Spatiotemporal dynamics of water quality and sediment nutrients in lakeshore wetlands of two Ethiopian highland lakes: Lake Logo and Lake Ardibo

Sedimentation and nutrient loading threaten Ethiopian lakes. This study investigated water quality and sediment conditions of Lakes Logo (also known as Lake Hayq) and Ardibo during 2023. The results show clear differences between the two lakes. Lake Logo is warmer (25.1°C) and more mineralized, with higher EC (930 µS/cm) and total dissolved solids (TDS) (460–475 ppm), while Lake Ardibo has better dissolved oxygen (DO) (6.3–6.6 mg/L). Both lakes are alkaline, with pH values above 8.9, and nitrogen-rich but phosphorus-limited. However, Lake Logo experiences higher nutrient pressure (total nitrogen (TN): 20.71 mg/L), especially at the river mouth, where DO is lower (5.0–5.8 mg/L). In contrast, Lake Ardibo shows more stable water conditions, but sediment analysis reveals strong spatial variation, with nutrient hotspots where sediment nitrogen and phosphorus are 4–5 times higher than in other sites. Multivariate analysis (principal component analysis [PCA]) explained 88.9% of the total variation and clearly separated the two lakes. Ammonia concentrations were low across both lakes but showed significant seasonal variation at Lake Logo sites (p < 0.05). Lake Logo was strongly associated with higher temperature, EC, TDS and turbidity, while Lake Ardibo aligned more with higher DO. Seasonal patterns further showed stronger wet-season impacts in Lake Logo, where turbidity (276 NTU) reflected intense runoff influence. Meanwhile, Lake Ardibo remained relatively stable with low turbidity (<20 NTU), indicating greater resilience to seasonal changes. These findings highlight how catchment processes and seasonal runoff shape lake conditions, with agriculture emerging as a key pressure on the sustainability of these water systems.