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1990
Many autecological effects of temperature on fish are known, and fishery biologists have begun to incorporate this knowledge into population-level relations that can be used to assess possible effects of climatic warming on fishes and their habitats. However, the problem of extrapolating these or...
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1985
Small, shallow seepage lakes in northern Wisconsin that have both low winter oxygen concentrations and low pH possess depauperate fish assemblages containing primarily or exclusively central mudminnows, Umbra limi, and yellow perch, Percaflavescens. Six times during three years I determined the...
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Density-Dependent Effects and the Regulation of Crucian Carp Populations in Single-Species Ponds
Download1994
Tonn, W. M., Holopainen, I. J., Paszkowski, C. A.
Crucian carp (Carassius carassius) is often the only fish species present in small ponds of northern Europe. Such populations are typically at high densities and consist primarily of small, relatively slender, and short-lived fish; populations in multispecies assemblages in lakes display opposite...
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Diet and Growth of Northern Pike in the Absence of Prey Fishes: Initial Consequences for Persisting in Disturbance-Prone Lakes.
Download2006
Venturelli, P. A., Tonn, W. M.
The northern pike Esox lucius is a renowned piscivore, but will prey opportunistically on invertebrates (e.g., in small lakes of boreal Alberta, where winterkill can unexpectedly reduce or eliminate prey fishes). We emulated such a disturbance by stocking a fishless lake with northern pike and...
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Fish Assemblages in Subarctic Lakes: Does Fire Affect Fish–Environment Relations in Northern Alberta?
Download2004
Tonn, W. M., Scrimgeour, G. J., Paszkowski, C. A., Aku, P. K. M., Boss, S. M.
In 1995, a wildfire swept through a large area of the Caribou Mountains, a remote subarctic plateau of northern Alberta, Canada, containing numerous unstudied and unexploited small lakes. To assess near-term effects of fire and to establish information on assemblage–environment relations in this...
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1998
Rask, M., Tonn, W. M., Toivonen, J., Magnuson, J. J., Banerjee, A., Sanchez, O.
To evaluate the roles of extinction and isolation in predicting richness and composition of fish assemblages in small forest lakes of Finland and Wisconsin, we analyzed data from 114 Finnish and 55 Wisconsin lakes 0.2-86.9 ha in area. Six isolation variables characterized properties of stream...
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Patterns in the species composition and richness of fish assemblages in northern Wisconsin lakes
Download1982
Fish assemblage structure, and factors and mechanisms appearing important in the ecological maintenance of these structures, were examined for 18 small lakes in northern Wisconsin during summer and winter. The study was focused around the following questions. Are there discrete, repeatable groups...
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1992
Paszkowski, C. A., Tonn, W. M., Holopainen, I. J.
Detecting mechanisms that structure ecological communities often requires investigations at appropriate spatial and temporal scales. A 15-mo, whole-lake experiment revealed direct and indirect mechanisms by which a fish predator structured its prey population, primarily by affecting recruitment...
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Trophic Relations of the Red-Necked Grebe on Lakes in the Western Boreal Forest: A Stable-Isotope Analysis.
Download2004
Tonn, W. M., Klatt, P. H., Paszkowski, C. A., Gingras, B. A., Wilcox, K.
We compared trophic ecology of grebes inferred from stable-isotope analysis to that from gut contents, and compared isotopic ratios of Red-necked Grebes (Podiceps grisegena) from lakes differing in their food webs. Analyses of different grebe tissues (egg yolk and albumen, pectoral and leg...