One-parent removal experiment in the brood-caring damselfish, Acanthochromis polyacanthus, with preliminary data on reproductive biology

Abstract

One-parent removal experiments were carried out in the monogamous damselfish Acanthochromis polyacanthus at One Tree Island, Australia, from 27 October to 4 November 1987. In eight of nine removal experiments, the vacant place was refilled by intrusion of another adult fish within two days. This was followed by the disappearance of the fry. A small number of fry was found in the stomach of one intruder, suggesting cannibalism. Those fry that were not eaten were abandoned by the adults and left to a free existence, but their survival was very low compared with fry tended by both parents. Analysis of fecundity suggests that females have the potential to lay a second clutch of nearly 200 eggs when the first one is lost. It seems that A. polyacanthus, on the loss of a partner, takes a new partner and deserts the current brood rather than trying to rear them alone. This implies that survival is lower in uniparental broods. The plasticity of the pair-bond and the fecundity of females suggest that death of brooding parents may be a relatively common event in the predator-rich environment of coral reefs.