Phenology and spatial and temporal distribution of larval fishes in a partially channelized warmwater stream

We studied the phenology and spatial and temporal dynamics of larval fish abundance with light traps from 5 locations along the length of Luxapalilia Creek, a partially channelized warmwater stream in northeastern Mississippi over 2 spawning seasops (March through August 1992 and 1993). The dominant, early spring spawners were catostomids (early-April to late-May) and darters (mid-March to early-June) whereas summer spawners were mainly cyprinids (mid-May to August) and centrarchids (late-May to August). The relative abundance of larvae collections differed based on: 1) site, 2) location, 3) date, 4) year, and 5) in larval stage. Total numbers of larvae and CPUE were high in mid- to late summer in downstream locations in both years when: 1) temperatures were high, 2) water velocities were low, and 3) depths were shallow compared to upstream locations. More mature larvae (meso- and metalarvae) were more common in the downstream locations whereas less mature larvae (yolk-sac and protolarvae) were more abundant at the upstream locations. The downstream channelized portion of Luxapalila Creek resembled a lentic habitat with littoral zones characterized by slow water velocities, shallow depths, fine sediments, and vegetation. Larvae of darters (Etheostorna and Pcrcina), which require gravel bars and swift currents, were not collected in great numbers downstream, although members of the Ictiobinae (Carpoides and Ictiobus), cyprinidae and centrarchidae (Lepomis spp., Pomoxis spp. and Micropterus spp.) were more abundant downstream than upstream. This suggests that the natural, upstream locations acted as sources of larvae for the channelized downstream location.