Ecological status of a freshwater tectonic lake of the indo-burmese province: Implications for livelihood development.

Tectonic lakes are among the most geologically fascinating and environmentally versatile hydrobiological systems found on the earth's surface. We conducted a study on the limnology of Tasek Lake, a tectonic lake located in the Indo-Burma Province of the South Asian region. Physico-chemical parameters of the lake's water along with its plankton were considered for the study. Their relationship was analysed by understanding their seasonal variations and through linear regression models. The water quality index (WQI), plankton diversity indices and canonical correspondence analysis (CCA) were computed. The ichthyofaunal diversity was also studied to get an insight into the lake's fishery potential. A preliminary assessment on the economic feasibility of converting Tasek Lake into a fishery was also completed. Results indicate moderate eutrophication in the lake and the plankton population is observed to be rich and abundant. The WQI value confirms the water to be of "very poor" quality. The CCA was done to analyze the relationships of physico-chemical parameters with months and seasons, and the relation between seasons and plankton assemblages. Results corroborate the results of WQI. Identified fish population suggest ample fishery potential of the lake. The economic assessment reveals that in order to maintain the ecological sustainability of the lake, it should be transformed into a recreational fishery, following a catch-and-release model. The study calls for urgent restoration of the lake so that not only its pristine ecology is survived but also its fishery potential is sustainably harnessed and local livelihood is improved.

Incidence of heavy metals and river restoration assessment of a major South Asian transboundary river.

Heavy metal contamination of river water has become a major issue affecting environmental and human health worldwide. This study makes an effort to observe the heavy metal incidence of River Brahmaputra, India, and its river restoration assessment for 2 years, 2017-2018 and 2018-2019. River Brahmaputra is the second longest and a major transboundary river of the South Asian region, which transcends the political boundaries of China, India and Bangladesh. The Pearson correlation analysis was used to analyse the interrelationships between physico-chemical parameters (which was also analysed during our study) and heavy metals. Heavy metal pollution index and multivariate analyses such as hierarchical cluster analysis and principal component analysis were used to establish our scientific observations. An assessment involving people's willingness to pay for river restoration was also done. Arsenic (As), lead (Pb), antimony (Sb), nickel (Ni), chromium (Cr), mercury (Hg) and cadmium (Cd) were monitored in three stations, namely, Dibrugarh Town (Tinkunia Ghat), Guwahati City (Bharalumukh) and Dhubri Town (Jahajghat), for the periods 2017-2018 and 2018-2019. The overall mean concentration was in the order Hg > Ni > Cr > Pb > Cd > As > Sb. Heavy metal pollution index was found in the order station 2 (344) > station 3 (320) > station 1 (317). Results clearly indicate the presence of heavy metal pollution in the Brahmaputra river, with very high levels in Guwahati City. Concentrations of Ni, Cr, Hg and Cd were found to be very high while As presence was marginally high. Concentration of Pb and Sb were nearly the prescribed World Health Organization and Bureau of Indian Standards limits. Multivariate analyses suggest that the heavy metal pollution is linked to similar sources in all the sampled sites. Further, the river restoration assessment revealed that citizens are willing to pay an average of INR 22.6 (USD 0.30) for restoring the water quality. Therefore, given the high levels of heavy metal contamination witnessed in the Brahmaputra river and citizens willingness to contribute towards restoring its water quality, the need for an appropriate river restoration strategy and water policy is strongly felt as an outcome of this study.