Life cycles, reproduction, and diets of Dina dubia and Erpobdella punctata (Hirudinea: Eropobdellidae) in Canagagigue Creek, Ontario

Abstract

The life cycles of Dina dubia and Erpobdella punctata were described from semimonthly (monthly in winter) collections made at two sites on Canagagigue Creek between May 1982 and July 1983. Observations on reproduction were made in the creek and in a flow-through stream tank. Most individuals of both species completed their life cycles in about 1 year, but some required 2 or more years to reach sexual maturity. The estimated average fecundity (138–173 young/adult), growth rate, and maximum size (1946 mg live weight) of E. punctata were all greater than for D. dubia (47–50 young/adult; maximum size, 725 mg), but D. dubia was much more abundant in Canagagigue Creek. Both species fed most frequently on Chironomidae and Oligochaeta, with the total variety of prey consumed reflecting the diversity of prey available at the site. The habitat preferences of the leeches were apparent from their diets: D. dubia ate relatively more animals associated with riffle habitats; E. punctata ate relatively more pool-dwelling organisms. The greater abundance of D. dubia at our study sites is attributed to this difference in habitat preference.