Pereira Alexandre L, Benedito Evanilde, Sakuragui Cássia M
Departamento de Agronomia, Universidade Estadual de Maringá, Maringá, PR, 87020-900, Brasil.
An Acad Bras Cienc. 2007 Mar;79(1):41-9. doi: 10.1590/s0001-37652007000100006.
Stable isotopes of carbon (delta13C) and nitrogen (delta15N) 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 identified in the isotopic composition. The maximum and minimum contribution of C4 plants calculated integrating the variation of plants and fish were 47.7% and 2.4%, respectively. Among C3 plants, periphyton presented closer isotopic values to those observed for fishes, corresponding to an important carbon source. The proportion of ingested plant item is larger in rivers upstream from the reservoir (42.7%), which justifies the smaller trophic level among there. However, in the reservoir, the ingestion of fish 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 delta15N values, the former elevated the trophic level of L. friderici in the food web, because estimated trophic positions were based on fish items belonging to the 2nd (a) and to the 3rd (b) trophic levels.
利用碳（δ¹³C）和氮（δ¹⁵N）的稳定同位素来描述巴西科伦巴水库地区成年弗里德里希氏兔脂鲤的能量来源和营养级。样本采集于1999年4月至2000年3月。未发现同位素组成的空间变化。综合植物和鱼类的变化计算得出，C4植物的最大和最小贡献率分别为47.7%和2.4%。在C3植物中，周丛生物的同位素值与鱼类的更为接近，是重要的碳源。水库上游河流中摄入的植物性食物比例更大（42.7%），这解释了那里较低的营养级。然而，在水库中，鱼类的摄入量为81.4%，而植物性食物的摄入量占18.6%。大坝下游，植物性食物的占比更小（14.4%）。尽管根据饮食数据计算出营养级与根据δ¹⁵N值计算出的营养级成正比，但前者提高了弗里德里希氏兔脂鲤在食物网中的营养级，因为估计的营养级是基于属于第二营养级（a）和第三营养级（b）的鱼类食物得出的。
