Longer-term population dynamics of Gyrodactylus bullatarudis and G. turnbulli (Monogenea) on adult guppies (Poecilia reticulata) in 50-I experimental arenas.

Two suprapopulations of monogeneans, one each of Gyrodactylus bullatarudis and G. turnbulli, on two groups of ten experimentally infected adult guppies (Poecilia reticulata) were maintained separately in 50.1 aquaria and monitored over 210 days. The G. bullatarudis population had a pattern of initial growth, then a subsequent decline to extinction after 40 days. G. turnbulli, after initial population growth and decline, maintained low-intensity infections (0.33-3.3 parasites/host) on six hosts over 94 days and did not become extinct during the experiment. There were some differences between the host-site specificity of G. bullatarudis and G. turnbulli on adult P. reticulata as compared with previously observed infections on immature fish.