DYNAMIC COUPLING OF REEF FISH REPLENISHMENT AND OCEANOGRAPHIC PROCESSES

Oceanographic processes have been shown to play a pivotal role in the control of recruitment variability in some commercial, northern temperate fish populations. This study investigates the link between inter-annual changes in larval supply and wind stress for unexploited reef fish populations at Lizard Island, northern Great Barrier Reef. For the first time, this relationship is analysed separately for front-reef and back-reef habitats and results for 3 major reef fish familes (Pomacentridae, Apogonidae, Blenniidae) reveal that the link between wind stress and larval supply appears to be habitat-dependent. In the back-reef habitat, there appears to be a positive correlation between interannual changes in the frequency of onshore winds and the level of larval supply. This phenomenon is associated with large-scale changes in weather systems, suggesting that the relationship may be predictable at a region-wide scale. Results for the front-reef habitat suggest that the effect of wind stress on inter-annual levels of larval supply is less important. Survival and advection of earlier larval stages may be more influential in determining fluctuations in the magnitude of replenishment to this habitat. Although not helpful in predicting inter-annual changes in larval supply, a local retention mechanism may keep larval supply into this habitat elevated above that of the back-reef side. Comparison of these results with a non-reef mixed-age group of schooling pelagic fishes suggests that these patterns are a unique feature of the replenishment process.