陕西瀛湖富营养化特征与控制对策

陕西省安康市境内的瀛湖是南水北调中线工程丹江口水库的重要水源地,随着社会经济的发展和人类活动的加剧,2001年开始出现水华。为保护其水生态环境,依据2015年实测数据,采用综合营养指数法对瀛湖水体进行营养状态评价。结果表明:(1)瀛湖目前年均综合营养指数为43.78,整体上处于中营养水平,总磷、总氮和叶绿素a对综合营养指数的贡献率最大,合计达到78.34%;(2)瀛湖水体TP和TN浓度分别为0.2 mg/L和1.2 mg/L,从营养盐水平上看,已处于富营养化状态,存在暴发大面积水华的风险;(3)瀛湖各采样点的综合营养状态指数在39.58~46.31,相差不大,总氮、总磷的营养指数在整个湖区也比较均匀,表明总氮和总磷污染物来自安康市汉滨区以上更为上游的汉江流域;(4)基于瀛湖的生态特点,结合当地社会经济发展状况,建议瀛湖选择适宜的渔业发展模式,形成健康的水生生态系统结构,探究瀛湖热分层规律,优化大坝水调度方案,实施全流域环境-经济协同管理战略,削减入湖污染物。     

Design and performance of a recirculating aquaculture system for oyster larval culture

The major objective of this study was to introduce a newly designed recirculating aquaculture system (RAS) for oyster (Crassostrea angulata) larval culture. The system includes a culture tank, a suspended circular inlet‐pipe, an upwelling aeration pipe, combined “banjo” sieves and a bioreactor chamber containing microalgae life keeping installation. The system was designed to resolve three problems: (i) stranding of larvae caused by water level changes and aeration, (ii) physical clogging of the screens and also (iii) deterioration of diet microalgae. The culture tank, “banjo” sieve size, water flow rate and light intensity for maintaining microalgae activity were all designed according to the pattern of larval movement and feeding behaviour. Results of this study showed the best average SGR for larval length was 6.36%/d (9.5 μm/d) and survival rate was 80%, with initial rearing density of 50 larvae/ml, indicating the problems above were fully resolved. Consequently, the system is fit for larval culture in mass production of oysters.     

零换水条件下饲料蛋白水平对团头鲂幼鱼生长、消化酶活力和血清生化指标的影响

为探究零换水养殖水体中饲料蛋白水平对团头鲂(Megalobrama amblycephala)幼鱼生长、消化酶活力和血清生化指标的影响,实验设计投喂4个不同蛋白水平的生物絮团试验组(BF-20%、BF-25%、BF-30%、BF-35%)以及1个投喂35%蛋白的循环水对照组,每个处理组设置3重复,每个养殖桶放养初始体重为(6.06±0.01)g团头鲂幼鱼25尾,养殖周期为6周。结果表明:(1)形成的生物絮团可以有效地调节水质,降低水体中的氨氮、硝酸盐氮和亚硝酸盐氮水平;(2)BF-30%和BF-35%组和对照组的终末体重、增重率和饲料系数差异不显著(P0.05),但其显著高于BF-20%组(P0.05),各处理组间的存活率没有显著性差异(P0.05);(3)BF-25%组、BF-30%组和BF-35%组的肠道、肝脏超氧化物歧化酶和谷胱甘肽过氧化物酶活性显著高于对照组和BF-20%组(P0.05),而BF-20%组的肝脏丙二醛含量显著高于其他处理组(P0.05);BF-25%组、BF-30%组和BF-35%组的血清碱性磷酸酶和溶菌酶活性显著高于对照组和BF-20%组(P0.05),而其血清中总蛋白含量、白蛋白含量、谷丙转氨酶和谷草转氨酶活力差异不显著(P0.05)。研究表明,零换水条件下饲料中35%蛋白水平减少至25%并不影响团头鲂幼鱼的生长和非特异性免疫力。     

盐度对条纹锯鮨(Centropristis striata)仔鱼的活力、开口、摄食的影响

观察研究了10个盐度梯度(7、12、17、22、27、32、37、42、47和52)对条纹锯鮨(Centropristis striata)仔鱼的活力、开口和摄食情况的影响,记录分析其在不同盐度条件下不投饵存活系数、开口率、摄食率及摄食强度等指标.结果显示,盐度对条纹锯鮨仔鱼的活力、摄食及存活有明显影响,其存活和摄食的适宜盐度范围为12-37,最适盐度范围为27-32.盐度低于12时,仔鱼存活率、开口率和摄食强度随盐度的降低而降低,盐度高于37时,仔鱼存活率、开口率及摄食强度则随盐度的升高而降低.不同盐度条件下,条纹锯鮨仔鱼SAI值的波动范围为0.034-6.401,盐度为12-37的实验组与7、42、47、52实验组的SAI值存在显著性差异(P＜0.05),盐度为32时,仔鱼的SAI 值最大,为6.041,SAI值与盐度之间符合三次曲线函数关系,其表达式为y=-5.894+1.155x-0.034x2+0.000x3,R2 =0.895,其中,y代表SAI,x代表盐度.盐度为7、42、47和52时,仔鱼的存活率均低于50％,盐度为52、47时,仔鱼在第3、4天存活率分别降为0.盐度为22、27、32时,培育至第5天,仔鱼的存活率均在80％以上.盐度在17-37范围内,仔鱼开口率为60％-85％,且仔鱼均能较好摄食,盐度为32时,仔鱼开口率达到最大值,为85％,仔鱼摄食亦达到最佳状态,摄食率为85％,8日龄仔鱼摄食强度为5.45个轮虫/尾.     

Insecticidal activity of glufosinate through glutamine depletion in a caterpillar

The herbicide glufosinate‐ammonium (GLA) is a competitive inhibitor of glutamine synthetase (GS), an enzyme converting glutamate to glutamine in both plants and animals. Because GS is essential for ammonia detoxification in plants, GLA treatment disrupts photorespiration by causing a build‐up of ammonia and a loss of glutamine in plant tissues. This study reports that GLA applied to leaf surfaces is also toxic to 5th‐instar caterpillars of the skipper butterfly Calpodes ethlius (LD₅₀ = 400 mg kg⁻¹). After ingesting GLA, caterpillars stopped feeding and became dehydrated through a loss of rectal function. Caterpillars showed symptoms of neurotoxicity, such as proleg tremors, body convulsions and complete paralysis before death. Incubation of several tissues isolated from normal feeding‐stage caterpillars with the GS substrates glutamate and ammonium showed that GLA inhibited GS activity in vitro. Within 24 h of ingesting GLA, caterpillars had a greatly reduced glutamine content and the ammonium ion levels had more than doubled. Injection of ammonium chloride into non‐GLA‐treated caterpillars had no deleterious effect, suggesting that glutamine depletion, and not a rise in body ammonium, was the primary cause of GLA toxicity following GS inhibition. This was supported by the observation that the onset of the symptoms of GLA poisoning could be postponed by giving GLA‐fed caterpillars several subsequent daily injections of glutamine. The effective GLA dose fed to 5th‐instar caterpillars in this study was comparable to the amount that might realistically be acquired from feeding on GLA‐treated crops. © 2001 Society of Chemical Industry     

川南山地黄牛放牧及放牧补饲的增重试验

本试验在三峡库区丰都县选用川南山地黄牛 1 2头 ,随机分成 3组 ( 2个试验组 ,1个对照组 ) ,进行放牧和放牧加补饲的增重试验。经过 60 d的试验 ,2个试验组的平均日增重 ( ADG)分别为 5 4 4.5 8g和 60 2 .92 g,比对照组的 1 37.92 g分别提高 2 94.85 %和 337.1 5 % ;增重毛利润分别为 5 2 .45元 /头和 80 .31元 /头 ,比对照组的 41 .40元分别增加 1 1 .0 5元 /头和 38.91元 /头。试验结果表明 ,与放牧相比 ,放牧加补饲能显著提高日增重 ,增加经济效益     

日粮中添加不同比例棉秆对后备种公羊生产性能、血清激素和睾丸组织的影响

[目的]研究日粮中添加不同比例棉秆对后备种公羊生产性能、血清激素和睾丸组织的影响.[方法]采用单因素完全随机试验设计,将体重相近的60只小尾寒羊后备种公羊随机分为6组,每组10只.设计2个对照组,即饲粮中对照1组(CK1组)不含棉源饲料,对照2组(CK2组)含棉籽粕、不含棉秆.在CK2组饲粮基础上,试验组饲粮分别添加2...     

Feeding‐deterrent activity of α‐asarone isomers against some stored Coleoptera

All isomers of α‐asarone [(E)‐4‐prop‐1‐enyl‐1,2,5‐trimethoxybenzene] were tested for their feeding deterrent activity against adults of Sitophilus granarius and Tribolium confusum and larvae of Trogoderma granarium and Tribolium confusum. (E)‐2‐prop‐1‐enyl‐1,3,5‐trimethoxybenzene exhibited the strongest deterrent activity against all the species tested. The total coefficients of deterrency for this compound were 140.6 and 169.7 for Tribolium confusum adults and larvae, respectively, and 144.9 and 104.6 for larvae of Trogoderma granarium and adults of Sitophilus granarius, respectively. © 2000 Society of Chemical Industry     

2005～2015年吉林省农机化作业水平定量预测

以1992-2001年吉林省机械化耕、种、收作业水平的统计数据为依据,采取了平滑预测与回归预测相结合的方法,预测了2005-2015年吉林省机械化耕、种、收作业水平。模型预测结果表明,吉林省2005年耕种收综合机械化水平为42．60％,2010年将达到49．90％,2015年将达到59．36％。“十一五”和“十二五”时期吉林省机收和机播的发展速度可能会快于预测值,机耕的发展速度可能会小于预测值。