Inhaltszusammenfassung

The signal crayfish, Pacifastacus leniusculus, is the most widespread and one of the most successful crayfish invaders in Europe. In 2012 it was recorded in a karstic river in the continental part of Croatia, the Korana River, where it was illegally introduced. Here, it presents an alarming threat to native crayfish diversity, since three native crayfish species have viable populations in the Korana River and its tributaries. We explored the dynamics of signal crayfish range expansion in the ...The signal crayfish, Pacifastacus leniusculus, is the most widespread and one of the most successful crayfish invaders in Europe. In 2012 it was recorded in a karstic river in the continental part of Croatia, the Korana River, where it was illegally introduced. Here, it presents an alarming threat to native crayfish diversity, since three native crayfish species have viable populations in the Korana River and its tributaries. We explored the dynamics of signal crayfish range expansion in the Korana River, by i) examining the increase in its range, ii) analysing changes in its relative abundance, size and sex structure at former invasion fronts in 3 years (since the first study), and iii) examining the status of the native narrow-clawed crayfish (Astacus leptodactylus) in the area. Signal crayfish range increased 2.5 times since 2012, and currently covers 18.7% of the entire watercourse. Recorded dispersal rate (2.23 – 2.84 km/year) was similar in upstream and downstream direction. At both former invasion fronts, increase in the relative signal crayfish abundance by 4.9 – 6.1 times resulted in significant decrease in the size of signal crayfish individuals, demonstrating the prominent effect of density and competition intensity on the size structure its populations. The native A. leptodactylus was completely displaced from mixed populations at former invasion fronts, while at new invasion fronts no narrow-clawed crayfish were recorded. Abundant A. leptodactylus populations are still present in the Mrežnica and Kupa Rivers, and outside the invaded area in the Korana River. We discuss these findings in the context of potential management actions and legal requirements for such actions under EU Regulations.» weiterlesen» einklappen

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Klassifikation

DDC Sachgruppe:
Biowissenschaften, Biologie