Population and feeding responses of the corallivorous pufferfish Arothron meleagris to coral mortality in the eastern Pacific

Abstract

Arothron meleagris occurs at densities rangng from 0 to 320 fish ha-' of live coral on eastern Pacific coral reefs of Costa hca, Panama, Colombia and the Galapagos Islands. On reefs in Panama and Costa hca, over 50n& of corals died during the 1982-83 El Nino event and 40% of remaining corals at Cano Island, Costa Rica, died during red tides in 1985. The population density of A. meleagns is not related to coral density on different reefs and fish densities did not change in a consistent manner follow~ng the coral mortalities. Diets and feeding preferences of A. meleagris at different sites are not related in a consistent way to the abundance of various corals or to changes in coral abundances following coral mortalities. At Cafio Island A. meleagn's prefers Pontes lobata over the less abundant Pocillopora damicornis. At Uva Island, Panama, where P. damlcornis is the more abundant species, A. rneleagns does not prefer either coral. The relationship between the availability and consumption of the uncommon coral Psamrnocora stellata also differs among localities. Changes in this fish's diet following the mass coral mortalities varied among sites. At Cano Island fish switched first to coralline algae and then to corals. Fish do grow when expenmentally fed only coralline algae, but grow better when fed corals. The ability of the puffer to switch diets and maintain its populations following coral mortality may affect the recovery of coral populations. Even when uncommon, the puffer may have an impact on rare corals.