Status and challenges of aquatic invertebrate research in Ethiopia: A review

No Abstract. Ethiopian Journal of Biological Sciences Vol. 5(1) 2006: pp. 75-11

Duration of development, biomass and rate of production of the dominant copepods (Calanoida and Cyclopoida) in Lake Tana, Ethiopia

No Abstract. SINET: Ethiopian Journal of Science Vol. 29 (2) 2006: pp. 107-12

Major factors that structure the Benthic fauna of a shallow, tropical lake, Lake Kuriftu, Ethiopia

The aim of this study was to determine the community structure of the benthos in Lake Kuriftu in relation to some environmental variables. Benthic samples were collected with an Ekman grab (0.0225 m2) from three sites (littoral, sub-littoral and profundal zones) on a monthly basis from September 2009 to February 2010. Dissolved oxygen and temperature were measured with a probe at different depths of each site. Sediment texture was determined by the Bouyoucos hydrometer and organic matter content by loss on ignition method. Chironomids, EPT (Ephemeroptera, Plecoptera, Trichoptera), oligochaetes and coleopterans were abundant in littoral and sub-littoral zones, with EPT much higher in the vegetated littoral area. The mean density of benthic macro-invertebrates in littoral, sub-littoral and profundal zones was 20,443, 18,251, and 4,388 ind/m2, and that of Chironomids was 12,545, 14,003 and 3,215 ind/m2, respectively. The profundal zone had the lowest diversity with abundant oligochaetes but no EPT samples, despite the high oxygen content of the profundal zone (6.33 mg/l). Chironomids and oligochaetes were present in all zones which had negligible difference in dissolved oxygen and organic matter content. The littoral zone had highest diversity (H’=1.26) and richness (d=2.72). Our results indicate that abundance of benthic macro-invertebrates of Lake Kuriftu was best correlated with the presence of vegetation in the littoral zone and sediment texture (high clay) in the littoral and profundal zones. We conclude that benthic macro-invertebrate community structure in Lake Kuriftu is mainly influenced by spatial variation in vegetation, sediment texture and temperature, but not dissolved oxygen and organic matter content. Keywords: Benthic macro-invertebrates, Lake Kuriftu, Littoral, Profundal, Sub-littoral

Testing of the applicability of European diatom indices in the tropical rift valley lake, Lake Hawassa, in Ethiopia

Quantitative ecological monitoring of African lakes is needed to understand growing human pressures on ecosystems. Diatom-based indices are routinely used for this purpose elsewhere in the world, but have not yet been produced for the flora of African freshwater lakes. Here we tested the applicability of the European diatom indices on the biomonitoring system of Lake Hawassa, Ethiopia. Physico-chemical and benthic diatom sampling was done at nine sites with different degrees of human disturbance along the lakeshore area from February to November 2015 and 2016. A percentage disturbance score (PDS) was calculated at each site and categorised from no evident disturbance (0–25%) to high disturbance (75–100%). Based on this criterion and selected physico-chemical parameters, the sampling sites categorized into minimal, moderate and high disturbance. Seventeen diatom indices were calculated using Omnidia software version 5.3. Out of a total of 17 indices that were calculated using the Omnidia software, six were selected as potential metrics. The diatom indices had a high discrimination efficiency and were significantly correlated with most the environmental parameters (r > 0.6; p < 0.05). Among these, the trophic diatom index (TDI) and generic diatom index (IDG) showed the best potential to discriminate the three clustered sites, based on their ecological classification. Accordingly, although robust locally based indices are needed, the TDI and IDG diatom indices could be used in monitoring of water quality in tropical African rift lakes

Chironomid distribution along a pollution gradient in Ethiopian rivers, and their potential for biological water quality monitoring

Water pollution resulting from the rapidly intensifying use of freshwater resources in Ethiopia is increasing the need for continuous follow-up and monitoring of the country's aquatic ecosystems, in order to maintain their biological diversity and water quality. Chironomids (non-biting dipteran midges) are often used for biological water quality assessment because their larvae tend to respond rapidly and sensitively to changes in the aquatic environment. Larval chironomid assemblages from 37 sites in 20 Ethiopian rivers were analysed in 2010 to assess the relationship between species composition and water quality. Cluster analysis of local physical and chemical variables was used to classify sites into three different water quality classes: 15 sites were classified as not or slightly polluted, 16 as moderately polluted and six as heavily polluted. We recovered 21 chironomid taxa, representing three subfamilies, with Chironominae (13 taxa) making the largest contribution, followed by Tanypodinae and Orthocladinae (four taxa each). Polypedilum nubifer, P. wittei, Polypedilum type Wabe, Cryptochironomus sp. and Conchapelopia sp. were the dominant species in unpolluted or slightly polluted sites. Chironomus alluaudi and C. imicola were indicators of heavily polluted sites, typified by low (<2 mg l(-1)) concentrations of dissolved oxygen. Heavily polluted sites, such as the Modjo and Sebata rivers, also held a lower number of species and genera than less-impacted sites. Larval chironomid assemblages proved useful as indicators of river water quality in Ethiopia when taxa are identified at the species and/or genus level

Prevalence of termites and level of damage on major field crops and rangelands in the Manasibu District, western Ethiopia

ABSTRACT: The current status of termite damage on maize (Zea mays(L.)), teff (Eragrostis tef (Zuccagni) Trotter), sorghum (Sorghum bicolor(L.)) and rangelands was studied in five Kebele administrations (study sites) and on three farmers' fields in every Kebele, in Manasibu District, Wellega Zone of Oromiya Regional State. Termite samples were collected from infested crop fields and rangelands, identified to the genus level with keys to the Ethiopian termites, and percentage occurrence for each genus was determined. Six genera of termites: Ancistrotermes, Macrotermes,Microtermes, Odontotermes, Pseudacanthotermes and Trinervitermes wereidentified. The first five genera belong to the subfamily Macrotermitinaewhereas Trinervitermes belongs to Nasutitermitinae. All of the generabelonged to the family Termitidae. Subterranean termites in general andMicrotermes in particular, were found to be the most prevalent termites in the study area. The damage that termites caused to maize and sorghum were assessed by the use of quadrates and that of teff by laying wooden frames in the quadrates. For all the three crops, damage was assessed at vegetative, flowering, and maturity stages. It was found out that the levels at which the three crops were damaged by termites were significantly different from each other. Teff was the most seriously damaged crop in the study area, followed by maize, while sorghum was the least affected crop. Damage at different stages, within each crop, were also found to be significantly variable from each other. To evaluate the impact of termites on rangelands in the absence and presence of grazing by livestock, three plots of rangelands were fenced and protected for six months. It was found that the protected plot of the rangelands significantly had higher percent vegetation cover and lower number of termite foraging holes per m2. From the study, it can be concluded that the genus Microtermes was the major termite species attacking crops and rangelands in Manasibu district, implying that most control strategies should focus on this genus, especially to control termites on teff and maize