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Stable isotope evaluation of population‐ and individual‐level diet variability in a large, oligotrophic lake with non‐native lake trout
Author(s) -
Ng Elizabeth L.,
Fredericks Jim P.,
Quist Michael C.
Publication year - 2017
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/eff.12273
Subject(s) - trout , ecology , biology , trophic level , food web , interspecific competition , littoral zone , isotope analysis , ecological niche , salvelinus , δ13c , population , forage fish , fishery , stable isotope ratio , fish <actinopterygii> , habitat , predation , physics , quantum mechanics , demography , sociology
Non‐native piscivores can alter food web dynamics; therefore, evaluating interspecific relationships is vital for conservation and management of ecosystems with introduced fishes. P riest L ake, I daho, supports a number of introduced species, including lake trout S alvelinus namaycush , brook trout S . fontinalis and opossum shrimp M ysis diluviana . In this study, we used stable isotopes (δ 13 C and δ 15 N ) to describe the food web structure of P riest L ake and to test hypotheses about apparent patterns in lake trout growth. We found that isotopic niches of species using pelagic‐origin carbon did not overlap with those using more littoral‐origin carbon. Species using more littoral‐origin carbon, such as brook trout and westslope cutthroat trout O ncorhynchus clarki lewisi , exhibited a high degree of isotopic niche overlap and high intrapopulation variability in resource use. Although we hypothesised that lake trout would experience an ontogenetic diet shift, no such patterns were apparent in isotopic signatures. Lake trout growth rates were not associated with patterns in δ 15 N , indicating that variation in adult body composition may not be related to adult diet. Understanding trophic relationships at both the individual and species levels provides a more complete understanding of food webs altered by non‐native species.