ABSTRACT: Sexual reproduction of the coral Goniastrea aspera in subtropical Okinawa (Japan) was studied by dissection, histology, and laboratory observation of spawning. G. aspera is a simultaneous hermaphrodite, and in its annual cycle of gametogenesis, oocytes appear earlier than spermatozoa. Spawning of sperm and, momentarily thereafter, eggs, occurred at night 3 to 6 d after the full moons of June and July in 1993; 12% and 100% of the observed colonies spawned in June and July, respectively. Histological studies showed that 15% and 100% of the colonies had mature sperm 1 wk before the June and July spawning peaks, respectively. Brooded planulae were found in all colonies after the major spawning. These planulae were very likely the products of sexual reproduction, because eggs remained in the polyps after spawning and no sign of asexual reproduction was detected. The planulae settled soon after emerging from the parent polyps, which suggests that brooding is for short-distance dispersal.

KEY WORDS: Coral · Goniastrea aspera · Reproduction · Gametogenesis · Spawning · Planula brooding

Published in MEPS Vol. 151 (1997) on May 22
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997