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

Abstract

Influence of a large dam and importance of an undammed tributary on the reproductive ecology of the threatened fish matrinxã Brycon orthotaeniaGünther, 1864 (Characiformes: Bryconidae) in southeastern Brazil , when compared with the site 1.In site 2 was registered the highest GSI means (9.97 ± 2.96 for females and 0.93 ± 0.52 for males), compared with the site 1 means. Reproduction period occurred from October to February. Unlike site 2, no spawned females or spent males were captured in site 1. Significant differences were found between females and males in site 2 (χ 2 = 26.84, df = 1, P < 0.05). Physical-chemical parameters of the water presented higher values in site 2. The canonical correlation test indicated that the reproduction of males is less susceptible to environmental factors than that of females. These results show that B. orthotaenia finds favourable conditions to reproduction just in site 2.Um total de 312 adultos de matrinxã foram capturados bimestralmente entre 2011-2012, em dois pontos do rio São Francisco: imediatamente a jusante da barragem de Três Marias (ponto 1) e na confluência com o rio Abaeté (ponto 2). Exemplares de Brycon orthotaenia do ponto 2 apresentaram maiores valores de comprimento total (32,24 ± 5,70 cm para fêmeas e 26,64 ± 3,79 cm para machos) e peso corporal (506,66 ± 332,17 g para fêmeas e 267,36 ± 145,84 g para machos) quando comparado com peixes do ponto 1. No ponto 2, foi registrado as maiores médias de IGS (9,97 ± 2,96 para fêmeas e 0,93 ± 0,52 para machos) em comparação com o ponto 1. O período reprodutivo ocorreu de outubro a fevereiro. Ao contrário do ponto 2, fêmeas desovadas e machos espermiados não foram capturados no ponto 1. Foram encontradas diferenças significativas entre fêmeas e machos no ponto 2 (χ 2 = 26,84, gl = 1, P < 0,05). Parâmetros físico-químicos da água apresentaram maiores valores no ponto 2. A análise de correlação canônica indicou que a reprodução de machos é menos susceptível a fatores ambientais do que de fêmeas. Estes resultados mostram que B. orthotaenia encontra condições favoráveis para a reprodução apenas no ponto 2.

Reproductive characteristics of pike‐characids Boulengerella cuvieri (Ctenoluciidae) in the middle Xingu River, Eastern Amazon

“…The sex ratio was 1:1 ( χ 2 = 1·44; P > 0·05) throughout the study period. Similar results were observed in Leporinus taeniatus Lütken 1875 (Thomé et al, ) and in Brycon orthotaenia Günther 1864 (Nunes et al, ). The mass–length relationship was obtained for both sexes resulting in the following equation, M T = 0·0019 L s 3·36 ( r 2 = 0·97) and the inference is that B. cuvieri shows positive allometric growth.…”

Comparative analyses of reproductive activity in Schizodon knerii (Steindachner, 1875) (Characiformes: Anostomidae) in three sections of the São Francisco River basin

“…In section 2, neither spawned females nor spermiated males were captured, indicating lack of favourable conditions for reproduction in this section. Other studies on the same section 2 showed the reservoir impacting fish populations and affecting the reproduction of various species: Prochilodus argenteus (Arantes, Santos, Rizzo, Sato, & Bazzoli, ), Leporinus reinhardti (Weber et al., ), Astyanax fasciatus and A. bimaculatus (Normando et al., ), and Brycon orthotaenia (Nunes et al., ). Similar impacts immediately downstream of hydroelectric dams have also been observed in the Hanjiang River in China (Zhong & Power, ), the Colorado River basin in the United States (Clarkson & Childs, ), and the Naomi and Mitta Mitta rivers in Australia (Preece & Jones, ; Todd et al., ).…”

The critical importance of an undammed river segment to the reproductive cycle of a migratory Neotropical fish

“…characteristics of the river. Thus, it is critically important that this segment of the São Francisco River continues to flow unimpeded so that P. costatus (and other migratory species) can access spawning and feeding sites and their offspring can develop in the floodplain systems during the rainy period.Recent studies conducted in different Neotropical basins have underscored the importance of undammed tributaries and river segments for the conservation of Neotropical fish biodiversity, especially concerning reproductive aspects(Casarim, Prado, Loures, & Pompeu, 2018;Marques, Dias, Perbiche-Neves, Kashiwaqui, & Ramos, 2018;Nunes et al, 2015;Reynalte-Tataje et al, 2012). These findings should be taken into consideration in the academic, private and government sectors and measures should be taken to identify and protect these ecologically relevant areas.…”