Examining use of habitat fragments by larval and juvenile fishes in Lake Texoma river-reservoir interface zones



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Lake Texoma is home to several isolated coves walled off by sedimentation as a result of reservoir aging. The habitat fragments are relatively new features on the landscape, isolated from the reservoir and taking diverse forms. These fragments have been formed on the arms of two physicochemically distinct rivers entering Lake Texoma (Red and Washita). Fragmented coves are located within the river-reservoir interface, a highly productive and ecologically important transitional zone. I examined the structure of young-of-the-year (YOY) fish assemblages utilizing these habitats and investigated the influence of environmental factors on taxonomic and guild composition. Sampling was carried out from March through August in 2014 and 2015 using light traps and push nets to target larval and juvenile fishes. Differences in YOY fish abundance and assemblage structure were observed between river arms and individual fragments. Analyses using non-metric multidimensional scaling (NMS) and a follow-up analysis of similarity (ANOSIM) revealed significant differences in the structure of larval assemblages between years, and diversity was higher in the very wet, flooded 2015 season. While habitat generalists were dominant throughout our study area, some fragments provided habitat to species that rely upon river floodplain habitats for reproduction, especially during the year with more extensive hydrological connectivity. This work should provide managers with insights into the role that these novel habitats play in supplementing reservoir fish assemblages.



Fisheries, ecology