Oecologia

, Volume 156, Issue 3, pp 523–534

The role of density-dependent individual growth in the persistence of freshwater salmonid populations

  • Simone Vincenzi
  • Alain J. Crivelli
  • Dusan Jesensek
  • Giulio A. De Leo
Population Ecology - Original Paper

DOI: 10.1007/s00442-008-1012-3

Cite this article as:
Vincenzi, S., Crivelli, A.J., Jesensek, D. et al. Oecologia (2008) 156: 523. doi:10.1007/s00442-008-1012-3

Abstract

Theoretical and empirical models of populations dynamics have paid little attention to the implications of density-dependent individual growth on the persistence and regulation of small freshwater salmonid populations. We have therefore designed a study aimed at testing our hypothesis that density-dependent individual growth is a process that enhances population recovery and reduces extinction risk in salmonid populations in a variable environment subject to disturbance events. This hypothesis was tested in two newly introduced marble trout (Salmo marmoratus) populations living in Slovenian streams (Zakojska and Gorska) subject to severe autumn floods. We developed a discrete-time stochastic individual-based model of population dynamics for each population with demographic parameters and compensatory responses tightly calibrated on data from individually tagged marble trout. The occurrence of severe flood events causing population collapses was explicitly accounted for in the model. We used the model in a population viability analysis setting to estimate the quasi-extinction risk and demographic indexes of the two marble trout populations when individual growth was density-dependent. We ran a set of simulations in which the effect of floods on population abundance was explicitly accounted for and another set of simulations in which flood events were not included in the model. These simulation results were compared with those of scenarios in which individual growth was modelled with density-independent Von Bertalanffy growth curves. Our results show how density-dependent individual growth may confer remarkable resilience to marble trout populations in case of major flood events. The resilience to flood events shown by the simulation results can be explained by the increase in size-dependent fecundity as a consequence of the drop in population size after a severe flood, which allows the population to quickly recover to the pre-event conditions. Our results suggest that density-dependent individual growth plays a potentially powerful role in the persistence of freshwater salmonids living in streams subject to recurrent yet unpredictable flood events.

Keywords

Compensatory responses Flood disturbance Marble trout Population dynamics Resilience 

Supplementary material

442_2008_1012_MOESM1_ESM.doc (90 kb)
ESM1 (DOC 89.5 kb)
442_2008_1012_MOESM2_ESM.doc (42 kb)
ESM2 (DOC 42 kb)

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Simone Vincenzi
    • 1
  • Alain J. Crivelli
    • 2
  • Dusan Jesensek
    • 3
  • Giulio A. De Leo
    • 4
  1. 1.Dipartimento di Scienze AmbientaliUniversità degli Studi di ParmaParmaItaly
  2. 2.Station Biologique de la Tour du ValatArlesFrance
  3. 3.Tolmin Angling AssociationMost na SociSlovenia
  4. 4.Dipartimento di Scienze AmbientaliUniversità degli Studi di ParmaParmaItaly

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