Feeding Ecology of a Larval Fish Assemblage During its Passage Through a Coastal Inlet in the Northwestern Gulf of Mexico

Throughout the Gulf of Mexico (GoM), coastal inlets provide vital pathways for marine fish larvae spawned offshore to reach estuarine nursery habitat. While survivorship of fish larvae is dependent on many factors, feeding success has been highlighted as the most important. Currently, little is known about the feeding ecology of larval fish during their passage through coastal inlets. The purpose of this study was to investigate the trophodynamics of fish larvae passing through a GoM estuarine tidal inlet during a fall spawning season. Several trophic niches existed within the δ 13 C’ and δ 15 N’ (lipid and baseline corrected values) stable isotope-derived food web of larval fish, with multiple taxa present within most trophic niches. These trophic niches changed throughout the fall season, however. Micropogonias undulatus , an estuarine-dependent species common to the region, was selected for a closer look at dietary shifts through ontogeny and showed an overall shift to higher trophic level prey with size, although there was not yet evidence of a shift towards estuarine prey indicative of settlement. Their diet mainly consisted of Calanoida copepods across all sizes of larvae with significant electivity for only Acartia (Calanoida), and this selection was likely due to a difference in behavior rather than taxonomy or size. This study provides information about larval fish trophodynamics at coastal inlets, advancing our understanding of larval fish survivorship and recruitment to adult fish stocks.