Resolution of the early life history of a reef fish using otolith chemistry

We used the elemental signatures in otoliths of the damselfish Pomacentrus coelestis as a proxy for conditions experienced prior to settlement. Fish from the southern Great Barrier Reef (GBR) differed in their pre-settlement otolith chemistry, indicating that they had occupied different water masses during their pelagic stage, thus suggesting multiple larval sources. Fish from reefs in the northern GBR did not differ greatly in their pre-settlement otolith chemistry, suggesting a single larval source. Using "near-natal" signatures, we determined that ∼67% of these signatures matched the signature established for Lizard Island (LZ), suggesting LZ could be a source reef. However, these results could also be the result of poor separation among reefs caused by reefs sharing water masses. Otolith chemistry also revealed that 50-70% of all fish examined settled on the reef the day they encountered it, while some fish spent up to 4 days near the reef prior to settlement.