Interannual variation in larval survival of snapper (Chrysophrys auratus, Sparidae) is linked to diet breadth and prey availability

Larval snapper (Chrysophrys auratus, Sparidae) sampled over 7 years had different diets and feeding strategies between years with lower versus higher larval and 0+ abundances. We analysed stomach contents of snapper larvae from each year to determine diet composition, prey selectivity, prey quality, and trophic niche breadth and compared larval diet with prey availability. Snapper larvae from higher abundance years were specialized foragers selecting for calanoid nauplii at 2-4 mm standard length (SL) and calanoid copepodites and cladocerans at >4 mm SL. These larvae were characterized by either a constant or dome-shaped trophic niche breadth and an increase in prey quality (size of consumed prey) with increasing larval size. Snapper larvae from lower abundance years were generalist foragers characterized by an increase in trophic niche breadth, but not prey quality, with increasing larval size. Changes in foraging strategies were concordant with changes in the prey environment, with low zooplankton densities corresponding with generalist diet (lower larval abundance) years and high zooplankton densities with specialist diet (higher larval abundance) years. These findings suggest that snapper larval survival and juvenile recruitment strength is linked to changes in larval diet that relate to prey abundance and composition.