The water quality degradation of upper Awash River, Ethiopia

Benthic macroinvertebrate based assessment of water quality in the upper Awash River, along the river course of about 500 kms was conducted on quarterly bases between September 2009 and August 2010. This paper reports the complete identification of macroinvertebrates together with measurements of physico-chemical parameters and heavy metal concentrations which were considered as a tool for assessing the water quality status of upper Awash river, Ethiopia. Benthic animals and water samples were collected from three different sampling sites located in the upper Awash River, and analyzed to evaluate stressor sources and the general stream water quality. The percentage abundance of families of various macroinvertebrates taxonomic groups was identified from all sites. Accordingly, Koka bridge site of the upper Awash River had low water quality status which is likely to be due to poor farming, untreated effluents from factories and poor provision of sanitation facilities to the riparian communities. Apparently, the concentrations of the selected nutrients and heavy metals did not differ significantly among the sampling sites (ANOVA, P > 0.05), presumably due to pollution of the whole stream reach by the catchment nutrient sources. Ten orders of benthic macroinvertebrates consisting of 36 families were identified. The highest family richness was observed in Ginchi, slightly impacted site (1) whilst the least faunal diversity was observed in Koka Bridge (7 families) indicating the effect of water quality class differences among the sampling sites.Key words: Macroinvertebrates, organic pollution, heavy metals, water quality, anthropogenic impact, upper Awash Rive

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

Genetic diversity and symbiotic effectiveness of Bradyrhizobium strains nodulating selected annual grain legumes growing in Ethiopia

Vigna unguiculata, Vigna radiata and Arachis hypogaea growing in Ethiopia are nodulated by a genetically diverse group of Bradyrhizobium strains. To determine the genetic identity and symbiotic effectiveness of these bacteria, a collection of 36 test strains originating from the root nodules of the three hosts was investigated using multilocus sequence analyses (MLSA) of core genes including 16S rRNA, recA, glnII, gyrB, atpD and dnaK. Sequence analysis of nodA and nifH genes along with tests for symbiotic effectiveness using δ15N analysis were also carried out. The phylogenetic trees derived from the MLSA grouped most test strains into four well-supported distinct positions designated as genospecies I–IV. The maximum likelihood (ML) tree that was constructed based on the nodA gene sequences separated the entire test strains into two lineages, where the majority of the test strains were clustered on one of a well-supported large branch that comprise Bradyrhizobium species from the tropics. This clearly suggested the monophyletic origin of the nodA genes within the bradyrhizobia of tropical origin. The δ15N-based symbiotic effectiveness test of seven selected strains revealed that strains GN100 (δ15 N=0.73) and GN102 (δ15 N=0.79) were highly effective nitrogen fixers when inoculated to cowpea, thus can be considered as inoculants in cowpea production. It was concluded that Ethiopian soils are a hotspot for rhizobial diversity. This calls for further research to unravel as yet unknown bradyrhizobia nodulating legume host species growing in the country. In this respect, prospective research should also address the mechanisms of symbiotic specificity that could lead to high nitrogen fixation in target legumes

Lentil (Lens culinaris Medik.) nodulates with genotypically and phenotypically diverse rhizobia in Ethiopian soils

To determine the symbiotic, phenotypic, and genetic diversity of rhizobia nodulating lentil in Ethiopia, 48 lentil-nodulating rhizobia were isolated from soil samples collected from diverse agro-ecological locations, and characterized based on 76 phenotypic traits. Furthermore, 26 representative strains were selected and characterized using multilocus sequence analyses (MLSA) of core (16S rRNA, recA, atpD, glnIIand gyrB) and symbiotic (nodA and nifH) genes loci. Numerical analysis of phenotypic characteristics showed that the 48 test strainsfell into three major distinct clusters.The evidence obtained from phylogenetic trees based on 16S rRNA genes of the 26 test strains showed that they belong to the Rhizobium genus. Our phylogenetic reconstruction based on combined gene trees (recA,atpDand glnII) supported three distinct sub-lineages (clades I, II and III). Based on thephylogenetic groups constructed from the concatenated genes, strains in genospeciesIand II could be classified with R. etliand R. leguminosarum, respectively. GenospeciesIII, however, might be an unnamed Rhizobium genospecies. Phylogenetic reconstruction based on the symbiosis-related genes supported a single cluster, indicating these genes were highly conserved and suggesting differences in the evolutionary histories of chromosomal and symbiotic genes. Overall, these results confirmed the presence of a great diversity of lentil-nodulatingRhizobium species in Ethiopia, inviting further exploration. Moreover, the differences in symbiotic effectiveness of the test strains indicated the potential for selecting and using them as inoculants to improve the productivity of lentil in the country

Genetic and phenotypic diversity of rhizobia nodulating chickpea (Cicer arietinum L.) in soils from southern and central Ethiopia

Forty-two chickpea-nodulating rhizobia were isolated from soil samples collected from diverse agro-ecological locations of Ethiopia and were characterized on the basis of 76 phenotypic traits. Furthermore, 18 representative strains were selected and characterized using multilocus sequence analyses of core and symbiotic gene loci. Numerical analysis of the phenotypic characteristics grouped the 42 strains into 4 distinct clusters. The analysis of the 16S rRNA gene of the 18 strains showed that they belong to the Mesorhizobium genus. On the basis of the phylogenetic tree constructed from the combined genes sequences (recA, atpD, glnII, and gyrB), the test strains were distributed into 4 genospecies (designated as genospecies I–IV). Genospecies I, II, and III could be classified with Mesorhizobium ciceri, Mesorhizobium abyssinicae, and Mesorhizobium shonense, respectively, while genospecies IV might represent an unnamed Mesorhizobiumgenospecies. Phylogenetic reconstruction based on the symbiosis-related (nifH and nodA) genes supported a single cluster together with a previously described symbiont of chickpea (M. ciceri and Mesorhizobium mediterraneum). Overall, our results corroborate earlier findings that Ethiopian soils harbor phylogenetically diverse Mesorhizobium species, justifying further explorative studies. The observed differences in symbiotic effectiveness indicated the potential to select effective strains for use as inoculants and to improve the productivity of chickpea in the country

Helminth parasites in the endangered Ethiopian wolf, Canis simensis

Ethiopian wolves, Canis simensis, are an endangered carnivore endemic to the Ethiopian highlands. Although previous studies have focused on aspects of Ethiopian wolf biology, including diet, territoriality, reproduction and infectious diseases such as rabies, little is known of their helminth parasites. In the current study, faecal samples were collected from 94 wild Ethiopian wolves in the Bale Mountains of southern Ethiopia, between August 2008 and February 2010, and were screened for the presence of helminth eggs using a semi-quantitative volumetric dilution method with microscopy. We found that 66 of the 94 faecal samples (70.2%) contained eggs from at least one group of helminths, including Capillaria, Toxocara, Trichuris, ancylostomatids, Hymenolepis and taeniids. Eggs of Capillaria sp. were found most commonly, followed by Trichuris sp., ancylostomatid species and Toxocara species. Three samples contained Hymenolepis sp. eggs, which were likely artefacts from ingested prey species. Four samples contained taeniid eggs, one of which was copro-polymerase chain reaction (copro-PCR) and sequence positive for Echinococcus granulosus, suggesting a spillover from a domestic parasite cycle into this wildlife species. Associations between presence/absence of Capillaria, Toxocara and Trichuris eggs were found; and egg burdens of Toxocara and ancylostomatids were found to be associated with geographical location and sampling season