Influence of feeding structures and early development on foraging guild assignment in four co-occurring fishes (Family Sciaenidae)

The use of a functional guild, which distills organisms into groups based on a shared role within an ecosystem, is a beneficial tool for fisheries management because it reduces data complexity, streamlines statistical analyses, and places species in an ecosystem context by defining their functional role within a community. However, few studies consider the ramification of ontogeny on guild assignments and assume species occupy a static foraging guild throughout their lives. The aim for this study was to examine the development of feeding structures and diet in four, closely related species of sciaenids (Family Sciaenidae) that forage in the water column throughout their life history (1) to determine if the structures needed to exploit microhabitat use of the water column are present at early ontogenetic stages and (2) to assess guild transitions using a hierarchical clustering approach. Significant differences were only detected in ascending process length and cb1 gill raker count among the examined sciaenids. Larimus fasciatus consumed zooplankton throughout ontogeny and possessed a shorter ascending process and a greater number of cb1 gill rakers. Cynoscion nebulosus transitioned from zooplanktivory in the larval period to piscivory as an early juvenile and possessed a longer ascending process and fewer cb1 gill rakers. Bairdiella chrysoura and C. regalis were both zooplanktivorous as early juveniles and consumed more epibenthic (benthic crustaceans and worms) prey and possessed more elongate gill rakers compared to C. nebulosus. Foraging studies that combine diet and morphological analyses are needed to place individuals into foraging guilds while capturing key life history transitions that influence foraging habits and guild assignment.