McKeown C A, Irwin S W
School of Applied Biological and Chemical Sciences, University of Ulster, Co Antrim, UK.
Int J Parasitol. 1997 Apr;27(4):377-80. doi: 10.1016/s0020-7519(96)00204-4.
Unlike other long-term studies of Diplostomum spp. metacercariae in fish eyes, this study investigated accumulation of the parasites in the eyes of very young roach for 3 consecutive years. Fish were caught by electro-fishing in the summers of 1990, 1991 and 1992 and the numbers of parasites located in the hosts eyes were recorded. Two distinct peaks of parasite abundance were observed, 1 in late June and the other in mid-September each year. Significantly, parasite abundance decreased after each of the peaks. Results obtained in a parallel investigation of the accumulation of the same parasites in rainbow trout in an adjacent fish farm showed the same 2 periods of accumulation each year. However, in the fish farm, no decrease in parasite abundance was observed at any time. The decreases in parasite abundance in the wild population can be attributed to mortality of the most heavily parasitized fish. As this did not occur in the farmed fish, in which similar levels of parasitism existed, it is likely that mortality in the wild population was an indirect result of the parasites.
与其他关于双穴吸虫属尾蚴在鱼眼中的长期研究不同，本研究连续3年调查了极幼龄拟鲤眼中寄生虫的积累情况。1990年、1991年和1992年夏季通过电捕鱼捕获鱼类，并记录宿主体内眼部寄生虫的数量。观察到寄生虫丰度有两个明显的峰值，每年一个在6月下旬，另一个在9月中旬。值得注意的是，每次峰值后寄生虫丰度都会下降。在相邻养鱼场对虹鳟中相同寄生虫积累情况进行的平行调查中获得的结果显示，每年也有相同的两个积累期。然而，在养鱼场中，未观察到寄生虫丰度在任何时候下降。野生种群中寄生虫丰度的下降可归因于寄生虫感染最严重的鱼类的死亡。由于在存在类似寄生虫感染水平的养殖鱼类中未发生这种情况，野生种群中的死亡很可能是寄生虫的间接结果。
