Patterns of emergence and survival of Conchophthirus acuminatus (Ciliophora: Conchophthiridae) from Dreissena polymorpha (Bivalvia: Dreissenidae)

This is the first study to quantify the periodic emergence of a Conchophthirus sp. from its bivalve host. Emergence rates of C. acuminatus from Dreissena polymorpha over the entire 24-day experiment appeared to be directly correlated with infection intensity. The rate of ciliate emergence from individual mussels varied considerably throughout the experiment at both 14°C and 21°C. It was not uncommon to have a sampling period in which no emergence was observed immediately followed by a period of high emergence, e.g., at 14°C from 0 to 25 ciliates and at 21°C from 0 to 720 ciliates. The total mean number of ciliates that were observed to have emerged from each mussel during the 24-day experiment was significantly higher at 21°C (207 ciliates/mussel) than at 14°C (29 ciliates/mussel). Our experiments suggested that C. acuminatus have a short survival period outside their host. Although we observed a maximum survival period of 144 hr (6 days), most ciliates died within 48 h.