Short Communication: Recruitment of Acanthaster planci over a five-year period at Green Island Reef

Abstract

The distribution and abundance of crown-of-thorns starfish was studied at Green Island from 1986 to 1990. The abundance of Acanthaster planci declined over this period. The highest densities of starfish now occur in two areas of high coral cover. In 1990, a possible cohort was present with a mode of 26-30 cm diameter, which is larger than that of previous years. Growth in this cohort was evident after several years in which no growth was detected. Only two 0+ year starfish were found in four intensive broad-scale rubble-sampling surveys (1986 to 1989), suggesting low or very patchy recruitment. These patterns suggest that either (i) there have been only low rates of recruitment since 1986, or (ii) the present starfish population arose from localized settlement in 1988 that was not detected in 1989, or (iii) subadult and adult starfish moved to areas of high coral cover from other parts of the reef depauperate in coral.