REEF CORAL REPRODUCTION IN THE EASTERN PACIFIC - COSTA-RICA, PANAMA, AND GALAPAGOS-ISLANDS (ECUADOR) .3. AGARICIIDAE (PAVONA-GIGANTEA AND GARDINEROSERIS-PLANULATA)

The reproductive ecology of Pavona gigantea Verrill and Gardineroseris planulata (Dana) was investigated in the equatorial eastern Pacific r egion from 1985 to 1994. These zooxanthellate scleractinian corals wer e adversely affected in this region during the 1982-1983 El Nino warmi ng event. Both species were hermaphroditic, with individual colonies s howing sequential cosexual development, thus resulting in dominantly o utbreeding reproduction. Sexuality was mixed, with high percentages of gonochoric and hermaphroditic colonies in both species. Approximately 1:1 male-to-female gonad ratios were found in gonochoric and hermaphr oditic colonies combined. Broadcast spawning was observed in P. gigant ea in the Galapagos Islands, and the sudden disappearance of mature ga metes and the presence of spent gonads suggest that G. planulata is al so a broadcast spawner. Colonies of both species with less than or sim ilar to 200 cm(2) (10 cm diam) live tissue were nonreproductive. Estim ated ages of the youngest reproductive colonies were 11 yr for P. giga ntea and 20 yr for G. planulata. The percentage of all colonies of P. gigantea with gonads at nonupwelling sites (Cano Island, Costa Rica an d Uva Island, Panama) ranged from 37 to 47%, respectively; colonies wi th gonads from upwelling environments (Saboga and Taboga Islands, Pana ma) ranged from 31 to 39%, respectively, and reproductively active col onies from the thermally variable Galapagos Islands comprised 40% of t he collections. Compared with P. gigantea, the numbers of sexually act ive G. planulata colonies were roughly one-half at nonupwelling Cano I sland (20%) and Uva Island (25%) sites, or less (10%) at the upwelling Saboga Island site. Peak reproductive activity in P. gigantea occurre d during the rainy season at all study sites. In the nonupwelling Cost a Rican (Cano Island) and Panamanian (Uva Island) sites, mean monthly sea-surface temperatures (SSTs) were high (28 to 29 degrees C), but sl ightly lower than in the dry season (29 degrees C). In the upwelling G ulf of Panama (Saboga and Taboga Islands), reproduction occurred after mean monthly SSTs increased from 24 to 28-29 degrees C. In the Galapa gos Islands, reproductive activity peaked during sea warming, when mea n monthly SSTs reached 25 degrees C. Sexually active colonies of G. pl anulata, present only at the main collection sites of Cano and Uva Isl ands, were also observed during the wet season. The presence of mature or spawned gonads in both species mostly around new and full lunar ph ases suggests that spawning is at least weakly synchronized with moon phase. Fecundity estimates disclosed the following nonsignificant diff erences between sites for P. gigantea, expressed as egg production cm( -2) colony surface yr(-1): Galapagos (10300 to 30800), Uva Island (490 0 to 9800), Cano Island (1800 to 7400), Saboga Island (600 to 1300) Ta boga Island (1200 to 2400). Fecundity estimates for G. planulata were considerably lower: Uva Island (700 to 1400) Cano Island (500 to 1000) . The sexual recruitment of P. gigantea into El Nino-Southern Oscillat ion (ENSO) 1982-1983-disturbed, equatorial eastern Pacific coral commu nities has been low, with only moderate recovery evident since 1983. G . planulata has revealed no sexual recruitment where seed populations are absent or rare (Cano Island, Galapagos Islands), and only low recr uitment (Panama) in areas with colonies that survived the ENSO disturb ance.