3种浮游生物网对强壮箭虫捕获效率的比较研究

为了比较大型浮游生物网(网孔505μm)、WP-2型浮游生物网(网孔200μm)和小型浮游生物网(网孔77μm)对强壮箭虫(Sagitta crassa)的捕获效率,利用2012年11月在渤海中部采集的浮游动物样品进行了分析。结果显示:小网的捕获效率最高,分别为大网的2.9倍、WP-2网的1.3倍;大网对体长9mm以下个体有明显漏采,WP-2网对体长4mm以下和部分4~5mm个体有明显漏采,小网对体长9mm以上个体的捕获效率略低于大网和WP-2网。不同网具的捕获效率与箭虫个体大小密切相关,个体越小,网具间捕获效率的差异越明显,随着体长增大,差异缩小。建议今后在强壮箭虫的繁殖季节采集小网样品,作为其他网具样品的必要补充,为毛颚动物的种群动力学研究提供更全面、准确的基础数据。

A comparison study of the capture efficiency for Sagitta crassa of three types of plankton nets

To compare the capture efficiency for Sagitta crassa(chaetognatha) of three types of plankton nets (505 μm meshed coarse net,200 μm meshed WP-2 net and 77 μm meshed fine net),zooplankton samples were collected in central Bohai Sea in November,2012. The fine net outperformed the other two nets,respectively capturing 1.3 and 2.9 times the abundance of the WP-2 net and the coarse net. The coarse net apparently under-sampled less than 9mm long individuals; the WP-2 net under-sampled less than 4 mm long and a fraction of 4-5 mm long individuals; while the fine net appeared to be slightly less efficient when capturing more than 9 mm long individuals. The capture efficiency was closely correlated to the body size of S. crassa: smaller body size caused greater differences in capture efficiency of the nets. As for more than 9mm long individuals,avoidance of S. crassa probably accounted for the slightly lower capture efficiency of the fine net. We recommend that the fine net be employed for sampling S. crassa during reproduction periods to provide supplementary results to other types of nets,thus more reliable data could be obtained for future research of population dynamics.