In situ culturing as a test of the larval starvation hypothesis for the crown‐of‐thoms starfish, Acanthaster planci1

Abstract

As a test of the hypothesis that larvae of the crown‐of‐thorns starfish, Acanthaster planci, are severely food limited, larvae were reared in situ in natural seawater and in natural seawater enriched with cultured phytoplankton. Although phytoplankton levels remained below the minimum threshold needed to support A. planci larval development in the laboratory (0.4 µg Chl a liter−1), there was no evidence of starvation. Larvae began settling at 14 d after fertilization, which is 2 d sooner than the shortest time to settlement reported for A. planci from laboratory rearing. Enrichment of diet resulted in no significant difference in survivorship (compared to larvae feeding only on natural seawater) and only a slight difference in development rate. These data, along with other indirect evidence, suggest that A. planci larvae develop at near‐maximal rates under normal conditions (i.e. in the absence of phytoplankton blooms) and that fluctuations in larval food resources may be of little importance in explaining interannual variation in their larval recruitment.