Dual‐isotope isoscapes for predicting the scale of fish movements in lowland rivers
Dual‐isotope isoscapes for predicting the scale of fish movements in lowland rivers
复制标题
用于预测低地河流鱼类运动规模的双同位素等景图
作者：
E. Winter;A. M. Hindes;Steve Lane;J. Britton
动物运动模式的评估对于了解它们的空间生态学非常重要。地质统计模型的稳定同位素（SI）景观（'isoscapes'）提供了一个补充工具，遥测评估和预测动物的运动，但很少适用于河流物种。通常，淡水环境中的单一同位素梯度的变化不足以在相对精细的空间尺度上提供高的isoscape分辨率。这是潜在的克服使用双同位素分配程序，因此，这里的目的是应用单一（δ 13 C）和双重（δ 13 C和δ 15 N）isoscape分配河流鱼类的起源和预测他们的运动。以英国的布尔河为研究系统，利用其SI数据和常见的猎物（片足类）的SI数据，对一种低游动性的小型低地河流鱼类（roach Rutilus rutilus）的觅食地点进行了预测。然后将这些觅食位置与它们的捕获位置进行比较，这些位置之间的距离是它们的“预测位移距离”。结果表明，δ 13 C和δ 15 N在轮虫鳍组织和端足类中随下游距离的增加而显著富集;轮虫双变量同位素生态位在空间上是可变的，上下游河段之间没有生态位重叠。此外，双isoscape分配程序导致蟑螂的最低预测位移距离，从而提高模型的性能。双isoscape的方法，然后应用于确定预测的位移距离的个别共同的鲷，一个更大的，更狡猾的物种，这些数据，然后对随后的空间范围内的运动记录声学遥测进行比较。当使用高概率密度阈值的同位素分配，预测的位移距离的共同鲷是一个显着的预测的空间范围内，他们随后的运动记录声学遥测，虽然它是不太能够预测位移的方向。这第一次使用双同位素同位素
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.