Multi‐scale effects of resource patchiness on foraging behaviour and habitat use by longnose dace, Rhinichthys cataractae

Abstract

1. We examined the response of a predatory benthic fish, the longnose dace (Rhinichthys cataractae), to patchiness in the distribution of benthic macroinvertebrates on cobbles at three hierarchical spatial scales during summer and autumn 1996, and spring 1997 in a southern Appalachian stream. 2. At the primary scale (four to five individual cobbles separated by <1 m), the intensity of foraging was not correlated with the biomass of benthic macroinvertebrates/cobble, regardless of season. 3. At the secondary scale (i.e. foraging patches <5 m in diameter) we found that benthic macroinvertebrates were patchily distributed in summer, but not in autumn or spring. Concomitantly, in summer, longnose dace foraged on cobbles with a significantly higher biomass of benthic macronvertebrates than nearby, randomly selected cobbles with similar physical conditions (i.e. longnose dace tended to avoid low‐prey foraging patches). In contrast, when benthic macroinvertebrates were distributed homogeneously (spring and autumn), dace did not select patches with a significantly higher biomass of benthic macroinvertebrates than that available on randomly selected cobbles. 4. At the tertiary scale (i.e. stream reaches 11–19 m long), the biomass of benthic macroinvertebrates (per cobble per reach) was patchily distributed (i.e. differed significantly among reaches) in all seasons. Among reaches with physical characteristics preferred by longnose dace, (i.e. erosional reaches dominated by cobble/boulder substratum and high current velocity), we detected a significant, positive correlation between the biomass of benthic macroinvertebrates/cobble and longnose dace density in all seasons. 5. Our results demonstrated that both spatial and temporal patchiness in resource availability influenced significantly the use of both foraging patches and stream reaches by longnose dace.

Re-examining the Importance of Fish in the Diets of Stream-dwelling Crayfishes: Implications for Food Web Analyses and Conservation

“…More specifi cally, because crayfi sh are patchily distributed within streams (DiStefano et al 2003), mink may respond to presence of prey hotspots instead of to average prey densities for sites. Studies across multiple taxa indicate prey hotspots can be important determinants of predator space use and foraging behavior (Th ompson et al 2001, Davoren et al 2003, Gende and Sigler 2006, L ó pez-Bao et al 2011. Mink use some parts of their home range more intensively than others (Yamaguchi et al 2003), which could refl ect prey distributions and suitable hunting places (Gerell 1970).…”

Comparison of the Channel Darter (Percina copelandi) Summer Habitat in Two Rivers from Eastern Canada

“…Heterogeneous substrates, such as those present in lotic zones with moderate to high water velocities, offer a large colonization surface for insect larvae (Beisel et al 2000, Thompson et al 2001, Boyero 2003, and the density of aquatic insects is often significantly higher in lotic zones than in quieter lentic waters. The lotic habitats show sufficient current velocities to avoid the deposition of fine sediment, and thus these heterogeneous habitats are favorable feeding grounds for the channel darter.…”

Using a continuous riverscape survey to examine the effects of the spatial structure of functional habitats on fish distribution

“…These observations are consistent with the concept of ideal free distribution, which predicts that fish will occupy the next 'best' patch of habitat if density increases in a high-quality patch (Schilling 2005). At segment scale, the use of feeding patches for these benthic mobile species could be influenced by spatial patchiness of food resources as shown for the longnose dace (Thompson et al 2001). The spatial patchiness of lotic invertebrate densities is demonstrated at the riffles scale within a segment (Downes et al 1993).…”