5科11种鱼类ITS1特征分析及其在系统分类研究中的适用性

为了探讨ITS1作为分子标记用于鱼类系统演化的适用性,实验选取鲈形目5科11种鱼类为研究对象,包括尖吻鲈科、射水鱼科、军曹鱼科、剑鱼科和鲹科。通过克隆和测序等技术共获得了348条ITS1序列,长度范围为442~661 bp;通过对所有序列的长度、变异位点数量、GC含量、核苷酸多样性及单倍型多样性指数等遗传特征比较分析发现,11种鱼类ITS1序列无论是在种内还是在种间,长度和序列都表现出较为明显的多态性。特别是在军曹鱼中,70条克隆的长度范围为648~661 bp,但有一条序列存在55 bp缺失,结合该序列的GC含量,二级结构和最小自由能,推断该序列为假基因。以鮣为外类群,基于核糖体ITS1序列构建的邻接树显示在物种种类水平上,不同个体的克隆都按种类聚支,ITS1可以用于该类群物种的区分;在属级水平上,ITS1将11属鱼类完全区分开,能够用于属级水平的区分;在科级水平上,虽然鲹科分为2支的分子结果和形态分类存在差异,但ITS1构建的系统关系与线粒体分子标记构建的系统进化树相似。研究表明,核糖体ITS1可以作为一种有效的分子标记用于研究鱼类的系统分类研究,并且不同的分类阶元其解析能力不同,这将为鱼类核糖体的研究提供科学依据。     

Influence of oceanographic conditions on abundance and distribution of post‐larval and juvenile carangid fishes in the northern Gulf of Mexico

Relationships between abundance of post‐larval and juvenile carangid (jacks) fishes and physical oceanographic conditions were examined in the northern Gulf of Mexico (GoM) in 2011 with high freshwater input from the Mississippi River. Generalized additive models (GAMs) were used to explore complex relationships between carangid abundance and physical oceanographic data of sea surface temperature (SST), sea surface height anomaly (SSHA) and salinity. The five most abundant carangid species collected were: Selene setapinnis (34%); Caranx crysos (30%); Caranx hippos (10%); Chloroscombrus chrysurus (9%) and Trachurus lathami (8%). Post‐larval carangids (median standard length [SL] = 10 mm) were less abundant during the spring and early summer, but more abundant during the late summer and fall, suggesting summer to fall spawning for most species. Juvenile carangid (median SL = 23 mm) abundance also increased between the mid‐summer and early fall. Most species showed increased abundance at lower salinities and higher temperatures, suggesting entrainment of post‐larval fishes or feeding aggregations of juveniles at frontal convergence zones between the expansive river plume and dynamic mesoscale eddy water masses. However, responses were species‐ and life‐stage specific, which may indicate fine‐scale habitat partitioning between species. Ordination methods also revealed higher carangid abundances at lower salinities for both post‐larval and juvenile life stages, with species‐ and life‐stage specific responses to SST and SSHA, further suggesting habitat separation between species. Results indicate strong links between physical oceanographic features and carangid distributions in the dynamic northern GoM.     

Temperature and dissolved oxygen influence growth and digestive enzyme activities of yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

A 5 week experiment was carried out with juvenile yellowtail kingfish Seriola lalandi to investigate the interactive effects of water temperature (21, 24, or 27°C) and dissolved oxygen regime (normoxic vs. hypoxic) on the growth rate, feed intake and digestive enzyme activity of this species. Specific growth rate (SGR) was highest at 24°C, regardless of oxygen regime, but the SGRs of the fish exposed to hypoxia at 21, 24 and 27°C were 13%, 20% and 17% lower, respectively, than the SGRs recorded for the fish reared under normoxic conditions. The digestive enzyme activities (i.e. trypsin, lipase and α‐amylase) were influenced by temperature but did not appear to be affected by dissolved oxygen concentration. Information about the effects of water temperature and dissolved oxygen on feeding, growth and digestive capacity of juvenile yellowtail kingfish could contribute to improving feed management decisions for production of this fish species under different environmental conditions.     

Diversity and distribution of early life stages of carangid fishes in the northwestern Mediterranean: responses to environmental drivers

The diversity and distribution of the early stages of carangid fishes were investigated in relation to environmental conditions off the Catalan Coast (NW Mediterranean). Data were obtained during four oceanographic cruises conducted in spring–summer 2003 and 2004. A total of 4743 larvae from seven species and five genera were identified. Most were thermophilic species very abundant in the warm waters of the south and eastern Mediterranean. The presence of larvae and juveniles of Caranx crysos, Caranx rhonchus, Seriola dumerili and Trachinotus ovatus in the northwestern Mediterranean is reported for the first time. Except for Trachurus trachurus, which spawns in winter–spring, all species reproduce in spring–summer with a temporal succession in their spawning peaks. On average, the spatial patterns of different species (except T. trachurus) showed common features: a clear preference for spawning in coastal areas, high abundance of larvae in the south warmer zone in relation to the surface productive waters of Ebro river runoff and relatively high larval concentrations south of the thermal front and its associated anticyclonic eddy. The presence of larvae of thermophilic species of carangids in the northwestern Mediterranean indicates successful reproduction and establishment of these species in the cold part of the basin.     

基于16S rRNA部分序列探讨12种鲹科鱼类的分子系统进化关系

鲹科鱼类在传统形态分类与分子遗传水平构建的系统分类存在争议，本文通过PCR扩增获得了鲹科（Carangidae）8属9种的线粒体16S rRNA基因片段序列约598bp碱基，结合来自GenBank的3种鲹科鱼类的相应片段序列，并以大斑石鲈Pomadasys maculates为外群，生成供系统发育分析的序列矩阵，利用MEGA version 3.0软件分析序列的碱基组成、差异百分比和转换/颠换值等，应用最大简约法和邻接法构建系统树。结果显示：（1）支持鲹科下设四个亚科（鲹亚科，鰤亚科，鲳鲹亚科，鰆鲹亚科）阶元的分类系统；（2）所测种类鲹亚科鲹属下不宜设亚属分类阶元；（3）及达副叶鲹与丽叶鲹亲缘关系近，16S rRNA基因片段序列碱基只有1.07%的差异，未达到分属水平，应同属于副叶鲹属的两个不同种，并建议丽叶鲹的中文名用“丽副叶鲹”。     

南海北部陆架区海域鯵科鱼类的分布

1997年12月至1999年6月对南海北部陆架区海域进行了底拖网渔业资源调查。调查分春(4-6月)、夏(7-9月)、秋(10-12月)、冬(12-2月)4个季节,每个季节都进行全海域的大面积定点调查,共采获科鱼类31种,分隶属于11属。通过对渔获种类组成和渔获率在不同区域、不同季节、不同水深以及昼夜变化等的分析,结果表明,北部湾海区的渔获率最高,粤东海区最低,并由西往东呈逐渐递减的趋势;夏、冬季科鱼类的渔获率较高,而春、秋季较低;渔获率沿水深梯度的变化为≤100m水深海域沿水深的增加而增加,>100m水深海域随水深的增加而下降,以80～100m海域的渔获率相对较高;午夜的渔获率最低,14时最高。     

中国南海东沙群岛海域7种鲹科鱼类矢耳石形态特征

对采自中国南海东沙群岛海域的135尾鲹科鱼类(长体圆鲹Decapterus macrosoma、泰勃圆鲹D.tabl、无斑圆鲹D.kurroides、竹?鱼Trachurus japonicus、短吻丝鲹Alectis ciliaris、高体若鲹Caranx equula、脂眼凹肩鲹Selar crumenophthalmus)的矢耳石形态特征进行研究。7种鲹科鱼类矢耳石整体形态呈长椭圆形、四边形、半圆弯钩形等多种形态,耳石周围存在脊突,均有基叶和听沟发育,听沟从耳石前部的主间沟部分一直延伸至耳石后部。研究结果表明,7种鲹科鱼类耳石形态特征种间差异明显,通过耳石形态建立的系统分类检索,以及应用聚类分析识别耳石形态效果显著。这将为鲹科鱼类鱼种识别及系统分类提供参考资料。     

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.     

南海北部陆架区海域科鱼类的分布

1997年12月至1999年6月对南海北部陆架区海域进行了底拖网渔业资源调查。调查分春(4-6月)、夏(7-9月)、秋(10-12月)、冬(12-2月)4个季节,每个季节都进行全海域的大面积定点调查,共采获科鱼类31种,分隶属于11属。通过对渔获种类组成和渔获率在不同区域、不同季节、不同水深以及昼夜变化等的分析,结果表明,北部湾海区的渔获率最高,粤东海区最低,并由西往东呈逐渐递减的趋势;夏、冬季科鱼类的渔获率较高,而春、秋季较低;渔获率沿水深梯度的变化为≤100m水深海域沿水深的增加而增加,>100m水深海域随水深的增加而下降,以80～100m海域的渔获率相对较高;午夜的渔获率最低,14时最高。