Gigantic cannibals driving a whole-lake trophic cascade.
Trophic cascades have been a central paradigm in explaining the structure of ecological communities but have been demonstrated mainly through comparative studies or experimental manipulations. In contrast, evidence for shifts in trophic cascades caused by intrinsically driven population dynamics is meager. By using empirical data of a cannibalistic fish population covering a 10-year period and a size-structured population model, we show the occurrence of a dynamic trophic cascade in a lake ecosystem, in which the community over time alternates between two different configurations. The intrinsically driven change in the size structure of the fish population from a dominance of stunted individuals to a dominance of gigantic cannibals among adult individuals is the driving force behind distinct abundance switches observed in zooplankton and phytoplankton. The presence of the phase with gigantic cannibals depends critically on the energy they extract from their victims, allowing strong reproduction for a number of years.
Persson
Lennart
L
Department of Ecology and Environmental Science, Umeå University, SE-90187 Umeå, Sweden. Lennart.Persson@eg.umu.se
De Roos
Andre M
AM
Claessen
David
D
Bystrom
Par
P
Lovgren
Johan
J
Sjogren
Stefan
S
Svanback
Richard
R
Wahlstrom
Eva
E
Westman
Erika
E
D000818:Animals; D017753:Ecosystem; D005618:Fresh Water; D010471:Perches / Q000254:growth & development / Q000502:physiology*; D011156:Population Density; D015048:Zooplankton