Foraging Capacity and Resource Synchronization in an Ontogenetic Diet Switcher, Pikeperch (Stizostedion Lucioperca)

Abstract

Foraging capacity and resource synchronization in an ontogenetic diet switcher, pikeperch (Stizostedion lucioperca)Persson, Anders; Brönmark, Christer Link to publication Citation for published version (APA): Persson, A., & Brönmark, C. (2002). Foraging capacity and resource synchronization in an ontogenetic diet switcher, pikeperch (Stizostedion lucioperca). Ecology, 83(11), 3014-3022.General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Abstract. Species undergoing ontogenetic diet shifts face a risk of resource competition that delays transitions between feeding stages. Such ontogenetic bottlenecks are common in piscivorous fish because competition with future prey may retard growth and prevent a size advantage. In pikeperch (Stizostedion lucioperca), year class strength of 0ϩ cohorts is highly variable and positively related to early onset of piscivory. To identify the causes of this pattern, we experimentally quantified size-dependent planktivorous and piscivorous foraging capacity and incorporated the data into a growth model. For any given prey type and size, foraging capacity described a hump-shaped relationship with predator size. Foraging capacity on daphnids peaked at a pikeperch length of 66 mm, suggesting a narrow scope of planktivory. The highest capacity in the piscivorous niche was reached at a predator-to-prey length ratio of 5, where the ratio was an integrated measure of predator size over several prey sizes. With the growth model, we derived size distributions of 0ϩ cohorts as functions of resource levels. Simulations revealed two major determinants for the year class strength of pikeperch. First, discontinuous availability of prey sizes counteracted switching to piscivory within the first growing season. This was accentuated by prey fish growth, which caused the planktivory and piscivory niches to separate over time and limited the time window when diet shift was possible. Second, the hump-shaped relationship between size and foraging capacity resulted in growth reduction when growing out of the planktivorous niche. Switching to piscivory in our model occurred along a perpendicular relationship between fish prey and zooplankton density. Zooplankton density determined whether pikeperch reached a size advantage over prey, and fish prey density affected whether the foraging return of piscivory was higher than planktivory. Individuals not reaching a size advantage over prey and failing to become piscivorous were stunted at a size when consumption bal...

Resource heterogeneity, diet shifts and intra-cohort competition: effects on size divergence in YOY fish

“…The timing of ontogenetic niche shifts, i.e. from zooplankton to macroinvertebrates, has been shown to depend on a decline in the availability of the Wrst prey as well as on the relative availability and proWtability of both prey types (Persson and Greenberg 1990;Persson and Brönmark 2002;Galarowicz et al 2006). Thus, for a diet shift to occur, it requires both a high enough density of the second prey in relation to the Wrst prey and that the consumers have reached a size large enough to feed eYciently on the second prey (Hambright 1991).…”

“…These diet and habitat shifts over ontogeny relate to gape-constraints and size-dependent diVerences in foraging eYciency on diVerent prey types (Mittelbach 1981;Werner and Hall 1988;Mittelbach and Persson 1998). The timing of diet shifts also depends on prey densities, related to the possibility to adjust resource use in accordance to the relative proWtability of available resources (Persson and Greenberg 1990;Olson 1996;Persson and Brönmark 2002;Galarowicz et al 2006). Variation in the timing of diet shifts can thus be hypothesised to result in diVerent degrees of size variation within cohorts depending on the relative size-dependent resource proWtability in diVerent niches, ultimately leading to bimodal size distributions (e.g.…”

“…Furthermore, factors related to the interaction between individual life histories and the environment, such as predation risk, unequally distributed resources and resource heterogeneity combined with Xexible behaviour in resource use, may inXuence the degree by which size variation among individuals develops over time (DeAngelis et al 1993;Persson and Brönmark 2002;PWster and Stevens 2002;Post 2003;Peacor et al 2007). Variation in resource use among individuals can, for example, be due to a substantial variation in the rate by which growing individuals reach diVerent ontogenetic niches (Olson 1996;Mittelbach and Persson 1998;Hjelm et al 2000;Post 2003) as a result of food-dependent growth and development (PWster and Stevens 2002;De Roos et al 2003).…”

The origin and development of individual size variation in early pelagic stages of fish

“…This is particularly likely for light competition among plants, but has also been evoked as a potential mechanism behind growth depensation in animal populations. Still, in the latter case, the argument has been based on specific assumptions about ontogenetic niche shifts or has not taken population feedbacks via resources into account (Harper 1977;DeAngelis et al 1993b;Persson and Brönmark 2002). Individual variation in growth may also result from positive correlations in growth independent of size, i.e.…”

Guppy populations differ in cannibalistic degree and adaptation to structural environments

“…We relate these changes mainly to a change in overall cannibalism, and to the fact that we always included size combinations in the trials for which it was very diYcult for the females to cannibalise. The victim/cannibal size-ratio in our experiments varied from 0.19 to 0.32, which is high in comparison with the observed optimal size ratio for other species of Wsh (range of 0.15-0.2) (Malmquist et al 1992;Claessen et al 2000;Finstad et al 2001;Persson and Brönmark 2002;Keskinen and Marjomäki 2004). Guppies are born at a relatively large size (compared to the adult size) and are thus exposed to the highest risk of being cannibalised when Wrst born; the risk declines as they grow.…”