Lake size and fish diversity determine resource use and trophic position of a top predator in high-latitude lakes

Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the extent and determinants of such coupling remains a topical area of ecological research and is largely unknown in oligotrophic high-latitude lakes. We analyzed food-web structure and resource use by a generalist top predator, the Arctic charr Salvelinus alpinus (L.), in 17 oligotrophic subarctic lakes covering a marked gradient in size (0.5–1084 km2) and fish species richness (2–13 species). We expected top predators to shift from littoral to pelagic energy sources with increasing lake size, as the availability of pelagic prey resources and the competition for littoral prey are both likely to be h...

顶级捕食者的猎物偏好及跨栖息地边界的能量流动，对于水生和陆地生态系统的结构与功能具有基础性意义，因其可能对生产力、物种多样性及食物网稳定性产生强烈影响。在湖泊中，沿岸带与敞水带食物网组分通常相互耦合，并受广食性鱼类顶级捕食者调控。然而，这种耦合的程度与决定因素仍是生态学研究的热点领域，且在贫营养（oligotrophic）高纬度湖泊中大多未知。我们分析了17个亚北极贫营养湖泊中广食性顶级捕食者——北极红点鲑（Salvelinus alpinus (L.)）的食物网结构与资源利用情况，这些湖泊的大小（0.5–1084 km²）和鱼类物种丰富度（2–13种）呈现显著梯度。我们推测，随着湖泊面积增大，顶级捕食者会从利用沿岸带能量源转向敞水带能量源，因为敞水带猎物资源的可获得性以及对沿岸带猎物的竞争都可能会h...