A benthic invertebrates-based biotic index to assess the ecological status of West African Sahel Rivers, Burkina Faso.

Conserving aquatic resources in the West African Sahel requires water management tools to assess the ecological status of surface water bodies threatened by mounting pressures from agricultural intensification and urbanization. Macroinvertebrate communities of Sahelian rivers were examined to test if a multi-metric index approach could be developed to assess the ecological quality of rivers. A total of 40 sample sites falling within a continuum ranging from "unimpaired reference sites" to "impaired sites" were assessed during this study. Macroinvertebrates were sampled with a hand net following a multi-habitat sampling approach. Key environmental parameters, both physico-chemical and hydro-morphologic, were recorded. More than 20 candidate metrics were evaluated in four categories: composition, functional feeding, diversity, and tolerance. We used detailed analysis procedures to exclude unsuitable metrics from the data set. After excluding redundant metrics, six-core metrics were selected to compose the Sahel River Multimetric Index (SRMI): Total-taxa, Shannon & Weiner index, EPT-taxa, ASPT-NEPBIOS and ASPT-SASS and Collector-filterers. The final index derived from these metrics was divided into five ecological quality classes (high, good, moderate, poor, and bad). The results showed that the SRMI responded to a set of environmental parameters associated with a gradient of human pressures affecting the ecological integrity of water bodies (R2≥|0.50|; p < 0.05; p < 0.001). This work produced a data base and analysis that confirms the usefulness of an unprecedented and promising tool for biological monitoring and decision-making in Sahelian regions' water management.

Developing reference criteria for the ecological status of West African rivers.

Awareness of sustainable management of water and its biological resources is rising in West Africa, but application of effective tools for biomonitoring and detecting habitats at risk in aquatic ecosystems is limited. In this study, we provide key environmental descriptors to characterize reference sites by applying the following "a priori criteria" (physical and chemical, hydro-morphological, and land use parameters) by exploring their potential to determine suitable reference sites. Using data collected from 44 sites, we identified 37 criteria that reliably identify reference conditions in semi-arid rivers by reflecting the impacts of multiple pressures ranging from low to very high intensity of human uses and impairments. We integrated all these impacts in an overall pressures index, which showed that protected areas can reasonably be considered as credible reference sites as far as they show low overall impact levels from cumulative pressures. We recommend that development of bio-indicator standards should be based on the collection and integration of all the available information, especially quantitative, spatially-explicit data, from benthic macroinvertebrates and fish. Rigorous standardization of bio-indicator protocols will make them more easily applicable for management and conservation of aquatic ecosystem resources in semi-arid zones of Africa.

Prevalence of schistosomiasis and soil-transmitted helminth infections among schoolchildren in Burkina Faso.

To determine the current status of schistosomiasis and soil-transmitted helminth (STH) infections among schoolchildren after 10 years of mass treatment with praziquantel. Parasitological surveys were conducted in 2013 in 22 primary schools located in 11 regions of Burkina Faso. Urine filtration methods and Kato-Katz techniques for stool were used to detect the eggs of Schistosoma hæmatobium, Schistosoma mansoni, and STH. 3514 schoolchildren aged from 7 to 11 (1.415 ± 9) years participated in the study. The prevalence of S. hæmatobium was 8.1% and of S. mansoni, 1.2%. The prevalence of intestinal schistosomiasis ranged from 0.6% to 26.2% and that of urinary schistosomiasis from 0.6% to 56.2%. The prevalence of hookworms was 1.1%, Ascaris lumbricoides 0.1%, and Trichuris trichiura 0.06%. The arithmetic mean of S. hæmatobium and S. mansoni were respectively 6 eggs/10 mL and 1.07 epg (eggs per gram). The arithmetic means of eggs were 0.07 epg, 0.03 epg, and 1.89 epg respectively for A. lumbricoides, T. trichiura, and Ankylostoma spp. This study shows the current situation for schistosomiasis and STH infections in different regions of Burkina Faso. Elimination of this parasitic disease requires the inclusion of other control methods, in addition to mass treatment.