Assessing Population Viability and Habitat Preference of Eastern Sand Darter in Illinois Running Waters

Routine monitoring of fish communities often provides inadequate information about the habitat, abundance, and distribution of Species in Greatest Need of Conservation (SGNC). This knowledge gap limits the management options for protecting and restoring SGNC. In the present study, we aim to build habitat-suitability models for the Eastern Sand Darter (ESD) in Illinois streams. ESD prefers natural sand bottom streams and thus could be stressed by sediment loading and flow alternation. We used seines to sample ESD in a watershed that is known to have a relatively strong population, the Embarras River, a tributary of the Wabash River. We plan to sample 23 sites where ESD were previously recorded, 7 sites where ESD had not been detected, and 6 sites where ESD presence was unknown. We took habitat and water quality information, used side-scanning to map the substrate composition of the river over 250 km, and gained access to the Statewide Streams Application (SSA) layers (GIS-based) created by IDNR, which includes channel, watershed, and riparian information for the streams of Illinois. Over two field seasons in 2018 and 2019, we surveyed 35 sites in the Embarras watershed and recorded 368 ESD individuals. We also collected other darters (14 species found in the Embarras, Slenderhead and Dusky Darters captured most often with ESD) to assess their niche partitioning with ESD. This information along with the habitat and GIS-based data will be used to construct ESD habitat models. An additional 10 sites will be surveyed in the Vermilion (Wabash) River, another known occupation area for ESD, in 2020 for validating and enhancing the habitat model. The final model will be used to infer the distribution of the species in un-sampled streams and the stressors to ESD populations in the state and contribute to a conservation management or recovery plan.