RESEARCH ARTICLE Size-dependent response of tropical wetland fish communities to changes in vegetation cover and habitat connectivity Izaias Fernandes . Jerry Penha . Jansen Zuanon Received: 27 September 2013 / Accepted: 10 April 2015 Ó Springer Science+Business Media Dordrecht 2015 Abstract Context The replacement of native vegetation by exotic grasses for livestock production is driving landscape homogenization, habitat fragmentation and reducing connectivity between habitat patches in floodplains ecosystems. Objective In this context we examined how changes in native and exotic vegetation cover, connectivity and water depth affect the attributes of the small [standard length (SL) \ 80 mm as adults] and large-sized fish assemblages (SL C 80 mm as adults). Method We assessed the effects of water depth, exotic and native vegetation cover and habitat con- nectivity on the abundance, species richness, body size and biomass of fish assemblages in a 25 km 2 area of the seasonal habitats of the Pantanal wetland over 5 years. Results We showed that fish assemblage response to meso-scale variation in water depth, vegetation cover and habitat connectivity in seasonal habitats is size- dependent. The gradient from exotic to natural vegeta- tion cover did not affect the assemblages of small-sized fish, which were mostly regulated by water depth, habitat connectivity and the gradient from grassland to forest. However, besides being affected by water depth and habitat connectivity, large-sized fish were also affected by the gradient from exotic to natural vegetation cover. Conclusion Our results indicate that transformations in the landscape and changes in the dynamics of inundation may have negative consequences for the long-term persistence of fish assemblages in the Pantanal wetlands. Keywords Temporary habitat  Effective distance  Landscape connectivity  Exotic species  Water depth  Cattle ranching impacts  Pantanal Introduction Floodplains are among the most diverse and produc- tive natural systems in the world (Tockner et al. 2000). Electronic supplementary material The online version of this article (doi:10.1007/s10980-015-0196-2) contains supple- mentary material, which is available to authorized users. I. Fernandes (&) Programa de Po ´s-Graduac ¸a ˜o em Biologia de A ´ gua Doce e Pesca Interior, Instituto Nacional de Pesquisas da Amazo ˆnia, Manaus, AM CEP 69080-971, Brazil e-mail: biomedice@gmail.com I. Fernandes  J. Penha Universidade Federal de Mato Grosso, Instituto de Biocie ˆncias, Av. Fernando Correa da Costa s/n, Coxipo ´, Cuiaba ´, MT CEP 78060-900, Brazil e-mail: jpenha.bio@gmail.com J. Zuanon Coordenac ¸a ˜o de Biodiversidade, Instituto Nacional de Pesquisas da Amazo ˆnia, Av. Andre ´ Arau ´jo, 2936, Petro ´polis, Manaus, AM CEP 69080-971, Brazil e-mail: jzuanon3@gmail.com 123 Landscape Ecol DOI 10.1007/s10980-015-0196-2