Introduced Goldfish Affect Amphibians through Inhibition of Sexual Behaviour in Risky Habitats: an Experimental Approach

Abstract

The introduction of alien species is one of the major causes of current and global biodiversity loss. The introduction of fish can be a particular threat to native amphibian populations, which are declining worldwide. One way for amphibians to persist in such altered environments is to adopt anti-predator strategies especially at the behavioural level. However, although it has been shown that avoidance behaviour may decrease the probability of being detected by a potential predator, little is known on the consequences on sexual behaviour. In this study, we tested the hypothesis that adult Alpine newts (Ichthyosaura alpestris) use shelters more often and exhibit less sexual activity in the presence of goldfish (Carassius auratus) and that they reduce sexual activity more in risky micro-habitats than in safe environments. To this end, we assessed behavioural patterns of adult newts in a replicated laboratory design. Goldfish were present in direct contact with newts in half of the tanks. Consistently throughout the study period, significantly more newts used shelter in the presence of fish than in their absence. Newts also significantly decreased their sexual activity level overall, but specially outside the shelter when they were in direct contact with fish. These results show that fish presence can affect newts in complex ways, such as through inhibition of their reproduction. Our work highlights that integrating behaviour in conservation studies is essential to understanding the patterns of coexistence and exclusion between introduced fish and amphibians.

Amphibians breeding in refuge habitats have larvae with stronger antipredator responses

“…Recent studies have proposed that direct contact with a potential predator can be perceived as a threat by aquatic newts more than the simple presence of cues (Winandy & Deno€ el, 2013b). In direct contact, salamander larvae might also experience a closer disturbance or perception of potential risk from the dragonfly, increasing their caution and decreasing their movement.…”

“…Moreover, we stopped them from extending their mouthparts and were always ready with tweezers to block snaps. This design was needed because one of the aims of the study was to compare indirect and direct contact with dragonfly larvae (see also Winandy & Deno€ el, 2013b.…”

The importance of phenotypic diversity in conservation: Resilience of palmate newt morphotypes after fish removal in Larzac ponds (France)

“…The fish invaders can have both consumptive and non-consumptive effects on native species such as amphibians (Finlay and Vredenburg 2007;Winandy and Denoël 2013). In Larzac, we mainly found goldfish to be present in ponds, but also pumpkinseed to a lesser extent (Supplementary Table 1; Denoël et al 2005a), whereas single cases of other species introductions have also been reported (Rondeau et al 2000).…”

Gambusia holbrooki, the ‘tadpolefish’: The impact of its predatory behaviour on four protected species of European amphibians

“…As a further example, generalist feeding fish (e.g. the goldfish Carassius auratus ), widely released in small ponds and fountains as ornamental pets, may alter the sexual behaviour and activity patterns of adult newts that reach breeding sites in spring (Mori et al, ; Winandy & Denoël, ). Herbivorous and omnivorous fish may damage amphibian eggs as well as the vegetation upon which they have been laid by the females (Monello & Wright, ).…”