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

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

Impacts of community-based fish culture in seasonal floodplains on income, food security and employment in Bangladesh

This paper examines the impact of community based fish culture in seasonal floodplains on fish production, consumption, income, and food security of the participating households in Bangladesh. An analysis was performed using a randomly selected 46 % of the households from the three project and control floodplains; data were collected using longitudinal surveys on a seasonally, quarterly and monthly basis for the years 2007, 2008 and 2009. Fish production, income and food security of the participating households was improved due to the adoption of an equitable and inclusive multi-stakeholder approach introduced by the project. Average fish production increased from 124 kg/ha/yr. to 464 kg/ha/yr. The introduced community-based fish culture approach generated 3.74 times more fish income for households in the project sites in comparison to the control sites. Per capita monthly fish consumption increased from 1.26 kg to 2.31 kg in the project sites, which was 32 % higher than the control sites. Project implementation reduced the vulnerability of local beneficiaries, particularly of the landless and poor fishermen, by creating additional fishing opportunity for up to 6 months of the year. Promotion of the community based fish culture in seasonal floodplains may thus be useful in bringing about positive changes in the overall floodplain productivity and livelihood gains for the poor people of Bangladesh.Agricultural Science