Ethiopian Journal of Biological Sciences

THE FOOD AND FEEDING HABITS OF THE AFRICAN CATFISH, CLARIAS GARIEPINUS (BURCHELL, 1822) (PISCES: CLARIIDAE) IN LAKE HAWASSA AND SHALLO SWAMP, ETHIOPIA

Yosef Tekle-Giorgis, Solomon Wagaw, Elias Dadebo — Mon, 07 Mar 2016 00:00:00 +0000

Feeding habits of the African catfish Clarias gariepinus (Burchell, 1822) was studied based on 252 and 211 fish specimen collected from Lake Hawassa and Shallo swamp during dry and wet months of 2011. C. gariepinus in Lake Hawassa consumed insects (21% by volume), fish eggs (18.3%), fish (18.1%), gastropods (14.4%), macrophytes (13.6%), detritus (8.4%), zooplankton (2.6%), phytoplankton (1.7%), ostracods (0.7%), nematodes (0.5%) and fish scales (0.5%). In Shallo swamp, the fish mainly fed on macrophytes (31.7% by volume) and detritus (31.5%). Insects (12.2%), amphibians (9.5%), zooplankton (5.3%) and phytoplankton (4.9%) had also some contribution, while fish eggs, gastropods, ostracods, water mites and nematodes had insignificant contribution to the diet. Seasonal variation in the diet of C. gariepinus was slight in both habitats. Ontogenetic dietary shift was observed in Lake Hawassa. Smaller size C. gariepinus (<45 cm TL) in Lake Hawassa fed mainly on insects, fish and fish eggs and their importance decreased as the fish size increased while large sized C. gariepinus (>45 cm TL) tended to filter-feed more on zooplankton. All size groups of C. gariepinus in Shallo swamp mainly fed on macrophytes and detritus. Generally C. gariepinus in both habitats fed on food of plant and animal origin albeit in varying proportions, and the fish can be considered as omnivorous in its feeding habit.

ECOLOGICAL TRAITS PREDICT THE SUSCEPTIBILITY OF AFROMONTANE GRASSLAND BIRD SPECIES TO LIVESTOCK GRAZING IN THE BALE MOUNTAINS, ETHIOPIA

Addisu Asefa, Yosef Mamo, Girma Mengesha — Tue, 15 Mar 2016 00:00:00 +0000

Conversion of natural habitats to cultivation and grazing lands are among the major threats to biodiversity globally. However, different species of plants and animals respond differently to such land use change, possibly related to their species-specific ecological traits. Using available information on species-specific ecological traits of Afromontane grassland birds occurring in the Bale Mountains of Ethiopia, we predicted the susceptibility of 32 bird species to livestock grazing. We also collected data (along transects) on abundance of these species in 2014 in livestock grazed and ungrazed sites of the northern Afromontane grassland of the Bale Mountains. Using Generalized Linear Model, we then tested the effects of five species’ ecological traits (habitat preference, substrate use, dietary requirements, migratory status and body size) on the observed responses; i.e., whether species predicted to decrease in abundance in the grazed site actually decreased and vice-versa. Our findings show that most of species’ observed responses to grazing were found to concord with the predictions. However, only habitat and substrate preference traits had significant effects on the observed responses. Species preferring tall grass or shrubby vegetation as their primary habitat or foraging substrate preference were less abundant in the grazed site. This approach enables managers to identify which species are most likely to be affected by over-grazing and can be used to guide proactive management decisions. Further, this is the first study of its kind conducted in the internationally important Bale Mountains and the findings here are further transferable to many similar areas across the globe.

POPULATION SIZE AND STRUCTURE OF BEISA ORYX AND ITS HABITAT OVERLAP WITH SYMPATRIC SPECIES IN ALLEDEGHI WILDLIFE RESERVE, NE ETHIOPIA

Simeneh Admasu, Afework Bekele, Addisu Asefa — Sun, 03 Apr 2016 00:00:00 +0000

This study was undertaken in Alledeghi Wildlife Reserve, NE Ethiopia, to determine the current population size and structure of Beisa oryx [Oryx beisa (Linn. 1758)] and to examine its habitat overlap with two sympatric ungulate species: Soemmering’s gazelle [Gazella soemmeringi (Cretzschmar 1828)] and gerenuk [Litocranius walleri (Brooke 1879)]. Wet and dry season wildlife surveys were undertaken in September 2015 and January 16 along 12 line transects in each of three major habitat types, grassland wooded grassland and bushland. The results showed that estimated population of Beisa oryx in the reserve was 1119 ± 7.8, 58 ± 1 and 590 ± 7 during the wet season, dry season and pooled seasons, respectively. This population was female dominated during both seasons; males to females ratio remained 1:1.8. However, there was a marked seasonal variation in group sizes of the species: ranging from 1 to 5 and from 4 to 26 individuals in the dry and wet seasons, respectively. Considering habitat type, greater mean group size of oryx was recorded in the wooded grassland habitat than the other two habitat types. Beisa oryx showed stronger preference for wooded grassland habitat during wet season, but for bushland during dry season, possibly implying that, dependent on season, different habitats provide varying level of importance. The minimum habitat overlap among the ungulates was 35% during dry season between oryx and gazelle and maximum was 85% during wet season between oryx and gerenuk. The study has provided valuable information that would help conservation management efforts.

WATERLOGGING EFFECTS ON GROWTH, NODULATION AND PRODUCTIVITY OF DESI AND KABULI CHICKPEA (CICER ARIETINUM L.)

Walelign Worku — Wed, 16 Mar 2016 00:00:00 +0000

Early planting against terminal drought and increase in precipitation extremes due to climate change may expose chickpea production to transient waterlogging. Desi and kabuli type chickpea were subjected to 10 days waterlogging during three phases to assess relative sensitivity among phases and between genotypes and to identify traits that may contribute for performance under the stress. Waterlogging increased stomatal resistance with full conductance recovery made only after relief from early waterlogging. The desi type maintained consistently greater stomatal resistance against waterlogging. Root growth and nodulation were most resilient to early stress while irreversibly destroyed by mid and terminal waterlogging. On the other hand, aboveground vegetative growth suffered most from early and mid waterlogging while it was not affected by terminal stress. A moisture by genotype interaction showed that the desi type suffered a 21% loss in seed yield while the kabuli lost almost twice as much, 39%. The flowering phase was most susceptible to waterlogging followed by seed-filling irrespective of chickpea type with mean reductions of 97% and 56%, respectively. Susceptibility of the flowering phase was due to large flower abortion, severe root and nodule degradation, shortened seed filling duration, detrimental leaf senescence and persistently high stomatal resistance. Relative tolerance of desi type against vegetative waterlogging for yield performance may be associated with fast recovery from chlorosis, increased pod production on the main stem and better nodulation capacity. It seems that the desi genotype, Naatolii, can be a better choice when risk of early waterlogging is anticipated from early planting or weather variability.

PERFORMANCE EVALUATION OF SOME CHILI PEPPER (CAPSICUM SPP) GENOTYPES FOR ANTHRACNOSE (COLLETOTRICHUM CAPSICI (SYD)) RESISTANCE IN SNNP REGION OF ETHIOPIA

Serawit Handiso, Tesfaye Alemu — Sun, 03 Apr 2016 00:00:00 +0000

Ten chili (Capsicum spp) varieties were screened for resistance to anthracnose (Colletotrichum capsici) in field experiments at two locations, Alaba and Maraqo. Starting seven days after transplanting, plants in each plot were monitored for diseases symptoms and infections. Data on incidence and severity of anthracnose were collected. Besides, the disease progress curve (AUDPC) and yield components were recorded before and after harvest. The data showed that the incidence of anthracnose disease and yield parameters such as dry fruit weight per plant, number of fruit per plant, pulp weight per plant, unmarketable fruits weight per plant, fruit length and days to 50 percent maturity, differed significantly among the tested genotypes at both locations. The majority of the genotypes were rated as moderate resistant to susceptible ones and none of the genotypes was free from the disease at both locations. Total yield per plant was higher at Alaba than Maraqo. This variation is related to the level of disease intensity, which was higher at Maraqo. After thorough multi-location researches, the identified sources of resistance were recommended to be utilized in future pepper breeding programs.

POPULATION STRUCTURE, FEEDING HABITS AND ACTIVITY PATTERNS OF THE AFRICAN SACRED IBIS (THRESKIORNIS AETHIOPICUS) IN DILLA KERA AREA, SOUTHERN ETHIOPIA

Meseret Chane, M. Balakrishnan — Sun, 03 Apr 2016 00:00:00 +0000

A study on population structure, feeding habits and activity patterns of the African sacred ibis (Threskiornis aethiopicus) was carried out around Dilla Kera area during April–September, 2015. Two 3 km long transects were laid using GPS. Birds were counted within a 50 m belt on either side of the transects twice a day (06:30–10:30 h and 15:30–18:30 h) by walking along the transect lines. Focal animal sampling method was used to study activity patterns. Data were documented twice monthly for six months including dry and wet seasons. Data were analysed using descriptive statistics, independent t-test and chi-square test. Kruskal-Wallis test was performed to compare activities between time blocks. A total of 165 individuals were counted during the dry season and 53 individuals during the wet season. Counts during the dry season were significantly higher than those during the wet season (2=56.8 df=1, p<0.05). The average mean population density of African sacred ibis in the area was estimated to be 20.55±3.28 individuals/km2. The age ratio of adult to juvenile was 1:0.46 and 1:0.56 during dry and wet seasons, respectively. Feeding on carrions, worms, insects, and other invertebrates was the most important diurnal activity of the African sacred ibis, followed by scanning, flying, preening and resting. African sacred ibis is an opportunistic feeder, which can shift to non-natural food items when the abundance of the prey is less.