摘要

Predation on the black sea urchin, Diadema, by the striped beakfish, Oplegnathus fasciatus, has been witnessed by divers. The sea urchin is also used as bait to angle the fish in Japan. Surrounding the Izu peninsula, barrens caused by a high density of Diadema are restricted to the southern coast of Uchiura Bay in the northwest of the peninsula, while O. fasciatus is limited in population size and occurs only seasonally in this region. The possibility of a top-down control on Diadema by O. fasciatus is discussed by conducting field observations and feeding experiments in tanks in parallel with a review of the spatial and temporal distribution of these species. The fish O. fasciatus, the hermit Dardanus crassimanus, and the sea star Coscinasterias acutispina were found to feed on Diadema juveniles. Among them, O. fasciatus is the only species that can voraciously consume juveniles (>80 juveniles/day by only a single fish) and prey on larger sea urchins (when their long spines are partially removed). However, predation by fish may not be critical for Diadema populations because of the cryptic nature of sea urchin recruits, their effective armor (with long spines) in adults, variations in appetite among the fishes, and the seasonality and limited size of the fish at the study site.

  • 出版日期2013