Abstract

MARTINEZ-TORO, Lina María; RESTREPO-SANTAMARIA, Daniel; VALENCIA-RODRIGUEZ, Daniel  and  JIMENEZ-SEGURA, Luz Fernanda. Assemblages of fishes in highland Andean reservoirs: The case of the Quebradona and Riogrande II reservoirs in the Magdalena basin. Caldasia [online]. 2022, vol.44, n.2, pp.442-452.  Epub May 24, 2024. ISSN 0366-5232.  https://doi.org/10.15446/caldasia.v44n2.93495.

The development of hydropower production in the north of the Andes of South America has focused on the Magdalena basin. For this basin, it is reported that 68 % of the fish species are endemic and the effects that these structures produce on their assemblages in high mountain rivers have not been studied. This work answers the questions associated with the characteristics that describe the fish assemblage and the influence that some environmental variables influence on their distribution during the dry and rainy hydrological periods in the area of influence of two reservoirs. Seven fish species were caught, four of these are not native from the basin. No significant differences in abundances were found between aquatic systems and between climatic seasonality. The richness was higher in the streams and rivers. The assemblages changed according to the aquatic system; in reservoirs, the non-native species Micropterus salmoides and Cyprinus carpio dominated, while in streams and rivers, the assemblage consisted mainly of Hemibrycon caucanus and Trichomycterus sp. There were no statistical differences in the assemblages according to the climatic period. We observed that physicochemical variables such as oxygen and transparency are important for the distribution of non-native species in reservoirs, and for species distributed in rivers and streams, the conductivity was the most influential variable. The information provided in this study will serve as a basis for fish conservation management in the Andes.

Keywords : Neotropical fish; non-native species; Andean rivers.

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