Water quality assessment of East Kolkata Wetland with a special focus on bioremediation by nitrifying bacteria

East Kolkata Wetlands (EKW) is designated as International Ramsar site and are the hotspot for large-scale wastewater aquaculture practices. However, the continued surveillance of physicochemical properties of water and application of an eco-friendly approach are essential to ensure safe aquaculture practices. In the present study, we assessed the seasonal variation in physicochemical parameters of water across EKW and investigated the role of nitrifying bacteria as probiotics. We statistically analyzed various physicochemical properties of water samples from EKW. Results of the statistical analysis indicated a significant variation in all the physicochemical parameters across the selected water bodies of EKW (p < 0.01). We isolated and enumerated Nitrosomonas sp. and Nitrobacter sp. and assessed their ability to degrade trichloroethylene (TCE). The role of Nitrosomonas and Nitrobacter sp. were further investigated and established through a small-scale experiment. Two microbial isolates, NSW3 and NBW2, displayed superior TCE degradation ability at pH 5, and the application of these strains as probiotics were found to improve the quality of water and survival rate of fishes in the treated experimental tanks. Our findings suggest that the application of the above mixed bacterial cultures in aquaculture could be an effective and environment-friendly approach for safe and productive aquaculture operations.

Influence of Aquatic pH on Dissolved Pb in East Kolkata Wetlands: A Case Study With Reference to Climate Change Induced Acidification

The present study was undertaken with the databank of dissolved Pb and pH of the aquatic system in the East Kolkata Wetlands, an internationally unique Ramsar Site of Eastern India during a period of twenty years (2000-2019). Our study site is receiving huge amounts of domestic and industrial wastewater from surrounding areas of highly populated metropolitan city of Kolkata. The data on pH exhibits a decreasing trend with the passage of time, which may be attributed to the phenomenon of acidification in which CO2 dissolves with the water and shifts the pH to a lower value. This may result in the dissolution of accumulated Pb in the sediment and transfer the same to the overlying aquatic phase. The increasing trend of dissolved Pb confirms the hypothesis. The significant negative correlation between pH and dissolved Pb (r= -0.7763; p≤0.01) supports the view of the regulatory effect of pH on the dissolved Pb level in the aquatic systems of East Kolkata Wetland.

Stress responses of Indian major carps cultured in the East Kolkata Wetland, West Bengal, India

Fish are continuously exposed to multiple environmental stressors that work cumulatively and synergistically. This study assessed the stress responses of Indian major carps (IMCs) cultured in a sewage-fed pond (SP) in the East Kolkata Wetland (EKW), India and compared with the normal carps in situ. The experiment was conducted in two farms that cultured Labeo rohita, Catla catla and Cirrhinus mrigala for seven months, covering the summer and winter periods. Serum biomarkers of primary (cortisol) and secondary (glucose, total protein, creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH)) stress responses, and oxidative stress (superoxide dismutase (SOD)) were quantified using standard kits. The health status of carps was evaluated as a tertiary response. The biological oxygen demand, hardness, total dissolved solids, ammonia and phosphate levels of both ponds exhibited marked variations. The SP carps had significantly low haemoglobin and total protein, and high serum glucose, creatinine, ALT, AST and LDH levels. The SOD and cortisol levels were comparatively low in SP carps. The winter temperature had a significant effect on serum glucose, cortisol, SOD, creatinine, ALT and AST. Carps had a high degree of ectoparasitic infestation during the winter. Cirrhinus mrigala of the SP had significantly high serum creatinine levels. The increasing levels of serum glucose, creatinine, ALT and AST suggested that these indices, which were more pronounced in the carps of EKW in conjunction with winter temperature, could be useful biomarkers of stress, kidney and liver functioning in carps, respectively.

Methodology for sustainable development along an eco-fragile zone for land use management and mitigating climate change: Evidence of East Kolkata Wetlands

<p>Kolkata’s city core is getting depopulated but has experienced an explosive population growth leading to rapid urbanization which is encroaching the ecologically fragile wetlands of the eastern fringe of the main city. This contrasting urban growth along the East Kolkata wetland is accounted mainly for the increase in city size, expansion of tertiary and service sector activities especially the IT boom, and the improved transit facilities along the eastern fringe. This has helped the real estate sector to thrive along the vulnerable eastern fringe of the city, leading to a drastic change in the wetland ecosystem. Secondary studies have also indicated that consumption of wetlands, indicated by fragmented land use has altered the microclimate of Kolkata. The significant land cover change due to human-induced perturbations has led to an insurgence of temperature in the region <strong>(Li, Mitra, Dong, & Yang, 2018)</strong>. The entire transit corridor is subjected to verticalization juxtaposing the cultural essence of Kolkata bringing with it a myriad of Economic, Social, Cultural and subsequent planning challenges. The critical review of the selective literature shows how the best planning practices have integrated transit policies with land use. This has further helped the researcher in formulating strategies and policies specific to the regional context in order to render sustainable development in the study area. The study explores how the transit policies in Kolkata have actually transformed the city physically, socially, culturally and changed its microclimate. The study identifies future trends and assesses the future development potential, intensification with the help of qualitative and quantitative analysis. The study also conducts land suitability analysis for framing proposals and recommendations for ensuring sustainable development along the East Kolkata Wetland.  The outcome of this study is a methodology for sustainability strategic planning for developing the growth node along the eastern fringe of Kolkata which will curb the encroachment of the East Kolkata Wetlands. The study also provides a platform for policy recommendations for land use management and mitigate future climate changes in this eco-fragile zone.</p><p>Keywords: landuse; climate change; transit policies; sustainable planning; wetlands</p><p>Reference</p><p>Li, X., Mitra, C., Dong, L., & Yang, Q. (2018). Understanding land use change impacts on microclimate using Weather Research and Forecasting (WRF) model. Physics and Chemistry of the Earth, 103, 115–126. https://doi.org/10.1016/j.pce.2017.01.017</p>