p> Fertilization may be internal or external. Reproduction may be seasonal or continue throughout the year. The release of planwas shown to have a marked lunar periodicity in Pocillopora bulbosa. Winter spawning of this species coincided with the full moon, while summer and autumn spawning coincided with the new moon. Agarica fragilis in the Bermudan Atlantic Ocean and Manicina areolata in the Tortugas Atlantic Ocean only released planulae in summer. The Hawaiian corals Pocillopora damicornis and Cyphastrea ocellina released planulae every month of the year.
Corals with large polyps tend to have many eggs per polyp. Favia doreyensis of Low Isles had a minimum of 93 eggs. Porites haddoni varied from 6 to 250 planulae per colony. Pocillopora bulbosa had from 1 to 100 planulae per colony based upon collection of a group of branches. Thus, a moderate size colony may produce a few thousand planulae (eggs) per breeding season.
Newly released planulae may swim upward and towards the light. Some planulae swim away from weak light and towards strong light. Within the first two days behavior changes so that the planulae swim toward the bottom where attachment occurs. A few species swim from 3 weeks to 2 months. The amount of time swimming and moving with the plankton is a factor affecting distribution patterns.
The corals that are pioneers in colonization of newly vacated surfaces are Pocillopora bulbosa, Porites, and Cyphastrea. The rates of recruitment and mortality vary, but the commoner species at Low Isle had high rates of both recruitment and mortality that enabled a maintenance of abundance.
Corals grow fastest with maximum light--calcification rates were found to be doubled on sunny days when compared to cloudy days. Heavy shade can be lethal to corals. Deep water species appear adapted to low light. Corals may compete for space in the light; indirect interference of Acropora by shading out Montipora has be...