The historical focus of research on temperate freshwater systems has resulted in a large data gap in the tropics, particularly in Afrotropical regions. As most conceptual models have been developed in temperate systems, their applicability to Afrotropical waters is uncertain. The aim of this study is to use trait and diversity information from freshwater fish assemblages to characterize the functional ecology of lotic communities in an Afrotropical region. Secondly, we aimed to test conformity of these systems to gradient (River Continuum Concept, Patch Dynamic) and landscape (Riverine Habitat Template) conceptual models. Sampling of fish communities was undertaken at eighty-two sites in coastal and inland locations in the Republic of Congo. Abiotic data included measurements of stream morphology, landscape variables, water quality and habitat integrity. Landscape data were modeled using ArcGIS, and biotic-abiotic relationships analysed using Non-Metric Multidimensional Scaling. Functional traits were assessed using a Principle Component Analysis, and trait diversity calculated using functional trait-space occupation, functional evenness and divergence.
Results/Conclusions
Preliminary results indicate that functional diversity increases with species richness along the longitudinal gradient from first-order streams within both inland and coastal basins. Habitat preference and swimming traits were associated with both local and broad-scale environmental variables, where broad physiographic differences between sampled ecoregions also influence taxonomic and functional structure. As with diversity and taxonomic structure, the functional composition of fish communities changes across the longitudinal gradient of the basins. Functional trait and environment patterns documented in this study partly confirm established theoretical assumptions and show patterns that may assist in developing a greater understanding of responses and vulnerabilities of fish assemblages to environmental modification in Afrotropical systems.