Landscape-scale variation in coral recruitment in Moorea, French Polynesia

Abstract

In this study, we describe spatio-temporal variation in coral recruitment in the back reef of Moorea, French Polynesia, and explore the extent to which it is associated with community structure, seawater temperature, and wave regimes. Recruitment was assessed with settlement tiles deployed at 10sites on the north, southeast, and southwestshores and sampled every 5 to 7 mo from 2005 to 2007. Temperature andwaveswere measured using thermistors and pressure sensors, and community structure was assessed using in situ surveys. Meanrecruitment varied from 0 to 6 recruits tile-1 (510cm2) andwasgenerally greater in the second compared to the first year of the study. Recruitment varied amongsites, and this variation was similar between years but differed among sampling periods: acroporids were common on the southwest shore between January and September, but rare fromSeptember to January; poritids were common on the north shore betweenSeptember and January, but rare on the southwest shore from January to September; and pocilloporids were foundall year, but at slightly elevated densities between Januaryand September.The mean daily seawatertemperature, and the daily range, varied among sites, but neither wasclosely related to coral recruitment, and both were of biologically small magnitudes. The coral community structure also varied among sites, but likewise, was not associated with coral recruitment. In contrast, outer reef wave energy exposure, which likely played animportant role in driving cross-reef transportof seawaterintothe lagoon, differed between shores and seasons in a patternconsistent with the variation in coral recruitment in the back reef. We hypothesize that coral recruitment in the backreef of Moorea is influenced by the interactionof seasonal variation in wave exposure, family-level differences in coral reproductive timing, and the spatial distribution of adult corals. © Inter-Research 2010.