They do not fear the unknown: Ancylus fluviatilis (Mollusca, Planorbidae) shows no predator avoidance behavior towards a novel invasive predator

Abstract Biological invasion is a strong threat to native biodiversity, with limnic systems being especially vulnerable due historical separation and resulting prey naivety. The naivety hypothesis states that species may not be able recognize novel predators lack of common evolutionary background and, therefore, become easy targets. In laboratory experiment, we added cues European bullhead ( Cottus gobio Linnaeus, 1758) invasive round goby [ Neogobius melanostomus (Pallas, 1814)] Ancylus fluviatilis Müller, 1774 originating from two different populations within the same river (one naive, one experienced towards goby) compared their predator avoidance behavior. Individuals both recognized known C. reduced locomotive activity. To cues, however, naive individuals did respond, thereby supporting hypothesis. Experienced individuals, in contrast, activity, suggesting learning effect co-occurrence prey. At fast moving fronts highly like N. melanostomus, can, hence, enhance negative impact on ecosystems. Behavioral adaptation reactions could, play an important role ecosystem resilience temporal dynamics.