Use of submerged trunks by stream fishes in the Lower Negro River, Amazon

Uso de troncos submersos por peixes de igarapés no Baixo Rio Negro, Amazonas

Abstract

Fish make use of different microhabitats, such as submerged trunks, branches, foliage, crevices and stones, with different purposes, in search of shelter, refuge, food and even as a substrate for reproduction. The present study aimed to increase the knowledge about fish species that make use of the micro-habitat of trunks on the banks of streams in the protected area known as the Tupé Sustainable Development Reserve, Lower Negro River region, Amazonas. The data analyzed come from two days of collections, carried out in the falling water periods of 2020 in the Central stream. Six species, Pseudanos trimaculatus, Tatia strigata, Trachelyopterichthys taeniatus, Trachelyopterichthys sp. "negro", Ancistrus dolichopterus and A. hoplogenys were captured inside the submerged trunks. The order Siluriformes was the most abundant and represented (83.33%) of all individuals. The most abundant species were T. strigata (N=46), followed by A. dolichopterus (N=35). Although most species belonged to the order Siluriformes, it is worth mentioning the sampling of one Characiformes, P. trimaculatus (N=1). In addition, an individual of A. hoplogenys was found in association with eggs deposited and fixed within a trunk, displaying protective behavior. The record of these species inside trunks may be associated with their foraging site, refuge and parental care to increase the chances of survival of the offspring. Therefore, the conservation of these microhabitats is important for the maintenance of some fish species.

Keywords:  ichthyofauna; microhabitats; ornamental fish; Siluriformes