Indicators of movement and space use for two co-occurring invasive crayfish species

P.M Anastácio,F Banha,C Capinha,J.M Bernardo,A.M Costa,A Teixeira,S Bruxelas

doi:10.1016/j.ecolind.2015.01.019

Abstract

Red swamp crayfish (Procambarus clarkii) and signal crayfish (Pacifastacus leniusculus) are two invasive freshwater species with a worldwide distribution. The objective of this work was to investigate how the two species move and use space in an area of recent coexistence. Simultaneously, we test the use of new tools and indices to describe their movement patterns. To accomplish this we performed a radio-tracking program within a river-type habitat during two different periods (September/October 2010 and June/July 2013). We used spatial analysis tools to map crayfish radio-location data with and without accounting for the curvature of the river. To assess the consistency of the direction of movement and of the distances traveled by crayfish, two indices were developed. To assess the habitat preferences of each species we applied Ivlev's Electivity Index and the Standardized Forage Ratio. Movement of P. clarkii and P. leniusculus differed. The average detected movement was 8.8mday−1 for P. clarkii and 17.5mday−1 for P. leniusculus. However, crayfish behavior ranged from almost complete immobility – sometimes during several days – to large movements, in half a day, up to a maximum of 255m for P. clarkii and 461m for P. leniusculus. The proportion of upstream or downstream movements was independent of the species and both species displayed no preference for either direction. The indices of consistency of movement showed a large interindividual variation. Species and period (2010 or 2013) affected the mean daily distance traveled, maximum observed distance from location of release and percentage of observations under vegetation cover. The Ivlev's Electivity Index and the Standardized Forage Ratio presented similar results. P. clarkii showed a preference for pool areas with riparian vegetation cover while P. leniusculus preferred riffle and pool areas with riparian vegetation cover. Our work provided new and valuable data for modeling the active dispersal of these two problematic invaders in a context of coexistence.

Highlights

Due to their economic value, several species of crayfish were introduced outside their native ranges
Crayfish behavior ranged from almost complete immobility – sometimes during several days – to large movements, in half a day, up to a maximum of 255 m for P. clarkii and 461 m for P. leniusculus
The mean movement was 8.8 m day−1 (95% confidence interval: 2.575–15.025) for P. clarkii and 17.5 m day−1 (95% C.I.: 8.554–26.446) for P. leniusculus (Fig. 3)

Summary

Introduction

Due to their economic value, several species of crayfish were introduced outside their native ranges. There are numerous freshwater crayfish species becoming invasive in the areas of introduction (Holdich, 1988; Henttonen and Huner, 1999; Gherardi, 2013) and the two major examples are the red swamp crayfish (Procambarus clarkii) and the signal crayfish (Pacifastacus leniusculus). The red swamp crayfish is native to subtropical regions of northeastern Mexico and south-central USA This species has a highly plastic reproductive cycle (Gherardi, 2006) and a wide ecological plasticity (Gherardi, 2006; Souty-Grosset et al, 2006) and currently it is the most widely introduced crayfish in the world (Gherardi, 2006). In Europe the species was first introduced in 1973 in southern Spain (Habsburgo-Lorena, 1978) and it rapidly spread across several European countries (Laurent, 1997; Souty-Grosset et al, 2006) showing the widest invasive range for an alien crayfish

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