鲢和草鱼鳃部寄生单殖吸虫的种群分布和季节动态

作者在 1995— 1996年期间 ,对同一口池塘中的鲢和草鱼寄生鲢指环虫 (Dactylogyrushypophthalmichthys)和鳃片指环虫 (D .lamellatus)进行了种群分布和季节动态研究。两种单殖吸虫种群丰盛度的季节变化与其感染率的变化基本相似 :鲢指环虫 2— 3月种群的丰盛度逐渐增加 ,4月达到高峰 ,随后逐渐下降 ,在秋冬季维持在一个较低的水平上 ;鳃片指环虫在 11至来年 3月种群的丰盛度逐渐上升 ,4月达到高峰 ,随后迅速下降 ,在夏秋季维持在一个较低的水平。

POPULATION DISTRIBUTION AND SEASONAL ALTERNATION OF TWO SPECIES OF MONOGENEANS ON THE GILLS OF HYPOPHTHALMICHTHYS MOLITRIX AND CTENOPHARYNGODON IDELLUS

The population distribution and seasonal alternation of Dactylogyrus hypophthalmichthys on gills of silver carp Hypophthalmichthys molitrix, and D.lamellatus on grass carp Ctemopharyngodon idellus were studied.Two species of fish were collected in a fish pond in the Institute of Hydrobiology,Chinese Academy of Sciences in Wuhan,China from December 1995 to November 1996.The population dynamics of abundance and prevalence were similar for the two species of monogeneans.The prevalence was higher than 70% for D.hypophthalmichthys and higher than 60% for D.lamellatus, and no significant difference(G=?, P <0.05)was found between months for the two species of monogeneans.The abundance of D.hypophthalmichthys increased gradually from February to March,and reached the highest level in April,then declined gradually and remained at a low level in autumn and winter;while D.lamellatus increased from November to March,and reached the highest value in April,then decreased rapidly and maintained a low level in summer and autumn.Statistical analysis indicated that changes in abundance of D.hypophthalmichthys and D.lamellatus were both significantly seasonal (F=?, P <0.05).The pattern of distribution of D.hypophthalmichthys was over-dispersed,as the variance to mean ratio was more than 1 and the degree of aggregation was high in spring and autumn.The pattern of D.lamellatus was also over-dispersed,with its the degree of aggregation being high in spring and winter.