Effects of the invasive crayfish Procambarus clarkii on growth and development of Pelophylax perezi tadpoles in field conditions

L Benejam,S Saura–Mas

doi:10.32800/abc.2019.42.0245

Abstract

Introduced predatory aquatic invertebrates may contribute to the global decline of amphibians as their larval are extremely vulnerable to predators. The objective of this study was to examine the effects of the predatory invasive crayfish Procambarus clarkii on the growth and development of native Iberian green frog tadpoles, Pelophylax perezi, in field conditions. We hypothesized that P. clarkii might affect P. perezi development by (a) inducing a delay in its metamorphosis and (b) reducing survival and mass of metamorphs. The experiment was developed in two ponds (with and without P. clarkii’s presence) in the Natural Park of Aiguamolls de l’Empordà (NE of the Iberian Peninsula). For each pond, groups of 10 tadpoles were randomly assigned to 15 cylindrical field enclosures. These enclosures avoided direct contact (i.e. predation) between both species. Our results suggest that, in field conditions, the presence of P. clarkii accelerates metamorphosis of P. perezi tadpoles. The higher growth rate of P. perezi through shorter larval periods could be the result of behavioural plasticity in response to the strong pressure imposed by P. clarkii. This conclusion would be in accordance with the hypothesis that phenotypic plasticity plays an important role in the conservation of P. perezi in front of biological invasions.

Highlights

Global change, including biological invasions, habitat fragmentation and destruction, acidity, pollution and emerging infectious diseases, is known to be causing amphibian declines worldwide (Houlahan et al, 2000; Saura–Mas et al, 2002; Collins and Storfer, 2003; Kats and Ferrer, 2003; Stuart et al, 2004; Hayes et al, 2010)
The final weight of metamorph increased with the increase of the larval period, and growth rate was significantly higher in the pond with P. clarkii
Our results suggest that the presence of the invasive species P. clarkii influences tadpole development since tadpoles reared in the presence of P. clarkii had a shorter larval period, reaching metamorphosis earlier than tadpoles reared in an environment without P. clarkii

Summary

Introduction

Global change, including biological invasions, habitat fragmentation and destruction, acidity, pollution (such as insecticides and herbicides) and emerging infectious diseases, is known to be causing amphibian declines worldwide (Houlahan et al, 2000; Saura–Mas et al, 2002; Collins and Storfer, 2003; Kats and Ferrer, 2003; Stuart et al, 2004; Hayes et al, 2010). The joint action of natural fluctuations in populations’ and anthropogenic might result in local extinction more than either alone (Pechmann et al, 1991). Allochthonous species often cause declines and even extinctions of native amphibian populations around the world (Carey et al, 2003; Lever, 2003)

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