Spatial relationships between distribution patterns of many species and vegetated habitats over multiple scales have been used in terrestrial ecosystems to help identify and map important areas for conservation and management. This approach is not widely used in characterizing habitat use of nekton species in estuaries, but it has great potential because these systems contain fairly discrete vegetated habitat types, and the distribution of nekton species can be influenced by the spatial arrangement of habitat. We examined the spatial relationships between estuarine habitats and nekton species to help map estuarine nekton communities for use in conservation planning. Using a Geographic Information System (GIS), we measured area (m 2 ) and edge density (m km -2 ) of estuarine habitats over multiple scales in Charlotte Harbor, Florida (USA). We used redundancy analysis (RDA) to examine spatial patterns of nekton community composition, habitat, and local habitat characteristics. RDA revealed that spatial patterns in nekton community composition were most highly correlated with distance from the nearest pass to the Gulf of Mexico (r = -0.97) and with salinity (r = 0.94) and area of continuous seagrass habitat (r = 0.91). We used GIS maps of 2 variables (distance from the nearest pass and area of continuous seagrass habitat) to model spatial patterns in nekton community composition and the distribution of several juveniles of fishery species (red drum Sciaenops ocellatus, gray snapper Lutjanus griseus, lane snapper L. synagris, sand seatrout Cynoscion arenarius, and spotted seatrout C. nebulosus). The results suggest that incorporating measures of habitat area (over multiple scales) and spatial position into spatial models of nekton distribution is useful in conservation and management planning.

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We examined relationships between freshwater inflow and population abundance and distribution of two size classes (15-50 mm Standard Length and 51-100 mm SL) of spotted seatrout (Cynoscion nebulosus) and red drum (Sciaenops ocellatus) over our 13-year study covering shallow waters of Tampa Bay and several adjacent rivers. Juveniles of seatrout were relatively abundant most years and broadly distributed primarily in the bay. Freshwater inflow was positively related to spatial distribution and abundance of smaller juveniles of seatrout, yet it was unrelated to the larger size class. Red drum juveniles were less abundant and narrowly distributed primarily within the rivers. Lower portions of the Alafia, Little Manatee, and Manatee Rivers-a combined area comprising only 2 % of the study area-contained 40-96 % of the annual population. Freshwater inflow was positively related to population distribution and abundance of larger red drum suggesting that reductions in inflow can reduce both habitat area and populations. Inflow was related to abundance but not distribution of the smaller red drum suggesting that inflow may increase habitat quality but perhaps not quantity at this earlier growth stage. Comparing spatial and population dynamics of multiple species can help prioritize them for conservation and management issues, such as freshwater inflow regulation. Reductions in inflow reduce populations and spatial distribution of at least one juvenile life stage of these two fishery species. Due to their narrow spatial distribution in the rivers, juveniles of red drum appear to be particularly vulnerable to modification of the riverine environment.

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