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

Ecology and Evolution

Antti P. Eloranta³  Kimmo K. Kahilainen¹  Per-Arne Amundsen⁴  Rune Knudsen⁴  Chris Harrod² 

[1] Department of Environmental Sciences, University of Helsinki, Helsinki, Finland;Universidad de Antofagasta, Instituto de Ciencias Naturales Alexander von Humboldt, Antofagasta, Chile;Aquatic Ecology Department, Norwegian Institute for Nature Research, Trondheim, Norway;Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway

关键词: Benthic;    energy mobilization;    food‐chain length;    habitat coupling;    lake morphometry;    predation;    resource competition;    stable isotope analysis;    trophic niche;   

DOI  :  10.1002/ece3.1464

来源: Wiley

【 摘 要 】

Abstract

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 higher in large lakes with multispecies fish communities. We also expected top predators to occupy a higher trophic position in lakes with greater fish species richness due to potential substitution of intermediate consumers (prey fish) and increased piscivory by top predators. Based on stable carbon and nitrogen isotope analyses, the mean reliance of Arctic charr on littoral energy sources showed a significant negative relationship with lake surface area, whereas the mean trophic position of Arctic charr, reflecting the lake food-chain length, increased with fish species richness. These results were supported by stomach contents data demonstrating a shift of Arctic charr from an invertebrate-dominated diet to piscivory on pelagic fish. Our study highlights that, because they determine the main energy source (littoral vs. pelagic) and the trophic position of generalist top predators, ecosystem size and fish diversity are particularly important factors influencing function and structure of food webs in high-latitude lakes.

【 授权许可】

CC BY   
© 2015 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.