Hydrographic Processes in a Tropical Coastal Lagoon on Western Bay of Bengal

Abstract

In this article, hydrographic processes of a tropical coastal lagoon is studied that control inherent biological mechanisms of the lagoon environment. Realizing the interest of environmentalists over physio-chemical studies of a wetland tropical wetland system on the western boundary of the Bay of Bengal, a high-resolution intensive vertical hydrographic field campaign was carried during monsoon to uncover peculiarity in vertical hydrographic processes that was long-awaited to address many environmental issues. Vertical hydrographic profiles on spatio-temporal scale were made at nine stations in a zonal direction of the Chilika lagoon system. Results of vertical variability of salinity showed the presence of higher saline water over less saline water in the central-western region. The higher and lower water temperature in the western and eastern parts of the lagoon, respectively, indicated temperature dipole between the two regions. The encapsulation of water mass having higher temperature by the water of lower temperature at the central region resulted evolution of thermal inversion. The highest dissolved oxygen concentration was observed in the sub-surface layers of the western part of the lagoon. However, a layer of near-hypoxia occurred below 1.5 m depth in the central region. This study proposes comprehensive inter-seasonal studies to address the vertical variability of biogeochemical parameters and the fate of organic flux.

Exploring Water Quality as a Determinant of Small-Scale Fisheries Vulnerability

“…Seasonally low surface temperatures prevail in the winter, with the average lagoon temperature typically remaining within a range of 28.1-29.2 • C [54]. Temperature changes have a substantial impact on the microbial activity and mineralisation process that turns organic matter into nutrients [56]. Despite the fact that different species of phytoplankton have similar rates of photosynthesis and growth in relation to temperature, the growth rate has been found to be lower over a range of light and temperature conditions [52,53].…”