Floodplain forests drive fruit-eating fish diversity at the Amazon Basin-scale
Authors: Correa Sandra Bibiana , Coronado-Franco Karold V. , Jézéquel Celine , Cantarute Rodrigues Amanda , Evans Kristine O. , Granger Joshua J. , Ter Steege Hans , Leão do Amaral Iêda , de Souza Coelho Luiz , Wittmann Florian , de Almeida Matos Francisca Dionízia , de Andrade Lima Filho Diógenes , Salomão Rafael P. , Castilho Carolina V. , Guevara Juan Ernesto , Veiga Carim Marcelo de Jesus , Phillips Oliver L. , Fernandez Piedade Maria Teresa , Demarchi Layon O. , Schöngart Jochen , Cardenas Revilla Juan David , Pires Martins Maria , Irume Mariana Victória , da Silva Guimarães José Renan , Ferreira Ramos José , Costa Quaresma Adriano , Pitman Nigel C. A. , Luize Bruno Garcia , Moraes de Leão Novo Evlyn Márcia , Martins Venticinque Eduardo , Sanna Freire Silva Thiago , Núñez Vargas Percy , Manzatto Angelo Gilberto , Farias Costa Reis Neidiane , Terborgh John , Casula Katia Regina , Honorio Coronado Euridice N. , Montero Juan Carlos , Monteagudo Mendoza Abel , Feldpausch Ted R. , Machado Durgante Flávia , Castaño Arboleda Nicolás , Marimon Beatriz S. , Marimon-Junior Ben Hur , Killeen Timothy J. , Vasquez Rodolfo , Mostacedo Bonifacio , Assis Rafael L. , Dantas do Amaral Dário , Householder John Ethan , Simon Marcelo Fragomeni , Brilhante de Medeiros Marcelo , Lima de Queiroz Helder , Lopes Maria Aparecida , Lima Magalhães José Leonardo , Stevenson Pablo R. , Barçante Ladvocat Cintra Bruno , Araujo-Murakami Alejandro , Baker Tim R. , Oliveira Feitosa Yuri , Mogollón Hugo F. , Duivenvoorden Joost F. , Ferreira Leandro Valle , de Toledo José Julio , Comiskey James A. , Lopes Aline , Damasco Gabriel , Vicentini Alberto , Cornejo Valverde Fernando , Gomes Vitor H. F. , Alonso Alfonso , Dallmeier Francisco , P. de Aguiar Daniel P. , Gribel Rogerio , Licona Juan Carlos , Villa Zegarra Boris Eduardo , Carneiro Guedes Marcelino , Cerón Carlos , Thomas Raquel , Milliken William , Campelo Wegliane , Albuquerque Bianca Weiss , Klitgaard Bente , Tello J. Sebastián , Fuentes Claros Alfredo , Rivas-Torres Gonzalo , Phillips Juan Fernando , Hildebrand Patricio von , Gonzales Therany , Vela César I. A. , Hoffman Bruce , Flores Bernardo Monteiro , Pombo Maihyra Marina , Rocha Maira , Holmgren Milena , Cano Angela , Umaña Maria Natalia , Casas Luisa Fernanda , Balslev Henrik , Urrego Giraldo Ligia Estela , Bigorne Rémy , Oberdorff Thierry , Maldonado-Ocampo Javier A. , Ortega Hernan , Hidalgo Max , Martens Koen , Torrente-Vilara Gislene , Zuanon Jansen , Acosta Astrid , Agudelo Edwin , Barrera Maure Soraya , Bastos Douglas A. , Bogotá Gregory Juan , Cabeceira Fernando G. , Canto André L. C. , Carvajal-Vallejos Fernando M. , Carvalho Lucélia N. , Cella-Ribeiro Ariana , Covain Raphaël , Dias Murilo S. , Donascimiento Carlos , Dória Carolina R. C. , Duarte Cleber , Ferreira Efrem J. G. , Galuch André V. , Giarrizzo Tommaso , Leitão Rafael P. , Lundberg John G. , Maldonado Mabel , Mojica José I. , Montag Luciano F. A. , Ohara William , Pires Tiago H. S. , Pouilly Marc , Prada-Pedreros Saúl , Queiroz Luiz J. de , Rapp Py-Daniel Lucia , Ribeiro Frank R. V. , Ríos Herrera Raúl , Rodrigues dos Anjos Marcelo , Lourenco Igor Hister , Sarmiento Jaime , Sousa Leandro M. , Stegmann Lis F. , Valdiviezo-Rivera Jonathan , Villa Francisco , Yunoki Takayuki , Tedesco Pablo A. 
Published: January 2025

Unlike most rivers globally, nearly all lowland Amazonian rivers have unregulated flow, supporting seasonally flooded floodplain forests. Floodplain forests harbor a unique tree species assemblage adapted to flooding and specialized fauna, including fruit-eating fish that migrate seasonally into floodplains, favoring expansive floodplain areas. Frugivorous fish are forest-dependent fauna critical to forest regeneration via seed dispersal and support commercial and artisanal fisheries. We implemented linear mixed effects models to investigate drivers of species richness among specialized frugivorous fishes across the ~6,000,000 km
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Amazon Basin, analyzing 29 species from 9 families (10,058 occurrences). Floodplain predictors per subbasin included floodplain forest extent, tree species richness (309,540 occurrences for 2,506 species), water biogeochemistry, flood duration, and elevation, with river order controlling for longitudinal positioning along the river network. We observed heterogeneous patterns of frugivorous fish species richness, which were positively correlated with floodplain forest extent, tree species richness, and flood duration. The natural hydrological regime facilitates fish access to flooded forests and controls fruit production. Thus, the ability of Amazonian floodplain ecosystems to support frugivorous fish assemblages hinges on extensive and diverse seasonally flooded forests. Given the low functional redundancy in fish seed dispersal networks, diverse frugivorous fish assemblages disperse and maintain diverse forests; vice versa, diverse forests maintain more fish species, underscoring the critically important taxonomic interdependencies that embody Amazonian ecosystems. Effective management strategies must acknowledge that access to diverse and hydrologically functional floodplain forests is essential to ensure the long-term survival of frugivorous fish and, in turn, the long-term sustainability of floodplain forests.