Many parasite community structures in fish have been demonstrated non-random but the results were not consistent at any time. Some environmental factors and host traits are likely to influence the parasite community structure. Here, we address this question using data on the intestinal helminthes community of the Chinese hooksnout carp Opsariichthys bidens from the Danjiangkou Reservoir, China, and focus on the impactions caused by host body length and season variation.During the time from February 2004 to November 2005 848 specimens of O. bidens were collected and examined. In total, 14 species of the intestinal helminths were found: 7 nematodes,4 digeneans,2 acanthocephalans and I cestode. The result showed that 87.49% of O. bidens were parasitized by at least one parasite species and the mean intensity was 8.71 +/- 11.557. The mean infracommunity diversity was Brillouin index = 0.238 +/- 0.287. The infracommunity diversity showed significantly positive correlation with host's total length ( Spearman rank correlation coeffection r, = 0.09 p < 0.05), but prevalence showed not apparent negatively correlation (Pearson correlation coefficient r = 0.390, p > 0.05). The nematodes Carnallanus cotti and Rhabdochona cascadilla, the cestode Bothriocephalus acheilognathi, and the acanthocephalan Micracanthorhynchina motomurai with higher prevalence and intensity were the core species of this community. The infection intensities of the core species were significantly correlated with the host's body length (r, = 0.238, -0.159, 0.150, -0.115;p < 0.05).Spearman rank correlation and chi-square tests indicated there were significantly positive or negative correlations between the core species. Both of the two methods supported that the intensities between C. cotti and R. cascadilla, R. cascadilla and M. motomurai showed significantly positive or negative correlations (p < 0.05). The parasite community structure of O. bidens were proved to be not random.Variation of the Spearman's rank correlation coefficients of the intestinal helminths in seven body length groups, which was arbitrarily divided as L < 8cm, 8cm <= L < 10cm, 10cm <= L < 12cm, 12cm <= L < 14cm, 14cm <= L < 16cm, 16cm <= L < 18 cm, L >= 18 cm respectively, showed that the changes of diet and body length of the host had significant impact. The parasite community in host with longer body length inclined to have significantly interspecific correlation. Also the parasite community in summer and autumn show the same tendency.
Xi Bing-Wen (firstname.lastname@example.org) ; Wang Gui-Tang (email@example.com) ; Wu Shan -Gong; Gao Dian; Zou Hong; Yao Wei-Jian; Nie Pin.COMMUNITY STRUCTURE OF THE INTESTINAL HELMINTHS OF THE CHINESE HOOKSNOUT CARP, OPSARIICHTHYS BIDENS(GUNTHER), FROM THE DANJANGKOU RESERVIOR,Acta Hydrobiologica Sinica,2009,33(2):177-182