Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco Flipped reducetarianism: A vegan fish subordinated to carnivory by suppression of the flooded forest in the Amazon Taís Melo a, ⁎ , Gislene Torrente-Vilara b , Cristhiana Paula Röpke c a Laboratório de Ictiologia e Pesca, Universidade Federal de Rondônia, Porto Velho, Rondônia, Brazil b Departamento de Ciências do Mar, Universidade Federal de São Paulo, Santos, São Paulo, Brazil c Departamento de Ciências Pesqueiras e Ciências Biológicas, Universidade Federal do Amazonas, Manaus, Amazonas, Brazil ARTICLE INFO Keywords: Trophic ecology Plasticity Body condition Várzea White-water Hydropower ABSTRACT The effects of dams closure and floodplain forest removal on diet and body condition of a frugivorous migratory fish from the Amazon were evaluated herein. Fish were captured with gillnets in two different environmental conditions: before and after the construction of the Santo Antônio reservoir in Madeira River, preceded by clearing of floodplain forest to mitigate the effects of eutrophication into the run-of-river dam. A total of 493 Mylossoma duriventre specimens were accessed and showed a strong shift in diet while body condition did not change after reservoir formation. The vegan diet based on fruits and seed was associated to Mylossoma duriventre prior to damming, and replaced by a carnivorous one, mainly based on insects. Our results suggest that dietary plasticity has guaranteed its body condition, at least in the first two years after damming. Cutting offfloodplain forest to avoid eutrophication has immediate and direct impacts upon the supply of fruits and seeds for Mylossoma duriventre. Still, substitution with insectivorous diet over a frugivorous one, as observed for Mylossoma duriventre, may conceal an underlying problem of decreasing the local ichthyochory and floodplain forest maintenance or restoration of várzea areas over the time. 1. Introduction Wetlands are crucial landscape elements due to the high biological diversity, therein and, also to the ecosystem functions and services produced. The cyclic input of nutrients in the aquatic-terrestrial tran- sition zone caused by the seasonal flood pulse, a periodic inundation of lowlands, makes floodplain areas among the most biologically pro- ductive and diverse ecosystems on Earth (Junk et al., 1989, 2011; Gregory et al., 1991; Naiman and Décamps, 1997; Tockner and Stanford, 2002; Naiman and Latterell, 2005). Despite their ecological and economical value, wetlands have been lost, degraded, or strongly modified worldwide due to human uses practices, and are disappearing much faster than other kinds of landscape (Vitousek et al., 1997; Olson and Dinersteins, 1998; Revenga et al., 2000; Junk et al., 2013). More- over, the alteration of flow regimes due to climate changes (Arnell and Gosling, 2013) and hydropower damming of large rivers threaten the ecological integrity of river-floodplain ecosystems around the world (Nilsson and Berggren, 2000; Bunn and Arthington, 2002; Naiman et al., 2002; Kingsford, 2016; Pulles et al., 2016; Winemiller et al., 2016). In general, flow regulation of large reservoirs eliminates the seasonal flood-pulse and the exchange of nutrients between rivers and their floodplains. The consequence of these processes is a replace of the primary productivity based mostly on the flooded forest by plankton modifying availability of food resources for fishes and other animals, especially fruits and seeds (Junk et al., 1989, 2011; Agostinho et al., 2008). These changes reduce the overall contribution of allochthonous resources but may increase the availability of autochthonous ones (Hahn and Fugi, 2007). As a consequence of such transformations, fish populations that depend on resources from the forest may be strongly reduced or even locally extirpated, or have their diets adjusted to al- ternative available resources within the new environment. The abrupt change caused by the modification of the flow regime tends to favor generalist species, which have more flexible with their diets and may be able to quickly shift to more abundant resources (Poff and Allan, 1995). Impoundments also causes the decomposition of organic matter in flooded forest, resulting in eutrophication (Tundisi, 2007). The final stage in the decomposition of vegetation produces an acidic and hy- poxic (or even anoxic) environment and, furthermore, stratification of the water column (Fearnside, 1989; Kasper et al., 2014). Hydropower projects attempt to mitigate the effects of eutrophication through the clearing of floodplain forest before filling the reservoir, which provides https://doi.org/10.1016/j.foreco.2018.12.050 Received 20 August 2018; Received in revised form 25 December 2018; Accepted 27 December 2018 ⁎ Corresponding author. E-mail address: taaismelo@gmail.com (T. Melo). Forest Ecology and Management 435 (2019) 138–143 0378-1127/ © 2018 Published by Elsevier B.V. T