The crown-of-thorns starfish (COTS), Acanthaster cf. solaris, is an iconic keystone predator whose population outbreaks have devastating consequences for Indo-Pacific coral reefs. We tested the effects of algal food supply and larval density on the frequency of larval cloning by culturing the early bipinnaria larvae of COTS under variable conditions. Here we show that larval COTS are able to clone themselves in both low and high food conditions, and that the frequency of larval cloning increases with levels of food, but is unaffected by larval density. Across all density treatments (0.3, 1.0 and 3.0 larvae ml-1), the per-capita rate of cloning increased from 4.3% in low, oligotrophic conditions (0.17 µg chl a l-1) to 7.9% in high food conditions (1.7 µg chl a l-1). Larval cloning has the potential to increase both COTS larval supply and the dispersal distance of planktonic larval stages, both of which are critical factors in predicting the timing and location of outbreaks of this species. In addition, the relationship between algal food supply and larval cloning frequency lends support to bottom-up hypotheses (e.g. nutrient enrichment) as predictors of COTS outbreaks. However, cloning was observed even under the oligotrophic conditions characteristic of coral reefs.
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