Winter diet of brown trout Salmo trutta in groundwater-dominated streams: influence of environmental factors on spatial and temporal variation.
Winter diet composition of brown trout Salmo trutta was quantified from November to March in 35 temperate groundwater-dominated streams in south-eastern Minnesota, U.S.A., in relation to stream physical characteristics including drainage area, channel slope and influence of groundwater on stream thermal regime. Aquatic invertebrates made up the majority of S. trutta diet in all streams and sampling periods and individual S. trutta typically had consumed 30 or more prey items at each sampling event. Differences in diet composition were greater among streams than between sampling periods within a stream, with Gammarus spp., Brachycentrus spp., Glossosoma spp., Chironomidae and Physella spp. the most common taxa. Landscape-scale stream characteristics were not significantly associated with S. trutta consumption or diet composition. Winter was period of significant activity in groundwater-dominated streams, as S. trutta fed on a variety of aquatic prey taxa highlighting the importance of winter base-flow in moderating S. trutta populations in seasonally cold catchments.
University of Minnesota Conservation Biology Program, University of Minnesota, 1980 Folwell Ave, St Paul, MN, 55108, U.S.A.. will.french@state.mn.us.
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French
University of Minnesota Conservation Biology Program, University of Minnesota, 1980 Folwell Ave, St Paul, MN, 55108, U.S.A.|Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, 2003 Upper Buford Circle, St Paul, MN, 55108, U.S.A.
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Vondracek
Department of Entomology, University of Minnesota, 1980 Folwell Ave, St Paul, MN, 55108, U.S.A.. will.french@state.mn.us.
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Ferrington
Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, MN, 55108, U.S.A.
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Finlay
Fisheries Research, Minnesota Department of Natural Resources, 1801 South Oak Street, Lake City, MN, 55041, U.S.A.
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Dieterman
D000818:Animals; D004032:Diet; D017753:Ecosystem; D005247:Feeding Behavior; D060587:Groundwater; D007448:Invertebrates; D008910:Minnesota; D045483:Rivers; D012621:Seasons; D014337:Trout
Brachycentrus; Chironomidae; Gammarus; Physella; Salmonidae; trophic ecology