With a growing world population and increasingly demanding consumers, the production of sufficient protein from livestock, poultry, fish represents serious challenge for future. Approximately 1,900 insect species are eaten worldwide, mainly in ...Read More

In population models, omnivorous predation (i.e., on >1 trophic level) generally has a destabilizing influence, whereas habitat heterogeneity tends to stabilize both predatory and competitive interactions. I experimentally evaluated the impact of native predator structural complexity staegeri freshwater littoral macroinvertebrate community. Perch (Perca fluviatilis) were stocked at three densities (no fish, low high natural densities) into pond enclosures with dense submerged vegetation...

The effects of submerged macrophytes and light on the foraging behaviour capture rate three fishes, perch (Perca fluviatilis), bream (Abramis brama) roach (Rutilus rutilus), were studied in laboratory. Attack frequency number captured chironomid larvae decreased for all species with increasing complexity artifical vegetation. Perch was, however, less affected by vegetation density than roach. Opposite obtained through a reduction intensity. Capture efficiency was reduced markedly darkness,...

We theoretically explore consequences of warming for predator-prey dynamics, broadening previous approaches in three ways: we include beyond-optimal temperatures, predators may have a type III functional response, and prey carrying capacity depends on explicitly modelled resources. Several robust patterns arise. The relationship between temperature can range from near-independence to monotonically declining/increasing hump-shaped. Predators persist U-shaped region resource supply...

Species biomass and size composition of fish faunas along a productivity gradient were studied in south Swedish lakes. Generally, with increasing (measured as chlorophyll content), Salmoniformes replaced by percids, which turn cyprinids, suggested previous studies. However, percids showed two peaks biomass, one medium productive lakes due to perch highly zander. Benthic piscivores present all lakes, whereas pelagic absent the least The proportion total peak largely reflecting importance...

In a comparative study covering 11 temperate lake ecosystems of Iow to intermediate productivity, we tested the predictions food chain model developed by L. Oksanen et al. The pelagic habitat most unproductive lakes lacked secondary carnivores (piscivores), whereas inhabited more productive in agreement with assumption that length is limited productivity system. observed relationships between planktivores (primary carnivores), zooplankton (herbivores), and phytoplankton producers) were for...

Although omnivory (the consumption of resources from more than one trophic level) is widespread, this fundamental limitation to the applicability food chain theory real communities has received only limited treatment. We investigated effects enrichment (increasing carrying capacity, K, resource) on a system consisting resource (R), an intermediate consumer (N), and omnivore (P) using general mathematical model tested relevance some its predictions laboratory mixed bacteria (=R) ciliates...

Abstract Although the scale‐dependence of ecological patterns and processes is recognized by freshwater ecologists, current knowledge scale effects rudimentary non‐quantitative. We review issues spatial temporal in this paper to highlight conceptual problems relating some potential solutions. present examples how a study influences observed their interpretation, discuss size an experimental arena degree which dynamics studied populations are influenced exchange (immigration emigration). The...

We studied the effects of water column mixing depth and background turbidity on phytoplankton biomass, light climate, nutrients in two field enclosure experiments designed to test predictions a dynamical model. In 1997 1998, we created gradients by enclosing 100-μm-filtered community phosphorus-deficient lake cylindrical plastic bags varying (1.5–15 m) which were continuously mixed. To mimic different levels turbidity, surrounded transparent walls with layer opaque white (1997) or black...

Abstract A recent meta‐analysis indicates that trophic cascades (indirect effects of predators on plants via herbivores) are weak in marine plankton striking contrast to freshwater ( Shurin et al. 2002 , Ecol. Lett. 5, 785–791). Here we show a community consisting jellyfish, calanoid copepods and algae, jellyfish predation consistently reduced but produced two distinct, opposite responses algal biomass. Calanoid act as switch between alternative along food chains different length with...

Abstract Many human influences on the world's ecosystems have their largest direct impacts at either top or bottom of food web. To predict ecosystem‐wide consequences we must understand how these propagate. A long‐standing, but so far elusive, problem in this endeavour is to reduce web complexity a mathematically tractable, empirically relevant system. Simplification main energy channels linking primary producers consumers has been recently advocated. Following approach, propose general...

Although theoretical and empirical studies show that spatial heterogeneity has important effects on the dynamics of populations structure communities, there been little rigorous quantification terms like "patchiness" or "spatial heterogeneity" in lotic systems. In order to compare different systems understand causes consequences heterogeneity, we must first be able quantitatively measure it. Spatial many aspects change with scale our observations, so need a battery descriptive measures...

Omnivory (the consumption of resources from more than one trophic level) is widespread in nature and has the potential to produce a richness indirect effects. Nevertheless, its effects on popula ...

The depth of the well-mixed surface layer lakes and oceans fundamentally affects phytoplankton populations. Specific nutrient supply, specific algal production, sinking losses all decrease with increasing mixing depth. I use a dynamical model to investigate how biomass, light availability, distribution nutrients among various pools vary along gradient, relationships these variables depend on velocity, abiotic absorbents, enrichment, mode supply (closed system recycling vs. open external...

We investigated experimentally how presence or absence of different piscivores influenced habitat use, diet, and individual growth two size classes juvenile perch (Perca fluviatilis) abundances resources in habitats. Pond enclosures encompassed 3 x 6 m dense vegetation 9 open habitat, were stocked with 75 young—of—year 30 1—yr—old either three piscivorous perch, northern pike (Esox lucius), no piscivores. Northern Pike both larger possessed a gape than perch. To isolate behavioral responses...

I experimentally evaluated the impact of habitat structural complexity on interactions between a generalist predator and benthic macroinvertebrate prey assemblage in freshwater pond. Benthi ...

Abstract In deep temperate lakes, the beginning of growing season is triggered by thermal stratification, which alleviates light limitation planktonic producers in surface layer and prevents heat loss to deeper strata. The sequence subsequent phenological events (phytoplankton spring bloom, grazer peak, clearwater phase) results part from coupled phytoplankton–grazer interactions. Disentangling separate, direct effects correlated climatic drivers (stratification‐dependent underwater climate...

In shallow aquatic systems, benthic and pelagic primary producers typically compete for light nutrients along opposing vertical supply axes: algae shade the habitat; conversely, intercept nutrient flux from sediment to habitat. We present a general framework analyzing such spatially asymmetric resource competition across habitat boundaries using mechanistic, dynamical model. visualize mechanisms determining outcome of these cross‐habitat interactions zero‐net‐growth isoclines, points,...