The exchange of dissolved nutrients between the water column and substrate pore-water due to hydrodynamic adjustment at seagrass meadow edges:a flume study

Seagrasses need dissolved nutrients to maintain their productivity through uptake processes, from substrate pore-water via their roots and/or from the water column via their leaves. Here, we present the first study of exchanges of dissolved nutrients between pore water and the water column in the vicinity of seagrass canopies. We address the following research questions, using a laboratory flume experiment: (1) How does solute exchange between the water column and substrate pore water vary spatially within seagrass patches? (2) How does seagrass leaf length affect this solute exchange? (3) How does the measured rate of solute exchange compare with seagrasses’ rates of uptake of dissolved nutrients? Our results indicate that solute intrusion from the water column into the substrate pore water is highest in the area around seagrass patches’ leading edges, where flow deceleration is strongest, and decreases approximately linearly with downstream distance into the patch. The decrease in measured flow speed in the canopy fits well the predictions of previously reported models of arrays of rigid obstacles. The length of the region in which the concentration of solute that has infiltrated into the substrate at the upstream end of the seagrass patches is similar to the length scale predicted from model estimates of infiltration rate (based on the substrate permeability) and the length of time over 24-h runs. We conclude that the mechanism we identify only pertains near canopy edges, and therefore that other mechanisms must govern nutrient supply in the interior of seagrass meadows

Breeding performance of the grasshopper buzzard (<i>Butastur rufipennis</i>) in a natural and a human-modified West African savanna

Few studies have examined raptor reproduction in response to land-use change in sub-Saharan Africa, hampering conservation efforts to address regional declines. To further our understanding of mechanisms underlying the dramatic declines of West African raptors, we examined the relationship between environmental conditions, nest density, and measures of reproduction in the Grasshopper Buzzard (Butastur rufipennis). Analyses were based on 244 nest sites divided between transformed and natural habitat in northern Cameroon. At the landscape scale, nest density increased with the density of preferred nest trees. Nests were more widely spaced in transformed than in natural habitat. Dispersion was adjusted to differences in availability of small mammals, which was negatively associated with distance to nearest neighbor, and in the area under cultivation, which was positively associated with distance to nearest neighbor. Productivity was positively associated with rainfall, canopy shielding the nest, availability of grasshoppers, and the nest's visibility from ground level; canopy shielding, grass cover, rainfall, and distance to nearest neighbor were positively associated with nest success. In natural habitat, losses of eggs and nestlings to natural predators were greater than in transformed habitats, while losses through human predation were small. Productivity and nest success were unaffected by land use because of the opposing effects of greater predation pressure, closer spacing of nests, and more food in natural habitat than in transformed habitat. Thus transformed habitat may provide adequate breeding habitat for the Grasshopper Buzzard, but declining rainfall and intensifying anthropogenic land use are likely to affect future reproductive output

Pan-African Genetic Structure in the African Buffalo (Syncerus caffer): Investigating Intraspecific Divergence

The African buffalo (Syncerus caffer) exhibits extreme morphological variability, which has led to controversies about the validity and taxonomic status of the various recognized subspecies. The present study aims to clarify these by inferring the pan-African spatial distribution of genetic diversity, using a comprehensive set of mitochondrial D-loop sequences from across the entire range of the species. All analyses converged on the existence of two distinct lineages, corresponding to a group encompassing West and Central African populations and a group encompassing East and Southern African populations. The former is currently assigned to two to three subspecies (S. c. nanus, S. c. brachyceros, S. c. aequinoctialis) and the latter to a separate subspecies (S. c. caffer). Forty-two per cent of the total amount of genetic diversity is explained by the between-lineage component, with one to seventeen female migrants per generation inferred as consistent with the isolation-with-migration model. The two lineages diverged between 145 000 to 449 000 years ago, with strong indications for a population expansion in both lineages, as revealed by coalescent-based analyses, summary statistics and a star-like topology of the haplotype network for the S. c. caffer lineage. A Bayesian analysis identified the most probable historical migration routes, with the Cape buffalo undertaking successive colonization events from Eastern toward Southern Africa. Furthermore, our analyses indicate that, in the West-Central African lineage, the forest ecophenotype may be a derived form of the savanna ecophenotype and not vice versa, as has previously been proposed. The African buffalo most likely expanded and diverged in the late to middle Pleistocene from an ancestral population located around the current-day Central African Republic, adapting morphologically to colonize new habitats, hence developing the variety of ecophenotypes observed today

Indigenous knowledge: Protecting the lions' share

Combining satellite and mobile phone technology with knowledge from nomadic herdsmen in Cameroon will help prevent confl ict between livestock and predatory lions

Savoirs autochtones : Préserver la part du lion

La technologie mobile et satellitaire conjuguée aux connaissances des éleveurs nomades camerounais permet de réduire les risques d'attaques du bétail par les lion

Food base of the spotted hyena (Crocuta crocuta) in Ethiopia

Context: Livestock depredation and scavenging of waste by the spotted hyena (Crocuta crocuta) occurs widely across Ethiopia. Aims: The aim of this study was to investigate the food base of the spotted hyena and livestock depredation across Ethiopia. Methods: The diet of spotted hyenas was assessed in 17 randomly selected study sites across the country, including two national parks, by scat analysis. We conducted an extensive survey of livestock depredation and economic impact in 10 randomly selected subdistricts using semistructured interviews with 3080 randomly selected households. Key results: We found that even spotted hyenas from national parks feed predominantly on anthropogenic waste. Households reported losses of 2230 domestic animals, 3.9% of their stock or an average annual financial loss of US$10.3 per household over the past five years. The diet of spotted hyenas showed only prey items of domestic origin except in Chebera Churchura National Park, where a few items of prey of wild species were found. Frequencies of prey remains of cattle, sheep, donkey and goat were highest in decreasing order. Key conclusions: Survival of hyenas in Ethiopia is thus largely and widely dependent on management of livestock conflict and waste. Some hairs in scats originated from depredation, but most food intake is from waste dumps and slaughterhouses. Implications: Waste management, spotted hyena persistence and environmental sanitation area are linked.Environmental Biolog

Adaptability of large carnivores to changing anthropogenic food sources : diet change of spotted hyena (**Crocuta crocuta**) during Christian fasting period in northern Ethiopia

Many large carnivores readily use anthropogenic food sources, which often leads to conflict. Spotted hyenas (Crocuta crocuta) around the regional capital Mekelle, northern Ethiopia, feed on waste and to a lesser degree on livestock, but not on natural prey. We investigated the impact on their diet of the 55 day fasting period prescribed by the Ethiopian Orthodox Tewahedo Church, during which the vast majority of people do not consume animal products. We collected spotted hyena scats before, during and after the fasting period and compared hairs from scat with hairs from a reference collection. We found a significant difference in species composition; donkey and cattle occurrence increased significantly during fasting compared to the non-fasting diet dominated by scavenged remains of goat and sheep. We infer that spotted hyenas opportunistically change their diet from scavenging on waste before and after fasting to predation on larger livestock species that are kept outside at night during fasting. Our findings confirm that spotted hyena are highly adaptable and opportunistic predators