Western Chad Research Articles

Deterioration of Plant Resources in Contact with Nigerian Refugees, Returnees and Internal Displaced Chadians in Kaya, Lake Region, Western Chad

Chad in general and Kaya in particular, hosts a large number of refugees, returnees and internally displaced persons. Wars, inter-community conflicts and the nebulous Boko Haram sect are the causes of massive displacement of populations from neighboring countries to Chad and Kaya. The arrival of Nigerian and Nigerian refugees, returnees and internally displaced Chadians has increased the population and the need for energy, especially firewood and charcoal. Moreover, to meet their food and financial needs, these migrants are forced to destroy the plant resources of the region and of Kaya in order to survive. This is damaging the natural environment and the economy of the Lac and Kaya region. Thus, 25 refugees, returnees and displaced persons were studied and empirical data collected in order to determine their responsibility in the degradation of vegetation in Kaya. Then, 3 people in charge of the environment in Bagassola were interviewed to gather their opinions on the role played by refugees, returnees and IDPs in Kaya in the environmental degradation in this area. Five interviews were held with NGOs in Bagassola to find out the underlying reasons that lead refugees, returnees and IDPs to destroy nature.

Ethnic fragmentation and degree of urbanization strongly affect the discrimination power of Y-STR haplotypes in central Sahel

Y chromosome short tandem repeats (Y-STRs) are commonly used to identify male lineages for investigative and judicial purposes and could represent the only source of male-specific genetic information from unbalanced female-male mixtures. The Yfiler Plus multiplex, which includes twenty conventional and seven rapidly-mutating Y-STRs, represents the most discriminating patrilineal system commercially available to date. Over the past five years, this multiplex has been used to analyze several Eurasian populations, with a reported discrimination capacity (DC) approaching or corresponding to the highest possible value. However, despite the inclusion of rapidly mutating Y-STRs, extensive haplotype sharing was still reported for some African populations due to a number of different factors affecting the effective population size.In the present study, we analyzed 27 Y-STRs included in the Yfiler Plus multiplex and 82 Y-SNPs in central Sahel (northern Cameroon and western Chad), an African region characterized by a strong ethnic fragmentation and linguistic diversity. We evaluated the effects of population sub-structuring on genetic diversity by stratifying a sample composed of 431 males according to their ethnicity (44 different ethnic groups) and urbanization degree (four villages and four towns).Overall, we observed a low discrimination capacity (DC = 0.90), with 71 subjects (16.5 %) sharing 27 Y-STR haplotypes. Haplotype sharing was essentially limited to subjects with the same binary haplogroup, coming from the same location and belonging to the same ethnic group. Haplotype sharing was much higher in rural areas (average DC = 0.83) than urban settlements (average DC = 0.96) with a significant correlation between DC and census size (r = 0.89; p = 0.003). Notably, we found that genetic differentiation between villages from the same country (ΦST = 0.14) largely exceeded that found among countries (ΦST = 0.02). These findings have important implications for the choice of the appropriate reference population database to evaluate the statistical relevance of forensic Y-haplotype matches.

Creative Encounters: African Trade and Chinese Oil Production in Western Chad

The oil industry tends to remain disconnected from local realities surrounding production sites, a situation that can be explained by theories of enclaving and technological zones. Despite these barriers, local people try to connect to and profit from oil projects that are set up in their vicinity. This article explores the relationships between a Chadian merchant, who started as a worker in the oil fields, his suppliers of goods and credit, and a Chinese oil company. The analysis focuses on the improvisation that the merchant and his Chinese clients undertook in order to develop trade in a difficult supply situation. The African system of trade enabled the Chinese company to overcome challenges to its project, while helping the merchant convert oil money into commercial capital.

Influence of biodegradation on carbazole and benzocarbazole distributions in oils from the Bongor Basin, Chad

A suite of oils from the Bongor Basin, South Western Chad was characterized geochemically to investigate the behavior of carbazoles and benzocarbazoles during biodegradation. The oils show similar maturity levels and organic facies type with biodegradation as the primary control on molecular compositions. According to compositional variation, the biodegradation levels of oils fell within PM level 0–8 [PM biodegradation scale (Peters, K.E., Moldowan, J.M., 1993)]. Absolute concentrations of carbazole, methylcarbazoles, C2-carbazoles, and benzocarbazoles in the oils show an increase from PM level 1–3, fluctuation at PM level 4–7, and sharp decrease above PM level 7. Relative abundances of the carbazole series indicate that C0–C2-carbazoles are more susceptible to biodegradation than benzocarbazoles, 2- and 3-methylcarbazoles are more susceptible than 1- and 4-methylcarbazoles, partially shielded dimethylcarbazoles are more susceptible than the exposed ones and both of these are more susceptible than shielded dimethylcarbazoles. Benzo[c]carbazole seems to show a higher ability to resist biodegradation than benzo[a]carbazole in heavily biodegraded oils. Therefore, ratios of 1-/(2-+3-) methylcarbazole, 4-/(2-+3-) methylcarbazole, 1,8-dimethylcarbazole/total dimethylcarbazoles, 1,8-/1,3-dimethylcarbazole, and 1,8-/2,4-dimethylcarbazole may be used to assess the degree of biodegradation in this area.

Diversity and Origin of Indigenous Village Chickens (<i>Gallus gallus</i>) from Chad, Central Africa

In this study we assess the maternal genetic diversity and origin of indigenous village chickens from Chad complementing previous phenotypic and biometric measurements studies. We analysed a 387 bp fragment of the mitochondrial DNA (mtDNA) D-loop region of 181 village chickens from three populations of western Chad (Lake Chad/Hadjer Lamis), central Chad (Guera) and south-west Chad (Pala) and at different poultry markets in N'Djamena. Twenty-five polymorphic sites and 20 haplotypes are identified. Phylogenetic and network analyses group all chicken into a single mtDNA haplogroup D. Comparison with reference sequences shows that this haplogroup is the commonest one observed in chicken and it supports the Indian subcontinent as the maternal center of origin for the village chicken in Chad. Little genetic variation was found within and between populations which is in agreement with a recent and a maternal founding effect for the chicken in the country.

Territoriality through Migration: Cases among the Tubu Teda Guna (Niger)

Abstract The present article discusses whether migration can be a means in order to realize territoriality. It is based on pre-colonial, colonial and recent cases found among the Tubu Teda who live in eastern Niger and western Chad. It will be argued here that migration, in these cases, does not mean the uprooting of persons and the loss of a territory, but can lead to the amelioration of the territorial situation for the migrating group, including the enhancement of its socio-political status and economic situation.

West African Monsoon 2012

Living up to its reputation as a highly variable climate system, the West African Monsoon (WAM) 2012 contrasted strikingly with the previous year. In 2011, the West African rainy season was delayed, patchy, and irregular. In 2012, whilst it was anomalously wet in many area, the Guinea coastal countries and some crucial agricultural regions remained very dry, persisting from the previous year. As a result, 2012 generated the third big food crisis to hit the region in the last seven years. The 2012 WAM forecast, observed climate conditions and the ongoing socio-economic implications for the region are reviewed here.

A cytotaxonomic and DNA-based survey of rodents from Northern Cameroon and Western Chad

Rodent diagnosis has long remained obscured by the co-existence of cryptic species in many lineages. However, alternative and accessible methods, such as cytotaxonomy and DNA-based methods, are now available that allow biologists to accurately monitor biodiversity through the production of well documented lists of unambiguously species-specific identifications. As a continuation of our previous surveys of West African rodents, we here present the first rodent inventory of rodents from Northern Cameroon (as well as one locality in Western Chad) that fully relies on karyotypic and/or sequencing data. Doing so, we assess the presence of 18 species in this poorly documented region. Among them, we found several African spiny mice that could be referred as to A. johannis, a poorly documented species. Moreover, several Arvicanthis individuals could be aggregated with previously studied but still enigmatic specimens of ANI-2 and ANI-4 sensu Volobouev et al. (2002a,b), thus suggesting that they may all belong to one single species, namely A. rufinus. In addition, one specimen was shown to belong to a new biological species ( Praomys sp.) that will deserve further taxonomic investigations. Finally, several Taterillus specimens were found with 2 n = 28–30 chromosomes and a XX/XY1Y2 sex chromosome system. On the basis of these new results as well as a reinterpretation of previously published data, we propose to refer these individuals as to the poorly documented Taterillus lacustris. Altogether, our data suggest that Northern Cameroon is a “phylogeographical node” for several rodent lineages which may be at least partly explained by the past changes within the Lake Chad basin. Keeping this in mind, there is little doubt that biodiversity will undergo important modifications in the coming decades, following the increasing aridity and the drastic reduction of Lake Chad.

Malaria vectors and transmission dynamics in Goulmoun, a rural city in south-western Chad

BackgroundKnowledge of some baseline entomological data such as Entomological Inoculation Rates (EIR) is crucially needed to assess the epidemiological impact of malaria control activities directed either against parasites or vectors. In Chad, most published surveys date back to the 1960's. In this study, anopheline species composition and their relation to malaria transmission were investigated in a dry Sudanian savannas area of Chad.MethodsA 12-month longitudinal survey was conducted in the irrigated rice-fields area of Goulmoun in south western Chad. Human landing catches were performed each month from July 2006 to June 2007 in three compounds (indoors and outdoors) and pyrethrum spray collections were conducted in July, August and October 2006 in 10 randomly selected rooms. Mosquitoes belonging to the Anopheles gambiae complex and to the An. funestus group were identified by molecular diagnostic tools. Plasmodium falciparum infection and blood meal sources were detected by ELISA.ResultsNine anopheline species were collected by the two sampling methods. The most aggressive species were An. arabiensis (51 bites/human/night), An. pharoensis (12.5 b/h/n), An. funestus (1.5 b/h/n) and An. ziemanni (1.3 b/h/n). The circumsporozoite protein rate was 1.4% for An. arabiensis, 1.4% for An. funestus, 0.8% for An. pharoensis and 0.5% for An. ziemanni. Malaria transmission is seasonal, lasting from April to December. However, more than 80% of the total EIR was concentrated in the period from August to October. The overall annual EIR was estimated at 311 bites of infected anophelines/human/year, contributed mostly by An. arabiensis (84.5%) and An. pharoensis (12.2%). Anopheles funestus and An. ziemanni played a minor role. Parasite inoculation occurred mostly after 22:00 hours but around 20% of bites of infected anophelines were distributed earlier in the evening.ConclusionThe present study revealed the implication of An. pharoensis in malaria transmission in the irrigated rice fields of Goulmoun, complementing the major role played by An. arabiensis. The transmission period did not depend upon irrigation. Correct use of insecticide treated nets in this area may be effective for vector control although additional protective measures are needed to prevent pre-bedtime exposure to the bites of infected anophelines.

Coastal conglomerates around the Hadjer el Khamis inselbergs (western Chad, central Africa): new evidence for Lake Mega‐Chad episodes

AbstractThis paper reports on a study dealing with the rhyolitic inselbergs of Hadjer el Khamis that formed palaeoislands during Lake Mega‐Chad events. Field observations have shown that: (1) conglomeratic patches of immature to mature clasts are preserved at the feet of the Hadjer el Khamis inselbergs; (2) in cross‐section, their profile reveals a well defined cliff–platform junction at a constant elevation (325 m). The monolithological clasts show all degrees of roundness, from angular cobbles to well rounded pebbles. This wide range of maturity suggests a coastal origin for these cobbles. The system was permanently fed with angular clasts, which were progressively worn by waves. Cobbles that were wave‐worked for the longest time are the best rounded. The cliff–platform junction is the result of erosion by waves, which attacked and undercut the inselberg cliffs during Lake Mega‐Chad events. Asymmetrical erosion profiles moreover suggest a wind regime dominated by SW to NE oriented winds. These interpretations have two implications. The elevation of the cliff–platform junction is an indication of the highest water level of Lake Mega‐Chad at 320–325 m, which is in agreement with other observations elsewhere in the basin. The SW to NE oriented winds show that monsoon‐related winds were prevalent during Lake Mega‐Chad events, suggesting the Inter‐Tropical Convergence Zone was located higher in latitude than today. Copyright © 2003 John Wiley & Sons, Ltd.

The Late Cretaceous ammonite genusLibycocerasin the Iullemmeden Basin (West Africa) and its palaeogeographical significance

The ammonite speciesLibycoceras crossenseZaborski occurs in the Late Campanian part of the Nkporo Shale of southern Nigeria and in the (mid to Late?) Maastrichtian Farin Doutchi and Dukamaje formations of the Iullemmeden Basin in western Niger and north-western Nigeria. After an interval during whichLibycoceraswas able to migrate between southern Nigeria and the western Chad Basin, northern and southern populations ofL. crossensebecame isolated from one another during the Late Campanian by closure of the connecting route through the Benue Trough.Libycocerasevolved rapidly in southern Nigeria but disappeared from the region early in the Maastrichtian. The northern population ofL. crossensepersisted, being introduced into the Iullemmeden Basin during a gradual westerly shift of marine environments. During the later part of the Maastrichtian a regression brought about the disappearance of the species here. A subsequent Maastrichtian transgressive pulse introducedL. ismaelisinto the Iullemmeden Basin from the north, through a seaway located to the west of the Adrar des Iforas.

YEAR-ROUND MOVEMENTS OF A WAHLBERG'S EAGLE AQUZLA WAHLBERGZ TRACKED BY SATELLITE

Summary Meyburg, B.-U., Mendelsohn, J. M., Ellis, D. H., Smith, D.G., Meyburg, C. & Kemp, A.C. 1995. Year-round movements of a Wahlberg's Eagle Aquila wahlbergi tracked by satellite. Ostrich 66: 135–140. An adult female Wahlberg's Eagle from northern Namibia was tracked by satellite over a total distance of 8816 km and located 104 times between 11 February and 4 November 1994. It migrated on an almost due north heading to northern Cameroon, north-eastern Nigeria and western Chad through the rain forest belt of the Congo and Zaire after the breeding season. The total trans-equatorial distance between the breeding and non-breeding ranges was 3520 km. During the non-breeding season the bird ranged over a large area (ca. 60 000 km') for about six weeks (29 April – 14 June) in these three countries in a rather nomadic pattern covering a minimum distance of 1256 km. During two further months (14 June – 14 August) it restricted its movements to an area of about 5000 km2 near Maiduguri in the Sudan savannah of no...

High cloud increases in recent years

Summary Changes in cloud amounts will disturb the existing complex balance of radiative energy. An increase in high cloud would reduce the initial input of energy into the atmosphere, and this study is directed to examine the high cloud amounts during the periods 1950–54 and 1966–70. Using information from Albuquerque, Denver and Lander increases of 25, 68 and 57 % in amount, respectively, are shown. Even at a Pacific island an increase of 152% is noted while three stations in the Sudan average 47% increases. Eight stations in western Chad, well removed from major airlines, showed only an 11 % increase. This investigation suggests that the increases may be due to long‐term changes in atmospheric turbidity, perhaps aggravated by jet aircraft contrails.