Assessing Coral Community Recovery from Coral Bleaching by Recruitment in Two Reserves in Kenya

Abstract

In 2003 and 2005, studies were carried out on the density of small coral colonies (less than 10 cm) on three reefs in the Mombasa Marine National Park and Reserve on the southern fringing reef system of Kenya, and on three reefs in the Kiunga Marine National Reserve in the north of the country. All the study sites were impacted by a major coral bleaching event in 1998. A total of 28 coral genera from 12 families were recorded, of which 17 genera were recorded on both northern and southern sites. Two or three genera of corals contributed 50-60% of all small colonies in both regions, with Porites, Coscinarea and Pocillopora the main contributors of small colonies in Kiunga, and Pocillopora being the most abundant genus of small corals in Mombasa in both years. The densities of small colonies were lowest at the northern sites, and small colonies of genera of corals that suffered from high bleaching and mortality during the El Niño Southern
Oscillation in 1998 were less abundant in the north. These northern reefs are relatively isolated from sources of coral larvae from reefs in the south, and are seasonally influenced by nutrient-rich, cooler water due to the influence of the Somali Current and the northeast monsoon winds. The
data presented here support our preliminary assessment that these northern reefs are less likely to recover by natural recruitment. These reefs are therefore more vulnerable to environmental perturbation such as the conditions that elicited coral bleaching on the study reefs in 1998.