Patterns of coral larval settlement on lagoon reefs in the Mombasa Marine National Park and Reserve, Kenya

Abstract

Spatial and temporal patterns of coral larval settlement were studied on 2 lagoon reefs in the Mombasa Marine National Park and Reserve (4°S) from 2003 to 2005, to examine relationships between larval settlement and the timing and extended duration of coral spawning events in Kenya. In contrast to coral settlement in most other tropical regions, Pocilloporidae dominated on settlement tiles and comprised 93.7% of spat, while Acroporidae, Poritidae and Faviidae comprised 4.7% of spat. Coral settlement varied significantly spatially and temporally, with space-time interactions occurring. Annual mean spat densities in the park (101 spat m -2 ) were comparable to data from sub- tropical reefs, while densities in the reserve (908 spat m -2 ) were comparable to tropical reefs. These data suggest that there is no distinct latitudinal gradient in spat density along the East African coast. Spat settlement was seasonal, with peak settlement occurring predominantly on tiles immersed from February to May during the northeast monsoon, and was consistent with the timing of gamete release in Acropora and faviid species in Kenya. While non-coral fauna was 4 times more abundant than corals on settlement tiles, there was no evidence of significant competition among these spat groups. It is suggested that the relatively asynchronous and extended breeding season in Kenyan corals may result in reduced competition during settlement.