天津海域自由生活线虫分类学多样性

The Taxonomic Diversity of Free-living Nematodes in Tianjin Offshore

在我国海域进行了很多自由生活线虫的研究,但是线虫分类学多样性的报道极少。2007年春季在天津海域的15个站位进行了底栖生物调查,对自由生活线虫样品进行了分类学多样性的分析。共鉴定出自由生活线虫87种,隶属于2纲2亚纲5目7亚目14科39属。以色矛纲（Chromadorea）线虫居多,有74种,占总种数的85%。线虫平均分类学差异性指数（Δ^＋）的理论平均值为60.5,分类学差异性变异（Λ^＋）的理论平均值约为420。平均分类学差异性指数值随站位而变,变化幅度为49.8～63.0;各站位分类学差异性变异的波动范围较大,从233到514不等。这些结果表明,线虫在一些站位的分类学信息有较大的不同。漏斗图显示,西南部近岸海域的线虫群落组成的分类学多样性较差,预示着环境受到干扰。线虫在西南部近岸4个站位的分类学差异性受到了化学因素的影响,多个化学指标具有较高值;同时也与沉积物的粒径和叶绿素含量有一定关系。与一些传统多样性指数比较,分类学差异性指数在反应环境差异方面有较好的灵敏性。

Many studies on free-living marine nematodes were carried out in Chinese seas, but the taxonomic diversity of nematodes was seldom reported. A benthic survey with fifteen stations was conducted in Tianjin offshore（Fig. 1） in spring 2007, and the taxonomic distinctness of nematodes was analyzed based on the nematode samples. A total of 87 nematode species belonging to 2 classes, 2 subclasses, 5 orders, 7 suborders, 14 families and 39 genera were identified in this cruise, excluding the juvenile and incomplete individuals. The majority of nematodes belonged to Chromadorea, which included 74 species and accounted for about 85% of all nematode species. Two taxonomic indices, the average taxonomic distinctness index（Δ^＋） and the variation in taxonomic distinctness（Λ^＋） of nematode assemblage, were calculated with PRIMER software. The results of Δ^＋ and Λ^＋ in each station were listed in Table 1. The theoretical average value of Δ^＋ and Λ^＋ were 60.5 and ca. 420, respectively. The values of Δ^＋ varied with station, which ranged from 49.8 to 63.0; the fluctuation of Λ^＋ was huge, from 233 to 514. The two indices indicated that the nematode assemblages had big changes along with the station. The funnel plots, Fig. 2 and 3, showed that the taxonomic distinctness of nematode assemblages was lower in the coastal southwest area, indicating that the environment was disturbed. The taxonomic distinctness of nematodes in these four stations was affected by some chemical factors, and was related to the particle size and chlorophyll a content of sediment, too. Compared with four traditional diversity indices, the average taxonomic distinctness index was more sensitive to environmental difference. The results indicated that Δ^＋ and Λ^＋ were good indices to reflect the variations of nematode assemblage and environment.