Fish fauna destruction after the introduction of a non-native predator (Cichla kelberi) in a Neotropical reservoir

Abstract

In South America, the introduction of peacock-bass (Cichla), a voracious predator fish, has been an underestimated threat for native fish communities. Although this predator is widespread in many reservoirs, few studies have explored its impact on biodiversity. To investigate the relationship between invasion and fish diversity, the present study followed a natural experiment in the Rosana Reservoir (Paraná River basin), where Cichla kelberi were introduced in 2004. We monitored fish assemblages associated with submerged macrophytes between 2003 and 2007, using a 1 m 2 throw trap. In the years following the introduction, fish diversity dramatically changed. For example, in March 2007, mean fish density and richness were reduced by ca. 95 and 80%, respectively, and many small-sized species had vanished. One aspect was the gradual change of biodiversity, which unfolded at two times during each year: (1) impacts during summer/autumn periods, which coincided with large shoals of young C. kelberi in the patches; and (2) assemblage recovery during the spring. The sequence of extinction-colonization events, however, might not be able to maintain fish assemblages due to the decrease in recovery intensity each spring; assuming a constant decline rate in the coming years, we predict complete assemblage extinction by the summer of 2010. Results from this natural experiment provided evidence supporting the collapse of fish assemblages soon after the introduction of C. kelberi. Such rapid destruction (2 years) reveals an important homogenizing force behind this predator and stresses the need for control measures that prevent new transferences among South American basins.

Inventory of the fish fauna from Ivaí River basin, Paraná State, Brazil

“…Similar studies are not available for Micropterus salmoides, but the fact that this species is also a piscivore indicate that it also has a potential to affect negatively native species from the Ivaí River. This calls for a close observation upon invasive species, as in the study of Pelicice & Agostinho (2009), who reported on the relationship between the expansion of Cichla kelberi Kullander & Ferreira in the Rosana Reservoir and the decline of fish communities associated with macrophyte stands. Although this species is absent from the Ivaí River Basin, a similar threat may be posed by M. salmoides and P. squamosissimus.…”

The fish fauna of the Jacaré-Guaçu River basin, Upper Paraná River basin

“…The invasion and adaptive success of alien species are a major threat to the worldwide fish fauna (Rodríguez 2001, Pelicice & Agostinho 2009). In general, alien species show a rapid dominant groups of this basin also belonging to these two orders.…”

Spatial pattern of a fish assemblage in a seasonal tropical wetland: effects of habitat, herbaceous plant biomass, water depth, and distance from species sources

“…However, cattle farming in this system has led to replacement of native vegetation by exotic species, as an alternative to improving animal productivity (Junk, 2000). Many studies show that exotic species can reduce the survival, density, biomass, species richness, diversity and evenness as well ecosystem process in worldwide terrestrial (Hoffmann et al, 2008;Hejda et al, 2009) and aquatic environments (Latini & Petrere, 2004;Pelicice & Agostinho, 2009). Thus, the replacement of native vegetation by exotic pasture can affect the structure and dynamics of fish assemblages (Baber et al, 2002) by altering the composition and abundance of native plant species, as well as the hydrological conditions of the landscape.…”