Temporal and Spatial Dynamics of Larval and Juvenile Fish Abundance in a Temperate Floodplain River

We studied the dynamics of the young-of-the-year (YOY) fish community in a portion of the floodplain and adjacent channel of the Tallahatchie River, Mississippi, by quantifying temporal and spatial variation in abundances of larval and juvenile fishes. Multivariate comparisons of relative abundance data indicated that assemblage composition differed over time and among sampling locations. A spring assemblage consisting of larval gizzard shad (Dorosoma cepedianum), larval crappie (Pomoxis spp.), and larval darters (Etheostoma and Percina spp.) dominated samples from mid-April to early June. Composition of the spring assemblage did not differ among habitats although more larval fishes were caught in warmer, more lentic habitats. This assemblage was replaced in late June by a group consisting of larval and juvenile sunfishes (Lepomis spp.), YOY mosquitofish (Gambusia afinis), and juvenile shiners (Cyprinella and Notropis spp.). The relative abundance of fishes in this assemblage differed among habitats; larval and juvenile sunfish were most abundant in habitats exhibiting low flow rates and high temperatures, and juvenile shiners were most abundant in moderate to high flow habitats. High larval fish abundance in floodplains stems, in part, from the presence of larvae of species that inhabit both the channel and the floodplain as adults.