Hobbseus yalobushensis, a Crayfish of Intermittent Streams: Biotic and Habitat Associations, Life History Characteristics, and New Localities

Hobbseus yalobushensis, the Yalobusha rivulet crayfish, is a species of conservation concern because it is known from only six localities in parts of three central Mississippi counties. No studies have focused on the species since its description in 1989. Our objectives were to: (1) identify additional H. yalobushensis localities within a landscape managed intensively for loblolly pine (Pinus taeda) production, (2) relate stream size, water quality variables, and flow permanence to species presence or density, (3) characterize the aquatic community in relation to H. yalobushensis, (4) better define elements of the species' life history, and (5) compile unpublished H. yalobushensis localities from post-1989 collection records. During February and March 2011–2013, we made 56 samples in 24 reaches of 16 streams in Calhoun County, Mississippi. We documented captured crayfishes, fishes, and amphibians and measured habitat and water quality variables. Catch-per-unit-effort (CPUE, number per 100 s electrofished) of H. yalobushensis was significantly higher in intermittent than perennial stream reaches. Predatory fishes were the best indicator of H. yalobushensis absence, and the CPUE of all fishes had the strongest negative correlations with H. yalobushensis CPUE. Hobbseus yalobushensis CPUE was also negatively correlated with that of three other crayfishes. At least three age classes were evident based on length-frequency charts. Hobbseus yalobushensis has persisted in a landscape of intensively managed loblolly pine where streamside management zones were maintained according to Mississippi forestry best management practices. Future research needs include: evaluating the species' persistence under other land management practices (e.g., row crop agriculture); examining whether predatory fishes and other crayfishes influence the species' distribution; extending sampling to additional intermittent streams to clarify the species' range and distribution; and monitoring long-term population trends.