Gender-specific benefits of eating eggs at resident reef fish spawning aggregation sites

Abstract

Food resource availability has a fundamental role in shaping consumer populations through changes in energy intake. Tropical reef fish spawning aggregations provide a resource pulse for reef-based planktonic egg predators, and an opportunity to quantify the energetic repercussions of natural changes in food availability in tropical reef fishes. We examined the effects of the consumption of eggs from the broadcast spawning surgeonfish Ctenochaetus striatus on the allocation of energy to body condition, growth and reproduction in the planktivorous egg-predator damselfish Abudefduf vaigiensis. Fish that fed on eggs at resident fish spawning aggregation sites (FSASs) had significantly greater lipid storage in liver vacuoles compared to conspecifics from non-FSASs. Growth of male A. vaigiensis was faster at FSASs than non-FSASs. However, we found no differences in the growth of females among sites. Female A. vaigiensis from FSASs in vested more into reproduction, having larger gonadosomatic indices (GSI) than females from non-FSASs, while there was no difference in the GSI of males among FSASs and non-FSASs. At the same locations, no differences were found in the life-history traits of the reference species, Pomacentrus moluccensis, which does not consume eggs. This study demonstrates the role of natural variations in food availability on energetic processes in reef fish. Furthermore, the sex-specific energy allocation strategy highlights the complexity of the interaction between natural variations in food availability and life-history strategies. This study demonstrates that the conservation of FSASs may also benefit trophically linked reef fishes.