六冲河鱼类资源衰退的原因与对策建议

乌江上游主要干流六冲河多年来由于修建水利工程、人为过度捕捞、引进外来鱼种、水域污染、法律监督管理不力,导致该河中的野生优质鱼类趋于低龄化、小型化、低质化,资源量急剧下降,部分名优鱼类濒临灭绝的严峻形势.从加强领导、修建水利工程时应保护鱼类的生存,加快地方特有鱼类驯化养殖,实现人工放流进行资源修复,加强渔政管理等方面来实现对六冲河鱼类资源的保护.     

岗更湖鲫的生长和生活史对策研究

2008年5～9月于岗更湖取得803尾鲫标本,研究了其生长及生活史类型.用鳞片鉴定年龄,鳞径(R)和体长(L)的关系为L=3.667R-1.737;用特殊von Bertalanffy生长方程、一般von Bertalanffy生长方程、Gompertz生长方程和灰色动态生长模型共4种生长模型拟合了岗更湖鲫的生长,根据各模型拟合残差平方和的大小判断,特殊von Bertalanffy生长方程拟合效果最好;根据r-选择和k-选择的典型特征及7个生态学参数值,判断出岗更湖鲫偏向r-选择,应用平衡产量模式计算改变瞬时捕捞死亡率(F)和渔业补充年龄(tc)对应的产量变化,同样证实岗更湖鲫偏向r-选择.作为渔业管理对策,岗更湖鲫的捕捞年龄应在3龄以上,捕捞强度不应超过2.0.     

Effects of embryonic exposure to α‐lipoic acid or ascorbic acid on hatching rate and development of zebrafish (Danio rerio)

This study investigates the effects of embryonic exposure to two different antioxidants on growth and development in fish. Zebrafish (Danio rerio) embryos (100 per group) were exposed to lipoic acid (LA, 6–12 μM) or ascorbic acid (AA, 100–200 μM) and the hatching rate, standard lengths (SL) at hatching, development and growth post‐hatching monitored. The SLs at hatching were increased (P<0.05) in both antioxidant‐exposed groups relative to the controls, with no effect on yolk reserves. This enhanced development persisted up to 15 days post hatching. At hatching, cell proliferation rates (P<0.0005) and basic fibroblast growth factor (P<0.001), were greater in the antioxidant‐exposed fish than in the controls (0 μM antioxidant); no oxidative DNA damage was detected (P>0.05). Activity of the endogenous antioxidant enzyme superoxide dismutase was greater (P<0.001) in LA‐treated fish than in the controls. The results suggest that embryonic treatment of zebrafish with LA or AA during embryogenesis enhanced cell proliferation, leading to increased somatic growth in the larval stages, persisting into the juvenile stage. The findings support the treatment of embryonic fish with antioxidants for enhanced results in aquaculture.     

马来眼子菜和POM稳定同位素对污染物的指示作用

为了探究大型植物马来眼子菜（Potamogeton malaianus）和颗粒有机物质（Particulate organic matter,POM）对湖泊主要污染来源的指示作用,在贡湖湾选取14个样点,采集马来眼子菜和POM样品,分析其碳、氮稳定同位素的变化。结果显示,马来眼子菜和POM有相似的δ15N值趋势,都是随着离入湖口距离越远,其δ15N值逐渐增加,马来眼子菜的δ15N值为10.8‰～14.1‰,POM的δ15N值为6.69‰～14.1‰;而马来眼子菜的δ13C值随着离入湖口距离越远有下降趋势,变化范围为-17.6‰ ~ -14.5‰;POM的δ13C值则有增加趋势,变化范围为-26.9‰ ~ -24.6‰。马来眼子菜较高的δ15N值指示了人类生活污水来源的氮,表明贡湖湾的主要污染源为生活污水。相关分析表明,水中总溶解磷（TDP）与马来眼子菜的δ15N值有明显的负相关关系,水中的总氮（TN）与POM的δ15N、δ13C值则呈很好的正相关关系。而POM的N占比和底泥的δ15N值分别与POM的δ15N值有明显的正相关性。研究表明,马来眼子菜和POM的δ15N、δ13C值能够指示太湖贡湖湾的主要污染来源。     

西瓜主要农艺性状与裂果性状的相关及通径分析

对西瓜的14个农艺性状进行相关与通径分析。相关分析结果表明,裂果率与果皮厚度、外果皮木质化程度呈显著或极显著相关。经过逐步回归,10个性状与裂果有直接和间接效应,决定系数为1.000,剩余通径系数为0.001 8。外果皮木质化程度对裂果的直接作用最大,直接通径系数达到0.796,可将其作为筛选抗裂品种的重要参考性状。     

试论景洪热带地区园林植物造景的特点

对景洪热带地区独有的少数民族,结合当地自然风貌,尝试将景洪热带地区总结出人与大自然植物景观和谐相处,重视"意"与"匠"的结合,傣族民间园林植物造景与园林其它要素的结合,公园的植物造景特色,重视热带景观的营造5个植物造景的特点,对其进行了分析,并对热带地区园林植物造景研究的意义提出看法.     

海南省瓜菜农药残留监控模式探讨

海南省是我国重要的商品蔬菜生产基地之一,是冬季"菜篮子"最大的生产基地,2007年反季节瓜菜种植面积154万hm2,总产量330万t,出岛量221.17万t,产值62.73亿元.因此,提高海南瓜菜质量安全水平,对蔬菜实行"从农田到餐桌"全程监控,生产优质蔬菜,不仅可以提高蔬菜的竞争力,增加农民收入,更重要的是能确保城乡居民食用瓜菜安全.本文就海南省瓜菜农药残留监控模式,提出了几点思考.     

不同药物及给药途径对仔猪白痢治疗效果的影响

选择自然感染大肠杆菌、拉白色或灰白色稀粪的哺乳仔猪(要求无弱仔和其他疾病)195头为试验动物,以每窝仔猪为单位,随机分成两大组(每组设5个试验组),给药途径选用肌肉注射和后海穴注射药物;观测三九克痢注射液、氟哌酸注射液、恩诺沙星注射液、痢菌净、链霉素等5种药物对仔猪白痢治疗效果的影响。结果表明,肌注的5个实验组即Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ组总有效率分别是75.0%、72.7%、58.8%、68.4%和52.9%(P﹤0.05),穴注的五个实验组即Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ组总有效率分别是77.3%、72.0%、66.7%、73.7%和62.5%(P﹤0.05);肌注组的总有效率66.3%、穴注组的总有效率71.0%。结果表明,三九克痢的疗效与安全性都是最好的;其次是恩诺沙星;后海穴注射药物的疗效更好。     

Jackknife method for estimating the variance of the age composition using two-phase sampling with an application to commercial catches of swordfish (Xiphias gladius)

An estimate of the age composition of a commercial swordfish catch and its variance was obtained using the replicate full jackknife estimator for two-phase sampling where the sampling units in the first phase are clusters (vessel-trips) and the units of the second phase are individual fishes. The jackknife variance estimator was compared with an analytical estimator of variance commonly used in fisheries studies which ignores the clustering, and assumes simple random sampling of individual fish. The application of these naïve estimators to the Chilean South Pacific swordfish fishery results in an underestimation of the variance. This is a consequence of using an inappropriate primary sampling unit of analysis in the first-phase sample where the vessel-trip unit is replaced by an individual fish unit, thus ignoring the intra-cluster correlation in age samples. The jackknife estimator of variance is an alternative useful for complex two-phase sampling designs.