Fish assemblage structure, and factors mechanisms appearing important in the ecological maintence of these structures, were examined for 18 small lakes northern Wisconsin during summer winter. The study was focused around following questions. Are there discrete, repeatable groups fish assemblages? If so, are they temporally stable? What relations between structure habitat complexity, physical disturbance, biotic interactions insular nature lakes? A comparative approach used to generate...

We compared characteristics of fish assemblages from Finland and northern Wisconsin on several scales to investigate community-level similarity in environmentally similar but faunistically different small lakes. Although has only half as many fishes its regional species pool, local richness did not differ between the two regions. Variability composition among was lower Finland, suggesting that a large proportion fauna could maintain populations across broad range environmental conditions,...

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 assess possible climatic warming fishes their habitats. However, the problem extrapolating these or other multispecies assemblages is not straightforward, given complexity community-level phenomena. I present a conceptual framework views as products series filters, operating at different spatial temporal scales, through...

Abstract – We examined whether solvent‐based lipid extractions, commonly used for stable isotope analysis (SIA) of biota, alters δ 15 N or 13 C values fish muscle tissue whole juvenile fish. Lipid extraction from led to only small (<1‰) shifts in and values. By contrast, ecologically significant (+3.4‰ +2.8‰ N) were observed Sample variance was not affected by extraction. For tissue‐specific SIA, two sample aliquots may be required: a lipid‐extracted aliquot carbon when differing content...

The probability of catching a fish in gill net may be separated into two components: (1) the encountering and (2) being caught retained net. We consider encounter to directly proportional distance travelled by during sampling period. This will increase with size if different-sized swim for same amount time because swimming speed increases size. Routine measured laboratory three size-classes bloater (Coregonus hoyi) increased length 0.8 power. Corrections were incorporated selectivity...

Detecting mechanisms that structure ecological communities often requires investigations at appropriate spatial and temporal scales. A 15—mo, whole—lake experiment revealed direct indirect by which a fish predator its prey population, primarily affecting recruitment of young—of—the —year (YOY) fish. Piscivorous Eurasian perch (Perch fluviatilis) were added to two four sections divided lake in eastern Finland previously stocked with crucian carp (Carassius carassius). Although the crucians...

FisheriesVolume 41, Issue 7 p. 385-391 Perspective: Canadian Aquatic Resource Section Climate Change Impacts on Freshwater Fishes: A Perspective Mark S. Poesch, Poesch poesch@ualberta.ca Department of Renewable Resources, University Alberta, 751 General Services Building, Edmonton, AB, Canada, T6G 2H1Search for more papers by this authorLouise Chavarie, Louise Chavarie Center Systems Integration and Sustainability, Michigan State University, East Lansing, MISearch authorCindy Chu, Cindy Chu...

To evaluate the roles of extinction and isolation in predicting richness composition fish assemblages small forest lakes Finland Wisconsin, we analyzed data from 114 Finnish 55 Wisconsin 0.2–86.9 ha area. Six variables characterized properties stream corridors, land barriers, source pools invading species; four were related to habitat severity, lake area, productivity. Two types multivariate analyses used: nonparametric classification regression trees (CART) parametric linear discriminant...

We surveyed 45 small lakes in central Alberta to determine if discrete, repeatable types of fish assemblages exist, identify the main environmental and biotic processes likely responsible for assemblage-level patterns, compare contrast patterns with those observed other regions North America. Overall, 11 species were caught 36 lakes; nine fishless. Hierarchical classification detrended correspondence analysis presence/absence identified two assemblage types, characterized by northern pike...

1. Community concordance measures the degree to which patterns in community structure a set of sites are similar between two different taxonomic groups. Although seldom incorporated into studies lake ecosystems, aquatic birds can be influenced by same environmental features lakes affect fish and invertebrates, interact with these organisms directly as predators, competitors or prey. We surveyed north‐central Alberta, Canada, determine if co‐occurring bird assemblages displayed concordance,...

We compared population densities and size structures of central mudminnows (Umbra limi) occurring with without yellow perch (Perca flavescens) in six small lakes northern Wisconsin over a 6-yr period. Our observations suggested that size-dependent predator–prey interaction was major mechanism organizing these assemblages. Densities cooccurring averaged 12% populations mudminnow-only lakes. Large (≥76 mm total length) predominated whereas smaller fish single-species Following severe...

Freshwater ecosystems and the fisheries they support are increasingly threatened by human activities. To aid in their management protection, we outline nine key principles for supporting healthy productive based on best available science, including laws of physics chemistry apply to ecology; population dynamics regulated reproduction, mortality, growth; habitat quantity quality prerequisites fish productivity; connectivity among habitats is essential movements fishes resources; freshwater...

Crucian carp, a common Eurasian cyprinid fish, shows striking dichotomies in several aspects of its physiology and ecology, at both the individual population levels. These consistently reflect communities ecosystems which they occur, contrasting crucian carp that occur monocultures (single-species fish assem blages) ponds with those occurring multi-species assemblages, primarily lakes. Dichotomies also physiological state individuals between summer winter. All these dichotomies, involving...

Abstract Stable isotope analysis has emerged as an important tool in aquatic ecology. For fish, dorsal muscle from sacrificed individuals traditionally been used stable studies; however, there are many instances when lethal sampling is undesirable. We evaluated the feasibility of using adipose and caudal fin clips alternatives to studies for five species salmonids. Because fish size water temperature can affect ratios, we also determined whether length date affected difference signatures...

Abstract Polymorphism in northern fishes is common, but the extent to which polymorphism occurs Lake Trout Salvelinus namaycush , a species generally associated with low intraspecific variation, not well known. This study examined of inhabiting shallow‐water zones (≤30 m) Great Bear Lake, Northwest Territories. We combined an analysis classical morphometric and traditional linear measures shape (geometric morphometrics) quantify morphological differences body shape, head fin length...

A review of headwater lakes in undisturbed watersheds on the Boreal Plain, with indirect gradient analyses chemical data, indicated a clear separation between those wetland-dominated (57–100% wetland variable proportions bog, fen, swamp, and marsh cover) upland-dominated (0–44% cover). In former, percentage cover watershed was positively correlated total phosphorus (TP, r 2 = 0.78, primarily bog), nitrogen (TN, 0.50), dissolved organic carbon (DOC, 0.74) concentrations. Rich fens appeared to...

The Arctic cod (Boreogadus saida), a key component of the marine food web Canadian high waters, occurs at temperatures close to or below zero. We established complete energy budget for this fish, based on laboratory measurements consumption (C), growth (G), respiration (R), egestion (F), and excretion (U) about 0°C. An average (N = 3) individual juvenile fed live zooplankton was 100C 50G + 24R 9SDA 3F 6U 8Z, where SDA is specific dynamic action (derived from previously published studies) Z...

1. Stable carbon and nitrogen isotope fish stomach content analyses were used to investigate food webs in five relatively undisturbed lakes on the Boreal Plain of Canada. analysis was also determine importance external internal sources. 2. Overlap signatures primary producers made it difficult unambiguously feeding habits many invertebrates. However, suggested that inputs detectable aquatic chains one lake with a short water residence time («1 year). In other four lakes, times ≥1 year,...

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 small, relatively slender, short—lived fish; multispecies assemblages lakes display opposite traits. Field laboratory experiments have implicated predation as an important mechanism structuring crucian assemblages. To investigate role(s) density dependence pond populations, we manipulated crucians stocked into four...

Great Bear Lake is the most northerly lake of its size and provides unique opportunities for intraspecific diversification. Despite increasing attention to polymorphism, several knowledge gaps remain (e.g. determining extent diversification in large relatively pristine lakes at which spatial scale it can occur). We focused on geographical patterns morphological differentiation within trout (Salvelinus namaycush) describe two levels intralake Lake. used a combination geometric traditional...

The distribution of lake trout (Salvelinus namaycush) with respect to water temperature, dissolved oxygen, and light intensity was surveyed in three small Canadian Shield lakes at the Experimental Lakes Area, northwestern Ontario. Based on hydroacoustic gillnet surveys, there considerable variation among temperatures occupied by during summer. During day, were concentrated 4-8°C Lake 375, broadly distributed from 6 15°C 442, epilimnion 19°C 468. At night, all epilimnetic waters 19-20°C....

Small, shallow seepage lakes in northern Wisconsin that have both low winter oxygen concentrations and pH possess depauperate fish assemblages containing primarily or exclusively central mudminnows, Umbra limi, yellow perch, perca flavescens. Six times during three years I determined the total densities of five by mark—recapture catch—per—effort methods. The richness these varied from one to species a nested pattern. While seasonal variations density occurred within among due growth,...

Decisions in fishery management usually are made on a species-by-species and site-by-site basis because most information about fishes has been collected organized this way. A comparative, community-level approach can contribute to the development of strategies for large sets lakes fish assemblages. Here we describe an similar concept lake classification, using techniques multivariate community analysis (ordination, multiple discriminant analysis). This reveal patterns among assemblages...