Spatial variation in the stable isotopes of 13C and 15N and trophic position of Leporinus friderici (Characiformes, Anostomidae) in Corumbá Reservoir, Brazil

Abstract

Stable isotopes of carbon (δ 13 C) and nitrogen (δ 15 N) were used to describe sources of energy and trophic position for adult Leporinus friderici in the area of the Corumbá Reservoir, Brazil. Samples were collected from April 1999 to March 2000. Spatial variations were not identifi ed in the isotopic composition. The maximum and minimum contribution of C 4 plants calculated integrating the variation of plants and fi sh were 47.7% and 2.4%, respectively. Among C 3 plants, periphyton presented closer isotopic values to those observed for fi shes, corresponding to an important carbon source. The proportion of ingested plant item is larger in rivers upstream from the reservoir (42.7%), which justifi es the smaller trophic level among there. However, in the reservoir, the ingestion of fi sh was 81.4%, while ingested plants contributed with 18.6%. Downstream from the dam, participation of plant item was even smaller (14.4%). Although the trophic position calculated with diet data was proportional to the one calculated with δ 15 N values, the former elevated the trophic level of L. friderici in the food web, because estimated trophic positions were based on fi sh items belonging to the 2 nd (a) and to the 3 rd (b) trophic levels.

Population structure, growth and fishery yield of Leporinus acutidens (Valenciennes, 1837) (Teleostei: Anostomidae) in Yacyretá Reservoir (Argentina)

“…During the first years after closing, impoundments present high abundance of small fishes (Agostinho et al, 1999), ensuring winter food availability. During this time, this species forages opportunistically on this resource (>75%; Luz- Agostinho et al, 2006;Pereira et al, 2007). During the spring, at the beginning of the spawning period (November to January; Hirt & Flores, personal communication), the reduction of the availability of small fish (prey growth) and the demand from gonads maturation can be related to low growth and ring formation.…”

“…However, Agostinho et al (2004) did not include it among migratory fishes in the high Paraná basin. Moreover, this species had a diet based on fish and terrestrial plants during the first years after the closing of the Corumbá reservoir, according to both stomach contents and stable isotope analysis (Luz- Agostinho et al, 2006;Pereira et al, 2007).…”

Fluxo De Energia Em Comunidades Aquáticas, Com Ênfase Em Ecossistemas Lóticos

“…Enquanto Lopes et al (2007) encontraram variabilidade quanto ao carbono utilizado por Prochilodus lineatus em diferentes ambientes do mesmo ecossistema, Benedito-Cecilio et al (2004) registraram para espécies da Amazônia predominância de C 3 , podendo ser proveniente das algas ou da vegetação ripária. Pereira et al (2007), por outro lado, apontam variações na abundância de C 4 e C 3 na dieta de Leporinus friderici, assim como , que também verifi caram predominância de C 3 na dieta dos peixes do Rio Baía, planície de inundação do alto rio Paraná..…”

Relações tróficas e isotópicas entre duas espécies de caracídeos e a cobertura do solo em córregos da bacia do rio Corumbataí, SP

“…Os valores de δ 15 N são freqüentemente utilizados para caracterizar a posição trófica dos organismos nas cadeias alimentares, pois os sinais de δ 15 N nos tecidos dos consumidores são normalmente enriquecidos em 3‰ em relação a suas presas (VANDER ZANDER; CABANA; RAMUSSEM, 1997;POST, 2002;HERSHEY et al, 2007;PEREIRA, BENEDITO;SAKURAGUI, 2007;RYBCYNSKI et al, 2008 BERNOT; ROSI-MARSHALL, 2007).…”