三种重金属离子对东方小藤壶幼虫的急性毒性效应

研究了3种不同浓度重金属离子对东方小藤壶(Chthamalus challengeri)二期幼虫的急性毒性效应。结果表明:铜、锌、镉离子均有较高的毒性,它们对二期幼虫的12 h半致死剂量分别为1.00mg/L、2.29mg/L和0.56mg/L,24h半致死剂量分别是0.71mg/L、1.71mg/L和0.14mg/L,毒性大小依次排为Cd~(2+)>Cu~(2+)>Zn~(2+)。     

东方小藤壶Chthamalus challengeri（甲壳动物亚门：无柄目）线粒体基因组：小藤壶科基因排列比较及藤壶亚目系统发育分析

藤壶是潮间带生态、幼体发育以及生物防污损研究中重要的模式生物。目前,线粒体基因组学的发展有助于从线粒体基因组水平上更好地理解系统发育关系。本研究获得东方小藤壶Chthamalus challengeri完整线粒体基因组,大小为15358bp的环状分子。与藤壶亚目其它物种相比,东方小藤壶非编码区的长度较长,而基因区的长度则相近。东方小藤壶线粒体基因组A+T含量为70.5%。现有藤壶物种的线粒体基因组中存在起始和终止密码子的变化。同属的东方小藤壶和触肢小藤壶C. antennus具有共同的基因排列。然而,小藤壶科中不同属之间却具有不同的基因排列,包括两个tRNA基因出现易位,一个基因块出现倒置。值得注意的是,与以往藤壶亚目物种不同,小藤壶属两个物种的srRNA和lrRNA基因都在重链上编码。小藤壶科中进化树的拓扑结构与基因排列证据相互支持,系统发育分析表明小藤壶科是单系群,而藤壶科和古藤壶科则是多系群。     

Spatial diversity of rocky midlittoral macro-invertebrates associated with the endangered species Patella ferruginea (Mollusca: Gastropoda) of Tunisian coastline

The present study focuses on horizontal spatial variability of benthic macrofauna associated with Patella ferruginea. Thirty-six samples collected at 12 transects belonging to 4 midlittoral sites along the rocky Tunisian coastline, were examined. A total of 44 species belonging to 5 taxa were found. Multivariate analysis applied on gathered data did not show a horizontal spatial variability at small scale (between transects), but at large scale, between sites as well as sectors. Thus, three groups of communities were identified (GI: Korbous and El Haouaria; GIIa: Zembra Island and GIIb: Kelibia). The distribution of species abundance within these groups revealed that crustaceans were the most abundant taxon, due to the overwhelming dominance of Chthamalus stellatus. This substratum appeared to create favourable micro-habitats for the installation of molluscs including gastropods. Regarding the low diversity index (H') and evenness (J), they seemed to reflect a disturbance and a demographic unbalance within these communities. The heterogeneity of substrate surface, created by C. stellatus specimens appeared to be caused by various complex interactions established between the key components of these communities in particular suspension feeders, predators, herbivorous molluscs and macroalgae. Thus, the dynamic status of each of these communities is the result of these complex interactions.