Fish passage ladders from Canoas Complex - Paranapanema River: evaluation of genetic structure maintenance of Salminus brasiliensis (Teleostei: Characiformes)

Carla Martins Lopes,Mário Luís Orsi,Leda Maria Koelblinger Sodré,Sandro Geraldo De Castro Britto,Rodolfo Nardez Sirol,Fernanda Simões De Almeida

doi:10.1590/s1679-62252007000200006

Carla Martins Lopes, Mário Luís Orsi + Show 4 more

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https://doi.org/10.1590/s1679-62252007000200006

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Abstract

The aim of this study, utilizing RAPD techniques, was to determine the genetic variability of Salminus brasiliensis groups collected at passage ladders of the hydroelectric plants (HEP) Canoas I and Canoas II - Paranapanema River (Brazil), as well as to estimate the population structure through different parameters of genetic diversity. The data obtained allowed us to conclude that S. brasiliensis of the Canoas Complex has a moderate index of genetic variability ( > 42.00%) when compared to that of other migratory fish species. All genetic diversity analyses (distance = 0.015 and genetic identity = 0.985, F ST =0.018, AMOVA) were signs of low genetic differentiation, and they led to the clustering of S. brasiliensis from Canoas I and Canoas II. This suggests that the species is genetically structured as a single population. Some findings indicate that this population of S. brasiliensis comes from the Capivara Reservoir (Canoas I downstream), probably fed by the Tibagi and Cinzas Rivers. Literature data denote that after fish transposition by passage ladders of the Canoas Complex, the migratory species are not concluding the reproductive cycle. This mechanism, therefore, could be one more impact factor causing the depletion in downstream recruitment, which could in medium and long term be compromising the natural S. brasiliensis population in the middle Paranapanema River.

Highlights

Over the last 50 years, the Paranapanema River, which has its headwater in the Paranapiacaba Mountains (Atlantic Forest) and flows into the Paraná River to the west, has suffered enormous human intervention with the building of 10 hydroelectric plants, forming a system of reservoirs in cascade
Collection of specimens Specimens of S. brasiliensis were collected in the fish passage ladders of the hydroelectric plants (HEP) of Canoas I ( 22o 56’S; 50o 31’W) and Canoas II (22o 56’S; 50o 15’W), in the middle Paranapanema River (Fig. 1) in the period of March, 2003 to March, 2005, always with respect to the spawning run period which includes the beginning of September of one year to the end of March of the following year
There was the possibility of existing genetic differentiation among these groups, in case they originated from S. brasiliensis shoals with different genetic structure

Summary

Introduction

Over the last 50 years, the Paranapanema River, which has its headwater in the Paranapiacaba Mountains (Atlantic Forest) and flows into the Paraná River to the west, has suffered enormous human intervention with the building of 10 hydroelectric plants, forming a system of reservoirs in cascade. The hydroelectric plants (HEP) of Canoas I and Canoas II located in the middle of the Paranapanema River form the Canoas Complex, where their respective reservoirs (Canoas I and Canoas II) were built in 1998 The banks of both reservoirs are occupied by pastures, with scarce remnants of riparian vegetation and where marginal lakes are absent (Dias, 2003). They are the only HEPs of this river where fish passage ladders were built, which began operating in November of 2000 with the aim of minimizing the impact of suppressing the maintenance of natural stocks of migratory fish species (Britto & Sirol 2005). Some indicators show that these works would have dubious effectiveness in the preservation or conservation of the stocks in a series of dams (Borghetti et al, 1994; Agostinho et al, 2002; Agostinho & Gomes, 2005)

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