中文摘要：

通过2009年4月至2010年1月在额尔齐斯河（中国段）野外取样调查，研究寄生于东方欧鳊（Abramis bra-ma orientalis）鳃部的奇异双身虫（Diplozoon paradoxum）的种群生态学特点。结果表明，东方欧鳊感染奇异双身虫的总感染率为24．16％，平均感染强度为4．19，在宿主体长L≤30 cm时，感染率随体长增大有升高的趋势；在体长25 cm＜L≤30 cm时，感染率达到最大，为42．11％；而体长L＞30 cm的宿主，没有感染奇异双身虫。奇异双身虫在东方欧鳊各体长段均呈聚集分布。

英文摘要：

In this study, we investigated the population dynamics of Diplozoon paradoxum Nordmann in gills of Abramis brama orientalis Berg by means of field sampling investigation from April, 2009 to January, 2010. The results showed that the prevalence of D. paradoxum was 24.16% and mean infection intensity was 4.19. Among the three size groups of Abramis brama orientalis Berg, the host length was the key determinant of the prevalence of D. paradoxum in Abramis brama orientalis Berg ： the prevalence increased with the body length in groups of L ≤ 30 cm; the highest prevalence （42.11% ） of D. paradoxum was in groups of 25 cm 〈 L ≤30 cm ; while no infection was found among groups of L 〉 30 cm. Our study suggested that D. paradoxum exhibited an aggregation distribution in host of different body lengths.