基于声学技术的红沿河核电站附近海域夏季水母通量测量

大量水母涌入核电站取水口会对核电冷源取水安全造成严重威胁,为把握夏季红沿河核电站附近海域水母的密度和基本运动规律,分别于2017年7、8、9月在红沿河核电站附近海域使用同时搭载科学探鱼仪(120、200 kHz)和多普勒流速剖面仪(ADCP)的调查船,沿垂直等深线方向进行25 h、10 n mile长垂直断面往复走航水母资源声学调查和潮流观测,并在次日昼间使用多锚张网进行水母样本采集;利用频差处理技术分离海月水母Aurelia aurita、沙蛰Nemopilema nomurai及浮游动物的叠加声学散射信号,使用回波积分法推定沙蛰和海月水母密度,并结合潮流数据计算水母通过调查断面的通量。结果表明:2017年7、8、9月份潮流流速最大值分别为0.80、0.70、0.65 m/s,流速随涨潮和落潮周期逐渐增大和减小;海月水母的平均密度高于沙蛰,二者7月分别为9.79、2.30 ind./m²,8月分别为11.05、1.51 ind./m²,9月分别为0.82、0.32 ind./m²;海月水母在7、8、9月份涨潮时平均通量分别为5.85、3.53、0.40 ind./(s·m²),落潮时平均通量分别为-2.84、-6.07、-0.36 ind./(s·m²),沙蜇在7、8、9月份涨潮时平均通量分别为1.45、0.44、0.17 ind./(s·m²),落潮时平均通量分别为-0.86、-0.76、-0.13 ind./(s·m²)。研究表明:水母通量与涨落潮流速变化具有相关性,能够较好地反映水母的移动趋势,并可作为核电站冷源生物监测预警的重要指标;水母在取水口外侧海域具有随机分布的特性,适合声学浮标监测。     

几种动物蛋白源对海月水母(Aurelia aurita)生长性能的影响

研究旨在发掘可替代卤虫的海月水母人工饲料原料,解决海月水母养殖瓶颈问题。在水温25℃、盐度30‰,pH值8.2~8.4条件下,将240只伞径为(3.64±0.33) cm海月水母随机均分至4组12口水母缸中,每组3个重复。对照组投喂活体卤虫无节幼体,试验组分别投喂虾仁肉泥、猪里脊肉泥和鸡蛋黄。每天观察记录各组水母摄食、消化与发病状况,每周定期检测海月水母伞径、收缩频率和温度、盐度、pH值、亚硝酸盐、氨氮等水质指标。结果显示,各试验组的水质一直处于海月水母适宜范围内。海月水母对卤虫无节幼体与鸡蛋黄的摄食消化较里脊肉与虾仁更为迅速。3周后,4种饲料原料对海月水母促生长效应优劣顺序依次为卤虫无节幼体、猪里脊肉、鸡蛋黄和虾仁,前3组伞径增长量显著高于虾仁组(P<0.05)。基于各组饲料原料营养差异,可利用猪里脊肉蛋白质营养,虾仁必需脂肪酸营养和鸡蛋黄矿物元素营养特点,进行适度配合,以替代卤虫无节幼体作为海月水母配合饲料。     

温度、盐度对黄海北部海月水母碟状幼体生长的影响

试验条件下采用两因素交叉分组法初步研究了温度、盐度及其交互作用对黄海北部海月水母碟状幼体生长的影响。结果表明,温度对海月水母碟状幼体的影响显著,温度10~25℃时,温度越高,海月水母碟状幼体的生长速度越快。25℃为碟状幼体生长的最适温度。海月水母碟状幼体生长的适宜盐度为22~31,在此范围内,不同盐度对碟状幼体生长的影响差异不显著。25为碟状幼体生长的最适盐度。而温度与盐度的交互作用对海月水母碟状幼体生长的影响不显著。     

Seasonal Variations in Proximate and Fatty Acid Composition of Viscera of Sardinella aurita,Sarpa salpa,and Sepia officinalis from Tunisia

Seasonal variations of the proximate composition and fatty acid profiles in viscera from Sardinella aurita, Sarpa salpa, and Sepia officinalis were studied. Significant seasonal variations were observed in the amounts of moisture, lipid, protein, and ash between species. Viscera protein content undergoes large fluctuations. This tendency is different from results observed for the edible parts or for the whole body of many marine species. Ash content also showed significant differences. Lipid contents varied with seasons, in a proportionally inverse manner to water contents. Fatty acid composition showed significant differences from October to December. Interestingly, the highest total omega-3 contents were comparable to many commercial marine fish oils.     

闽浙近海金色小沙丁鱼种群的初步研究

通过对闽南—台湾浅滩渔场,浙江近海渔场金色小沙丁鱼形态计数性状,量度性状特征差异的比较,并结合生物学、产卵场、洄游以及海洋环境条件等综合分析,研究结果表明闽浙近海的金色小沙丁鱼群体分别属于闽南—台湾浅滩地方种群和东海地方种群。本章还讨论了两个海域金色小沙丁鱼的分布。     

Ontogeny of anti-predator behavior in hatchery-reared jack mackerel Trachurus japonicus larvae and juveniles: patchiness formation, swimming capability, and interaction with jellyfish

ABSTRACT:   Laboratory rearing and behavioral observations of larval and juvenile jack mackerel Trachurus japonicus were conducted to elucidate their life-history traits with emphasis on the interaction with the moon jellyfish Aurelia aurita . Jack mackerel were raised from naturally spawned fertilized eggs and they attained 10.3 ± 0.7 (mean ± standard deviation) mm in body length (BL) by 30 days post hatching (dph) and 26.6 ± 1.8 mm BL at 48 dph raised at 19.3–25.0°C. Patchiness (dense aggregation) was confirmed from 5–16 dph (2.9–5.9 mm BL) during the day and from 9–48 dph (4.0–27 mm BL) at night. Cruise and burst swimming speeds were 1.5–1.9 BL/s and 16–24 BL/s, respectively, during larval and juvenile stages, in experimental tanks. Although escape performance from jellyfish was not different between the larvae of jack mackerel and chub mackerel Scomber japonicus , both species showed better survival compared to red sea bream Pagrus major larvae of a similar size. Although jack mackerel were slow in growth, their slow cruise swimming may reduce the chance of encountering predators and fast burst swimming may help escape from gelatinous predators.     

三种大型钵水母幼体对牙鲆和许氏平鲉仔稚鱼的捕食选择性

为探讨中国近海常见大型钵水母对鱼类资源补充的影响,本实验利用清除率法比较研究了伞径4 cm的3种大型水母幼体—海月水母(Aurelia aurita)、海蜇(Rhopilema esculentum)和沙海蜇(Nemopilema nomurai),对不同发育阶段的牙鲆(Paralichthys olivaceus)和许氏平鲉(Sebastes schlegeli)仔稚鱼的捕食量。结果表明,3种水母均可捕食牙鲆和许氏平鲉仔稚鱼,其捕食率随仔稚鱼生长而降低,其中海月水母可捕食规格15 mm牙鲆和20 mm许氏平鲉,海蜇能够捕食规格20 mm牙鲆和30 mm许氏平鲉,沙海蜇可捕食30 mm许氏平鲉;仔稚鱼密度对水母捕食率影响不显著,牙鲆的变态和底栖生活是其逃避被水母捕食的有效手段;不同水母物种对仔稚鱼的捕食效率主要与其活力相关,水母结构和毒性也是重要因素,相同规格3种水母对仔稚鱼捕食率由高到低为海蜇沙海蜇海月水母。本研究结果可为阐明水母与鱼类的动态关系,研究海洋鱼类的自然资源补充机制提供参考。     

海月水母排精诱导及胚胎发育研究

本文观察研究了海月水母的排精诱导因素、受精及胚胎发育过程。结果显示,长光照(14 L:10 D)、饥饿、机械损伤等因素能有效诱导性成熟的海月水母排精;海月水母体内受精过程为：雌性海月水母伞缘触手将雄性排出的精子细丝收集到伞缘的食物囊处,通过口腕进入口腕基沟,先后经胃口腕沟、胃循环沟等水管系统到达卵巢,精子与成熟卵子结合完成受精;海月水母受精卵为球形,卵径150 μm左右,胚胎发育过程包括卵裂期、囊胚形成期、囊胚期、原肠胚形成期、原肠胚期及浮浪幼虫期6个时期。受精卵在22±1℃的水温下,经29 h 20 min发育为浮浪幼虫,经过73 h 20 min发育为四触手螅状体。海月水母体内受精,胚胎体内发育的繁殖模式有利于幼体的存活,这或许是其广泛存在的重要原因之一。     

Jack mackerel <Emphasis Type="Italic">Trachurus japonicus</Emphasis> juveniles use jellyfish for predator avoidance and as a prey collector

ABSTRACT:   Juveniles of carangid fishes including jack mackerel Trachurus japonicus are known to associate with jellyfishes. The function of this association behavior was studied through rearing experiments and underwater visual observations. Association behavior of jack mackerel with moon jellyfish in experimental tanks was more frequent in the presence compared to the absence of predators (chub mackerel Scomber japonicus ). In the experimental tanks, the presence of jellyfish, however, did not mitigate predation by these predators. Although jack mackerel did not feed on the jellyfish itself, they frequently fed on the captured prey ( Artemia nauplii) whilst in the gut cavity of the jellyfish. Underwater observations of giant jellyfish Nemopilema nomurai off Kyoto and Fukui prefectures revealed that approximately 30% of these jellyfish were accompanied by jack mackerel juveniles with body sizes ranging 10–45 mm standard length (SL). Considering that jack mackerel juveniles found in subtidal rocky reefs ranged 40–120 mm SL, we considered that jack mackerel from 10 to 45 mm SL associate with jellyfish as a hiding place as well as a food collector, until they find a suitable reef habitat when they attain approximately 40 mm SL.     

绿鳍马面鲀(Navodon septentrionalis)对4种大型水母的捕食行为

以绿鳍马面鲀为研究对象,通过室内受控实验,比较研究了其对我国沿海4种常见大型水母(海蜇、沙海蜇、海月水母和白色霞水母)的捕食差异。结果显示,体重为(215±20)g的绿鳍马面鲀对海月水母的捕食能力最强,日均最大摄食量为(150.7±18.6)g/fish,其次是海蜇和白色霞水母,日均摄食量分别为(129.7±11.6)和(120.0±19.3)g/fish,对沙海蜇的摄食量最少,为(92.5±11.3)g/fish;绿鳍马面鲀对海月水母与海蜇摄食量主要受投喂量影响,与规格无关,当投喂量小于其最大捕食量时,绿鳍马面鲀可捕食其周围所有水母,当投喂量超过其最大摄食量并继续增加时,绿鳍马面鲀摄食量保持不变,但残余水母的触手和伞部边缘均被啃食,继而导致水母摄食能力丧失,难以继续生存;在适口饵料冰鲜玉筋鱼充足的情况下,绿鳍马面鲀对水母具有明显的摄食偏向性,与仅投喂水母实验组相比,其对海月水母和海蜇的日均摄食量仅降低了20.2%和16.9%。研究结果表明,绿鳍马面鲀对上述4种水母皆能捕食。