Assessment and Characterization of Physical Habitat, Water Quality, and Biotic Assemblages of the Tyronza River, Arkansas

Few studies within the last few decades have addressed water quality and biotic assemblages within Arkansas’s large channel-altered deltaic rivers. The Tyronza River is located in northeast Arkansas and its watershed has a heavy agricultural presence that drastically affects habitat quality. Meanwhile, the Tyronza River hosts one of the more recent documented range extensions of the federally endangered fat pocketbook mussel [Potamilus capax (Green, 1832)]. The purpose of this study was to assess physical habitat, water quality, and biotic assemblages of the Tyronza River using the Arkansas Department of Environmental Quality’s (ADEQ) regional biometrics. Water samples were collected at 9 stations across 4 seasonal intervals. Physical habitat, fish, and macroinvertebrates were collected at 9 stations during summer and fall. U.S. EPA Rapid Bioassessment Protocols for habitat indicated that habitat quality was suboptimal. Distinct seasonal differences were observed among all water chemistry parameters; however, seasonality was not as clear among nutrient constituents. Macroinvertebrate assemblages varied drastically among sites: taxa richness ranged from 3 to 14 and the Arkansas Macroinvertebrate Index for Small Watersheds values ranged from 16 to 28 (poor to very good condition). Fish Community Structure Indices were less variable among sites ranging from 6 to 16 (Not Similar to Somewhat Similar). The lack of instream habitat and habitat richness is likely resulting in low taxa richness in the biotic communities. Results from this study will provide managers and scientists with valuable information on seasonal variation of select water quality parameters and into the integrity of aquatic assemblages of the Tyronza River. Keywords: Water quality, rapi