Seasonal patterns of coral reproduction on equatorial reefs in Mombasa, Kenya
Mangubhai, S & Harrison, PL 2006, 'Seasonal patterns of coral reproduction on equatorial reefs in Mombasa, Kenya', Proceedings of 10th International Coral Reef Symposium, Okinawa, Japan, June 28 - 2 July, 2004, Japanese Coral Reef Society, Japan, pp. 106-114.
Only a few studies have examined sexual reproductive patterns of scleractinian corals in equatorial regions. It has been suggested that spawning synchrony breaks down on equatorial reefs due to weak environmental cues governing the onset and timing of reproduction. This paper present the first data on the seasonality and timing of coral reef reproduction events in lagoon reefs adjacent to Mombasa in Kenya, at latitude 4°S. Samples were collected from tagged colonies every 2-8 weeks from April 2003-May 2004, and reproduction was inferred from the disappearance of mature-colored oocytes and spermaries from sequential samples. Three faviids (Echinopora gemmacea, Platygyra daedalea, P. sinensis) and 17 Acropora species were found to be hermaphroditic, and are likely to be broadcast spawners. Echinopora gemmacea and the majority of Acropora species had a single annual gametogenic cycle, while some colonies of P. daedaleas and P sinesis reproduced bi-annualy. Less than 20% of Platygyra species participated in a minor reproductive event in August-October which coincided with the southeast monsoon, while >97% reproduced in late February-early March during the northeast monsoon. Acropora species reproduced over a 7-month period with the majority reproducing during the northeast monsoon between January-March when seawater temperatures were close to their summer maximum, averaging 28.3°C. Within the reproductive season indiviudal Acropora species had peak periods when 50% of the population reproduced. These peak periods for the different species suggesting some degree of "temporal reproductive isloation" similar to that observed in the Red Sea. However, some Acropora species had an extended reproductive season spanning 2-5 months.