Foraging preferences and microhabitat use of two crayfish species in the southwestern Missouri Ozarks

Crayfish are considered keystone organisms due in part to their abundance as potential food sources of other animals, increasing nutrient processing rates due to their omnivorous diet (invertebrates, algae, fish, etc.), and are ecosystem engineers due to their burrowing habits. Despite their ecological importance, most species of crayfish have not been thoroughly studied and their ecology, including foraging ecology, is not well known. Foraging preferences (aquatic invertebrates) and microhabitat characteristics were assessed for common crayfishes in the Bull Creek watershed in southwest Missouri, USA. Crayfishes were sampled using a 1m² quadrat sampler and aquatic invertebrates with Hester-Dendy multiple plate samplers submerged for 60 days, while abiotic habitat variables were quantified in the same 1m² quadrat and surrounding sampling sites. The ringed crayfish (Faxonius neglectus) appears to be a habitat generalist preferring no specific habitat, while the Ozark crayfish (Faxonius ozarkae) appears to be a habitat specialist preferring pool habitats. Foraging preferences were also described, comparing Hester-Dendy trap samples (prey availability) versus gut contents (actual prey composition). Diptera (Chironomidae), Ephemeroptera (Baetidae and Heptageniidae), and Basommatophora (Lymnaeidae) were the most abundant invertebrates captured.