Fish fauna disassembly after the introduction of a voracious predator: main drivers and the role of the invader’s demography

Small size today, aquarium dumping tomorrow: sales of juvenile non-native large fish as an important threat in Brazil

“…This index includes the screening of potential biological traits related to invasion risk, such as maximum adult length, aggressiveness, tolerance to salinity, history of establishment, breeding in the wild and competition with local species. For each species, traits were classified as + (low), ++ (moderate) and +++ (high), according to the literature (Nico et al, 2007;Ng, Tan, 2010;Herder et al, 2012;Jaafar et al, 2012;Liew et al, 2012;Carvalho et al, 2014;Pelicice et al, 2015;Motionaquaticsuk, 2016;Froese, Pauly, 2016). Traits were categorized in the following way: 1) Maximum adult length (+ = 20.0 to 40.0 cm, ++ = 40.1 to 60.0 cm, +++ = above 60.1 cm); 2) Aggressiveness (+ = harmless, ++ = peaceful, +++ = aggressive); 3) Tolerance to salinity (+ = freshwater, ++ = freshwater/brackish, +++ = saltwater); 4) History of establishment (+ = 0 to 7 countries, ++ = 8 to 15 countries, +++ = more than 16 countries); 5) Breeding in the wild (+ = absent, ++ = low to moderate, +++ = high); 6) Competition with local species (+ = absent, ++ = low to moderate, +++ = high).…”

“…These fishes are the major group of piscivorous cichlids in South America, successful invaders of environments disturbed by human activities (Espínola et al, 2010). In Brazil, two large cichlids, C. piquiti and C. kelberi, are extensively established in non-Amazonian basins (Carvalho et al, 2014), and studies have shown that the introduction of these fishes is associated with deleterious effects on local fish assemblages (Carvalho et al, 2014;Pelicice et al, 2015). Although the invasion of Cichla is usually associated to sport fisheries, the importance of aquarium dumping may increase in next years, since these species are now popular among hobbyists in Brazil and elsewhere.…”

Feeding and reproductive ecology of Cichla piquiti Kullander & Ferreira, 2006 within its native range, Lajeado reservoir, rio Tocantins basin

“…While severe impacts have been reported elsewhere (Pinto-Coelho et al, 2008;Menezes et al, 2012), there is no evidence of disturbance in Amazonian reservoirs. There are some competing/complementary hypothesis to explain its nuisance behavior when non-native (e.g., voracity, naiveté effect, lack of refuges, pulse of young predators; see Pelicice et al, 2015), but the high diversity of prey resources in Amazonian ecosystems may play a role in mitigating strong predatory effects. These systems are characterized by a mega-diversity of small-sized fish (Lowe-McConnell, 1999;Santos & Ferreira, 1999), which may represent a variety of resource options and avoid the excessive pressure upon a small set of populations.…”

“…In addition, the regional climate in the Tocantins basin is tropical warm, so temperature is not a limiting factor. In southern basins, where seasonal variation in temperature is remarkable (warm summers and cold winters), reproduction is restricted to warm months (Souza et al, 2008;Gomiero et al, 2009;Vieira et al, 2009;Pelicice et al, 2015). Therefore, environmental stability in Lajeado (water level and temperature) may explain the absence of trade-offs in energy allocation over the year, since reproductive and feeding activities are continuous among different individuals of the population.…”

“…For example, in natural fluvial environments, reproduction is usually constrained by water level variation (Jepsen et al, 1999;Muñoz et al, 2006), while feeding is diverse and essentially piscivorous (Jepsen et al, 1997;Winemiller, 2001;Montaña et al, 2011). In non-Amazonian reservoirs, reproduction is constrained by temperature (Souza et al, 2008;Gomiero et al, 2009;Vieira et al, 2009;Pelicice et al, 2015) and diet is poor and based on cannibalism, invertebrates and non-native fish (Fugi et al, 2008;Capra & Benneman, 2009;Villares Junior & Gomiero, 2010;Santos et al, 2011). In Amazonian reservoirs, however, feeding and breeding patterns may be less constrained by environmental variation, considering that seasonal variations in hydrology and temperature are small, and that prey fish (small-sized) are abundant and diverse.…”