Influence of Environmental Factors and Piscivory in Structuring Fish Assemblages of Small Alberta Lakes

Abstract

We surveyed 45 small lakes in central Alberta to determine if discrete, repeatable types of fish assemblages exist, to identify the main environmental and biotic processes likely responsible for assemblage-level patterns, and to compare and contrast Alberta patterns with those observed in other regions of North America. Overall, 11 species of fish were caught in 36 lakes; nine lakes were fishless. Hierarchical classification and detrended correspondence analysis of fish species presence/absence identified two main assemblage types, characterized by northern pike (Esox lucius) and yellow perch (Perca flavescens) versus brook stickleback (Culaea inconstans) and fathead minnow (Pimephales promelas). Pike/perch lakes were significantly deeper and larger than lakes of the stickleback/fathead assemblage type; however, a subset of the former group lacking yellow perch was environmentally similar to stickleback/fathead lakes. Piscivory by northern pike appears to be the dominant process maintaining nearly complete negative associations between members of the two assemblage types. Despite environmental and faunal-richness differences, our results were not unlike those from southern Ontario and northern Wisconsin. For small boreal lakes of North America, piscivory and processes related to a small number of environmental variables, such as maximum depth, surface area, and isolation, appear to be most important in structuring fish assemblages.

Apparent extirpation of prey fish communities following the introduction of Northern Pike (<em>Esox lucius</em>)

“…Northern Pike are generally considered to be piscivorous fish that subsist on a diet of prey fish, but pike-only lakes do exist in Canada (e.g., Robinson and tonn 1989;Beaudoin et al 1999;Venturelli and tonn 2006). Pike-only assemblages are thought to oc cur in small boreal lakes as a result of heavy piscivory by Northern Pike combined with winter hypoxia events that extirpate prey species less tolerant of harsh, low-oxygen conditions (Magnuson and Karlen 1970;Robinson and tonn 1989). Winterkill has never been observed in ElA lakes, despite very low oxygen levels measured under ice in a number of lake systems that support cyprinids year to year (M. Rennie, personal communication).…”

Development of a fish-based index to assess the eutrophication status of European lakes

“…Moreover, we focus here on the factors acting at the local scale. At the catchment scale, for example, connectivity can contribute to explain the structure of fish assemblages (Rahel, 1986;Robinson & Tonn, 1989) and probably also historical events (Banarescu, 1989).…”

L'habitat à une échelle globale : importance respective de l'immigration et de l'extinction pour les peuplements de poissons des petits lacs

“…Morphometry (area and depth) was highly ranked in both Wisconsin and Alberta ; a major pattern in these two North American regions was the presence of assemblages characterized by the presence of small-bodied fishes and the absence of piscivores. In both regions, the persistence of these small-bodied assemblages depends on the development of hypoxic winter conditions in these small shallow lakes, because hyoxia acts as a habitat filter that eliminates largebodied piscivores (TONN and MAGNUSON, 1982 ;ROBINSON and TONN, 1989 Bull. Fr.…”