Size distribution of individuals in the population of Asterias amurensis (Echinodermata: Asteroidea) and its reproductive cycle in China

To obtain baseline information on the size distribution of individuals in the population and reproductive features of sea star Asterias amurensis, monthly surveys of the population were carried out from May to December 2010 and March to May 2015 in coastal waters off Yantai, China. Spawning period was predicted by gonad and pyloric caeca indices as well as anatomical and histological methods. In the A. amurensis population, both large individuals (> 143 mm) and small ones (< 42 mm) were present in all sampling months. The population size structure was driven by the appearance of big cohorts of individuals less than 55 mm from May to August. The appearance of small individuals in all months suggested a prolonged spawning period at other sites in this bay or sea stars growing slowly because of food shortage. An arm length is a good predictor to wet body weight for A. amurensis. The development of gonad was relative slow from May to September but rapidly reached a peak of 20.95 in October 2010, and then dropped remarkably, indicating its spawning lasted from October to November. The same phenomenon was found from March to May 2015, suggesting another spawning during March to May, which was also verified by the results of histologic analysis on ovary. The gonad index (GI) and pyloric caeca index (PCI) tended to show a negative relationship. Due to the poor food availability, the reproductive characteristics of sea star were most likely affected by the shellfish mariculturein Yantai coastal waters

烟台近海大型底栖动物群落特征

根据2010年和2011年对烟台近海大型底栖动物的周年调查资料,采用优势度指数、物种多样性指数及Cluster聚类和MDS排序方法,进行群落特征和群落演替情况的。研究。结果表明,该海域共采集大型底栖动物176种,其中优势类群为多毛类。群落中的优势种主要包括短叶索沙蚕和不倒翁虫。烟台近海年平均生物量和丰度分别为16.72g/m~2和1022ind/m~2,且存在季节性差异。丰富度指数(D)、均匀度指数(J)和多样性指数(H')的年平均值分别为2.30、0.70和1.91。烟台近海大型底栖动物群落与底质和水深关系密切。群落特征发生了一定程度的变化,软体动物比例减少,多毛类比例增加。人类活动包括污水排放、养殖和捕捞、港口建设和船舶航运等干扰是导致上述变化的主要原因

一种四倍体鲤科鱼Sox基因的克隆和序列分析

为了研究重要功能基因在多倍体基因组中的演化情况,通过分子克隆的方法从四倍体大鳞结鱼(Tordouronensis)中获得13条Sox基因序列,分别为SoxB,SoxC和SoxE组成员.对大鳞结鱼Sox基因系统进化分析的结果支持鱼类特异的基因组重复的假说,同时表明,基因Sox19可能为真骨鱼特有的Sox基因家族成员.序列分析显示,与其他物种相比大鳞结鱼中Sox基因的碱基替代,绝大多数为同义替代.结果表明,所得到的Sox基因序列均受到净化选择,同时由多倍化所造成的重复基因对Sox4a,Sox9a和Sox9b

甘孜地热发电热力计算及优化

A geothermal well in Ganzi was chosen for the study. To provide a reference for the design and construc?tion of a geothermal plant, power generation techniques were selected and the thermodynamic process was calculat?ed based on cold and heat source dat

Long-Term Trends of Macrobenthos in Southern Bohai Sea, China, in Relation toEnvironmental Changes

根据50多年来渤海南部海域大型底栖动物群落的历史资料,以及2011~2013年的现场调查数据,从渤海南部包括黄河口邻近海域及莱州湾大型底栖动物群落结构变化特征出发,分析了其长期演变的过程和规律,旨在阐明底栖动物群落的演变趋势,识别其重要的演变时段.并结合50年来渤海南部海域相关底栖环境因子的变化特征,探讨底栖动物群落的演变原因.过去50余年来,渤海南部海域大型底栖动物群落在物种数、生物量、丰度以及群落结构组成等方面都发生了较大的变动,具体表现为寿命长、体积大、具有高竞争力的K对策种的优势地位正逐渐丧失,而被寿命短、适应能力宽、具有高繁殖能力的R对策种所取代.按照50余年来渤海南部海域大型底栖动..

Characteristics of macrobenthic communities in the estuary of Dagujia River and its adjacent water areas in Yantai, Shandong

为了解烟台大沽夹河河口及邻近海域大型底栖动物群落特征及受干扰情况,于2012年9月在上述区域设置12个采样点进行大型底栖动物群落调查和分析。对采集的生物样品进行物种鉴定、计数和称重,利用生物统计软件PRIMER计算优势度指数(Y)、Shannon-Wiener多样性指数(H')、Margalef丰富度指数(D)和Pielou均匀度指数(J),并进行等级聚类(CLUSTER)、非度量多维标度排序(non-metric multi-dimensional scaling,MDS)及丰度/生物量曲线(abundance and biomass curves,ABC)分析。共采集和鉴定大型底栖动物89..

贝叶斯联合模型与中国洞穴鱼类分化时间的估算(鲤科:金线鲃属)

金线鲃属分布于中国云贵高原及周边地区,包括10多种适应于洞穴生活、具有不同程度眼睛和色素退化的典型洞穴鱼类.迄今为止,金线鲃属的系统发育关系还存在很大争议.我们获得了34种金线鲃属鱼类及外类群的细胞色素b和ND4基因序列,用贝叶斯联合模型分析数据,重建了金线鲃属的系统发育关系;并用松散分子钟估算了本属及内部分支的起源时间.金线鲃属的单系性得到强烈的支持,本属可分为6个分支.此外,本研究结果还支持洞穴物种的多系起源假说以及季氏金线鲃(Sinocyclocheilus jii)的基部位置.松散分子钟估算表明