We need better understanding about functional diversity and vulnerability of tropical freshwater fishes (pdf)

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We need better understanding about functional diversity and vulnerability of tropical freshwater fishes

Biodivers Conserv DOI 10.1007/s10531-016-1258-8 COMMENTARY We need better understanding about functional diversity and vulnerability of tropical freshwater fishes Jean R. S. Vitule1,2 • Angelo A. Agostinho3,4 • Valter M. Azevedo-Santos5 • Vanessa S. Daga1,6 • William R. T. Darwall7 • Daniel B. Fitzgerald8 • Fabrı́cio A. Frehse1,2 • David J. Hoeinghaus9 • Dilermando P. Lima-Junior10 • André L. B. Magalhães11 • Mário L. Orsi12 • André A. Padial2,13 • Fernando M. Pelicice14 • Miguel Petrere Jr.15,17 • Paulo S. Pompeu16 • Kirk O. Winemiller8 Received: 6 September 2016 / Revised: 4 November 2016 / Accepted: 11 November 2016 Ó The Author(s) 2016. This article is published with open access at Springerlink.com Abstract Here we extend a discussion initiated by Toussaint et al. (Sci Rep 6:22125, 2016) concerning the relationship between global patterns of freshwater fish functional diversity (FD) and its vulnerability to human impacts. Based on a set of morphological traits, they concluded that Neotropical freshwater fishes have highest FD, but low vulnerability given high levels of functional redundancy. This conclusion implies that conservation efforts for freshwater fishes should emphasize temperate regions. This Communicated by Angus Jackson. & Jean R. S. Vitule 1 Laboratório de Ecologia e Conservação, Departamento de Engenharia Ambiental, Setor de Tecnologia, Universidade Federal do Paraná, Curitiba, Brazil 2 Programa de Pós-Graduação em Ecologia e Conservação, Universidade Federal do Paraná, Curitiba, Brazil 3 Núcleo de Pesquisa em Limnologia, Ictiologia e Aqüicultura (NUPELIA), Universidade Estadual de Maringá, Maringá, Brazil 4 Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, Universidade Estadual de Maringá, Maringá, Brazil 5 Laboratório de Ictiologia, Universidade Estadual Paulista, Botucatu, Brazil 6 Programa de Pós-Graduação em Zoologia, Universidade Federal do Paraná, Curitiba, Brazil 7 Global Species Programme, International Union for Conservation of Nature (IUCN), Cambridge, UK 8 Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, USA 9 Department of Biological Sciences and Advanced Environmental Research Institute, University of North Texas, Denton, USA 10 Laboratório de Ecologia e Conservação de Ecossistemas Aquáticos, Universidade Federal de Mato Grosso, Pontal do Araguaia, Brazil 11 Programa de Pós-graduação em Tecnologias para o Desenvolvimento Sustentável, Universidade Federal de São João Del Rei, Ouro Branco, Brazil 123 Biodivers Conserv perspective is risky, because Toussaint et al.’s study seriously underestimates the full scope of FD, including important ecosystem services provided by fishes in the tropics. We briefly discuss some additional and well-documented aspects of tropical freshwater fish FD and conclude that tropical fish FD is highly vulnerable. Keywords Conservation policy Extinction risk Functional traits Ecosystem services Megadiverse regions Multidimensional niche Toussaint et al. (2016) offered a thoughtful and much-needed analysis of global patterns in functional diversity (hereafter FD) of freshwater fishes. We applaud their effort to incorporate FD into discussions about the conservation of freshwater biodiversity and for providing a major stimulus for new research. Here we comment on their conclusions and argue for a more comprehensive perspective on FD and, particularly, threats to FD of tropical fishes in megadiverse regions. Toussaint et al. found greatest FD in the Neotropics, the region with highest species richness of freshwater fishes. Their study inferred that functional vulnerability, i.e. potential loss of FD represented by threatened species as assessed by IUCN (2015) and potentially threatened species that occur in a single basin as assessed by Tedesco et al. (2012), is low in the tropics compared to higher latitude regions. They advocate for a greater research and conservation focus on functionally unique species in Palearctic and Nearctic regions, because species in those regions likely contribute disproportionately to ecosystem processes, whereas many vulnerable tropical species are functionally redundant. Few would disagree with their recommendation to broaden the research agenda; however, their analysis clearly underestimated the FD of tropical fishes and its contributions to ecosystem processes and services, as well as the vulnerability of tropical fishes to human impacts. Importantly, their conclusion has potentially harmful implications for conservation given the political challenges in many developing countries in the tropics. Briefly, we address four main points. First, there is general consensus (e.g. Flynn et al. 2009; Hoeinghaus et al. 2009; Laliberté and Legendre 2010; Cadotte et al. 2011; Vitule et al. 2012; Costa-Pereira and Galetti 2015) that loss of FD can result from a wider range of negative impacts than those considered by Toussaint et al. (2016). Species loss at a regional scale is not required to have significant reduction of FD and impairment of ecosystem processes and services. Population declines lower than the thresholds applied TM for species assessments for the IUCN Red List of Threatened Species (hereafter the ‘‘Red 12 Departamento de Biologia Animal e Vegetal, Universidade Estadual de Londrina, Londrina, Brazil 13 Laboratório de Análise e Sı́ntese em Biodiversidade, Universidade Federal do Paraná, Curitiba, Brazil 14 Núcelo de Estudos Ambientais, Universidade Federal de Tocantins, Porto Nacional, Brazil 15 Programa de Pós-Graduação em Planejamento e Uso de Recursos Renováveis, Universidade Federal de São Carlos, Sorocaba, Brazil 16 Laboratório de Ecologia de Peixes, Universidade Federal de Lavras, Lavras, Brazil 17 Programa de Pós-Graduação em Sustentabilidade de Ecossistemas Costeiros e Marinhos, UNISANTA, Santos, Brazil 123 Biodivers Conserv List’’) can still be sufficient to impair important species interactions and ecosystem processes (e.g. Pendleton et al. 2014; Correa et al. 2015). For example, prochilodontid (e.g. Prochilodus spp.) and loricariid (e.g. Hypostomus spp.) fishes are important ecosystem engineers in the Neotropics. The influence of these species on ecosystem processes, such as nutrient cycling and benthic primary and secondary production, are functions of local population abundance (Flecker and Taylor 2004; Flecker et al. 2010; Mormul et al. 2012; Winemiller et al. 2015). Overexploitation of formerly abundant stocks can change nutrient dynamics (Flecker 1996; Flecker and Taylor 2004; Taylor et al. 2006; Flecker et al. 2010) or riparian forest dynamics (Correa et al. 2015; Costa-Pereira and Galetti 2015). Moreover, rare species can have important contributions to the functional structure of assemblages (Leitão et al. 2016), yet most rare fishes are poorly studied while being highly vulnerable. Second, curren (...truncated)