Reproductive ecology of the coral Astrangia lajollaensis: Sexual and asexual patterns in a kelp forest habitat.

The temperate water coral, Astrangia lajollaensis broadcasts a large number of small eggs. It propagates asexually by budding and regeneration, and forms two-dimensional colonies on hard rocky substrate. Sexual recruitment was absent and asexual propagation was slow during this study. I conclude that budding at the borders of colonies is not slowed by the presence of adjacent space competitors nor is it enhanced by their absence. A model of colony growth is presented and ages of colonies at the study site are predicted. The ecological roles of sexual and asexual reproduction in the kelp forest habitat of A. lajollaensis are discussed. The occurrence of A. lajollaensis population at a study site in Pacific Grove, California extends the northern range for the species. The nearest conspecifics are 200-300 km to the south. Establishment of this northern population probably occurred by settlement of planktonic planulae but the long-term persistence of the population may be possible only by the strategy of asexual propagation and regeneration.