ONE-PARENT REMOVAL EXPERIMENT IN THE BROOD-CARING DAMSELFISH, ACANTHOCHROMIS-POLYACANTHUS, WITH PRELIMINARY DATA ON REPRODUCTIVE-BIOLOGY

One-parent removal experiments were carried out in the monogamous dams elfish 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 withi n 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 ca nnibalism. 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 w hen 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 i n uniparental broods. The plasticity of the pair-bond and the fecundit y of females suggest that death of brooding parents may be a relativel y common event in the predator-rich environment of cord reefs.