Assessment of interspecific interactions between the invasive red-claw crayfish (Cherax quadricarinatus) and the Mozambique tilapia (Oreochromis mossambicus).

S Chivambo,A Mussagy,A Barki

doi:10.1590/1519-6984.217868

S Chivambo, A Mussagy + Show 1 more

Open Access

https://doi.org/10.1590/1519-6984.217868

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Abstract

The Australian red-claw crayfish, Cherax quadricarinatus, has been introduced for aquaculture purposes worldwide and consequently colonized natural environments, where it might cause ecosystem services losses or adversely affect native species and the local environment. This species was first found in Pequenos Libombos Reservoir in Maputo Province, Southern Mozambique in the late 2009 and is linked to reduction in tilapia fisheries. This study, conducted in 2015 under controlled conditions, aimed to assess the interspecific relationships between the Mozambique tilapia (Oreochromis mossambicus) and the alien crayfish. For both species, no significant differences in growth and survival rates were found between animals reared in the presence versus the absence of heterospecifics, indicating no direct deleterious interspecific effects. Behavioural observations revealed that fish and crayfish competed for shelter and food. Both species reduced the foraging in the presence of heterospecifics during feeding period, in the daytime. Crayfish seemed to have an advantage in competition for shelter, suggesting that they may interfere with tilapia sheltering activity and make tilapia vulnerable to predators in natural habitats.

Highlights

Freshwater ecosystems are often subject to human‐mediated introduction of invasive species
For both crayfish and tilapia, there was no significant difference in specific growth weight (SGR) between individuals reared in the absence versus presence of heterospecifics (F1,4=1.78, P=0.25 and F1,4=1.10, P=0.35, respectively)
No significant difference in survival rate was found between crayfish or tilapia reared in the absence versus presence of heterospecifics (Z=0.0, P=1 and Z=0.7, P=0.48, respectively) (Table 1). 3.2

Summary

Introduction

Freshwater ecosystems are often subject to human‐mediated introduction of invasive species. Tilapia species have been moved from Africa throughout the tropics (Reynolds, 2011) while crayfish have been moved from North America to Europe, Asia and Africa (Holdich et al, 2009; Reynolds, 2011) and from Australia to Africa, Europe and South America (De Moor, 2002; Harlioğlu and Harlioğlu, 2006; Leitão, 2009). Many of these species have been accidentally or deliberately introduced into natural freshwater ecosystems such as lakes, reservoirs and river basins, where self-sustaining feral populations became established and widespread (Ahyong and Yeo, 2007; Doupé et al, 2004; Goren and Galil, 2005; Leland et al, 2012)

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