Tsehaye Asmelash

Spotted hyena (Crocuta crocuta) concentrate around urban waste dumps across Tigray, northern Ethiopia

Abstract Context. The spotted hyena (Crocuta crocuta) lives in remarkably close proximity to humans in the degraded and prey-depleted landscapes in Tigray in northern Ethiopia, predominantly feeding on human organic waste. Aims. We sought to provide an estimate of spotted hyena abundance at garbage dumps and open agricultural areas across Tigray. Methods. We used 28 calling stations, including 12 at garbage dumps and 16 in open agricultural areas located in nine randomly selected urban districts across Tigray. We also used 65 randomly placed calling stations in three districts to establish spotted hyena abundance in Tigray. We also collected 610 scat samples during wet (n = 134) and dry season (n = 476) so as to identify diet. Key results. A total of 398 hyenas responded, including 356 hyenas at garbage dumps and 42 hyenas in open agricultural areas. The response at the garbage dumps was significantly higher. Approximately 2525 hyenas were estimated from 65 calling stations in three districts. There was no statistically significant difference in the diet of hyena between wet and dry seasons for any food item. Frequency occurrence of prey remains of donkeys and cattle were dominant, followed by human, goat and sheep, respectively. Key conclusions. We infer that a very large hyena population persists in unprotected areas of Tigray in northern Ethiopia, where they concentrate around urban waste dumps at night for scavengeable food resources, mainly originating from slaughterhouse waste of livestock. Implications. We suggest promotion of nature-based ecotourism of this exceptional coexistence of hyenas and humans in Ethiopia. We raise questions about local hyena social structure, movement, home-range, activity pattern and the implications for human–hyena coexistence.

Genetic diversity of Microcystis blooms (Cyanobacteria) in recently constructed reservoirs in Tigray (Northern Ethiopia) assessed by rDNA ITS

The cyanobacterium Microcystis is notorious for forming extensive and potentially toxic blooms in nutrient-rich freshwater bodies worldwide. However, little is known about the factors underlying the genetic diversity and structure of natural Microcystis populations, despite the fact that this knowledge is essential to understand the build-up of blooms. Microcystis blooms are common and occur year-round in Africa, but are underinvestigated in this continent. We studied the genetic diversity and structure of Microcystis populations in 30 man-made reservoirs in Tigray (Northern Ethiopia) using Denaturing Gradient Gel Electrophoresis of the 16S–23S rDNA internal transcribed spacer (ITS) region and assessed the importance of local environmental conditions and geographic position of the reservoirs for the observed patterns. The analyses showed that both regional and local Microcystis ITS diversity in these recently constructed reservoirs was relatively low, with several dense blooms containing only a single ITS type. Especially one non-toxic ITS type dominated a considerable fraction of Microcystis blooms, but appeared restricted in its geographic distribution. The relationship between Microcystis ITS population structure and abiotic variables (water clarity, pH) and with zooplankton (Daphnia biomass) indicates a (limited) influence of environmental conditions on Microcystis population structure in the reservoirs of Tigray.

The ecology of the riverine Garra species (Teleostei, Cypriniformes) in reservoirs of the semi-arid highlands of northern Ethiopia: temporal dynamics of feeding activity

Abstract Garra species are among the most abundant fish in small rivers of northern Ethiopia. Many manmade reservoirs in the region have been colonized by Garra, which often are the only fish species present and have become very abundant. Little is known about the ecology of these reservoir populations of riverine species. In this study we investigated the distribution patterns and gut fullness of 2 dominant species, G. blanfordii and G. geba, in 3 recently created reservoirs (Gereb Awso, Tsinkanet, and Mai Gassa I) in Tigray, northern Ethiopia. Species composition differed among reservoirs. Our data on fish catch densities and the fullness of the foregut suggest that the ecology of the Garra populations in the reservoirs is likely influenced by the avoidance of predation by birds. G. blanfordii, and to a lesser extent G. geba, foraged most actively after sunset.