Premium
Estimating the feeding range of a mobile consumer in a river–flood plain system using δ 13 C gradients and parasites
Author(s) -
Bertrand Micheline,
Cabana Gilbert,
Marcogliese David J.,
Magnan Pierre
Publication year - 2011
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1111/j.1365-2656.2011.01861.x
Subject(s) - food web , δ13c , perch , trophic level , zooplankton , ecology , apex predator , population , range (aeronautics) , biology , ecosystem , periphyton , spatial ecology , environmental science , primary producers , phytoplankton , fishery , stable isotope ratio , biomass (ecology) , fish <actinopterygii> , physics , quantum mechanics , demography , materials science , sociology , nutrient , composite material
Summary 1. The feeding range of an individual is central to food web dynamics as it determines the spatial scale of predator–prey interactions. However, despite recognition of its importance as a driving force in population dynamics, establishing feeding range is seldom done as detailed information on trophic interactions is difficult to obtain. 2. Biological markers are useful to answer this challenge as long as spatial heterogeneity in signal is present within the area investigated. A spatially complex ecosystem, Lake St. Pierre (LSP), a fluvial lake of the St Lawrence River (Québec, Canada), offered a unique opportunity to determine the feeding range of a secondary consumer, yellow perch ( Perca flavescens ) using isotopic ratios of carbon (δ 13 C). However, because food chains based on phytoplankton have generally more negative δ 13 C than those depending on periphyton, it was essential to determine the contribution of zooplankton in fish diet to correctly interpret spatial patterns of δ 13 C. We used parasites in perch to examine whether their δ 13 C was reflecting local δ 13 C baseline conditions rather than a feeding specialization on zooplankton. 3. δ 13 C of primary consumers was highly variable and exhibited a striking gradient along the shore–channel axis, suggesting that δ 13 C should reflect an individual consumer’s spatial position in LSP. 4. This strong isotopic gradient allowed us to estimate the spatial scale of the resources used by individual perch following an approach presented by Rasmussen, Trudeau & Morinville (Journal of Animal Ecology, 78, 2009, 674). By comparing the δ 13 C variability in perch to that of primary consumers, we estimated that the adults feeding range was around 2 km along the shore–channel axis. 5. The combined use of isotopic ratios and parasites allowed us to determine that the adult population uses a wide range of habitats between the flood plain and the main channel. However, individually, each perch depended on a limited foodshed.