Invasive tilapia juveniles are associated with degraded river habitats

Abstract

ABSTRACT1. Invasions are a main concern for conservationists. Identification of causes that raise or promote an invader's success is one of the first steps for preventing and/or fighting against invasions.2. In the Brazilian River Paraiba do Sul, juveniles of invasive tilapia Oreochromis niloticus were detected associated with degraded habitats (mainly pollution from various sources). The relative abundance of juveniles of the competitor native species pearl cichlid Geophagus brasiliensis, morphologically and ecologically very similar, was negatively associated with habitat degradation.3. A species-specific molecular marker was employed to permit unambiguous identification of these small juveniles (2-3 cm long), which represent the most vulnerable life stage of both species.4. It is suggested that adaptation to degraded habitats is one of the characteristics of invasive species, and consequently habitat conservation and restoration may help to prevent fish invasions.

Not all lineages are equally invasive: genetic origin and life-history in Atlantic salmon and brown trout acclimated to the Southern Hemisphere

“…Aquaculture is an activity in expansion worldwide (Reilly and Kaeferstein 1999;Naylor et al 2000;Vergara 2003;James 2009), but encompasses risks like potential invasions from accidental escapes (e.g. Linde et al 2008;Krishnakumar et al 2009). Total containment of cultured fish is not possible or is very difficult and total sterilization of all farm fish may not be feasible at this point (Piferrer et al 2009).…”

Heterotilapia buttikoferi (Hubrecht, 1881) (Perciformes: Cichlidae), an introduced exotic fish in the upper Paraná river basin

“…In Brazil it is likely that the introduction of this species was an accidental escape, as usual for other tilapia species (Linde et al 2008). The introduction of H. buttikoferi is worrying due to its biological characteristics such as high physiological plasticity and its ability in tolerate broad environmental variations, which are common features to other species of Tilapiini.…”

Fish invasion in the river systems of Guangdong Province, South China: Possible indicators of their success

“…management of aquaculture facilities, transportation and distribution, selective fishing and propagule pressure), among others (Moyle & Light, 1996;Kolar & Lodge, 2001;Lockwood et al 2005;Liu & Li, 2009;Winfield, Fletcher & James, 2011;Liu et al, 2014;Early et al, 2016). Many external factors influence invasion and spread of non-native aquatic species, including: (1) facilitated spread of non-native species by water diversion projects ; (2) the hydrological regime affects the distribution of the invasive fish species (Moyle & Light, 1996;Shuai et al, 2015); (3) level of human disturbance, a fluctuating environment may be one of the most important factors that favours invasion, and human disturbance is a significant influence (Linde, Izqouierdo, Moreira & Garcia-Vazouez, 2008;Meador et al, 2003). Many external factors influence invasion and spread of non-native aquatic species, including: (1) facilitated spread of non-native species by water diversion projects ; (2) the hydrological regime affects the distribution of the invasive fish species (Moyle & Light, 1996;Shuai et al, 2015); (3) level of human disturbance, a fluctuating environment may be one of the most important factors that favours invasion, and human disturbance is a significant influence (Linde, Izqouierdo, Moreira & Garcia-Vazouez, 2008;Meador et al, 2003).…”

“…Many external factors influence invasion and spread of non-native aquatic species, including: (1) facilitated spread of non-native species by water diversion projects ; (2) the hydrological regime affects the distribution of the invasive fish species (Moyle & Light, 1996;Shuai et al, 2015); (3) level of human disturbance, a fluctuating environment may be one of the most important factors that favours invasion, and human disturbance is a significant influence (Linde, Izqouierdo, Moreira & Garcia-Vazouez, 2008;Meador et al, 2003). Therefore, when biodiversity decreases, the biomass and numbers of invaders increases, and this mechanism is referred to as "biotic resistance" (Davies, Cavender-Bares & Deacon, 2010; Gu et al, 2014;Kimbro, Cheng & Grosholz, 2013;Meador et al, 2003;Moyle & Light, 1996); (5) water quality assists the establishment of invasive animals, as degraded water quality may promote invasion of non-native species (Greene, McElarney & Taylor, 2015;Linde et al, 2008); (6) the local diet and the commercial value of nonnative species (Irons et al 2007;Hu et al, 2015;Gu et al, 2015); and (7) the influence of the aquaculture industry on non-native species establishment and invasion, as the number of introduction events and the annual output of the non-native fish species impact the probability of their success (Early et al, 2016;Liu & Li, 2009). Therefore, when biodiversity decreases, the biomass and numbers of invaders increases, and this mechanism is referred to as "biotic resistance" (Davies, Cavender-Bares & Deacon, 2010; Gu et al, 2014;Kimbro, Cheng & Grosholz, 2013;Meador et al, 2003;Moyle & Light, 1996); (5) water quality assists the establishment of invasive animals, as degraded water quality may promote invasion of non-native species (Greene, McElarney & Taylor, 2015;Linde et al, 2008); (6) the local diet and the commercial value of nonnative species (Irons et al 2007;Hu et al, 2015;Gu et al, 2015); and (7) the influence of the aquaculture industry on non-native species establishment and invasion, as the number of introduction events and the annual output of the non-native fish species impact the probability of their success …”