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

Abstract

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 vitello genic 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.

Influence of a large dam and importance of an undammed tributary on the reproductive ecology of the threatened fish matrinxã Brycon orthotaenia Günther, 1864 (Characiformes: Bryconidae) in southeastern Brazil

“…In the present study, B. orthotaenia presented a periodic strategy, with high fecundity and total spawning, occurring during the period of high water temperature, dissolved oxygen concentration, and flow in site 2. The canonical correlation shows that reproduction in males of matrinxã is less susceptible to environmental factors than that of females especially in site 1 due to the colder water from the hypolimnion released by the Três Marias Dam, as has also been reported for other important Neotropical migratory characiforms from the rio São Francisco such as curimatã-pacu Prochilodus argenteus (Sato et al, 2005;Arantes et al, 2011), piau-três-pintas Leporinus reinhardti (Weber et al, 2013) and dourado Salminus franciscanus . Recently, a similar tendency also was observed in a small-sized non-migratory characid named lambari-do-rabo-vermelho Astyanax fasciatus downstream from the Três Marias Dam (Normando et al, 2014).…”

“…Total length, body weight and GSI values for females and males and FD for females captured in site 2 were higher than those of site 1. This is due to presence of riparian vegetation (Alvim & Peret, 2004) that allows conditions for somatic growth through feeding and warm water temperature and high dissolved oxygen (Weber et al, 2013), which assist in gonadal maturation, as this is one of the most preserved sections of the rio São Francisco (Alvim & Peret, 2004). Moreover, higher temperatures and higher dissolved oxygen rates are contributory factors for the production of oocytes that are larger in diameter and quantity in long-distance migratory fish species (Weber et al, 2013).…”

“…In the power generation process, the colder water from the hypolimnion (3°C colder) is released in the river, causing thermal and hydrodynamic changes that impact fish reproduction just downstream of the dam (Weber et al, 2013). Recent studies have shown the importance, for fish reproduction, of tributaries downstream from dams, acting as alternative routes for migratory species and minimising unfavourable water conditions (Antonio et al, 2007;Arantes et al, 2011;Weber et al, 2013;Freitas et al, 2013).…”

Population structure and reproduction of a migratory fish Leporinus piau (Characiformes: Anostomidae) in a semiarid tropical reservoir, Brazil

“…Filho et al (2012) and Nascimento et al (2013) estimated that the reproductive period of L. piau in the reservoir of Marechal Dutra (RN) occurred between April and June. L. friderici in the Upper Paraná River basin presented a reproductive period between October and April (2000), L. reinhardti in the São Francisco River presented a reproductive period between November and February (Weber et al, 2013), and L. muyscorum in the Magdalena River Basin (Colombia) presented a reproductive period between April and June (Jimenez-Segura, Palacio, & Leite, 2010). In all of these studies, the reproductive period of the Leporinus species occurred during the period of highest rainfall.…”

Importance of dam-free stretches for fish reproduction: the last remnant in the Upper Paraná River

“…These tributaries, in addition to maintaining the reproduction events, have still contributed with the input of larvae to the downstream stretches. Numerous studies carried out in this basin Daga et al, 2009;Gogola et al, 2010;Reynalte-Tataje et al, 2011Da Silva et al, 2015;Silva et al, 2016) and in the basins of the rivers Uruguay (Reynalte-Tataje et al, 2008, 2012aHermes-Silva et al, 2009;Corrêa et al, 2011) and São Francisco (Sato et al, 2005;Weber et al, 2013;Normando et al, 2014;Nunes et al, 2015), as well as in other parts of the world (Bottcher et al, 2013;Webber et al, 2013;López-Casas et al, 2016), have argued for the importance of free-flowing tributaries upstream of regulated rivers as alternative migratory routes. Nevertheless, it is important to emphasize the need for an adequate distance between the spawning site and the complete early embryonic and larval development, preventing the drift of larvae to inappropriate places, such as reservoirs, where they can be preyed upon or settle to the substrate Olden, 2016).…”