Spatial distribution of sediment bacterial communities from São Francisco River headwaters is influenced by human land-use activities and seasonal climate shifts

Riverbed sediments are dynamic freshwater environments colonized by a great diversity of microorganisms which play important roles in supporting freshwater ecosystem by performing a vast array of metabolic functions. Recent evidence generated by HTS approaches has revealed that the structure of sediment microbial communities is influenced by natural seasonal variations in water such as temperature or streamflow as well by disturbances caused by local human activities. Here, a spatiotemporal analysis of sediment microbial distribution from São Francisco River headwaters section was conducted using Illumina 16S rRNA-V4 region amplicon sequencing in order to accomplish three major goals: (i) to investigate whether the diversity and composition of bacterial communities accessed in riverbed sediments vary in response to distinct land-use activities; (ii) to estimate whether the diversity patterns vary between the dry and wet seasons; and (iii) to evaluate whether the diversity of bacterial metabolic functions, predicted by PICRUSt2 approach, varies similarly to the estimated taxonomic diversity. Our findings revealed that bacterial communities in the sediment show differences in diversity and taxonomic composition according to the anthropic activities performed in the local environment. However, the patterns in which this taxonomic diversity is spatially structured show differences between the dry and wet seasons. On the other hand, the most changes in predicted bacterial metabolic functions were verified between sediment samples accessed in portions of the river located in protected and unprotected areas. Our findings contributed with new evidence about the impact of typical land-use practices conducted in countryside landscapes from developing countries on riverbed bacterial communities, both in their taxonomic and functional structure.

A Systematic Study Site Selection Protocol to Determine Environmental Flows in the Headwater Catchments of the Vhembe Biosphere Reserve

Developing nations will be worst hit by the impacts of climate change because limited resources hinder the spatial reach of climate studies, effort, and subsequent implementation to help with the improvement of livelihoods. Therefore, finding the best-case study is an essential undertaking in environmental assessments. This study explains one systematic approach to selecting a study site for an environmental assessment project. A desktop review of relevant literature, a simple factor scoring assessment process, reliance on expert opinion, and a field survey for ground-truthing were conducted. The desktop review showed the most critical factors to site selection. The scoring of these factors selected those that were crucial for the study. Experts validated the results and suggested the best study site among the ones identified. While the design is simplified, the proposed approach selects the most appropriate study site for environmental assessments.