Trophic interaction between an introduced (peacock bass) and a native (dogfish) piscivorous fish in a Neotropical impounded river

Abstract

In order to investigate trophic interactions, the diets of peacock bass (Cichla kelberi) and dogfish (Galeocharax knerii) were studied in the Corumbá Reservoir between 1997 and 2000. This dietary study was performed to assess the niche breadth of each species and to determine the degree of niche overlap during different phases of reservoir colonization. During Period I, peacock bass were absent or recorded only in low numbers; during Periods II and III, peacock bass reached high abundances in the reservoir. Interactions between the species were weak during period I, but, during Periods II and III, they were found to interact intensively. The diet overlap was highest during Period II. The niche breadth fluctuated for both species in the different phases. Greater niche breadth was observed for dogfish during periods of low peacock abundance (i.e., Period I), and the lowest niche breadth value was observed during Period II. During the same period, the peacock bass exhibited a wide foraging niche. During Period III, the dogfish showed an increase of its niche breadth, while for the peacock bass a simultaneous decrease in the niche breadth, caused by increasing rates of cannibalism, was recorded. These results show that the presence of peacock bass induces changes in the diet of dogfish, probably due to a restricted number of prey items.

Limnology in the Upper Paraná River floodplain: large-scale spatial and temporal patterns, and the influence of reservoirs

“…and Hydrilla verticillata (L.f.) Royle) are observed mainly in the Paraná main channel and its associated habitats, and are due to the higher water transparency of these habitats (Thomaz et al, 2009). Similarly, the increase of peacock bass (Cichla kelberi Kullander and Ferreira, 2006) in the Paraná River may be explained by higher water transparency in this river, what has been shown for other Neotropical ecosystems (e.g., Fugi et al, 2008).…”

Feeding dynamics of Cichla kelberi Kullander & Ferreira, 2006 introduced into an artificial lake in southeastern Brazil

“…GSIs were calculated separately for males and females. Reproduction has a strong influence on cannibalism, as observed in several studies with Cichla in places where the species was introduced (Godinho et al, 1994;Duraez et al, 2000;Santos et al, 2001;Gomiero & Braga, 2004a, b;Fugi et al, 2008).…”

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

“…A diverse diet has been reported in other Amazonian systems, with predominance of fish and low rates of cannibalism (Jepsen et al, 1997;Winemiller, 2001;Montaña et al, 2011). When Cichla is non-native, however, its diet is poor and based on cannibalism, invertebrates and a few non-native fish (Fugi et al, 2008;Capra & Benneman, 2009;Villares Junior & Gomiero, 2010;Santos et al, 2011). In Lajeado reservoir, cannibalism and non-fish resources summed less than 1% of all volume ingested.…”

“…Basic ecological aspects (e.g., feeding, reproduction) have been studied in hydrographic basins where Cichla is nonnative, particularly in the rio Paraná basin (e.g., Fugi et al, 2008;Souza et al, 2008;Gomiero et al, 2009;Vieira et al, 2009;Espínola et al, 2010;Villares Junior & Gomiero, 2010;Luiz et al, 2011;Santos et al, 2011). This information is important to clarify issues related to impact and invasion, but has little significance for the understanding of colonization, dynamics and persistence of native populations in Amazonian reservoirs.…”

“…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.…”