Intraspecific resource partitioning in brown trout: the temporal distribution of foraging is determined by social rank

Abstract

Summary1. Animals can reduce the competition for a limiting resource by temporal segregation, whereby individuals exploit the resource at different times. However, the pay-offs may vary predictably over time, and it can be predicted that (a) more dominant competitors should gain access to resources at the preferred times and (b) the degree of temporal segregation will vary with the intensity of competition. 2. Here we show experimentally that individual brown trout Salmo trutta (L.) made sequential use of foraging areas, with dominant individuals feeding mainly at the most beneficial times of dusk and the early part of the night while more subordinate fish fed at other times. 3. However, the degree of overlap in foraging times between high-ranking fish was dependent on energetic demands. At low temperatures (when requirements were low) the temporal activity patterns of top-ranking fish were synchronized, with foraging concentrated at the preferred times. In contrast, when temperature was raised to increase energetic requirements, activity patterns showed strong temporal segregation: the most dominant fish remained predominantly nocturnal, whereas second-ranking fish became increasingly diurnal. 4. This is the first experimental demonstration of shifts in the daily pattern of activity caused by varying intensity of intraspecific competition.

Effect of Feeding with Different Dietary Protein Levels and Starvation on the Health, Nonspecific Immune Parameters, Behavior and Histoarchitectures of Fantail Goldfish (Carassius auratus L.)

“…While the effect of dietary protein levels and starvation on swimming frequency and duration, there was a significant increase in group B (low protein in diet) when compared with group and D (fasting group). This result was in harmony with that mentioned by Martínez M, Alanara A, Brannas E, et al [29][30][31] who illustrated that, food deprivation and deficiency in the diet leads to changes in metabolic activity and changes in territorial behavior strategies and activity pattern especially swimming.…”

Partitioning of Time as an Ecological Resource

“…In brown trout (Salmo trutta), individuals differ in their daily activity patterns, with dominant individuals feeding mainly at the most beneficial times of dusk and the early part of the night, while more subordinate fish feed at other times (Alanara et al 2001, Bachmann 1984, Giroux et al 2000. Moreover, the degree of overlap in foraging times between high-ranking fish depended on energetic demands related to water temperatures.…”

“…Theory postulates that temporal partitioning among competitors and between predators and their prey may promote coexistence in ecological communities (e.g., Schoener 1974a, Richards 2002, Wiens et al1986. Although the role of temporal partitioning in structuring communities has never been a strong focus of ecology, over the years a number of studies have accumulated that attach 154 KRONFELD-SCHOR DAYAN ecological significance to activity patterns (e.g., Kenagy 1973, Kunz 1973, as well as studies that record competition-or predation-induced shifts in activity patterns (e.g., Alanara et al 2001, Fenn & MacDonald 1995.…”

Dietary overlap and food resource partitioning among fish species of a tropical estuary in Northeastern Brazil

“…Overall, fish species exhibit different diets and feeding behaviors that help them to minimize niche overlap and interspecific competition for food estuarine resources (Alanara et al 2001;Dantas et al 2012). In estuaries, in particular, prior studies have shown that fish species commonly explore distinct food resources (Kanou et al 2004;Dolbeth et al 2008).…”