Feeding of holoshesthes Heterodon eigenmann (Teleostei, Cheirodontinae) of the cajuru reservoir (Minas Gerais, Brazil), in relation to the vegetal biomass on its depletion zone

Abstract

ABSTRACT. Stomach contents of Holoshesthes heterodoll Eigenmann, 1915 (Teleostei, Cheirodontinae), collected in the depletion zone ofCajuru reservoir when it was at its maximum water levei in two stations with different vegetal densities, were studied in order to investigate the influence ofthe flooded vegetal biol11ass on the food quantity and quality ingested by fi sh. Eighteen individuais from each station were examined. The standard length was 1.53±O.05 cm and 1.52±O.05 cm, respective1y at the lower biomass (8.19 kg dly weightJha) and higher biomass (38.10 kg dly weightJha) sampling stations. The stomach repletion Index (SRl) was applied for the quantitative ana1ysis. The alimentmy index (IA i) was used for the quali-quantitative analysis, with the volume of the items obtained through the points method. SR! did not show values significatively difterent between the two stations, p::::O.05 , by applying the Mann-Whitney test. ln both situations, Cladocera was the most important item. There were no correlation between the flooded vegetal biol11ass in lhe depletion zone and lhe intake of food by H. helerodon. However, as there were no empty stomachs, possibly even the lower vegetal biol11ass was enough to provide abundant feeding resources. KEY WORDS. Fish feeding, reservo ir, depletion zone, water leveI, vegetal biomass, Holoshesthes helerodol1.Reservoirs of tropical regions are young lakes and dominate fresh-water bodies in several are as (FERNANDO 1994). ln Brazil, and particularly in Minas Gerais State, the high number of dams, built for electric energy generation retains a significative portion of the superficial water volume (ELETROBRÁS 1990).The construction of hydroelectric dams and the consequent formation of artificiallakes arouses great changes in the fish community structure. The migratory species, also called piracema species, cannot transpose the barrier to complete their reproductive cycle, becoming less abundant upstream and downstream from the barrier and, in several times, absent in reservoirs (AGOSTfNHO et aI. 1992). ln these, the ichthyofauna becomes dominated by non-migrating species, of smaller size and low longevity (AGOSTINHO et aI. 1992). The changes tend to grow worse in rivers with successive dams (GODfNHO 1993).

Population structure, feeding and reproductive aspects of Serrapinnus heterodon (Characidae, Cheirodontinae) in a Mogi Guaçu reservoir (SP), upper Paraná River basin

“…Food items similar to those recorded here to S. heterodon were found in the diet of other cheirodontine species, differing only in the frequency they were ingested (Alvim et al, 1998;Luiz et al, 1998;Oliveira et al, 2001;Casatti et al, 2003;Hahn and Loureiro-Crippa, 2006;Pelicice and Agostinho, 2006;Hirano and Azevedo, 2007;Dias and Fialho, 2009;Santana-Porto and Andrian, 2009;Brandão-Gonçalves et al, 2010). Variations on food resource availability can lead to changes in frequency or quantity of items consumed by fishes (Deus and Petrere Junior, 2003).…”

“…Gomiero and Braga (2008), in lotic rivers of São Paulo State and Dias and Fialho (2009), in the Ceará Mirim River (RN), also classified S. heterodon as omnivorous species. Alvim et al (1998) classified this species as zooplanktivorous due to high consumption of cladocerans and Esteves (2000) as algivores, because of the predominance of filamentous algae. As in the present study, these authors also reported a reduced food spectrum for S. heterodon reflecting a diet with consumption Relating these results to the fecundity of these two species, we observed that M. uruguayanae have larger oocytes whereas S. heterodon has higher fecundity.…”

“…Studies with this species were conducted by Luiz et al (1998), Oliveira et al (2001), Casatti et al (2003, Hahn and Loureiro-Crippa (2006), Pelicice and Agostinho (2006) and Santana-Porto and Andrian (2009) that verified its feeding aspects, and Piana et al (2006), Andrade et al (2008), Lourenço et al (2008) and Benitez and Súarez (2009) which identified some population parameters of this species. Serrapinnus heterodon occurs in rivers, streams, oxbow lakes and reservoirs (Esteves, 2000;Oliveira and Garavello, 2003;Perez Junior and Garavello, 2007;Gonçalves and Braga, 2008), but it is still poorly known, with some studies regarding its diet (Alvim et al, 1998;Esteves, 2000; imaturas de insetos (Diptera e Odonata). Em comparação com outros queirodontíneos, S. heterodon tem fecundidade maior (média = 1.231 ± 440 ovócitos) e ovócitos menores (61 a 793 µm).…”

Cladocerans from gut contents of fishes associated to macrophytes from Taquari River Basin, MS, Brazil

“…Thus, some items, such as seeds and zooplankton eggs, may not be successfully digested, and may accumulate in the gut, while especially soft-bodied prey items, prone to rapid digestion, may be The great abundance of Cladocera associated with macrophytes could explain the importance of these organisms for the fish feeding in the present study (Lansac-Tôha et al, 2003;Güntzel et al, 2010). A similar conclusion was formed by Alvim et al (1998) for Holoshesthes heterodon feeding in macrophyte banks of a reservoir.…”

Diet shifts related to body size of the pirambeba Serrasalmus brandtii Lütken, 1875 (Osteichthyes, Serrasalminae) in the Cajuru Reservoir, São Francisco River Basin, Brazil

“…Its total flooded area is 27 km 2 and its maximum stored water volume is 192 x 10 6 m 3 (Mello, 1978). Studies of fishes feeding at this reservoir have already been developed for the Cheirodontinae subfamily species Serrapinnus heterodon (Eingenmann, 1915) (Alvim et al, 1997(Alvim et al, , 1998 and for young Serrasalmus brandtii (Alvim et al, 1999).…”