Latitudinal and taxonomic patterns in the feeding ecologies of fish larvae: A literature synthesis

The longtime focus on factors that influence the survival of marine fish larvae has yielded an extensive number of studies on larval fish diets and feeding success. In light of a recent increase in such studies within lower latitudes, results from the peer-reviewed literature were synthesized to examine both latitudinal and taxonomic differences in several trophic-related categories, including feeding incidence, trophic niche breadth, ontogenetic diet shifts, dominant prey types, diet broadness, and larval piscivory. A total of 204 investigations (taxon–article combinations) contained suitable results for at least one of these categories. Feeding incidences (proportions of larvae containing food) were significantly higher in lower latitudes with all taxa combined, as well as only within the order Perciformes. Feeding incidences also differed among orders, with Perciformes and Scorpaeniformes having the highest values. The number of larval taxa exhibiting a significantly increasing niche breadth (SD of the log of prey sizes) with larval size decreased toward lower latitudes, with some taxa in lower latitudes exhibiting a decrease in niche breadth with size. The frequency of exhibiting ontogenetic diets shifts decreased with decreasing latitude, as did relative diet broadness (a function of prey types). The most common dominant prey types in the diets of higher latitude larvae were nauplii and calanoid copepods, with cyclopoids being rare in higher latitudes. Dominant prey types in lower latitudes were more diverse, with nauplii, calanoids, and cyclopoids being equally important. Appendicularians increased in importance with decreasing latitude, and one of the clearest latitudinal distinctions was the display of larval piscivory (almost exclusively by scombroid taxa), which was highly concentrated in lower latitudes. Overall, the latitudinal differences observed for multiple trophic-related factors highlight inherent distinctions in larval fish feeding ecologies, likely reflecting differences in the overall structure of planktonic food webs over large latitudinal gradients.