Predator-induced changes in morphology of a prey fish: the effects of food level and temporal frequency of predation risk
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In a series of experiments, we investigated the effects of food availability and risk frequency on the dynamics of predator-induced changes in growth and morphology of prey fish using goldfish (Carassius auratus) as our test species. In experiment 1, we fed goldfish high or low food rations and exposed them to either alarm cues from conspecifics, cues from swordtails or a water control. After 60 days, goldfish in the alarm cue treatment significantly increased their body depth and body weight but had smaller body length than goldfish exposed to swordtails cues or water, likely reducing their vulnerability to gape-limited predators. Importantly, food level had an impact on the amplitude of the morphological changes. In experiment 2, goldfish were exposed to two different frequencies of predation cues or a water control for 50 days. The cues were either continued or discontinued from day 51 to 100, and all cues were resumed from day 101 to 150. We found that goldfish exposed to predation cues increased their depth and weight at a faster rate than did the goldfish exposed to water, and of particular significance was the fact that frequency of risk had an effect on the amplitude of the change. When the cues were interrupted, the increase in growth rate parameters was reduced to the level of the goldfish exposed to water. However, when the cues were resumed, the rate increased to match the growth rate of the goldfish that were continuously exposed to the cues. Finally, we staged encounters between goldfish of differing morphologies and yellow perch (Perca flavescens) and found that deep-bodied goldfish had better survival than the shallow-bodied ones. These experiments illustrate the dynamic nature of inducible morphological defences.
KeywordsPredator/prey interactions Morphological defences Inducible defences Chemical cues Goldfish
The Natural Sciences and Engineering Research of Canada and the University of Saskatchewan provided financial support to D. P. Chivers, M. C. O. Ferrari and X. Zhao. All work reported herein was in accordance with University of Saskatchewan Committee of Animal Care and Supply protocol # 19920077.
- Beauchamp P (1952a) Un facteur de la variabilite chez les Rotiferes du genre Bachionus. Comptes rendus hebdomadaires des seances. Acad Sci 234:573–575Google Scholar
- Beauchamp P (1952b) Variation chez les Rotiferes du genre Bachinus. Comptes rendus hebdomadaires des seances. Acad Sci 235:1355–1357Google Scholar
- Cadieux CL (1953) Giant goldfish: your dainty pets can become the bane of outdoor waters. Nat Hist 62:16–17Google Scholar
- Chivers DP, Mirza RS (2001) Predator diet cues and the assessment of predation risk by aquatic vertebrates: a review and prospectus. In: Marchlewska-Koj A, Lepri JJ, Müller-Schwarze D (eds) Chemical signals in vertebrates, vol 9. Plenum Press, New York, pp. 277–284Google Scholar
- Chivers DP, Smith RJF (1998) Chemical alarm signalling in aquatic predator-prey systems: a review and prospectus. Écoscience 5:338–352Google Scholar
- Edmunds M (1974) Defence in animals: a survey of antipredator defences. Longman, New-YorkGoogle Scholar
- Lima SL (1998) Stress and decision making under the risk of predation: recent developments from behavioral, reproductive, and ecological perspectives. Adv Study Behav: Stress Behav 27:215–290Google Scholar
- Pettersson LB, Brönmark C (1997) Density-dependent costs of an inducible morphological defence in crucian carp. Ecology 78:1805–1815Google Scholar
- Relyea RA (2002b) The many faces of predation: how selection, induction, and thinning combine to alter prey phenotypes. Ecology 83:1953–1964Google Scholar
- Wisenden BD, Chivers DP (2005) The role of public chemical information in antipredator behaviour. In: Ladich F, Collins SP, Moller P, Kapoor BG (eds) Fish chemoreception. Science Publisher, NH, pp 259–278Google Scholar
- Zar JH (1999) Biostatistical analysis, 4th edn. Prentice-Hall Inc., New JerseyGoogle Scholar