Environmental and spatial effects on coastal stream fishes in the Atlantic rain forest

Made available in DSpace on 2020-12-10T19:45:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-12-31 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) University of Florida Foundation COTEC IBAMA/ICMBio Contemporary and historical factors influence assemblage structure. The environmental and spatial influences acting on fish organization of rain forest coastal streams in the Atlantic rain forest of Brazil were examined. Fish (and functional traits such as morphology, diet, velocity preference, body size), environmental variables (pH, water conductivity, dissolved oxygen, temperature, stream width, flow, depth, substrate), and altitude were measured from 59 stream reaches. Asymmetric eigenvector maps were used to model the spatial structure considering direction of fish movements. Elevation played an important role-fish abundance, biomass, and richness all decrease with increasing elevation. Fish communities are influenced by both environmental and spatial factors, but downstream movements were shown to be more important in explaining the observed spatial variation than were bidirectional and upstream movements. Spatial factors, as well as environmental variables influenced by the spatial structure, explained most of the variation in fish assemblages. The strong spatial structuring is probably attributable to asymmetric dispersal limitation along the altitudinal profile: Dispersal is likely to be more limiting moving upstream than downstream. These fish assemblages reflect scale-dependent processes: At the stream-reach scale, fish respond to local environmental filters (habitat structure, water chemistry, and food supply), which are in turn influenced by a larger scale, namely the altitudinal gradient expected in steep coastal mountains. Thus, environmental drivers are not independent of spatial factors, and the effects of local factors can be confounded across the altitudinal gradient. These results may have implications for conservation, because downstream reaches are often neglected in management and conservation plans. in Portuguese is available with online material. Univ Estadual Paulista, Dept Zool & Bot, Lab Ictiol, Sao Jose Do Rio Preto, SP, Brazil Univ Florida, Dept Biol, Arthur R Marshall Jr Ecol Sci Lab, Gainesville, FL USA Univ Estadual Paulista, Dept Zool & Bot, Lab Ictiol, Sao Jose Do Rio Preto, SP, Brazil CNPq: 301755/2013-2 FAPESP: 2012/19723-0 FAPESP: 2013/20794-1 FAPESP: 2008/55029-5 COTEC: 260108-015.708/2012 COTEC: 260108000.197/2008 IBAMA/ICMBio: 37489-1/2 IBAMA/ICMBio: 15744