Browsing by Autor "Reinaldo Cholima"

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Effects of the non-native Arapaima gigas on native fish species in Amazonian oxbow lakes (Bolivia)
(Public Library of Science, 2025) Danny Rejas; Monika Winder; Reinaldo Cholima; Thierry Oberdorff
The introduction of non-native fish species into new environments has raised global concerns due to potential ecological impacts on recipient ecosystems. A previous study focusing on the introduced fish species Arapaima gigas in Bolivian Amazon waters showed that its isotopic niche significantly overlapped with most co-occurring native fish species, suggesting potential competition. To evaluate this hypothesis, we extended here the investigation by comparing the trophic position and isotopic niche width of eleven abundant native fish species inhabiting both colonized and non-colonized floodplain lakes. We found lower trophic positions in colonized versus non-colonized lakes only for native piscivores, mostly driven by a shift towards increased dietary proportion of detritivorous fishes. Conversely, results showed that the isotopic niche width of most fish species analyzed (i.e. 10 over 11 species) did not significantly decrease in colonized compared to non-colonized lakes. Our overall results suggest potentially low competitive interactions between A. gigas and native fishes, with the notable exception of piscivorous species. We attribute our findings to the high abundance of available resources in Amazon oxbow lakes.
Estimating the age of the tataruga (Podocnemis expansa) from femur bones in the Iténez River, Beni, Bolivia
(2025) Reinaldo Cholima; Aldo Echeverria; Bram Cornelis de Vries Robbé Akkersdijk; Guido Miranda
The South American river turtle or tataruga (Podocnemis expansa), distributed throughout the Amazon basin, is one of the largest turtle species in the world. It faces several threats that could put its populations at risk. Its distribution, abundance, and diet are well described, but not much is known about its population structure. To understand the growth pattern of this species, we investigated the relationship between carapace length and age in the turtles through a skeletochronological study. Femur samples were obtained from subsistence hunting in the community of Versalles, on the Iténez River in Bolivia. Incisions were made, and an annuli count was performed to determine the age of the turtles. A von Bertalanffy growth curve was then constructed relating age to carapace length. A total of 20 femurs were analyzed, and a higher growth rate was found during the first years of life in female turtles from the study population. Skeletonchronology is shown to be useful for assessing the growth and population structure of the turtles. However, the population range needs to be expanded to obtain more information on juveniles and mature males.
Inventario de las especies de peces del río Abuná (Pando, Bolivia)
(2025) Reinaldo Cholima; Luis Torres; Socrates Pinheiro; Diana Gutierrez; Freddy Flores
The Abuná River is one of the main tributaries of the Abuná subbasin and represents the natural border between Bolivia and the Federative Republic of Brazil. We evaluated 23 sites in rivers, streams, and lakes, with the objective of compiling an inventory of the fish species. To this end, intensive collections were made using gillnets and trawls on the banks, obtaining a total of 4 449 individuals. One hundred and seventy-eight species distributed in 34 families and 10 orders were identified. The orders Characiformes (85), Siluriformes (62), and Cichliformes (12) were the most diverse and abundant. The families with the highest number of species were Acestrorhamphidae (18), Loricariidae (18), Pimelodidae (14), Auchenipteridae (13) and Serrasalmidae, Cichlidae and Curimatidae (12 species each). The remaining families had fewer than nine species. Eighty-six new records were added to the previously known richness in the subbasin, of which 16 correspond to new records for the department of Pando, and 13 species are reported for the first time in Bolivia.