Factors affecting fertilization success in two species of patellid limpet (Mollusca: Gastropoda) and development of fertilization kinetics models

Laboratory experiments were undertaken to examine fertilization success in the intertidal prosobranch limpets Patella ulyssiponensis and Patella vulgata. Alkalization of eggs (10 min in pH 9.0 sea water) prior to fertilization trials improved fertilization rates greatly. Fertilization success was found to be a function of sperm concentration, gamete age and contact time. Sperm concentration needed for optimum fertilization success in vivo ranged between 105 and 107 sperm ml-1 for both species although at higher concentrations the number of normally developing trochophore larvae decreased. For P. vulgata, sperm longevity (at a concentration of 10 6 sperm ml-1) did not exceed 6 h, whereas eggs of both species were fertilizable for up to 12 h. Maximum fertilization success occurred after 15-30 min gamete contact time. The Vogel et al. (Math Biosci 58:189-216, 1982) fertilization kinetics model is developed to allow for non-complete fertilizations under optimal sperm concentrations, and a new parameter fitting technique is developed to improve estimates of fertilization success for short gamete contact times. © 2006 Springer-Verlag.