Reproductive ecology of the scleractinian corals Echinopora gemmacea and Leptoria phrygia (Faviidae) on equatorial reefs in Kenya

Abstract

Very few detailed studies on coral reproduction have been carried out in the Western Indian Ocean or on equatorial reefs. The reproductive ecology of Echinopora gemmacea and Leptoria Phrygia was studied in Mombasa lagoon in Kenya from 2003 to 2005. Permanently marked colonies were repeatedly sampled and spawning was inferred from the disappearance of mature oocytes and spermaries between sequential samples. Spawning occurred in the northeast monsoon when sea surface temperatures were at their summer maximum (averaging 28.3°C) and around spring tides. A single cycle of ametogenesis was recorded in E. gemmacea with oocytes developing over 6–7 months, spermaries developing over 4–5 months, and with gametes eleased over 3 consecutive lunar months (February to April). In L. Phrygia a range of oocyte size classes was recorded within some colonies throughout the gametogenic cycle, which suggested that asynchronous oogenic cycles occur in this species. Spawning occurred over 2–3 lunarmonths from December to February in L. Phrygia. Asynchronous oogenesis has not been previously recorded in L. phrygia or in hermaphroditic broadcast spawning corals in general, and provides some support for the hypothesis that spawning synchrony may break down towards the equator and corals may exhibit an extended reproductive season.

Key words:

• Sexual reproduction
• gametogenesis
• spawning asynchrony
• fecundity
• Indian Ocean