The reproductive ecology of two eastern Pacific zooxanthellate coral species was examined as part of a continuing series of studies relating bleaching/mortality events caused by the El Nino-Southern Oscillation disturbance, and is described for study sites in Costa Rica, Panama and the Galapagos Islands (Ecuador). This study deals with the sibling agariciid species Pavona varians and Pavona sp.a over a 13 yr period (1985 to 1997). Both Pavona species are broadcast-spawners with some gonochoric, but mostly sequential hermaphroditic colonies. Minimum colony sizes (and ages) at first reproduction were 5 cm (5 yr) and 3 cm (2 to 3 yr), respectively, in P. varians and Pavona sp.a. In the Panama and Galapagos populations, gonochoric colonies spawn eggs or sperm at least monthly. Six fecundity attributes were not significantly different in the two species, but the eggs of P. varians are white to beige and positively buoyant, and those of Pavona sp.a are dark green and neutrally to negatively buoyant. Eggs of both species lack zooxanthellae. Both species are reproductively active year-round, with maximum activity in the dry season in the nonupwelling Gulf of Chiriqui, and in the wet season in the upwelling Gulf of Panama. Spawning is predominantly during full moon, and possibly also at new moon at most study sites. Spawning in P. varians and Pavona sp.a is 12 h out of phase, with the former species spawning ~1 h before sunrise and the latter about 1 h after sunset. The fecundity of Pavona spp. at Cano and the Galapagos Islands was much greater (19900 to 27900 eggs cm-2 yr-1) than at all Panama sites (14800 to 19800 eggs cm-2 yr-1). Intraspecific crosses in both species resulted in swimming planula larvae after 25 to 36 h. Recruitment of P. varians was highest in Panama moderate in Costa Rica, and nil in the Galapagos Islands, matching, respectively, the contributions of P. varians to the pre-1982/1983 El Nino coral-population abundances in these areas. Recruitment success of P. varians at Uva Island was significantly related to maximum monthly positive sea surface-temperature (SST) anomalies that occurred in the year preceding recruitment over the period 1982 to 1996; recruitment failed when SST anomalies exceeded 1.6 to 1.9 C°during the severe ENSO events of 1982/1983 and 1997/1998.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science