Spatial variability in recruitment of acroporid corals and predatory starfish along the Onna coast, Okinawa, Japan

We compared spatial variability in re- cruitment patterns between acroporid corals and the predatory crown-of-thorns starfish Acanthaster planci along the Onna village coast of Okinawa Island, Japan. Our objective was to understand population dynamics of both predator and prey. To quantify re- cruitment, we established artificial recruitment plates for acroporid corals and conducted quadrat surveys for juvenile A. planci at 7 sites. We also examined dis- tributional patterns of adult populations of both spe- cies and observed surface currents during larval dis- persal periods using GPS-equipped surface drifters. Acroporid recruits typically arrived in greater num- bers at more northern sites. Despite high variability, A. planci recruits displayed similar spatial patterns. Drifter trajectories suggest that these spatial recruit- ment patterns are probably driven by near-shore currents in the summer. Moreover, current data imply a complicated metapopulation relationship in this region, especially for A. planci, new recruits of which may mainly originate outside of the Onna area. Meta - population dynamics within the study area and among surrounding regions must be explained by the com- plex surface current circulation, because simpler ex- planations involving only the Kuroshio Current do not adequately describe the relationship between these populations.