Extended breeding seasons and asynchronous spawning among equatorial reef corals in Kenya

Patterns of sexual reproduction in scleractinian reef corals have been widely studied, and vary both systematically and biogeographically. Extensive sampling and repeated monitoring of 401 marked colonies of 20 Acropora spp. over 2 yr on equatorial lagoon reefs in Kenya (4°S) demonstrated an overall asynchronous spawning pattern extending over a 7 mo period (Mangubhai & Harrison 2008a; Mar Ecol Prog Ser 360:85–96). Spawning occurred during all lunar phases, and during both rising and maximum sea surface temperatures. Although some degree of multispecies spawning occurs on Kenyan reefs, most coral species exhibited relatively asynchronous and extended spawning over 2 to 5 mo with some level of temporal reproductive isolation among species. These data support previous hypotheses of more protracted breeding seasons and a breakdown in spawning synchrony nearer the equator, and contrast markedly with the mass spawning of corals on the Great Barrier Reef and some Western Australian reefs. Baird & Guest (2009, this volume) question this conclusion based on their redefinition of the term ‘mass spawning’, which they define to encompass lesser multispecies spawning events. They assert that Mangubhai & Harrison (2008a) (1) categorically state that mass spawning does not occur in equatorial regions, and (2) do not cite recent studies that document spawning in synchrony by numerous species in equatorial assemblages; both of these assertions are incorrect. The conclusions in Mangubhai & Harrison (2008a) are valid, and clearly demonstrate an unusually extended and asynchronous spawning pattern among many corals on equatorial reefs in Kenya.