Seasonal Baseline Evaluation of Physicochemical Parameters and Culturable Bacterial Characteristics in Northwestern...

Freshwater wetlands in the Himalayan region are ecologically sensitive and microbiologically diverse ecosystems, yet their seasonal dynamics remain insufficiently characterised. This study investigated seasonal variations in physicochemical properties and bacterial diversity of two Ramsar wetlands in northwestern India, Renuka Ji Lake and Asan Conservation Reserve. Water samples were collected during pre-monsoon (June), monsoon (August) and post-monsoon (November) seasons. Physicochemical parameters were analysed using standardised IS:3025, APHA 24th Edition and SLS/SOP protocols. Bacterial isolation was performed by serial dilution-pour plating on nutrient agar, followed by Gram staining, biochemical characterisation and 16S rRNA gene sequencing. Both wetlands exhibited pronounced seasonal fluctuations in water chemistry. At both sites, dissolved oxygen (Renuka Ji), turbidity and dissolved oxygen (Asan Conservation Reserve) exceeded CPCB permissible limits during specific seasons. Eleven bacterial isolates were identified, predominantly representing freshwater associated genera. Agrobacterium cavarae was comparatively uncommon in freshwater environments. No bacterial colonies were recovered from Renuka Ji Lake during post-monsoon sampling within the tested dilution range (10¹-10⁴). Overall, culturable bacterial communities showed seasonal variation and were dominated by a limited number of genera. These findings highlight the ecological sensitivity of Himalayan Ramsar wetlands and emphasise the need for continuous physicochemical and microbiological monitoring for effective conservation and sustainable management.