪峰流量项的水流功率、单位面积径流能量及水流能量等复合能量指标能更好地描述侵蚀链不同尺度内及尺度间水沙关系;3)侵蚀链的输沙量主要取决于径流量,而洪峰流量能更好地解释侵蚀链内不同尺度径流输沙的差异,在侵蚀输沙的预测变量中引入表征径流变率的指标会提高中小型产沙事件泥沙预报的可靠性;单位洪峰流量(增加1 m3/s)引起的输沙增量是单位径流量(增加1 m3)增沙作用的875倍以上,欲消除侵蚀链内上下游径流输沙的空间尺度效应,则需将对应的洪峰流量比调控至5‰以下,或将对应的径流能量比调控至600以下;4)侵蚀链内上游含沙水流对下游的泥沙输移影响有限,随流域面积增大,含沙水流的空间尺度效应降低,输沙模数300 t/km2的大型侵蚀产沙事件尤为明显。分析结果突出了流域系统径流侵蚀的过程特性和洪水调控可能引起的巨大减沙潜力。因此,针对高含沙水流,侵蚀链内泥沙调控及其水土保持措施的效益评估和功能评价亦应基于过程。研究结果可为全面揭示径流调控系统的水土保持意义、推动水土保持措施效益的精细化评估提供理论依据和科学支撑。     

灌溉方式对不同筋力型小麦品种品质性状的影响

为给专用型小麦优质高产栽培提供理论依据和指导,以强筋小麦品种郑麦9023、豫麦34和弱筋小麦品种太空5号、豫麦50为材料,研究了灌溉方式对小麦籽粒蛋白质和面筋含量、面团流变学特性和拉伸参数的影响。结果表明,不同灌溉方式对4个小麦品种的容重、沉降值、湿面筋含量、出粉率、面团粉质参数和拉伸参数均有显著影响,但4个品种表现有所不同。随浇水量的增加,4个小麦品种容重均逐渐降低,而湿面筋含量均逐渐升高;太空5号沉降值逐渐降低,而其他3个品种的差异不显著;郑麦9023、太空5号和豫麦50出粉率呈增加趋势,而豫麦34出粉率逐渐降低。灌溉方式对豫麦34和豫麦50面团粉质参数的影响均显著,而仅对郑麦9023的形成时间、稳定时间和弱化度以及太空5号的弱化度影响显著。除豫麦34的延伸性和拉伸面积之外,灌溉方式对4个小麦品种的拉伸参数影响显著。在本试验条件下,W4（浇越冬水＋拔节水）是郑麦9023获得优质的最佳处理,W4和W5（浇越冬水＋灌浆水）是豫麦34获得优质的最佳处理,而W3（浇灌浆水）和W5是太空5号和豫麦50获得优质的最佳处理。在实际生产中,应结合品种的需水特性,并统筹考虑水氮交互,制定优质专用型小麦品种的灌水方案。     

天津重点水域底栖生物调查分析

于2018年9月,对天津大港,宝坻,华苑等地区的12个站点的大型底栖生物的群落结构及生物多样性进行了调查分析。结果表明,调查区共鉴定出大型底栖生物3门10种,其中软体动物4种,环节动物4种,水生昆虫2种,各站位丰度波动范围为20～840 ind/m^2,平均为205.33 ind/m^2,生物量范围为0.012～308.63 g/m^2,平均为59.69 g/m^2;囊螺为该地区绝对优势种。丰富度指数Margalefs.index在1.48～3.334之间波动, Goodnight修正指数在0.523～1之间波动。     

水库网箱养殖锦鲤常见病害及防治

锦鲤是当今世界上最具有欣赏价值的观赏鱼类之一,具有“观赏鱼之王”的美称,是一种高贵的大型观赏鱼,它以其艳丽的体色、灿烂的斑纹、高雅优美的游姿、雄健英武的风度,博得了越来越多国内外广大养鱼爱好者的喜爱。笔者从2003年起与浙江省宁波市宁海欣观赏鱼养殖场合作,从香港引进锦鲤鱼苗进行水库网箱养殖。水库网箱养殖是近几年兴起的锦鲤养殖方式,由于养殖环境为开放式,受环境因子影响大,因此出现的病害也较多,现将笔者在养殖中常见的几种病害及防治方法介绍如下:     

欧洲捕捞渔业节能降耗技术与措施

介绍了世界渔业的能耗现状,对捕捞渔业的能耗进行了分析。描述了目前全球使用的各种主要节能措施,包括:减少渔船阻力(如船型优化、采用球鼻艏、优化渔具等),优化动力推进系统(如螺旋桨推进系统的改进、应用新型燃油流量计等),新型能源技术的使用(如风能、生物柴油的应用、混合动力技术开发等)。研究表明,各种措施分别能实现5%~50%的节油量。在追求降低能耗的同时,也需要考虑使用各种节能措施的经济性。