Ethiopian Journals Online (EJOL)
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Determining regions of higher extinction risk occurrences in South African cycads
No full textExtinction crisis in South African cycads has been very high in recent times. This study used comprehensive distribution records of cycads that occurred in South Africa. The records obtained from the South African national herbarium named South African National Biodiversity Institute (sanbi) through the herbarium sheets were used to determine the regions of higher extinction crisis in South Africa. The threat status of the herbarium taxa was obtained from iucn 2019 version and was analysed. Threats to these taxa were extracted from iucn and the numbers of taxa facing each threat were determined to unravel the prominent threats. The herbarium records were used to construct a species distribution map for all the cycads in South Africa and another map for Critically Endangered and Extinct South African cycads. This study revealed that regions of high species richness for South African cycads are not the same as regions with highly threatened and extinct South African cycads. Prominent threats found in this plant group are also the major threats causing extinction crisis in the highly threatened and extinct cycads that occurs in few provinces in South Africa. This study therefore recommends that conservation efforts for South African cycads should be intensified in the hotspots of highly threatened and extinct South African cycads identified in this study to further mitigate extinction crisis of South African cycads
Distribution of benthic macroinvertebrates in relation to physicochemical parameters and macrophyte cover in the Ketar River, Ethiopia
No full textThe aim of this study was to determine the effects of physicochemical parameters and macrophyte on the macroinvertebrate assemblages in the Ketar River, which drains into Lake Ziway. Six sampling sites were selected along the river stretch and samples were collected from December to April 2017/2018 based on the method outlined in Ontario Benthos Biomonitoring Network Protocol Manual. A total of 5,450 individuals comprised of one class, 7 orders, and 23 families were collected during the study period. Hemiptera families were the predominant taxa and contributed the largest percentage of the total samples followed by the Coleoptera. Notonectidae and Corixidae shared the highest total abundance. This study confirmed that the sites covered with macrophytes were significantly different from the substrate both in taxa richness and total abundance (P < 0.05). Redundancy Analysis revealed that pH, Temperature, electric conductivity, DO, NO2, NO3, NH4, SiO2 and TP were the most important variables explaining the variation in macroinvertebrate assemblage patterns. The mean Shannon diversity index also indicated that the sites covered by the macrophyte stand had a significantly higher value than the sites sampled from the substrate, which implies that macrophytes support abundant, and promoting the diversity of macroinvertebrates. Thus, the conservation of macrophytes can enhance the conservation of macroinvertebrates along the course of the river, besides the role of macrophyte in sediment trapping and reducing sedimentation buildup in Lake Ziway
THE POTENTIAL MUTAGENIC EFFECT OF THE LEACHATES OF RURAL SOLID WASTE LANDFILL ON ALLIUM CEPA (L.)
Get PDFThe potential mutagenic effect of raw and simul~ted leachate from a rural refuse dump site at "Odo 000", in South-West Nigeria, on AUium cepa was evaluated. Roots of AUium at about· 2-3 cm long were treated with 1 %, 25%, 5%, 10% and 25% concentrations of the leachate samples for 24 hr. These were then used to prepare slides for the observation of chromosomal aberrations and frequency of mitotic division, Different types of chromosomal aberrations were induced and this was significant at P < 0.05 level at all doses tested except at 1 % concentration of the simulated leachate. There was also reduction in the number of cells dividing at the tested concentrations when compared with the control. The observed effects may be provoked by genotoxic chemicals found in the leachate samples. This finding may be useful in the practical aspects ·of waste management and for the assessment of the hazardous effects of the chemicals in the leachate from solid waste dumpsites
A PRELIMINARY SURVEY OF ERYTHROCEBUS PATAS IN ANBESA CHAKA, BAMBESI WOREDA OF BENISHANGUL-GUMUZ REGION, WESTERN ETHIOPIA
Get PDFA preliminary survey conducted in Benishangul-Gumuz Region, BambesiWoreda from late January to early February, 2010 resulted in finding two groups of the sametaxon of patas monkeys. Each of the two groups had one adult male, and one of themconsisted of 33 individuals, where as the other had a total of 23 individuals including theadult males, adult and sub-adult females and infants. The survey was conducted on foot andby a vehicle and behavioural data were collected using adlibtum method. From the structureof the two groups and the season during which they probably had their newborns, theybelong to the species Erythrocebus patas which are also found elsewhere. However, the longblack fur coloration along the shoulder, back and upper fore limbs of the males is differentfrom any of the four different subspecies, namely, E. patas patas, E. patas villiersi, E. pataspyrrhonotus and E. patas baumstarki, and others found in Athi plains, southeast of Nairobi andeast of the rift valley, which have pink faces and a blue nasal spot and not given subspecificnames. Thus, it is reasonable to think of the Benishangul patas as subspecies, as they aredistinct from the other subspecie
THE GEOTECTONIC EVOLUTION OF THE WESTERN ETHIOPIAN SHIELD
Get PDFThe western Ethiopian Shield comprises three lithotectonic units. The Birbir domain, an assemblage of mafic to felsic intrusive and extrusive rocks and mainly volcanogenic sedimentary rocks, is enclosed between the dominantly orthogneissic Baro and Geba domains. The earliest recorded deformation event (D1) resulted in the formation of a subhorizontal gneissosity within the gneissic terranes which was synchronous with an early upper amphibolite-facies metamorphic peak (M1) at 800–770 Ma which locally caused partial melting. All terrains were subsequently deformed in the D2 event which was the result of severe E-W crustal shortening. An anticlockwise P-T-t path is implied. Subsequent D3 deformation was concentrated within mylonitised domain boundaries which record major transcurrent movement. These structures were reactivated and suffered fluid incursion resulting in isotopic reequilibration at 635–580 Ma. A second metamorphic event, M2, related to crustal thickening and consequent granite genesis, occurred after the cessation of D3 shearing. Bulk chemical analyses show that the metamorphosed plutonic and volcanic rocks of the Birbir domain are predominantly calc-alkaline and similar to those generated by subduction in modern magmatic arcs. They belong in part to the low-K series, suggesting an oceanic environment. The evolution of the region can be explained in terms of the melting of a subducting slab, intrusion, metamorphism and the formation of an oceanic island arc complex. Continued plate convergence caused severe east-west shortening and basin closure. Further attenuation gave rise to transcurrent shearing, fluid influx, a second thermal event and accretion of microcontinents
FIELD EVALUATION OF NON-SYNTHETIC INSECTICIDES FOR THE MANAGEMENT OF INSECT PESTS OF OKRA ABELMOSCHUS ESCULENTUS (L.) MOENCH IN GHANA
Get PDFIn a two-year study, aqueous seed extracts of the neem tree Azadirachta indica A. Juss (Meliaceae) and Bacillus thurigiensis (Bt) were evaluated in the field for the management of pests of okra, Abelmoschus esculentus (L.) Moench. The aqueous neem seed extracts were applied at the rate of 30, 50, 75 and 100 g/l and B.thurigiensis was applied at the rate 1.0 g/l of water. Actellic 25 EC, a synthetic insecticide, was applied at the rate of 2 ml/l as standard check. Arthropod fauna on okra were sampled using traps, sweep nets, aspirators and handpicking. The nature of damage caused to the stems, leaves, flowers and fruit was assessed by visual observation. The major insect pests of okra collected were Podagrica uniformis Jac, Aphis gossypii Glov, Sylepta derogata (F.), Spodoptera litoralis Boisd, Prodenia litura (F.), Dysdercus superstitiosus (F.), Epilachna similis (F.), Bemisia tabaci (Genn.) and Zonocerus variegatus (F.). These pests were observed attacking mainly the leaves of okra. Some of the minor pests identified were Lagria villosa (F.), L. cuprina Thoms, Mylabris temporalis Wellni, M. trifasciata (Thumb.), Lapidognatha sp and Empoasca devastans (D.). Actellic, neem seed extract and Bt significantly reduced the population and damage caused by the major insect pests of okra recorded at Legon, Ghana compared to the untreated. Actellic and aqueous neem seed extracts were equally effective against the pests of okra and caused a significant reduction in insect damage to the leaves, flowers and fruit of the crop. There were no significant differences among the different dosages of neem seed extract on all the parameters assessed, with the exception of the final fruit yield. Actellic, neem extracts or Bt produced higher yield of marketable fruit of okra than untreated plants. Neem seed extract applied at the rate of 30 g/l of water to okra plants produced lower fruit yield than those treated with 50 g or more. Aqueous neem seed extracts and Bt can be used effectively by farmers as a component of integrated management of pests of okra in Ghan
PHYSICO-CHEMICAL PROPERTIES OF TEN COWPEA LINES ON RESISTANCE TO CALLOSOBRUCHUS MACULATUS (WALP)
No full textTen IITA Cowpea lines were evaluated for their Physico-Chemical properties to assess their potential for resistance to Callosobruchus maculatus. IT 90K–277–2 showed highest resistance while IT 97K–497–2 showed least resistance (high susceptibility) on the basis of number of insect F1 generation (i.e. 454.00+149.61) and grain weight loss (7.33g). Correlation between fecundity and grain weight loss was positive. The result of the proximate analysis has no correlation with susceptibility. The seed coat texture plays significant role in inducing ovipositional response. Non-preference was suspected to be the resistant mechanism
Potential of Water Hyacinth (Eichhornia crassipes (Mart.) Solms) for the Removal of Chromium from Tannery Effluent in Constructed Pond System
Get PDFThe objective of the present study was to evaluate the potential use of water hyacinth for the removal of chromium (Cr) from tannery wastewater. This experiment was performed using healthy, young and acclimatized water hyacinth collected from unpolluted Awash River. Cr concentrations of 3, 5, 7, 10 and 20 mg/L were added to five different polyethylene tanks, containing 40 litre tap water cultured with Hoagland’s solution. A sixth tank containing Cr-free water was used as a control group. Six plants of equal wet mass (each 12.5 ± 2 g), shoot length (11 ± 2 cm) and root length (6 ± 2 cm) were transferred into each tank and allowed to grow in a greenhouse for 42 days. From each tank plants were harvested randomly every week. Bioaccumulation factor, translocation factor, shoot and root length; wet biomass and dry weight of the shoot and root were measured, and relative growth rate, tolerance index of the root and tolerance index of wet mass were analyzed. The maximum accumulation of 2.52 X 103 µg/g of water hyacinth was achieved in the plants exposed to 20 mg/L Cr solution. The root part of the plant accumulated 2.42 to 3.82 times higher than the shoot part. An overall Cr removal efficiency of up to 91% was achieved in this study, but the efficiency decreased as the concentration of Cr in water increased. The growth of the plant was inhibited at high concentration due to Cr toxicity. Therefore, the application of water hyacinth for Cr removal will be sustainable, if the concentration of Cr in wastewater does not exceed about 10 mg/L. The relative growth rate (RGR) of the plant decreased with increasing Cr concentration and the growth was inhibited above 15.3 mg/L Cr in water. Based on the above data, it could be concluded that water hyacinth can potentially be used for the removal of Cr from tannery effluents which is a major environmental problem in Ethiopia. However, further investigation is needed to ascertain the optimum conditions for maximum removal
ORTHOGONAL AND SCALING TRANSFORMATIONS OF QUADRATIC FUNCTIONS WITH SOME APPLICATIONS
Get PDFIn this paper we present a non-singular transformation that can reduce a givenquadratic function defined on Rn to another simpler quadratic function and study the impact of thetransformation in relation to the problem of minimization of the function. In particular, weconstruct a non-singular transformation that can reduce a quadratic function whose level surfacesare ellipsoids to another quadratic function whose level surfaces are spherical while preserving theconvexity/concavity property of the given function. The relation between a minimizing point of thegiven function and that of the new simpler function obtained under the transformation is alsodescribe
SPECIES COMPOSITION, RELATIVE ABUNDANCE AND DISTRIBUTION OF THE AVIAN FAUNA OF ENTOTO NATURAL PARK AND ESCARPMENT, ADDIS ABABA
Get PDFA study on avian species composition, relative abundance, diversity anddistribution at Entoto Natural Park and escarpment was carried out during July 2009 - March 2010.The study area was stratified based on vegetation composition. Four habitat types: forest(rehabilitation and nursery areas), farmland, church compound (St. Mary’s and St. RaguelChurches) and eucalyptus plantation were considered. Point count method was employed for foresthabitat and eucalyptus plantation, line-transect method for farmland and total count method wasused for the church compound. T-test and ANOVA were applied for analysis of the effect of seasonand habitats on abundance of species. As a result, 124 avian species belonging to 14 orders and 44families were identified in the study area during the wet (July, 2009 to October, 2009) and dryseason (December, 2009 to March, 2010) surveys. The average temperature and rainfall for wet anddry seasons were 7.5°C and 315 mm and 20.5°C and 9 mm, respectively. During the dry season,highest avian diversity was observed in the farmland habitat (H’=3.73), followed by the forest(H’=2.92), whereas during the wet season, highest avian diversity was observed in the forest habitat(H’=3.98), followed by church compound (H’=3.25). Highest number of species was recorded onfarmland and forest habitats during the dry and wet seasons. Simpson’s Similarity Index showedthe highest species similarity between forest and farmland during both wet and dry seasons. Therewas no significant difference between seasons and habitats in the abundance of birds in thesehabitats. However, wet season had an effect on the avian abundance in eucalyptus plantation(t=2.952, P <0.05). Eucalyptus plantation, soil erosion, deforestation, habitat fragmentation,settlement and land degradation were the main threats for the distribution of birds in the presentstudy area