Reproductive investment and fecundity of Pacific crown-of-thorns starfish (Acanthaster cf. Solaris) on the Great Barrier Reef

摘要

Crown-of-thorns starfish (Acanthaster spp.) is reported to have exceptional reproductive capacity, but this has been largely inferred based on the overall weight of gonads (and mostly for females), and there are limited estimates of the concentration of gametes within gametogenic tissues. This study quantified gamete concentrations for both male and female Pacific crown-of-thorns starfish (Acanthaster cf. solaris), collected on Australia’s Great Barrier Reef in 2014–2019. Gamete concentrations varied greatly among female starfish (12,338–133,810 oocytes g−1), such that the estimated reproductive capacity ranged from < 1000 oocytes for the smallest (141 mm) individual up to 106 million oocytes for a 480-mm diameter female. Gamete concentrations were much more conserved for male starfish, and did not vary with size. Nonetheless, the total mass of gametogenic tissue increased with size, and fecundity of large males > 400-mm diameter approached 53 billion sperm. This study reaffirms that crown-of-thorns starfish have exceptional reproductive capacity, which is strongly size-dependent, but also varies greatly among individuals. Importantly, individual variation in reproductive output may be important in understanding for population irruptions of Acanthaster spp., and their concomitant effects on reef ecosystems.