鳙幼鱼在下行过程中应对加速流的行为响应研究

以具有下行洄游需求的鳙(Aristichthys noblis)幼鱼为研究对象, 在自行设计制造加速流的装置中进行下行实验, 结果发现: 在实验设置的3个入口流速下(入口流速分别为: 0.018、0.034和0.053 m/s), 鳙幼鱼的通过率均为100%。在下行通过孔口的方式上, 以尾部先通过为主(即顶流通过), 尤其是在流速较高的时候, 头部先通过比例仅为6.25%。在通过总时间(从实验开始至通过孔口的时间)上, 鳙幼鱼在低流速条件下显著小于在中流速条件下(P<0.05), 而在高流速条件下与中低两个流速条件下均无显著性差异(P>0.1)。在通过时间(从实验鱼最后一次进入加速区域, 至通过孔口的时间)上, 鳙幼鱼在三种流速条件下没有显著差异性(P>0.1)。研究表明, 加速流会对鳙幼鱼下行的时间和方式产生影响。研究旨在为鱼类资源保护, 帮助鱼类安全高效过坝提供基础数据, 同时也为研究鱼类在下行过程中应对加速流的行为研究提供一种研究方法。     

五大连池鳙的生长分析

为了分析五大连池鳙(Aristichthys nobilis)的生长情况,于2013和2014年在五大连池三池及二池随机采集223尾鳙样本,采用鳞片鉴定其年龄,退算体长、体重。同时采用von Bertalanffy生长方程分析了五大连池鳙体长、体重的生长规律。结果显示,鳙渔获物的平均体长、体重分别为54.61 cm和3 280.53 g,由3+~8+共6个年龄组组成,以5+龄个体为主,占总数的50.67%。五大连池鳙体长(L,cm)、体重(W,g)之间关系式为W=0.0289 L2.901(n=223,R=0.974)。体长、体重von Bertalanffy生长方程分别为:Lt=97.619[1﹣e﹣0.140(ti﹣0.004)]和Wt=17113.260[1﹣e~(﹣0.140(ti﹣0.004))]2.901。鳙体长生长速度曲线无拐点,随着年龄的增加生长速度逐渐降低。体重的生长速度曲线具有拐点,拐点年龄为7.61龄,所对应的体长和体重分别为63.94 cm和5 012.82 g。采用生长特征指数?对比分析五大连池与其他水域鳙的生长,结果显示五大连池鳙的生长较为缓慢,栖息环境的水温、饵料生物密度是影响五大连池鳙生长的重要因素。有效提高鳙生长速度的关键措施在于降低放养密度。     

鲢、鳙在天然条件下的摄食强度 (Ⅰ) 鲢、鳙鱼种在夏季的摄食强度

测定鲢(Hypophthalmichthy molitrix)、鳙(Aristichthys nobilis)鱼种在天然条件下肠管饱满度指数与水温及溶解氧的关系,在实验条件下鱼的排空率。根据修正后的Bajkov公式(D=C24·A/n)估计鱼的日摄食量。两种鱼在天然条件下具昼夜摄食节律,它们的摄食高峰在下午16—19时,低谷在清晨4—7时。鲢日粮为其体重12.81—23.08%;鳙为8.91—14.63%。它们的摄食强度随溶解氧的升高而加强,反之则下降。     

两种鲤科经济鱼类水声目标强度的实验测定与应用评估

鱼类目标强度(Target Strength,TS)及其与鱼体长度的关系是渔业声学技术研究和应用的核心内容之一。本文以我国广泛分布的鲤科经济鱼类鲤(Cyprinus carpio)和鳙(Aristichthys nobilis)为研究对象,选择湖北省宜昌市隔河岩水库的一处僻静库湾作为实验地点,于2017年5月1—20日采用绳系实验法和Simrad EY60型(频率120 kHz)分裂波束回声探测仪,在环境干扰小的实验网箱里逐一测量单体实验鱼游动状态下的目标强度,由此构建2种鱼的目标强度与个体大小关系式。用于实验的鲤和鳙均为26尾,其全长分别为19.9—29.6 cm和49.2—74.2 cm,体重分别为175—461 g和1200—4700 g,实验所测TS值分别为–59.35—–45.20 dB和–34.22—–17.49 dB。回归得到实验鱼目标强度(TS,dB)与全长(TL,cm)关系式(1)鲤: TS = 29.84×lgTL – 95.23(R^2 = 0.74,P<0.01),(2)鳙: TS = 35.88×lgTL – 90.33 (R^2 = 0.83,P<0.01)。同时选择一个小型封闭水体(盐龙湖)“赶、拦、刺、张”联合渔法捕捞之前的鱼探仪调查数据作为分析实例,通过本文鳙TS-TL关系式估算全湖鱼类资源总量为89360 kg,折合40.1 g/m^2,捕捞产量(73610 kg)与之较为接近,在一定程度上反映了实验目标强度测定及其与体长关系式的合理性,有助于丰富我国内陆水域鱼类资源水声学评估技术的基础参数。     

鳙鱼受精早期扫描电镜研究

镛鱼(Aristichthys nobilis)受精是精子通过卵膜孔附着于卵质膜表面精子穿入部的微绒毛,两者迅即发生融合,但未见到有明显的受精锥。授精一分钟,精子整个头部已与卵的质膜发生融合,并看到有精子整个尾部已被微绒毛包裹的情况。在受精精子附近有一尚未与卵完全分开的第一极体。本文还讨论了精子穿入部的功能。     

Ecology and management of exotic and endemic Asian longhorned beetle Anoplophora glabripennis

• 1 The Asian longhorned beetle is native to China and Korea, and was found for the first time outside its native habitat in the U.S.A. in 1996, with subsequent detections being made in Canada and several European countries.
• 2 We review the taxonomy, distribution, basic biology, behaviour, ecology and management of endemic and exotic Anoplophora glabripennis, including information that is available in the extensive Chinese literature.
• 3 This species has caused massive mortality of Populus species in China and models have demonstrated that it could become established in many locations worldwide.
• 4 Anoplophora glabripennis is polyphagous but prefers Acer, Salix and Populus, section Aigeiros.
• 5 Although A. glabripennis adults do not disperse far when surrounded by host trees, they have the potential to fly more than 2000 m in a season.
• 6 Volatile organic compounds from preferred host trees are attractive to A. glabripennis and this attraction is heightened by drought stress. Males and females orientate to a volatile released by female A. glabripennis and males attempt to copulate after contacting a sex pheromone on the female cuticle.
• 7 At present, A. glabripennis is being (or has been) eradicated from areas where it has been introduced. After detection, extensive surveys are conducted and, if breeding populations are detected, at the very least, infested trees are removed and destroyed. Close attention is paid to imported solid wood packaging material to prevent new introductions.
• 8 Standard practice to control A. glabripennis in China is to spray insecticides in tree canopies. In North America, largely as a preventative measure, systemic insecticides are injected into trees. Entomopathogenic fungi have been developed for the control of A. glabripennis, and entomopathogenic nematodes, coleopteran and hymenopteran parasitoids and predatory woodpeckers have been investigated as biocontrol agents.
• 9 Ecological control of A. glabripennis in China involves planting mixtures of preferred and nonpreferred tree species, and this practice can successfully prevent outbreaks.

     

华贵栉孔扇贝♀×栉孔扇贝♂远缘杂交的受精细胞学观察

用HOECHST33258对华贵栉孔扇贝(Chlamys nobilis)♀×栉孔扇贝(Chlamys farreri)♂的受精卵进行染色,在荧光显微镜下观察其受精细胞学过程。观察表明:栉孔扇贝的精子能够使华贵栉孔扇贝卵子受精。精子入卵后呈一圆形亮点,体积稍有膨大成球形;授精后成熟卵母细胞释放出第一极体和第二极体后,精核解凝、稀疏、泡状化,形成雄性原核(male pronucleus);雌性原核(female pronucleus)在完成两次成熟分裂之后,染色质去浓缩,扩散膨大;雌雄原核相互靠拢,当雌雄原核膨胀到最大程度时,发生融合,形成合子。受精卵能够正常发育,完成第一次卵裂,卵裂时细胞核分离未观察到异常现象。与华贵栉孔扇贝和栉孔扇贝种内交配对照组相比,异源受精卵的细胞学过程明显滞后,同时其发生过程具明显的不同步现象。实验中还观察到少数的雌核发育现象。     

First Report of Calonectria ilicicola Causing a New Disease on Laurus (Laurus nobilis) in Europe

Crown and root rot has been detected on potted Laurus nobilis plants in a nursery located in the Catania province (Italy). Perithecia referable to a Calonectria species were consistently detected on crowns and stems of symptomatic plants. Based on morphology, cultural features and molecular analysis, the species was identified as Calonectria ilicicola. Koch’s postulates were fulfilled by pathogenicity tests carried out on potted Laurus nobilis seedlings. To our knowledge, this is the first report of the occurrence of a disease caused by Ca. ilicicola on Laurus nobilis.     

台湾棘带吸虫囊蚴在鳙鳃丝、鳃耙上的分布

通过对鳙为期16个月的定期取样研究发现,1993年8月到1994年3月,台湾棘带吸虫的囊蚴主要分布在鳃耙上,1994年4月至11月,囊蚴则主要分布在鳃丝上;当鳙体长范围为30-90mm时,囊蚴主要分布在鳃耙上,当体长大于90mm时,囊蚴主要分布在鳃丝上,随着鳙的生长,鳃丝囊蚴所占的比例逐渐增大,从0增加到100%,而鳃耙囊蚴所占的比例逐渐减小,从100%下降到0;不同月份、不同体长组鳙其不同组鳃丝囊蚴分布规律相同,第2组鳃丝囊蚴分布较多,第3、第1、第4组鳃丝囊蚴分布依次减少：其不同组鳃耙囊蚴分布规律也相同,总是第1组鳃耙囊蚴分布较多,其余依次为第2、第3、第4组鳃耙;囊蚴在鳙鳃丝和鳃耙上的分布都呈聚集分布,且聚集的强度随囊蚴内种群密度的增高而增高。