Factors influencing the structure and spatial distribution of fishes in the headwater streams of the Jaú River in the Brazilian Amazon

Abstract

The aim of this study was to investigate the influence of spatial variation in river channels and habitats on the distribution of fish communities in the headwater streams of the Jaú River System, a blackwater tributary of the Negro River. Collections and measurements were made in 34 headwater streams during the period of November-December, 1998. Fish were captured with fish traps and hand nets along standard reaches of two meanders. Data on benthic habitat structure, stream depth and width were collected along lateral transects in each sample reach. A total of 66 fish species from 24 families were collected and classified into seven trophic guilds: allocthonous insectivore, autochthonous insectivore, general insectivore, piscivore, detritivorous planktivore, detritivorous insectivore and insectivorous piscivore. Variations in the distribution and diversity of bottom substrates were important factors influencing fish community structures in these systems. Also, variation in stream size explained the observed variability in fish communities.

Feeding ecology of Serrapinnus notomelas (Characiformes: Cheirodontinae) in small forest streams in the Machado River basin, Rondônia, Brazil

“…The importance of allochthonous Feeding ecology of Serrapinnus notomelas (Characiformes: Cheirodontinae) in small forest streams in the Machado River basin, Rondônia, Brazil ACTA AMAZONICA material for the feeding of stream fishes is relevant (Nogueira and Costa 2014;Kemenes and Forsberg 2014;Costa and Soares 2015). This shows that S. notomelas depends almost exclusively on resources provided by the terrestrial environment.…”

Trait–environment relationships in Amazon stream fish assemblages

“…dibaphus and Nannostomus marginatus, which exploit autochthonous and allochthonous resources respectively (Kemenes & Forsberg, 2014). These basins are located at higher altitudes, with steeper terrain, which contributes to higher flow velocities that restrict the width of the channel and prevent the deposition of woody fragments .…”

“…As these streams are relatively shady, the resident species tend to feed on items obtained from the riparian vegetation, as observed in the invertivorous Laimosemion cf. dibaphus and Nannostomus marginatus, which exploit autochthonous and allochthonous resources respectively (Kemenes & Forsberg, 2014). The allochthonous insectivores forage near the surface while the autochthonous insectivores feed on submerged leaves and branches (Brejão et al, 2013;Kemenes & Forsberg, 2014).…”

“…dibaphus and Nannostomus marginatus, which exploit autochthonous and allochthonous resources respectively (Kemenes & Forsberg, 2014). The allochthonous insectivores forage near the surface while the autochthonous insectivores feed on submerged leaves and branches (Brejão et al, 2013;Kemenes & Forsberg, 2014). The consumption of allochthonous resources tends to increase in streams with greater riparian cover (Collins, Kohler, Thomas, Fetzer, & Flecker, 2016), given that the vegetation restricts the incidence of sunlight onto the streams, and thus limits the primary productivity of these bodies of water, forcing the fish to depend more on terrestrial prey (Kraus et al, 2016).…”

Do local environmental factors structure the trophic niche of the splash tetra, Copella arnoldi? A test in an Amazonian stream system

“…Copella arnoldi (Characiformes: Lebiasinidae) has a high commercial importance as ornamental fish and is the most abundant species in the streams of Caxiuanã (Montag et al 2008;Benone 2012;Freitas et al 2018). Lebiasinids are omnivorous and opportunistic species, and most studies found that they feed mainly on allochthonous arthropods (Román-Valencia 2004;Kemenes and Forsberg 2014), although Silva et al (2016) reported allochthonous plant material (e.g. leaves, fruits and stems) as their main food source.…”