The stream fish fauna of a pristine area in the South Amazon, rio Machado basin, Rondônia
Ohara, Willian MassaharuZdradek, Dihon LeoneTomaz, Fabíola Silva
Abstract This study represents an inventory of fish collected in six small tributaries from the rio Tarumã river, in the Jaru Biological Reserve, middle rio Machado, Vale do Anari town, Rondônia, Brazil. The fieldwork was carried in August 2019 and 2021 in streams of up to third order during the low water period, in a 50 m blocked stretch located 1 km upstream of the mouth of the Tarumã river. The sampling effort in each stream was standardized with five people collecting with hand-nets and seinenets for 2 hours. A total of 2.989 individuals, 64 species, 55 genera, 22 families and seven orders were captured. Seven species not identified at the species level belonging to the Cetopsorhamdia, Hemigrammus, Knodus, Microcharacidium, Paracanthopoma, Pyrrhulina, and Synbranchus, were considered as new. No exotic species was captured. The fish of the orders Characiformes and Siluriformes had the greatest abundance. Characidae was the family with greatest richness of captured species (13 species), being Hyphessobrycon agulha, Hemigrammus bellottii, Apistogramma resticulosa, and Elachocharax pulcher the species with the highest richness and abundance. This study illustrates the fish composition in a pristine area from the rio Machado and will serve as a baseline for future studies in view of the rapid replacement of forests in production systems of southern Amazonia.
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