EGG-SPERMATOZOID RECOGNITION DURING FERTILIZATION IN HORMOSIRA-BANKSII (PHAEOPHYCEAE)

In laboratory experiments with fresh field material, Hormosira banksii (Fucales, Phaeophyceae) exhibited a very efficient system of gamete f usion yielding a mean value of 93.6% zygotes. This required a saturati ng spermatozoid concentration of 50 spermatozoids per egg (half satura tion at 4 spermatozoids egg(-1)), and a 10 min mixture of the gametes. Half saturation was reached 1 min after mixing. Preincubation of eggs with 13 different lectins (0.1-1.0 mg ml(-1)) or 8 different monosacc harides (0.1-0.2 M) did not reduce fertilization success significantly . There may be a different system of gamete recognition without involv ing carbohydrates in Hormosira.