Lake drying and livelihood dynamics in Lake Chad: unravelling the mechanisms, contexts and responses

This article examines lake drying and livelihood dynamics in the context of multiple stressors through a case study of the ‘‘Small Lake Chad’’ in the Republic of Chad. Livelihoods research in regions experiencing persistent lake water fluctuations has largely focused on the wellbeing and security of lakeshore dwellers. Little is known about the mechanisms through which lake drying shapes livelihood drawbacks and opportunities, and whether locally evolved responses are enhancing livelihoods. Here we address these gaps using empirical, mixed-methods field research couched within the framework of livelihoods and human well-being contexts. The analysis demonstrates that limited opportunities outside agriculture, the influx of mixed ethnic migrants and the increasing spate of violence all enhance livelihood challenges. Livelihood opportunities centre on the renewal effects of seasonal flood pulses on lake waters and the learning opportunities triggered by past droughts. Although drying has spurred new adaptive behaviours predicated on seasonality, traditional predictive factors and the availability of assets, responses have remained largely reactive. The article points to where lake drying fits amongst changes in the wider socioeconomic landscape in which people live, and suggests that awareness of the particularities of the mechanisms that connect lake drying to livelihoods can offer insights into the ways local people might be assisted by governments and development actors

Detoxifying effect of Nelumbo nucifera and Aegle marmelos on hematological parameters of Common Carp (Cyprinus carpio L.)

The objective of this study was to investigate the efficacy of Nelumbo nucifera and Aegle marmelos on common carp exposed to sub-lethal concentrations of combined heavy metals (5 ppm) under laboratory conditions. The fish were treated with Nelumbo nucifera (500 mg/kg bwt) and Aegle marmelos (500 mg/kgbwt) for 30 days as a dietary supplement. The blood biochemical parameters of the fish were evaluated by analyzing the level of red blood cells (RBC), packed cell volume (PCV), hemoglobin concentration, glucose, cholesterol, iron and copper. The findings of the present investigation showed significant increase in hemoglobin (p<0.001), RBC (p<0.01) and PCV (p<0.01) of herbal drug-treated groups compared with metal-exposed fish. Conversely, glucose and cholesterol level in blood of common carp showed significant reduction compared with heavy-metal-exposed groups. All the values measured in Nelumbo nucifera and Aegle marmelos treated fish were restored comparably to control fish. Our results confirmed that Nelumbo nucifera and Aegle marmelos provide a detoxification mechanism for heavy metals in common carp

Protein - Sparing Activity of Lipid and Carbohydrate in the Giant African Mudfish, H. longifilis Diets

In two different experiments on lipid and carbohydrate requirement, H. longifilis was fed diets containing 13.68% to 24.66% of lipid, 17.00% to 20.86% of carbohydrates for 56 days. There was positive response in terms of growth of H. longifilis in the various diets fed in the experiments. There was significant variation (P<0.05) in the specific growth rate (SGR), food conversion ratio (FCR), protein efficiency ratio (PER), apparent net protein utilisation (ANPU) and percentage survival (PS) in the fish fed varying lipid levels. As for the fish fed varying levels of carbohydrates, there was no significant variation (P>0.05) in the SGR and FCR but there was significant variation (P<0.05) in the PER, ANPU and PS. The protein/lipid ratio was 1.58 while the protein/carbohydrate ratio was 2.22. These ratios are very important in the formulation of H. longifilis feed for optimal growth of fish in that protein is spared for growth while the lipid and carbohydrate portions of the diet are used for energy production. @JASE

Permeate microbiome reflects the biofilm microbial community in a gravity-driven woven-fiber microfiltration (WFMF) system for wastewater treatment

United Nations Sustainable Development Goal 6.3 aims to half the proportion of untreated wastewater and increase recycling and safe water reuse. Therefore, developing robust technologies to achieve these goals, specifically in low- to middle-income countries, is of concern. One such technology, gravity-driven woven-fiber microfiltration (WFMF) has been shown to be a reliable, low-cost, and versatile water treatment process. This study investigated a gravity-driven WFMF system for treating secondary wastewater. Given the significant role of the microbial community in biological treatment processes, this investigation focused on the inter-relationship between the microbiomes of the influent, biofilm, and permeate, while further examining the system's performance regarding microbial activity and permeate water quality. The WFMF system reached a quasi-steady state after approximately 10 days. The microbiome analysis, specifically beta diversity analysis, showed that the biofilm and permeate had similar microbiomes, proving a direct impact of the biofilm's microbial community on the permeate water quality. It also showed that the microbial community composition changed within the system. Alpha diversity analysis indicated that biofilm had higher richness and alpha diversity indices (e.g., OTUs and Shannon) than the influent. The system reduced the concentrations of fecal indicators Escherichia coli and Enterococcus spp. and the relative abundance of putative pathogens such as Legionella spp. Furthermore, it reduced microbial activity, as measured by intact cell counts and intracellular ATP, by 48.7% and 58.0%, respectively. Biofilm structure, investigated by various imaging techniques, including scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT), depicted a heterogeneous distribution over the membrane surface. The findings of this study underscore the role of the biofilm on the permeate's microbiome and, consequently, its impact on the permeate's biological stability and suitability for discharge and reuse. Thoroughly understanding microbial dynamics has implications for performance optimization, field implementation, and permeate discharge or reuse

Giant paleo-seafloor craters and mass wasting associated with magma-induced uplift of the upper crust

Giant seafloor craters are known along many a continental margin with recurrent mass-wasting deposits. However, the impact of breakup-related magmatism on the evolution of such craters is barely understood. Using high-quality geophysical datasets, this work examines the genetic relationship among the location of magmatic sills, forced folds and the formation of giant paleo-seafloor craters underneath an ancient mass-transport complex in the Møre and Vøring basins, offshore Norway. The data reveal that forced folding of near-seafloor strata occurred because of the intrusion of several interconnected magmatic sills. Estimates of 1-dimensional uplift based on well data show that uplift occurred due to the intrusion of magma in Upper Cretaceous to Lower Eocene strata. Our findings also prove that subsurface fluid plumbing associated with the magmatic sills was prolonged in time and led to the development of several vertical fluid flow conduits, some of which triggered mass wasting in Neogene to Recent times. The repeated vertical expulsion of subsurface fluids weakened the strata on the continental slope, thereby promoting mass wasting, the selective cannibalization of the paleo-seafloor, and the formation of elongated craters at the basal shear zone of the mass-transport complex. Significantly, the model presented here proves a close link between subsurface magmatic plumbing systems and mass wasting on continental margins.</p