MEPS prepress abstract - doi: 10.3354/meps07385
Asynchronous coral spawning patterns on equatorial reefs in Kenya
Sangeeta Mangubhai*, Peter L. Harrison
ABSTRACT: This study examined patterns of reef coral reproduction on lagoonal reefs adjacent to Mombasa in Kenya, at latitude 4ºS. A total of 401 colonies comprising 20 Acropora species was marked and repeatedly sampled between 2003 to 2005 to determine patterns of reproduction at the individual and population level. Spawning was inferred from the disappearance of mature oocytes and spermaries from sequential samples. In comparison to other regions, the overall pattern of coral reproduction in Kenya is one of asynchrony with Acropora species releasing gametes over a 7-month period (October to April) with some level of ‘temporal reproductive isolation’ occurring between species in relation to the lunar months and lunar periods when the main spawning occurred. Extended gametogenic cycles were recorded in A. tenuis, A. valida and Acropora sp. 1, and quiescent non-reproductive periods between cycles were either very short or absent. Spawning occurred during both rising and maximum sea surface temperatures, during both neap and spring tides and across all lunar periods. The findings from Kenyan reefs support the hypothesis of protracted breeding seasons and a breakdown of spawning synchrony nearer the equator. It is hypothesised that the high fecundities recorded in coral species in Kenya compared to other regions may allow individual reef coral populations to stagger their reproduction over 2–5 months, without incurring a significant reduction in fertilisation rates.