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

中文翻译：

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双同位素等值线预测低地河流鱼类运动的规模

对动物运动方式的评估对于理解其空间生态学非常重要。稳定同位素（SI）地貌（isoscapes）的地统计学模型为遥测提供了补充工具，以评估和预测动物的活动，但很少应用于河流物种。通常，淡水环境中的单同位素梯度变化不足，无法在相对精细的空间尺度上提供高等值线分辨率。这是潜在地克服使用双同位素分配程序，因此，其目的是这里适用单（δ ¹³ C）和双（δ ¹³ C和δ ¹⁵N）等值线以将河边鱼类指定为起源并预测其运动。使用英格兰的布尔河作为研究系统，使用SI数据和常见猎物（两栖动物）的预测性来预测低流动性的小河岸低地河鱼（Rutilus rut​​ilus蟑螂）的觅食位置。然后将这些觅食位置与它们的捕获位置进行比较，它们之间的距离是它们的预测位移距离。结果表明的δ显著富集¹³ C和δ ¹⁵N在蟑螂鳍和两足动物的下游具有距离；蟑螂的双变量同位素生态位在空间上是可变的，上游和下游河段之间没有生态位重叠。此外，双重等值线分配程序使蟑螂的预测位移距离最小，从而提高了模型性能。然后采用双重等距方法来确定单个常见Abramis brama的预计位移距离（更大，更易变的物种），然后将这些数据与通过声遥测记录的其运动的后续空间范围进行比较。当使用高概率密度阈值进行同位素分配时，普通的预测位移距离是通过声遥测记录的其后续运动的空间范围的重要预测指标，尽管它无法预测位移的方向。使用双同位素等值线技术对河流物种的起源进行第一个概率分配表明，如果淡水中动物运动所需的空间分辨率适中（5-10 km），则双同位素等值线可以提供可靠的替代方法或补充方法遥测。