Population Biology of the Cestode Caryophyllaeus laticeps (Pallas, 1781) in Dace, Leuciscus leuciscus L., of the River Avon

Abstract

The distribution and abundance of C. laticeps infecting a population of dance L. leuciscus was studied over a period of 1 year. The degree of infection was independent of the size of fish, but was generally higher in females and the negative binomial could be taken as a satisfactory model of the parasites'' distribution. It is suggested that this may be due to variations in fish feeding habits or to differences in resistance to infection between fish. Records of incidence, burden and degree of development show that the parasite exhibits seasonal cycles in both incidence and maturation, being present only from Dec. to June and becoming gravid after March. It is suggested that the incidence cycle is also related to differences in fish feeding habits or resistance. The maturation cycle does not, however, appear to be initiated by annual temperature changes, and it is postulated that the host hormone levels may play a significant role in the seasonal maturation of caryophyllaeids.