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The trophic niche of sculpins Cottus spp. in forage fish assemblages of boreal lakes
Author(s) -
Mozzon Christina M.,
Lescord Gretchen L.,
Savage PascaleLaure,
Johnston Thomas A.
Publication year - 2020
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.14188
Subject(s) - trophic level , sculpin , biology , salvelinus , forage fish , esox , ecology , piscivore , cottidae , ecological niche , cottus , fishery , pelagic zone , trout , habitat , pike , predation , fish <actinopterygii> , predator
We compared the trophic niches of freshwater sculpins Cottus spp. with those of other co‐habiting forage fishes in two groups of boreal lakes with distinct habitats and fish communities. Near North Lakes (45° 00′ to 47° 30′ N) were deeper, stratified and contained lake trout Salvelinus namaycush as the apex piscivore, whereas Far North Lakes (51° 10′ to 52° 20′ N) were shallower, did not stratify and contained pike Esox lucius and walleye Sander vitreus as the apex piscivores. Trophic niches of sculpins and other forage fishes were compared based on niche metrics calculated from muscle stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope ratios. In Near North Lakes, sculpins were found almost exclusively in deep, offshore waters and their niche positions reflected a greater reliance on pelagic production (lower δ 13 C) and a higher trophic elevation (higher δ 15 N) compared with most other forage fishes. Furthermore, sculpins in Near North Lakes tended to have larger trophic niches (occupied greater area in δ 13 C– δ 15 N space), particularly in the food chain (δ 15 N) dimension, than other cohabiting forage fishes. In contrast, sculpins in Far North Lakes were commonly found in the nearshore and had trophic niche positions and sizes that were similar to those of the other cohabiting forage fishes. This study illustrates the flexibility in the realised trophic niches of sculpins in relation to habitat availability and fish community composition in boreal lakes.