Reef coral reproduction in the eastern Pacific: Costa Rica, Panama and Galapagos Islands (Ecuador). IV. Agariciidae, recruitment and recovery of Pavona varians and Pavona sp.a

The reproductive ecology of two eastern Pacific zooxanthellate coral specie s was examined as part of a continuing series of studies relating bleaching /mortality events caused by the El Nino-Southern Oscillation disturbance, a nd is described for study sites in Costa Rica, Panama, and the Galapagos Is lands (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 sp ecies are broadcast-spawners with some gonochoric, but mostly sequential he rmaphroditic colonies. Minimum colony sizes (and ages) at first reproductio n were 5 cm (5 yr) and 3 cm (2 to 3 yr), respectively, in P. varians and Pa vona sp.a. In the Panama and Galapagos populations, gonochoric colonies spa wn eggs or sperm at least monthly. Six fecundity attributes were not signif icantly 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 an d neutrally to negatively buoyant. Eggs of both species lack zooxanthellae. Both species are reproductively active year-round, with maximum activity i n the dry season in the nonupwelling Gulf of Chiriqui, and in the wet seaso n in the upwelling Gulf of Panama. Spawning is predominantly during full mo on, and possibly also at new moon at most study sites. Spawning in P. varia ns and Pavona sp.a is 12 h out of phase, with the former species spawning s imilar to 1h before sunrise and the latter about 1h after sunset. The fecun dity of Pavona spp. at Cano and the Galapagos Islands was much greater (199 00 to 27900 eggs cm(-2) yr(-1)) than at all Panama sites (14800 to 19800 eg gs cm(-2) yr(-1)). Intraspecific crosses in both species resulted in swimmi ng planula larvae after 25 to 36 h. Recruitment of P. varians was highest i n Panama, moderate in Costa Rica, and nil in the Galapagos Islands, matchin g, respectively, the contributions of P. varians to the pre-1982/1983 El Ni no coral-population abundances in these areas. Recruitment success of P. va rians at Uva Island was significantly related to maximum monthly positive s ea surface-temperature (SST) anomalies that occurred in the year preceding recruitment over the period 1982 to 1996; recruitment failed when SST anoma lies exceeded 1.6 to 1.9 C degrees during the severe ENSO events of 1983/19 83 and 1997/1998.