Assessing the in situ bacterial diversity and composition at anthropogenically active sites using the environmental DNA (eDNA)

Environmental DNA as a tool for biodiversity monitoring in aquatic ecosystems – a review

The monitoring of changes in aquatic ecosystems due to anthropogenic activities is of utmost importance to ensure the health of aquatic biodiversity. Eutrophication in water bodies due to anthropogenic disturbances serves as one of the major sources of nutrient efflux and consequently changes the biological productivity and community structure of these ecosystems. Habitat destruction and overexploitation of natural resources are other sources that impact the equilibrium of aquatic systems. Environmental DNA (eDNA) is a tool that can help to assess and monitor aquatic biodiversity. There has been a considerable outpour of research in this area in the recent past, particularly concerning conservation and biodiversity management. This review focuses on the application of eDNA for the detection and relative quantification of threatened, endangered, invasive and elusive species. We give a special emphasis on how this technique developed in the past few years to become a tool for understanding the impact of spatial-temporal changes on ecosystems. Incorporating eDNA based biomonitoring with advances in sequencing technologies and computational abilities had an immense role in the development of different avenues of application of this tool.

Impact of untreated sewage and thermal effluent discharges on the air-sea CO2 fluxes in a highly urbanized tropical coastal region

Various biotic and abiotic factors regulate carbon dioxide (CO₂) absorption and emission in coastal waters. Factors controlling the regional air-sea CO₂ fluxes were studied in Tuticorin Bay, a highly urbanized region along the southeast coast of India. Significant spatial heterogeneity in the distribution of inorganic carbon components in the bay was observed based on the exposure to different anthropogenic pressures. Thermal effluent discharges made the south zone of the bay a strong CO₂ source by enhancing heterotrophy. Untreated sewage discharges in the middle zone mediated eutrophic conditions leading to strong autotrophy and restricting the zone as a weak source of CO_2. Irrespective of the anthropogenic stressors, biological processes dominated the air-sea CO₂ fluxes in the Tuticorin Bay. The results indicated that micro-level studies are needed in understanding the carbon cycle in environments with multiple anthropogenic stressors.