Feeding ecology of immature Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) in a tidal environment, estuary of the rio Amazonas

Thiago Augusto Pedroso Barbosa,Ronaldo Borges Barthem,Luciano Fogaça De Assis Montag

doi:10.1590/1982-0224-20130014

Thiago Augusto Pedroso Barbosa, Ronaldo Borges Barthem + Show 1 more

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https://doi.org/10.1590/1982-0224-20130014

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Abstract

Studies of feeding ecology are important for the evaluation of interactive processes in fish communities. This study evaluated the feeding ecology of Lithodoras dorsalis (Doradidae) from streams within the Amazon estuary delta (Brazil), a macro-tidal area, on different pluviometric periods. A total of 371 young specimens was collected during 12 months of sampling (July 2010 to June 2011). The species diet was composed of 28 food items analyzed by Repletion Index, Alimentary Index and Niche Breadth. Young L. dorsalis was classified as herbivore with a frugivory tendency due to the high importance of fruit and seeds in its diet. Food intake varied among sampled months, with the lowest intake being recorded during the rainy-dry season transition period, and the highest at the beginning of the dry season. The importance of food items and the composition of the diet were different throughout the year, probably due to the daily tides that allow fish to access new environments and the pluviometric periods. These results provide important data on the feeding ecology of Amazonian doradids. The study also emphasized the importance of allochthonous resources, derived from the riparian forest, which reinforces the importance of this habitat for the conservation of Neotropical freshwater fishes.

Highlights

Studies of feeding ecology are of fundamental importance for the understanding of interactive processes in fish communities (Winemiller, 1989; Hahn et al, 1997; Abelha et al, 2001), including those involving habitat features
The dominance of young individuals at the rio Amazonas mouth region is because the rock-bacu is a migratory fish with different feeding and reproductive sites
Essential for migrating species such as L. dorsalis, are sites where young individuals meet food and shelter needs all year long and are able to invest on body growth until attain sexual maturity, when they migrate to other regions (Goulding, 1980; Barthem et al, 1991)

Summary

Introduction

Studies of feeding ecology are of fundamental importance for the understanding of interactive processes in fish communities (Winemiller, 1989; Hahn et al, 1997; Abelha et al, 2001), including those involving habitat features. The abundance of these resources may vary considerably over the course of the year, reflecting seasonal fluctuations in rainfall levels or hydrological parameters (Junk, 1980). This limits the degree of ecological specialization of most fish species for a single type of food item. Most Neotropical fish species are dietary generalists or opportunists (Lowe-McConnell, 1999), and present considerable versatility in response to fluctuations in food availability (Abelha et al, 2001; Correa & Winemiller, 2014).

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