Diet composition of Plagioscion squamosissimus (Heckel, 1840), a fish introduced into the Tietê River system

Abstract

Plagioscion squamosissimus is a species from the Amazon basin that was introduced into the Tietê River system. The present study aimed to analyse the feeding habits of this species in Bariri Reservoir and to verify the possible occurrence of ontogenetic changes in its diet composition. The samples were gathered in four periods of the year: February, June, September and November 2003. The fish were gathered with different fishing net meshes in three different reservoir portions. The alimentary items found in the stomachs were identified to the lowest possible taxonomic level and had abundance, occurrence frequency, volume and biomass determined. The Alimentary Index (IAi) was calculated for each alimentary item consumed by "corvina" for each studied period. Comparisons among the diet of different size classes of P. squamosissimus were done using the similarity coefficient of Jaccard and the Cluster Analysis (UPGMA). The Friedman proof was performed to verify if there is a significant ontogenetic variation in the species diet and changes in the consumption of different alimentary categories by P. squamosissimus among the sampled periods. P. squamosissimus presented a piscivorous feeding habit, although other items were also consumed. The biggest values of IAi were obtained for the alimentary item fish in the months of June (0.47) and November (0.39). The item Ephemeroptera (Campsurinae) was the most representative in February (0.30) and June (0.45). Despite the fact that P. squamosissimus consumed an ample spectrum of alimentary items, the ontogenetic changes were evident through the exploration of aquatic insects by the younger classes and by a diet mainly composed of fish in adult individuals. The alimentary plasticity of P. squamosissimus evidenced in this study might have contributed to the success of this species in Bariri Reservoir.Keywords: fish diet, "corvina", Plagioscion squamosissimus, introduced species. According to Braga and Braga (1987) the changing food habit of a species during its development is an adaptation intended to diminish intra-specific competition or to satisfy physiological demands that the fish might have, due to migration, sexual maturation and reproduction. Composição da dieta deThe aim of the present study was to characterise the food consumed by Plagioscion squamosissimus ("corvina") and to determine whether there are changes in the items consumed attributable to ontogenetic changes, in Bariri Reservoir, Middle Tietê River basin, São Paulo State, Brazil. Study Area MethodsSampling was carried out in four periods of the year: February, June, September and November of 2003, which cover the dry (June/September) and wet (February/ November) seasons. Fishes were sampled in three portions of the reservoir: upper, middle and lower (near the dam). At each sampling site, three batteries of gill nets were used, containing mesh sizes of: 3, 4, 6, 8, 10 and 11 cm opposite knots. Nets were placed in the reservoir and left for 12 hours. Species caught and respective numerical abundances...

Population structure and reproductive period of two introduced fish species in a Brazilian semiarid region reservoir

“…The decrease in the abundance of these species over the course of the study seems to be related to the trophic depression period of the ecosystem. Our results are also in agreement with other studies of introduced species that established successfully in many reservoirs in Brazil (Santos, Rocha, & Frédou, 2010;Chellappa et al, 2003;Santos, Silva, & Viana, 2003;Novaes et al, 2004; Bennemann, Carpa, Galvez, & Shibatta, 2006;Gomes, Dias, & Branco, 2008;Stefani & Rocha, 2009) and other countries (Japsen et al, 1997;Muñoz et al, 2006). Introduced species are extremely difficult to eradicate (Britton & Orsi, 2012), but a proposal to manage and control them is necessary to minimize their potentially harmful effects on the local aquatic community.…”

Genetic characterization of native and invasive Plagioscion squamosissimus (Perciformes, Sciaenidae) populations in Brazilian hydrographic basins

“…Further, trophic habits that permit the occupation of greater varieties of habitats and reproductive strategies are another important aspect that may have contributed towards the success of the species (Oliveira et al, 2005). Food flexibility must have helped in the adaptation of P. squamosissimus to the Paraná River basin since juveniles have different feeding habits than adults (Stefani and Rocha, 2009). The piscivorous habit may also be related to the species' success since most exotic species are fish-eating species (Agostinho et al, 2008;Pinto-Coelho et al, 2008).…”

“…According to Lockwood et al (2005), an important step in the study of biological invasion is the identification of biological variables that are useful to predict which species will become invasive and successful in a specific environment. An important characteristic of Plagioscion squamosissimus is its wide feeding spectrum (Stefani and Rocha, 2009), which may overlap with the diet of native fish and bring this introduced species into competition with native species for space and spawning sites.…”

Feeding patterns, trophic structure and damming rivers effect: studies applied in freshwater environments in the Brazilian semi-arid region

“…This species has been documented with great trophic and opportunistic plasticity Ferreira Filho et al 2014). Research carried out in reservoirs in other regions indicates P. squamosissimus with piscivorous habit, as in the Paranapanema and Tibagi rivers (Bennemann et al 2006), Tietê (Stefani and Rocha 2009) and Sobradinho reservoir . However, this species was also classified as carcinophagous in the ecological station reservoir J Anim Behav Biometeorol (2018) 6:41-47 of Tapacurá (PE) (Ferreira Filho et al 2014).…”