Gametogenesis of the Hermatypic Coral Siderastrea siderea in Broward County, FL, USA and the Effect of Bleaching on Fecundity

Massive Caribbean scleractinians are slow to replace themselves in the population due to long life spans, low recruitment, and slow growth rates. Disruption of reproductive synchronicity or reduced fecundity may adversely affect their ability to recover and repopulate degraded areas. Reproductive information on Siderastrea siderea, an abundant Caribbean broadcast spawning species, is particularly sparse. In order to track gametogenesis and identify the time of spawning, tissue samples from S. siderea were collected from August 2007 on a weekly basis until November, when a reduction in gametes, indicative of spawning, was observed. Estimated spawning time was compared with lunar phase as well as water temperature data obtained from permanent digital temperature recorders deployed throughout Broward County to determine if either of these environmental cues affected spawning time. Information on colony condition and presence of bleaching was obtained for each colony sampled. Tissue samples were processed for histological analysis and examined for late stage gametes. Fecundity was estimated from measurements of the volume of oocytes cm^-2 tissue and was compared between bleached and unbleached colonies. Initial analysis suggests that S. siderea spawned between November 8 and 11, 2007 which coincided with the new moon on November 9th. Samples collected on the 8^th contained both ova and spermaries extruded from the mesenteries into the gastrovascular cavity and un-spawned gametes absorbed by the gastrodermis. Further collections of S. siderea in 2008 will be used to corroborate spawning correlation of S. siderea with lunar period.