Downstream impacts of a dam and influence of a tributary on the reproductive success of Leporinus reinhardti in São Francisco River

Downstream impacts of dams on fish fauna are poorly studied, despite causing thermal and hydrological changes that affect the reproductive activity of the fish community. The present study aims to evaluate the reproduction of Leporinus reinhardti in 2 sections of the São Francisco River, Brazil, downstream from the Três Marias Dam. Section 1 (S1) is the first 34 km downstream from Três Marias Dam and section 2 (S2) is 34 to 54 km downstream from the dam, where the São Francisco River receives a mid-sized tributary called the Abaeté River. In S1, the values of temperature, dissolved oxygen and flow were lower than those obtained in S2. In S1, females and males did not complete reproduction, a fact proven by the absence of spawned females and males. In S2, reproductive success was proven due to the presence of spawned females and males. Furthermore, the values of total length, body weight, gonadosomatic index, fecundity and vitellogenic oocytes were statistically higher than those obtained in S1. The canonical correlation test indicated that the reproduction of females is more dependent on environmental factors than that of males. In S2, L. reinhadti found appropriate conditions for reproduction, probably influenced by the Abaeté River, confirming the need of preserving this tributary for the reproductive success of this species.