Dual‐isotope isoscapes for predicting the scale of fish movements in lowland rivers

Assessments of patterns animal movements are important for understanding their spatial ecology. Geostatistical models stable isotope (SI) landscapes (isoscapes) provide a complementary tool to telemetry assessing and predicting movements, but rarely applied riverine species. Often single-isotope gradients in freshwater environments insufficiently variable high isoscape resolution at relatively fine scales. This is potentially overcome using dual-isotope assignment procedures, thus, the aim here was apply single (δ13C) dual (δ13C δ15N) isoscapes assigning fish origin movements. Using River Bure, England, as study system, foraging locations small-bodied lowland river (roach Rutilus rutilus) low vagility were predicted SI data those common prey item (amphipods). These then compared capture locations, with distance between these being displacement distance. The results indicated significant enrichment δ13C δ15N downstream roach fin tissue amphipods; bivariate isotopic niches spatially variable, no niche overlap upstream reaches. Furthermore, dual-isoscape procedure resulted lowest distances roach, therefore enhancing model performance. approach determining individual bream Abramis brama, larger, more vagile species, against subsequent extent recorded by acoustic telemetry. When probability density threshold assignment, predictor telemetry, although it less able predict direction displacement. first probabilistic species technique demonstrated that where required moderately broad (5–10 km), can reliable alternative or method