Longitudinal river zonation in the tropics: examples of fish and caddisflies from the endorheic Awash River, Ethiopia

• DOI: 10.1007/s10750-020-04400-0
• Publication Date: 2020-09-16T22:56:01Z
• Authors: Gernot K. Englmaier; Daniel S. Hayes; Paul Meulenbroek; Yonas Terefe; Aschalew Lakew; Genanaw Tesfaye; Herwig Waidbacher; Hans Malicky; Alemayehu Wubie; Patrick Leitner; Wolfram Graf
• Keywords: Caddisfly; Ecotone; River ecosystem; Freshwater ecosystem; Nestedness

Abstract Specific concepts of fluvial ecology are well studied in riverine ecosystems the temperate zone but poorly investigated Afrotropical region. Hence, we examined longitudinal zonation fish and adult caddisfly (Trichoptera) assemblages endorheic Awash River (1,250 km length), Ethiopia. We expected that species structured along environmental gradients, reflecting pattern large-scale freshwater ecoregions. applied multivariate statistical methods to test for differences spatial assemblage structure identified characteristic taxa observed biocoenoses by indicator analyses. Fish were clustered into highland lowland communities, following ecoregions, separated an ecotone with highest biodiversity. Moreover, results suggest separating heterogeneous highlands a forested deforested zone. Surprisingly, drainage is rather species-poor: only 11 (1 endemic, 2 introduced) 28 (8 new records Ethiopia) recorded from mainstem its major tributaries. Nevertheless, specialized characterize forests, whereas lowlands primarily host geographically widely distributed species. This study showed combined approach caddisflies suitable method assessing regional characteristics tropics.