Trophic Resource Use by Sympatric vs. Allopatric Pelomedusid Turtles in West African Forest Waterbodies.

Organisms that are similar in size, morphological characteristics, and adaptations, including vertebrates, often coexist by partitioning the available resources (food, space, and time). So, studies of the dynamics of these cases of coexistence are scientifically interesting. Here, we study a coexistence case of two species of freshwater turtles inhabiting the forest waterbodies of West Africa, focusing on the dietary habits of the two species. We found that both turtle species are omnivorous generalists, eating both vegetal and animal matter abundantly. However, there were clear interspecific differences, with the larger of the two species (P. cupulatta) eating more vertebrates (mainly fish but occasionally other vertebrates), whereas P. castaneus consumed more invertebrates. These patterns appeared consistently within the species and across sites, highlighting that the same patterns were likely in other conspecific populations from the Upper Guinean forest streams (Côte d'Ivoire and Liberia). Our study also showed that interspecific competition for food does not occur between these two species; instead, previous studies uncovered that a clear partitioning of the habitat niche occurs. We conclude that the food resource is likely unlimited in the study areas, as it is not the case in more arid environments (since food shortages may occur during the dry season). We anticipate that, within the Pelomedusidae communities throughout Africa, intense competition for food probably occurs in the Sahel and Sudanian vegetation zones, particularly during the dry months, but is unlikely within the Guinea and wet savannah region and even less likely in the Guineo-Congolian rainforest region.

High concentrations of dissolved biogenic methane associated with cyanobacterial blooms in East African lake surface water.

The contribution of oxic methane production to greenhouse gas emissions from lakes is globally relevant, yet uncertainties remain about the levels up to which methanogenesis can counterbalance methanotrophy by leading to CH4 oversaturation in productive surface waters. Here, we explored the biogeochemical and microbial community variation patterns in a meromictic soda lake, in the East African Rift Valley (Kenya), showing an extraordinarily high concentration of methane in oxic waters (up to 156 µmol L-1). Vertical profiles of dissolved gases and their isotopic signature indicated a biogenic origin of CH4. A bloom of Oxyphotobacteria co-occurred with abundant hydrogenotrophic and acetoclastic methanogens, mostly found within suspended aggregates promoting the interactions between Bacteria, Cyanobacteria, and Archaea. Moreover, aggregate sedimentation appeared critical in connecting the lake compartments through biomass and organic matter transfer. Our findings provide insights into understanding how hydrogeochemical features of a meromictic soda lake, the origin of carbon sources, and the microbial community profiles, could promote methane oversaturation and production up to exceptionally high rates.

Smallholder Farmers' Practices and African Indigenous Vegetables Affect Soil Microbial Biodiversity and Enzyme Activities in Lake Naivasha Basin, Kenya.

Loss of soil biodiversity and fertility in Sub-Saharan Africa (SSA) may put the food security of smallholder farmers in peril. Food systems in SSA are seeing the rise of African indigenous vegetables (AIVs) that are underexploited but locally consumed without being considered a primary source of food and income. Here we present a field study, a first of its kind, in which we investigated the effects of different cropping systems and inclusion of AIVs in the farming approach on bacterial and fungal biodiversity and community structures, enzymatic activity, and the alteration status of soils of the smallholder farmers in Kenya. When compared to mainstream farming approaches, the composition and biodiversity of bacteria and fungi under AIV cultivations was significantly different. Tillage had a significant impact only on the fungal communities. Fertilization and soil amendments caused shifts in microbial communities towards specialized degraders and revealed the introduction of specific microorganisms from amendments. Traditional homemade plant protection products did not cause any disturbance to either of soil bacteria or fungi. The soil alteration index based on enzyme activity successfully differentiated the alteration status for the first time in SSA. These findings could be useful for farmers to integrate AIVs with correct sustainable practices for a sustainable future.

Environmental background assessment: basic principles and practice.

Background assessment is crucial in setting remediation and management goals, in identifying contamination trends and in providing screening tools for the selection of contaminants of concern. Legal requirements and guideline documents place great emphasis onto the establishment of background levels. This contribution discusses background estimates for metals and organics in relation to bioavailability and to its potential impact onto living systems. Methods for defining background in Environmental Risk Assessment are provided by the US EPA and by the Dutch Added Risk Approach. Cited case studies, taken from projects carried out in Italy and abroad, show that practical approaches vary significantly. A standardised database of soil, sediment and water background levels for different contaminants, as well as a more comprehensive guideline of background assessment, are urgently needed.

[Wetland management according to the Water Framework Directive 2000/60]. / La gestione delle zone umide secondo la Direttiva Quadro sulle Acque 2000/60.

The Water Framework Directive sets the basis for a new water management regulatory perspective, which is of immediate relevance to wetlands. Up to recently, these were perceived solely as marginal habitats, fulfilling a specific role in the conservation of rare and protected species. The principles established by the Directive for the evaluation of the ecological status of significant water bodies relate directly to the relevance of the hydromorphological elements which are part of them, including ecotonal and riparian habitats, as well as other humid habitats connected to the main network. By recognising the moderation role played by wetlands in relation to the impacts affecting the river basin, a new interesting opportunity opens up. This new perspective welcomes forms of management which maximise the environmental quality of riparian areas, of small ponds and of all those situations which are conducive to the restoration of natural processes leading to the control of discharge and pollution loads.