Title: Species-specific Responses of Planktivorous Fish to the Introduction of a New Piscivore: Implications for Prey Fitness
Citation: FRESHWATER BIOLOGY vol. 52 p. 1793-1806
Publication Year: 2007
JRC N°: JRC32803
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC32803
Type: Articles in periodicals and books
Abstract: The antipredator behaviours of facultative planktivorous fish species roach (Rutilus rutilus), perch (Perca fluviatilis), bleak (Alburnus alburnus), and rudd (Scardinius erythrophthalmus) were studied in a multi-year whole-lake experiment to evaluate species-specific behavioural and numerical responses to the stocking of pikeperch (Sander lucioperca), a predator with different foraging behaviour than the resident predators large perch (Perca fluviatilis) and pike (Esox lucius). Behavioural responses varied greatly during nighttime, ranging from both reduced activity and a shift in habitat use towards the littoral zone in roach and a reduced activity in small perch to unchanged habitat use and activity in rudd and to a lesser extent also in bleak. The former responses are consistent with a behavioural response that reduces predation risk in response to increased predation risk in the pelagic zone (relative to the littoral zone) from the introduced pikeperch. The divergent responses of the different planktivorous prey species highlight the potential variation in phenotypic response to predation risk from species of similar vulnerability (defence). The differential response had profound effects on fitness; the density of species that exhibited antipredator responses only slightly decreased (roach) and even increased (small perch), however the density of rudd, which did not exhibit antipredator response, decreased dramatically (more than 80%). The maladaptive behaviour of rudd can be explained by a behavioural syndrome, i.e. conflicting selection pressures. Our study extends previous studies, typically limited to more controlled venues, by illustrating the variability in intensity of phenotypic responses to predators, and the consequences to population density, in a large whole-lake setting.
JRC Directorate:Space, Security and Migration

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