Allocation of nutrients during the reproductive cycle of Ophidiaster ophidianus (Echinodermata: Asteroidea)

Abstract

The reproductive cycle of Ophidiaster ophidianus (strictly protected status) from São Miguel Island, in the Azorean Archipelago was studied. The reproductive strategy; the energy allocation of each sex during the reproductive cycle and the nutritional condition of the population were analyzed. Gonadal index (GI) showed a clear seasonal pattern with spawning between August and October but histological examination revealed that gamete release can occur throughout the entire year. The pyloric caeca index (PCI) showed little annual variation but with an inverse relationship with the GI. Allocation of energy to the gonads and to the pyloric caeca reflected the seasonal reproductive strategy of this species. Individuals were able to simultaneously develop gonads, pyloric caeca, and quickly regenerate lost arms. There was a major expenditure of energy by females compared to males but, sexual size dimorphism was not observed. The reproductive pattern observed in O. ophidianus combining rich food availability and seawater temperatures characteristic of a temperate zone may be the key to the success of this species in the Azorean oceanic Island.

Keywords:

• biochemical cycle
• echinoderm
• strictly protected status
• temperate zone

Acknowledgements

The authors thank Dr Pedro Rodrigues (University of Azores) for his support in the field, Paulo Jorge Melo (University of Azores) for his support with the histology, and the Portuguese Foundation for Science and Technology (FCT) for the PhD grant SFRH/BD/27550/2006 for Joana Micael.