Agradecimentos: We thank to fishers of the Negro, Tapajós and Tocantins rivers who participated and contributed to this study. We thank to A. Schiavetti and L. F.A. Montag for useful comments on a previous version. We thank the team of the HSTM Herbarium at Universidade Federal do Oeste do Pará for the identification of the plants. We thank L. Capitani and J.T. da Silva for help to collect data and K. Calini for preparing the map. We thank to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for research grants to P.E.R.P (140957/2017-0 and 151005/2021-4), A.B (301592/2017-9) and R.A.M.S (303393/2019-0), and to the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior for a grant to R.A.M.S (CAPES-PRINT, 88887.467553/2019-00). This study was funded by the National Academy of Sciences (NAS)/ USAID (AID-OAA-A-11-00012) and by Eletronorte/ANEEL (Contract 4500057477) Ver menos

Abstract: Frugivory and seed dispersal by fish is an important mutualistic interaction in complex and species-rich tropical rivers. The local ecological knowledge (LEK) held by fishers can provide new information on relationships between fishes and plants in less studied rivers. This study aims to investigate the feeding interactions between frugivorous fish and plants through interaction networks based on the fishers' LEK in three rivers in the Brazilian Amazon (Negro, Tapajós and Tocantins). A total of 418 fishers were interviewed in 24 communities (eight in each river). The studied fishes were tambaqui (Colossoma macropomum), matrinxã (Brycon spp.), pacu (Myloplus spp.), pacu manteiga (Mylossoma duriventre), pirapitinga (Piaractus brachypomus), and jaraqui (Semaprochilodus spp.). The interviewed fishers cited a total of 92 plants consumed by the six frugivorous fishes in the three rivers. The interaction networks showed a higher nestedness in the Tocantins, greater connectance and modularity in the Tapajós and more specialization in the Negro, where the protected areas may have contributed to a more complex and specialized interaction network. The more nested network in the Tocantins River indicated the loss of specialized interactions in disturbed communities. The Tapajós River network showed the highest number of interactions between fish and plants, but this river has been threatened by environmental changes. Fishers' LEK associated to network analyses can advance our understanding on ecological interactions. This approach can be also useful to evaluate and mitigate ecological effects from anthropic changes in the Amazon and other high diverse tropical rivers Ver menos