曼氏无针乌贼精子的超微结构

采用透射电镜的方法研究曼氏无针乌贼(Sepiella maindroni)成熟精子的形态及结构特征.结果表明,曼氏无针乌贼的成熟精子由头部和尾部组成,尾部可明显地分为中段、主段和末段3部分.头部由顶体和细胞核构成,顶体呈倒"U"形,位于核的顶端,其内电子密度均匀.细胞核呈稍弯的长柱状纺锤形,为高电子密度的均质结构.尾部中段可见,是由无数个线粒体组成的线粒体距(mitochondrial spur)围绕尾部鞭毛.鞭毛由"9+2"结构的轴丝及外围9束粗纤维组成,形成"9+9+2"结构.尾部主段线粒体距消失,粗颗粒物质包绕轴丝.精子末段呈细长鞭状,由轴丝和质膜组成,随后包围轴丝的9束粗纤维直径变细直至消失,最终,轴丝仅为单一微管.研究认为,曼氏无针乌贼的精子类型是介于原生型与修饰型之间的中间型.[中国水产科学,2009,16(1):8-14]     

曼氏无针乌贼对溶解氧耐受力的研究

在封闭的容器内,设置不同的温度梯度,进行不同规格的曼氏无针乌贼对溶解氧耐受力的实验.采用隔膜法检测实验过程中不同阶段的溶解氧,及结合乌贼养殖生产实际情况,研究其对溶解氧耐受情况.结果表明曼氏无针乌贼耗氧率与水温成正比例关系、与个体体重成反比例关系,耗氧率为146.0～431.4mg/kg·h-1,窒息点为1.96～3....     

曼氏无针乌贼胚胎发育的初步观察

将曼氏无针乌贼受精卵卵膜剥离,在显微镜或解剖镜下观察胚胎发育的全过程,结合室内人工育苗的孵化技术进行探讨。曼氏无针乌贼卵为粘性卵,呈黑色,类型属端黄卵,卵膜属三级卵膜,卵裂类型为不全卵裂,囊胚呈盘状,发生类型为直接发生型。在水温为23.8～26.2℃、盐度29.3时,最快14d孵出幼体,最慢23天孵出幼体,孵出幼体高峰期为18～21d,高峰期的孵出量占总孵出量的79.4%,孵化率为83.1%。胚胎发育速度与温度高低（20～30℃）成正比,盐度低于22对孵化率有严重影响。     

北方地区曼氏无针乌贼越冬养殖技术

为解决春季育苗亲体需求,日照市海洋与渔业研究所进行了曼氏无针乌贼的人工养殖,并进行了越冬养殖技术研究。经过几年的越冬实践证明,用太阳能作为热源进行曼氏无针乌贼越冬是可行的。     

曼氏无针乌贼遗传多样性的RAPD分析

用随机扩增多态DNA(RAPD)技术对曼氏无针乌贼(Sepiella maindroni)10个个体的遗传多样性进行了检测,从24个随机引物中筛选出10个,对每个曼氏无针乌贼的DNA进行扩增,结果表明,每个引物扩增出2～8条清晰可辨且重复性强的条带,10个引物共检测到48条清晰且重复性好的条带,相对分子质量在200～2 000 bp,其中多态位点为7个,占14.6%,平均杂合度H0为0.032.实验所得出的曼氏无针乌贼的遗传多样性是比较低的.由于缺乏历史资料和数据的比较,只依据本实验的结论不能断定究竟是过度捕捞还是环境破坏影响了曼氏无针乌贼的遗传多样性.     

曼氏无针乌贼苗种繁育试验

曼氏无针乌贼（Sepiella maindroni）俗称墨鱼,体型中等,肉厚鲜美,具有较高的经济价值。     

曼氏无针乌贼规模化全人工育苗技术初探

为研究曼氏无针乌贼规模化全人工育苗技术,2008～2010年以人工养殖的曼氏无针乌贼成体作亲本进行了育苗试验.试验中采取了下列技术措施:对乌贼亲体进行强化培育和生殖调控,促进性腺发育成熟;确立乌贼幼体的饵料系列并保障供给;做好育苗水体的水质调控和苗种的病害防治.3年共获受精卵4075.8 kg,平均孵化率82.5％;培...     

曼氏无针乌贼的卵子发生及卵巢发育

采用组织学方法对人工养殖曼氏无针乌贼(Sepiella maindroni)卵子发生、卵巢发育周期进行组织学、细胞学观察。根据细胞大小、胞核形态及卵母细胞与滤泡细胞的关系,将曼氏无针乌贼卵子发生划分为卵原细胞期、卵母细胞期、成熟期和退化吸收期4个阶段,并阐述了各期卵母细胞的组织学特征。曼氏无针乌贼卵子发生过程具有种的特异性,大约孵化出膜12 d的乌贼可见有卵原细胞,此后进入增殖期。卵母细胞属于典型的滤泡型,发育过程中同时存在同步性与异同步性;卵母细胞无初级卵膜,只有次级卵膜和三级卵膜,次级卵膜由滤泡细胞分泌,三级卵膜由输卵管腺、缠卵腺以及墨囊分泌物共同构成。通过对卵巢的外观形态和组织学观察,将曼氏无针乌贼卵巢发育划分为6个时期。     

曼氏无针乌贼胚胎发育生物学零度和有效积温的研究

通过室内恒温培育试验和数理统计方法,研究了曼氏无针乌贼（Sepiella maindroni）受精卵发育的生物学零点温度、有效积温及胚胎发育的温度系数（Q10）。结果表明,曼氏无针乌贼受精卵发育的生物学零点温度为（6．48±0．44）℃;受精卵发育为初孵幼体的有效积温为（396．91±2．81）℃·d;18．0～24．0℃为曼氏无针乌贼胚胎发育的最适温度范围。     

浙江大陈海域曼氏无针乌贼人工放流初见成效

自2009年4月份以来,在浙江大陈海域进行蟹笼作业的渔船每天都能捕获10余只曼氏无针乌贼,规格为胴体长10～12厘米、体重150～200克。初步统计,到目前已捕获到该类乌贼300余只。这表明大陈海域曼氏无针乌贼人工放流初见成效。     

A test of two methods for marking larvae and postlarvae of the giant freshwater prawn, Macrobrachium rosenbergii

This paper describes the successful use of two tagging systems, both produced by Northwest Marine Technology Inc., on larval and postlarval giant freshwater prawns, Macrobrachium rosenbergii. Visible implant (VI) elastomer tags (a coloured liquid that solidifies under the epidermis) were used on stage XI larval prawns (mean weight 0.01 g) and postlarval prawns (mean weight 0.07 g). VI alphanumeric tags (small biocompatible plastic labels also inserted under the epidermis) were tested on postlarval prawns (from a weight of 0.5 g). Tags were inserted using clove oil as anaesthetic, and survival, mortality and growth rates of tagged animals were compared with those of controls that were handled but not anaesthetized or marked. Twenty per cent of the larval prawns (the smallest of the group) died just after tagging, but thereafter the remaining prawns survived well, as did all the tagged postlarval prawns. Visibility of the VI elastomer tags in larval prawns deteriorated with time, though 79% of marks were still visible to the naked eye 70 days after tagging. VI elastomer tags in the postlarval group remained clearly visible for up to 100 days. Visibility of the VI alphanumeric tags fell shortly after tagging, but remained adequate thereafter. Moult rates in control and tagged animals were the same in larvae with VI elastomer tags and postlarvae with VI alphanumeric tags, but the moult rate in the postlarval prawns given elastomer tags was slower than in controls. Rates of growth were similar in tagged (elastomer and alphanumeric) and control postlarval prawns, once the size‐dependent mortality of tagged larval prawns was taken into account. We conclude that VI elastomer tags could be used to mark small numbers of individual larval and immediately postlarval prawns for periods of several months, and that VI alphanumeric tags could be used to mark an unlimited number of individuals from a size of approximately 0.5 g.     

A method for inducing muscle relaxation in the abalone, Haliotis iris

Four chemical and two non-chemical methods for induction of relaxation in the abalone, Haliotis iris, were tested for prospective use in pearl seeding. Requirements were for rapid onset of relaxation, full extension and softening of the foot and epipodium muscle for at least 10 min, and recovery with minimal stress and no mortality. Nembutal at 1 ml/l was most successful, producing relaxed and soft muscle with good accessibility to operation sites, and no mortality. Benzocaine and MS-222 made animals release from container walls within 30–60 min, but the animal's muscle was hard and contracted. Propylene phenoxytol caused muscle contraction and mortality at 2.5 ml/l. The effects of the chemical relaxants were similar in warm (21–22.5°C) and cool (15–16°C) water. Elevation of the water temperature from 18°C to 23°C (without chemicals) caused some softening of the muscle, but was much less effective than Nembutal. Air exposure for up to 4 h was ineffective. This work provides a simple method to relax live abalone for pearl nucleation or other manipulations.     

A proposal for modelling the thermal‐unit growth coefficient and feed conversion ratio as functions of feeding rate for gilthead sea bream (Sparus aurata,L.) in summer conditions

Modelling growth as a function of feeding rate (FR) could be one of the most important tools for fish farms, because this knowledge allows growth to be maximized, or the feed conversion ratio (FCR) to be minimized, thereby improving profits. All growth models should include the three principal variables involved in growth: initial body weight, temperature and feeding rate. The thermal‐unit growth coefficient (TGC) already includes water temperature variation and initial body weight. Studying variation in TGC for fish fed the same diet, but at several feeding rates provides interesting information for modelling. Six different trials were conducted where gilthead sea bream of several different initial weights (24, 38, 50, 110, 220 or 289 g) were fed increasing amounts, and growth and the conversion index response were measured. The TGC response was modelled as a function of FR, and both asymptotic and quadratic responses were examined. The asymptotic model, TGC × 1000 = 2.037*(1?e ^{(?0.8*(FR?0.22)}), had an adjusted R² value of 96.18, whereas the quadratic model, TGC × 1000 = ?0.381 + 1,715 × FR?0,382 × FR², had an adjusted R² value of 96.42. Simulations of the FCR and the economical profitability index (EPI) were conducted to provide tools for maximizing efficiency and profitability, and the results suggest that these tools will be useful for future investigations.     

A low cost field‐survey method for mapping seagrasses and their potential threats: an example from the northern Gulf of Aqaba,Red Sea

1. In the Gulf of Aqaba (GoA), coral reefs are considered the dominating ecosystem, while seagrass meadows, recognized worldwide as important ecosystems, have received little attention. Absence of comprehensive seagrass maps limits awareness, evaluations of associated ecosystem services, and implementation of conservation and management tools. 2. Presented here are the first detailed maps of seagrass meadows along the Israeli coast of the northern GoA. Mapping was performed by snorkelling along transects perpendicular to the shore above meadows growing at 15–25 m. Measurements along these transects included position, meadow depth and visual estimations of seagrass cover. Shallow boundaries of meadows, parallel to shore, were recorded by GPS tracking. Supplementary work included drop‐camera boat surveys to determine the position of the deeper edge of meadows. In addition, GIS layers were created that indicated shoreline infrastructures, near‐shore human activities and potential pollution threats. Ecosystem services of seagrass meadows mapped were valuated using a benefit transfer approach. 3. In total, 9.7 km of the 11 km shoreline were surveyed and 2830 data points collected. Seagrasses were growing along 7.5 km of the shoreline, with shallow (15–25 m) meadows found to cover an area of 707 000 m² and valued at more than US$ 2 000 000 yr^‐1 in associated ecosystem services. Pilot drop‐camera surveys (additional 283 data points) indicated that meadows can extend down to 50 m in some places. Coastal uses and threats varied in character and location. A municipality runoff point and drainage canal located close to the largest meadow were identified as the main threats to local seagrasses. 4. These low‐cost methods enhance our understanding of seagrass distribution in the northern GoA. They demonstrate a GIS‐based tool for assessing how environmental changes might affect the cover and state of seagrasses, improving efforts to conserve seagrass, and have particular relevance to seagrass mapping in developing countries and/or island nations. Copyright © 2016 John Wiley & Sons, Ltd.