Spatial and temporal variation of the diet of the flag tetra Hyphessobrycon heterorhabdus (Characiformes: Characidae) in streams of the Eastern Amazon

Abstract

Spatial and temporal variations in streams promote large fluctuations of resource availability, thus affecting the diet of fishes. We evaluated the effects of hydrological periods and stream order within periods on the diet of the flag tetra Hyphessobrycon heterorhabdus. We analyzed 160 stomachs in eight streams ranging from 1st to 3rd order between dry and flood period. Sampled streams belonged to a well-preserved area in the Eastern Amazon. The flag tetra is omnivorous, with a tendency towards insectivory. During the dry period, the species exhibited a higher amount of autochthonous than allochthonous items. Fish consumed more allochthonous items in 1st and 2nd order streams in the dry period and in 1st and 3rd order streams in the flood period. These results reflect the interactions between temporal and longitudinal factors on resource availability and its influence on fish diet. This pattern is probably dependent on the extensive riparian vegetation as a direct and indirect source of food for stream fish.

Spatial factors overcome seasonality in increasing the consumption of allochthonous food resources by fishes from tropical lotic ecosystems

“…In fact, we argue that the support for this prediction depends heavily on the local characteristics of the sampling sites, the taxonomic resolution, and the trophic guild composition included in studies. If we consider the population level of an omnivorous-insectivorous stream fish species, individuals indeed may consume higher amounts of allochthonous food resources during HW periods, but still presenting autochthonous-based diet in some streams (Benone et al, 2020). When dealing with herbivorous inhabiting flood-plain systems, then individuals will consume more allochthonous food resources during floods (Correa & Winemiller, 2014).…”

“…Primary changes are related to the relative importance of allochthonous food resources coming from terrestrial environments and autochthonous food resources based on the instream primary productivity. Studies in tropical freshwaters may report high amounts of allochthonous food resources in the diet of consumers under specific environmental conditions (Cardoso et al, 2017;Neves et al, 2018;Benone et al, 2020), but, still, the larger importance of autochthonous resources to the assimilation by most consumers have been pointed out (Thorp & Delong, 2002;Neres-Lima et al, 2016;Reis et al, 2020). This contrasting evidence makes it difficult to reach to a general theory on how these systems work.…”

“…Studies have shown the importance of such spatial and temporal variations for tropical aquatic consumers (e.g. Baptista et al, 1998;Tomanova et al, 2007;Correa & Winemiller, 2014;Davis et al, 2018;Benone et al, 2020), but since seasonality in environmental conditions are locally dependent, so might be the response of consumers to these variations. To our knowledge, no effort has yet been made to synthesize local environmental determinants of the seasonal relative consumption of these food resources by consumers from tropical lotic ecosystems in a large-scale approach.…”

Effect of logged forests on diet of small characids from Neotropical streams

“…The feeding plasticity in omnivorous fish represents a feeding advantage (Ferreira et al, 2012) and allows them to switch between different food sources (Sanchez‐Hernandez, 2020). Insects preyed by fishes may be terrestrial or aquatic in origin (Benone et al, 2020; Nakano et al, 1999). Ants may have arboreal habits, and the action of winds and rain may promote the fall of these individuals from the riparian vegetation (Chan et al, 2008; Harada et al, 2013), mainly in streams with pristine and selective logged forests.…”

“…This is of great concern because Amazonian riparian cover has been modified by conversion of forest to pasture, agro‐industrial plantations and especially for timber harvesting (Marengo et al, 2018). In the Amazon, studies on fish trophic ecology have been conducted (Benone et al, 2020; Catarino & Zuanon, 2010; Freitas et al, 2022; Mendonça et al, 2005; Moraes et al, 2013; Sabino & Zuanon, 1998), but with a special focus on flood pulse effects or spatial–temporal variations. However, there is a lack of information linking fish diet with riparian cover in small streams.…”