Frequency Distribution and Seasonal Dynamics of Intestinal Helminths in the Yellowhead Catfish Pelteobagrus fulvidraco from Liangzi Lake, China

摘要

The frequency distribution and seasonal changes of intestinal helminths in Pelteobagrus fulvidraco were investigated from February 2001 to July 2002 in Liangzi Lake in the floodplain of the Yangtze River, central China. Four parasite species were found: the cestode Gangesia pseudobagri and the digeneans Orientocreadium siluri, Coitocoecum plagiorchis, and Echinoparyphium lingulatum. There was a significant difference in the mean abundance of O. siluri between male (8.12 +- 16.99) and female hosts (3.19 +- 5.42). Parasite distribution patterns were all overdispersed (s~2/X > 1) and followed the negative binomial distribution. In the analysis of changes in mean parasite abundance and variance to mean ratio with host age, convex curves were observed for G. pseudobagri and O. siluri. This suggests that these 2 helminths may have had deleterious effects on the hosts. Significant seasonal changes were detected in the prevalence and mean abundance of the 4 helminths other than for the prevalence of O. siluri. The mean abundance of O. siluri, C. plagiorchis, and G. pseudobagri reached a peak in the spring, and E. lingulatum had the highest infection levels in the spring and early summer.