Naturwissenschaften

, Volume 98, Issue 1, pp 57–66

Innocent until proven guilty? Stable coexistence of alien rainbow trout and native marble trout in a Slovenian stream

  • Simone Vincenzi
  • Alain J. Crivelli
  • Dusan Jesensek
  • Gianluigi Rossi
  • Giulio A. De Leo
Original Paper

DOI: 10.1007/s00114-010-0741-4

Cite this article as:
Vincenzi, S., Crivelli, A.J., Jesensek, D. et al. Naturwissenschaften (2011) 98: 57. doi:10.1007/s00114-010-0741-4

Abstract

To understand the consequences of the invasion of the nonnative rainbow trout Oncorhynchus mykiss on the native marble trout Salmo marmoratus, we compared two distinct headwater sectors where marble trout occur in allopatry (MTa) or sympatry (MTs) with rainbow trout (RTs) in the Idrijca River (Slovenia). Using data from field surveys from 2002 to 2009, with biannual (June and September) sampling and tagging from June 2004 onwards, we analyzed body growth and survival probabilities of marble trout in each stream sector. Density of age-0 in September over the study period was greater for MTs than MTa and very similar between MTs and RTs, while density of trout ≥age-1 was similar for MTa and MTs and greater than density of RTs. Monthly apparent survival probabilities were slightly higher in MTa than in MTs, while RTs showed a lower survival than MTs. Mean weight of marble and rainbow trout aged 0+ in September was negatively related to cohort density for both marble and rainbow trout, but the relationship was not significantly different between MTs and MTa. No clear depression of body growth of sympatric marble trout between sampling intervals was observed. Despite a later emergence, mean weight of RTs cohorts at age 0+ in September was significantly higher than weight of both MTs and MTa. The establishment of a self-sustaining population of rainbow trout does not have a significant impact on body growth and survival probabilities of sympatric marble trout. The numerical dominance of rainbow trout in streams at lower altitudes seem to suggest that while the low summer flow pattern of Slovenian streams is favorable for rainbow trout invasion, the adaptation of marble trout to headwater environments may limit the invasion success of rainbow trout in headwaters.

Keywords

Rainbow troutMarble troutInvasionSurvivalBody growth

Supplementary material

114_2010_741_MOESM1_ESM.pdf (139 kb)
Appendix 1Mean daily water temperature in Sectors S (marble trout in sympatry with rainbow trout) and A (marble trout in allopatry) (PDF 138 KB)
114_2010_741_MOESM2_ESM.pdf (32 kb)
Appendix 2Model selection for estimation of apparent monthly survival (ϕ) and recapture (p) probabilities for marble and rainbow trout living in sympatry and for marble trout living in allopatry in Upper Idrijca. First, we modelled probability of recapture p by keeping the global model of survival. Then, we used the best model for p to model survival probabilities ϕ. For each candidate model, we report the AICc, Delta AICc, AICc weight, Model Likelihood (ML), number of parameters (N par) and deviance (Dev) (PDF 31.8 KB)
114_2010_741_MOESM3_ESM.pdf (22 kb)
Appendix 3Mean ± SD weight (g) for species-age combinations of trout sampled in Station A1 (allopatric marble trout, MTa) and Station S (sympatric rainbow and marble trout, RTs and MTs). Mean weight of rainbow trout is clearly higher than mean weight of marble trout living either in allopatry and sympatry. Sample size is reported in parenthesis (PDF 21.6 KB)
114_2010_741_MOESM4_ESM.pdf (25 kb)
Appendix 4Results of ANCOVAs for effect of distribution (marble trout in sympatry with rainbow trout vs marble trout in allopatry) on ln final weight (ln W2) as the dependent variable and ln initial weight (ln W1) as the covariate for each interval. Subscripts indicate d.f. associated with the F-statistics. Interaction between distribution and ln W1 was never significant in the ANCOVAs. Therefore, the interaction term was removed from the model and adjusted mean (at a common initial mass) and R2 were computed for the reduced model. Sampling intervals were from June (J) to September (S) of year t (summer) or from September of year t to June of year t+1 (winter) (PDF 25.2 KB)

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Simone Vincenzi
    • 1
  • Alain J. Crivelli
    • 2
  • Dusan Jesensek
    • 3
  • Gianluigi Rossi
    • 1
  • 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