engleski

Antagonistic interactions between native and invasive crayfish in laboratory conditions

Competitive exclusion is one of the mechanisms by which invasive crayfish displace native crayfish species. In this study, we examined competitive interactions between one of the most successful crayfish invaders of European freshwater ecosystems, the signal crayfish (Pacifastacus leniusculus), and the native narrow-clawed crayfish (Astacus laptodactylus). Both species already co-occur in the same river system in Croatia (the Korana River), where the invasive signal crayfish is gradually displacing the native narrow-clawed crayfish. In order to test the ability of one species to dominate the other, agonistic interactions between pairs of conspecifics (approximately 22 pairs per species) were compared to the characteristics and relative success in heterospecific dyads (mixed pairs, 5 in total). Comparisons between intraspecific pairs showed that context dynamics did not differ significantly between the species, except in fight number and duration. The signal crayfish dyads had engaged in fewer fights than the native narrow-clawed, but their duration was significantly longer. In mixed pair trials, P. leniusculus clearly dominated A. leptodactylus, being more likely to win heterospecific agonistic encounters. Furthermore, signal crayfish initiated a higher number of interactions and physical contacts than the native A. leptodactylus. This indicates that the success of P. leniusculus in agonistic encounters with the native counterpart might stem from its readiness to engage in and escalate a fight, and also through its readiness to withstand a fight for a longer period of time.

competitive exclusion; freshwater invasions; signal crayfish

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