Macro-habitat preferences by the African manatee and crocodiles – ecological and conservation implications

African manatees (<i>Trichechus senegalensis</i>) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles <i>Crocodylus suchus</i> and dwarf crocodile <i>Osteolaemus tetraspis</i>) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant

Macro-habitat preferences by the African manatee and crocodiles – ecological and conservation implications

Abstract. African manatees (Trichechus senegalensis) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles Crocodylus suchus and dwarf crocodile Osteolaemus tetraspis) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant

The conservation status of West African vultures: an updated review and a strategy for conservation

The vulture populations in West Africa are undergoing dramatic decline over the last 30 years. Their particular ecology and sociality makes them vulnerable to various risks, including environmental changes, poisoning and bioaccumulation of toxic substances from agricultural products, pesticides, and veterinary drugs used in cattle livestock. In addition, these birds are subject to direct persecution for the trade of products used in traditional medicine. This manuscript analyzes the conservation status of eight vulture species in West Africa and the threats affecting their survival. In order to assess the conservation status of vultures in West Africa, this paper analyzes all the available literature that has been published in scientific peerreviewed journals, including also technical reports and unpublished reports related to the whole West African region. Overall, and despite the high risk of extinction facing several vulture species all throughout the world, our literature surveys revealed that the scientific papers on the conservation of West African vultures are relatively few. Therefore, due to limited available literature, the main causes of vulture declines in West Africa remain relatively unclear. Apparently, all African vultures suffer from similar threats, especially poisoning, habitat alteration and conversion to agro-pastoral systems, loss of wild ungulates leading to a reduced availability of carrion, hunting for trade, for use in traditional medicine and bushmeat, persecution and human disturbance. Our review also addresses future steps that are needed for reversing the negative population trend of their free-ranging populations, including some specific conservation measures that are proposed to mitigate their decline

Exploring the main threats to the threatened African spurred tortoise Centrochelys sulcata in the West African Sahel

AbstractThe African spurred tortoiseCentrochelys sulcatais the second largest terrestrial turtle, with a scattered distribution across the West African Sahel. This species is threatened and declining consistently throughout its range, but little is known about the causes of its decline. It has been hypothesized that the decline is attributable to (1) competition with domestic cattle, (2) wildfire, and (3) the international pet trade. We conducted a series of analyses to investigate these three causes. Hypotheses 1 and 2 were analysed using a spatially explicit approach, using a database of the Food and Agriculture Organization of the United Nations and logistic regression modelling; hypothesis 3 was tested by analysing the CITES trade database for 1990–2010. We found a significant negative correlation between intensity of grazing (expressed as density of cattle, km−2) and the presence of spurred tortoises, and this negative effect increased when coupled with high fire intensity, whereas wildfires alone did not have a significant influence on the species' distribution at the global scale. There was a decrease in the annual export of wild individuals for the pet trade after the introduction of export quotas by country and by year, but trade data must be considered with caution

Maternal exposure to carbon monoxide in the first trimester (7-13+6 weeks) of pregnancy in the core Niger Delta

Background: Irrespective of the fact that the Niger Delta was known for its environmental pollution, neither organized environmental assessment nor human biomonitoring, including that of carbon monoxide (CO) had been performed in the region. The aim of the study therefore was to establish the severity of maternal impact on exposure to CO in the first trimester of pregnancy by quantifying the exhaled CO concentrations (ECOC) and to assess the effect of maternal age, body mass index (BMI) and parity on the severity of the impact.Methods: The study was of cross-sectional design carried out at the Rivers State University Teaching Hospital (RSUTH) in Rivers State. 490 consecutive pregnant women in the first trimester were recruited from the antenatal clinic from January 2021 to January 2022. Gestational age was estimated with the aid of ultrasound scan. Demographic, social and obstetric characteristics were taken. Exhaled carbon monoxide concentration (ECOC) was measured with the aid of a smokerlyzer. Data was analyzed, using the statistical package for social sciences (SPSS) version 25.0 (Armonk, NY) software. Ethical approval was obtained from the RSUTH ethics committee.Results: The mean value of ECOC 3.25±2.51 ppm was more than that obtained in other studies. Out of the total 490 patients that were assessed, 335 (68.37%) had mild impact from CO exposure (ECOC=1-3 ppm), 129 (26.33%) – moderate impact (ECOC=4-6 ppm) and 26 (5.31%) had severe impact (ECOC=more than 6 ppm). Moderate and severe impacts were more prominent in women of age groups 25-39 years and the differences in various age groups were statistically significant [X2=20.671, p<0.036, 95% CI (0.032, 0.040)]. Patients with higher BMI were more likely to have moderate and severe impact than those with lower BMI- 6 (33.33%) and 4 (22.22%) out of the 18 patients with class III obesity had moderate and severe impacts respectively. The differences in the impact at various BMI were statistically significant [X2=20.671, p<0.001, 95% CI (0.001, 0.002)]. There was inverse relationship between parity and the severity of the impact and the differences in various parity groups were statistically significant [X2=10.580, p<0.012, 95% CI (0.101, 0.113)]. There was also a paradoxical finding of 3 smokers having only mild impact.Conclusions: The mean value of ECOC 3.25±2.51 ppm was more than that obtained in other studies in non-pregnant women. Mild, moderate and severe impact from maternal CO exposure were established with the moderate and severe impact more prominent at maternal ages of 25-39 years, at higher BMI and at lower parity

Predicting the structure of turtle assemblages along a megatransect in West Africa

Understanding large- and small-scale patterns as well as the determinants of species richness is central for the study of evolutionary mechanisms. The extent to which species richness in local communities is related to larger scale processes is a pre-eminent topic in ecological and evolutionary research. To investigate how local and regional species richness are related, we sampled freshwater turtle assemblages in seven localities to represent the variation in ecological conditions along a 90km South-North megatransect in Benin, West Africa. In each locality, all turtles captured were identified and measured, and microhabitat classified in which individual turtles were observed. Based on these data we used community diversity metrics to compare turtle assemblages. Spatial autocorrelation did not affect our data. For all localities pooled, only two species (Pelusios castaneus and Pelomedusa olivacea) were the most common, and one species (Trionyx triunguis) the rarest. Analyses of the commonest and more numerous species showed that the abundance of P. castaneus declined with an increase in latitude and longitude, but the opposite was true for P. olivacea. We showed that various microhabitat characteristics were significantly correlated with the abundance of the two common species. We found significant but variable South-North gradients in microhabitat use for different turtle species. Our results highlight the importance of studying interactions between local environments, the ecological requirements of each species, and their synecological relationships

A comprehensive description of kidney disease progression after Acute Kidney Injury: results of a prospective, parallel group cohort study

Acute kidney injury (AKI) is associated with adverse long-term outcomes, but many studies are retrospective, focussed on specific patient groups or lack adequate comparators. The ARID (AKI Risk in Derby) Study is a 5-year prospective parallel-group cohort study. Hospitalised cohorts with and without exposure to AKI were matched 1:1 for age, baseline renal function and diabetes. Estimated glomerular filtration rate (eGFR) and urinary albumin:creatinine ratio (uACR) were measured at 3-months, 1, 3 and 5-years. Outcomes included kidney disease progression, heart failure episodes and mortality.In 866 matched individuals, kidney disease progression at 5-years occurred in 94 (30%) of the exposed group versus 24 (7%) of those non-exposed (adjusted odds ratio (OR) 2.49 [95%CI 1.43 to 4.36]; P=0.001). In the AKI group, this was largely characterised by incomplete recovery of kidney function by 3-months. Further episodes of AKI during follow-up were more common in the exposed group (OR 2.71 [95% CI 1.94 to 3.77]; P<0.001) and had an additive effect on risk of kidney disease progression. Mortality and heart failure episodes were more frequent in the exposed group, but the association with AKI was no longer significant when models were adjusted for 3-month eGFR and uACR. In a general hospitalised population, kidney disease progression after 5-years was common and strongly associated with AKI. The time-course of changes and the attenuation of associations with adverse outcomes after adjustment for 3-month eGFR and uACR suggest that non-recovery of kidney function is an important assessment in post-AKI care and a potential future target for intervention. Study registration: ISRCTN2540599

Age-stratified interview campaigns suggest ongoing decline of a threatened tortoise species in the West African Sahel

Face-to-face interviews with local populations are often used to determine the distribution and population trends of elusive threatened species. Although interviewee responses may suffer from some bias, historical trends in the status of a species can be investigated from age-structured questionnaires. In this paper, we tested this idea by analysing separately answers given by older (> 60 years age) and younger respondents (25-44 years old) on the status of the African spurred tortoise, (Centrochelys sulcata), a charismatic large reptile listed as Vulnerable in the IUCN Red List. We interviewed 619 persons (hunters/farmers/cattle farmers) of different ages in three of the species’ habitat countries (Burkina Faso, Niger and Nigeria). Interviewees were asked whether in their experience the tortoise was common, rare or absent. By using Generalized Linear Models we showed that the probability to answer “common” increased with age in Nigeria and Burkina Faso, whereas the probability of responding “absent” declined with age in Nigeria and Niger. There were no significant effects of age for the answer 'rare' in any country and no differences were found between villages in any of the studied countries. From our data we conclude that spurred tortoises have been extirpated in 16.7% of study sites. We argue that if statistical differences emerge between answers given by respondents of various age classes on the population status of a target species, it is possible to conclude that the species’ situation may have significantly changed during the last 30-40 years

Bushmeat consumption in large urban centres in West Africa

Bushmeat consumption in large Sub-Saharan African cities is perceived as a major threat to the conservation of many species because their considerable population sizes can generate a significant demand for bushmeat. The study of the effect of age, sex and geographic location in bushmeat eating in African cities may offer valuable insights on which population groups to target in behaviour change campaigns. Using 2,040 interviews in six West African cities from four countries, in forest and savannah settings, we analysed the differences between age and sex in people’s frequency of bushmeat consumption. Overall, we found similar patterns in all sampled cities. As many as 62.2 % males and 72.1% females replied that they ‘would not eat bushmeat at all’, though only 12.8% males and 8.8% females mentioned they regularly ate bushmeat. Younger generations of both sexes answered that they ‘would never eat bushmeat’ more often than older age groups, independently of their city of origin. These trends are encouraging though further research needs to be undertaken to find out whether bushmeat volumes consumed in cities are unsustainable and having a serious impact of prey populations

Bushmeat consumption in large urban centres in West Africa

Bushmeat consumption in large Sub-Saharan African cities is perceived as a major threat to the conservation of many species because their considerable population sizes can generate a significant demand for bushmeat. The study of the effect of age, sex and geographic location in bushmeat eating in African cities may offer valuable insights on which population groups to target in behaviour change campaigns. Using 2,040 interviews in six West African cities from four countries, in forest and savannah settings, we analysed the differences between age and sex in people’s frequency of bushmeat consumption. Overall, we found similar patterns in all sampled cities. As many as 62.2 % males and 72.1% females replied that they ‘would not eat bushmeat at all’, though only 12.8% males and 8.8% females mentioned they regularly ate bushmeat. Younger generations of both sexes answered that they ‘would never eat bushmeat’ more often than older age groups, independently of their city of origin. These trends are encouraging though further research needs to be undertaken to find out whether bushmeat volumes consumed in cities are unsustainable and having a serious impact of prey populations