Fishes from the Lower Urubamba river near Sepahua, Amazon Basin, Peru

Abstract

We report results of an ichthyological survey of the Lower Urubamba river, a tributary of the Ucayali river located in the southwestern portion of the Amazon Basin in southeastern Peru. Collections were made at low water (July, 2009) from 280 - 310 m elevation, near the town of Sepahua within the Fitzcarrald Arch, an upland associated with Pliocene (c. 4 Ma) uplift of the Peruvian Andes. This is the second of four planned expeditions to the region with the goal of comparing ichthyofaunas across the headwaters of the largest tributary basins in the western Amazon (Juruá, Ucayali, Purús and Madre de Dios). Twenty-one sites were sampled using seine nets, hook lines, cast nets and dip nets. A total of 98 species in 22 families and eight orders were captured and identified. The most diverse families are Characidae (40 spp.) and Loricariidae (20 spp.), and 12 families are represented by a single species. These data suggest that the fish fauna of the Lower Urubamba river near Sepahua is distinct from, and less diverse than, adjacent areas of lowland Amazonia.

Aquatic Biodiversity in the Amazon: Habitat Specialization and Geographic Isolation Promote Species Richness

“…Identifications were based on catalogued vouchers with associated color digital images and cross referenced tissue samples ( Appendix 1 ). This represents a 76% increase over the 118 fish species previously documented with vouchers from this region [ 55 - 65 ]. The taxa listed in Appendix 1 represent approximately 4.5% (208 of 4,581) of the freshwater fish species of tropical South America, in an area spanning about 2.6% (400,000 of 15,400,000 km 2 ) the total land surface area occupied by this fauna [ 5 ].…”

“…This number is about one third more than the number used in the quantitative analyses of the present paper. The higher estimate was made by comparing species lists and photos presented in literature sources [ 55 - 65 ], and from examination of museum lots archived at the Natural History Museum of the University of San Marcos (MUSM), Lima. The quantitative comparisons of species diversity reported here were based on the more accurate and comparable species level identifications of our own collections, and not the higher species richness estimate based on literature references.…”

Ichthyofauna of sandy beaches along the Acre river, Brazil

“…As observed in previous studies, the beaches surveyed in the present study were dominated by small characids (Ibarra & Stewart 1989, Jepsen 1997, which reflects their ability to obtain oxygen in the upper layers of the water column, their high trophic plasticity (Abelha et al 2001), and their ample distribution in the Neotropical region (Jungfer et al 2013). The considerable abundance of characids, in particular K. orteguasae and C. barrigai, may be related to their generalist habitat use and high trophic plasticity (Lowe-McConnell 1999, Albert & Reis 2011, Carvalho et al 2016, Torgler 2016. Trophic plasticity is linked to environmental structure (Abelha 2001), which affects the availability of food, and obliges the species to adapt to different environments, being reflected in the ample feeding spectrum of most teleosts.…”

First records of freshwater fish species in Colombia: extending the distribution of 17 Amazonian and Orinoco fish species

“…Remarks. Scopaeocharax rhinodus is restricted to the western Amazon river basin (Ortega and Vari 1986;Carvalho et al 2011;Barriga 2014 ; found below the waterfall from a terra firme stream; voucher CIACOL 2498. Identification.…”