Larval brooding in the marine damselfish Acanthochromis polyacanthus (Pomacentridae) is correlated with highly divergent morphology, ontogeny and life-history traits

Abstract

The unusual life-history mode of the coral-reef damselfish Acanthochromis polyacanthus is rare in the marine environment and especially remarkable because it lacks a dispersive pelagic larval stage. Other highly divergent morphological, ontogenetic, behavioral, and life-history traits in this species provide comparative evidence for hypotheses about the requirements for survival of very young fish on the reef. The following correlates observed in Acanthochromis diverge significantly from the norm within the pomacentrid family and are concurrent with non-pelagic larvae: very large eggs (for a tropical damselfish); extended egg-stage duration; a mid-day hatching time; slow early embryonic development; much delayed skeletal ossification; large and well-developed hatchlings with fully formed caudal fins; no scales at hatch/settlement; a distinctly high and variable number of vertebrae; very extended and intense biparental care; unusual parent-juvenile interactions such as glancing; and selection of mates of extremely similar size and color. Furthermore, differences among disparate Great Barrier Reef populations of Acanthochromis in major life history traits, such as egg-clutch size, age at maturity, size at fledging, and mode of post-brooding dispersal, are suggested by the available data.