The Biogeochemical cycles are crucial for aquatic ecosystems, particularly the functioning of nutrient cycles. Growing anthropogenic pressure alters their functioning, causing accelerated eutrophication. Understanding the scale of alteration in ecological functions could assist with combat strategies. Bacterial communities regulate the transition of functional traits in aquatic ecosystems. However, current knowledge is still elusive regarding the variability of the environmental drivers dictating the functional roles in dynamic regimes like littoral zones. This study assessed how seasonal and circumlimnal conditions influenced sediment characteristics, bacterioplankton communities, and putative ecological functions (specifically biogeochemical cycling of carbon, nitrogen, and sulphur) in the hypertrophic freshwater Lake Pichola (Rajasthan, India). Findings suggest a significant seasonal drivers’ influence on sediment characteristics, while the anthropopressure-aided niche partitioning promoted species richness and diversity in the hypertrophic lake. Proteobacteria, Bacteroidota, and Firmicutes were abundant phyla; chemoheterotrophy and fermentation are the dominant potential putative functions; methylotrophy, nitrate reduction, and sulfate reduction are prominent nutrient cycling biogeochemical functions. Redundancy analysis accurately explained the influence of sediment characteristics on the variability of biogeochemical functions. Shifts in bacterioplankton communities were evident within circumlimnal regimes with greater anthropogenic stress, promoting higher abundance and diversity of putative bacteria orchestrating the ecological functions. This study emphasizes the importance of considering the interplay among the functional traits and environmental factors dynamics in littoral sediments for studying biogeochemical transformation in lakes.

This study encompasses the grain size distribution of the playa lakes (Pachpadra, Pokhran, and Didwana) of the Thar Desert in Rajasthan, India. The grain size of sediment particles is the most fundamental feature, giving essential information regarding their origin, transport history, and depositional conditions. The aeolian and fluvial transport processes were evaluated through environmentally sensitive grain size subpopulations to identify the differential sedimentary sources and dynamics in the playas. End-member modelling further determined the sediment grain size distribution through statistical analysis. The playa sediments mainly consist of very fine sand (46–54%) and very coarse silt (22–37%). The results show that the average fine fraction of Pachpadra, Pokhran, and Didwana playa was 46.29%, 66.11%, and 66.28%, respectively. In contrast, the average coarser fraction deposition in Pachpadra, Pokhran, and Didwana corresponds to 53.71%, 33.89%, and 33.72%, respectively. This suggests that the playas mostly contain aeolian sediment rather than fluvial sediment transported by dust/sand storms. Additionally, the textural pattern and depositional distribution of the sediments determined through the Passega CM diagram and bivariate plots indicate that 82% of the samples were poorly sorted, and 18% were very poorly sorted. Furthermore, an environmentally sensitive grain size component (ESGSC) was also assessed to identify the spatial variability and transport processes of sediment between these playas. Three ESGSCs in Pokhran (250 µ, 31 µ, and 2 µ) and Pachpadra (125 µ, 31 µ, and 4 µ), while two ESGSCs in Didwana playa (125 µ and 16 µ) were identified, indicating sediment deposition with moderate velocity in a low energy environment with a mixed sediment population transported by aeolian and fluvial activities.