Abstract

Myctophids are central in ocean food webs, yet knowledge of the ecology of larval stages is sparse. We investigated if larval feeding ecology is different in continental shelf break waters compared to waters off oceanic islands in the western Tropical Atlantic. The larvae were collected through diurnal and nocturnal oblique hauls using a Bongo net and stomach contents were analyzed. The larvae ranged between 2.27 and 16.5 mm in standard length. Diet composition was different in the slope and islands (Permutational Multivariate Analysis of Variance (PERMANOVA), P < 0.001). Diatoms (mainly Thalassiosira spp. and fragments of diatoms) were numerically important in the diet at the slope site (69% of relative importance). Copepods were the most relevant prey (71% of relative importance) near the islands. Copepods were the biomass-dominant dietary item at both areas, alongside ostracods near the islands. Smaller prey items were more important for smaller larvae, particularly those measuring up to 4 mm. Larger prey became relatively more important as the larvae grew to at least 8 mm. Larvae fed mostly during the daytime regardless of their size class.