This study constitutes the first report of the gametogenic cycle of the scleractinian corals Solenastrea bournoni and Stephanocoenia intersepta. Tissue samples were collected near Ft. Lauderdale, Florida, USA between July 2008 and November 2009 and processed for histological examination in an effort to determine reproductive mode and potential spawning times. Both S. bournoni and S. intersepta are gonochoric, broadcast spawning species. Gametogenesis of S. bournoni began in April or May while S. intersepta had a much longer oogenic cycle that began in December with spermatogenesis beginning in July. Though spawning was not observed in situ, spawning was inferred from the decrease of late stage gametes in histological samples. In addition, histological observations of oocyte resorption and released spermatozoa were used to corroborate spawning times. Data indicate that S. bournoni spawns in September while S. intersepta spawns after the full moon in late August or early September. 1. Introduction Reproduction of scleractinian corals is one of the most important processes influencing their continued existence [1]. Sexual reproduction is the first step in establishing new colonies necessary for repopulating degraded reefs. It creates genetic variability essential for adapting to changing environmental conditions. Information on the reproductive biology and ecology of corals is critical for understanding their distribution, evolutionary mechanisms [2, 3], and for management and restoration of damaged areas [4]. For broadcast spawning species, synchronous maturation and release of gametes is essential for successful fertilization [5]. Coral gametogenesis and spawning are thought to be driven by a number of environmental cues including sea temperature, day length, moonlight tidal cycles, and daylight cycles [6, 7], but the exact association remains unknown [1, 7, 8]. For a number of species, temperature defines the season and month of spawning and timing tends to correlate strongly with lunar phase [5]. Sunset time can define the hour of spawning [6, 9, 10] and tidal fluctuations may decrease water movement and lead to increased fertilization opportunities [11]. It is very likely that coral gametogenesis and spawning are not prompted by a single environmental cue, but rely on more than one environmental signal [12]. In the last few decades, there have been numerous studies on scleractinian coral reproduction [4, 7, 13–16]. About 60% of the approximate 60 known Caribbean species have been investigated [3]. Species of particular interest in southeast Florida
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