Hydrographic Features of Nearshore Waters along Mangalore Coast

Abstract

Monthly and seasonal variations of some hydrographic features at 9 stations in the sea off Mangalore along the South Kanara coast were studied. Air and sea water temperatures showed a double oscillation during the year. Lowering of sea water temperature in May before the break of south west monsoon was perhaps due to upwelling at this time. Surface salinity showed a triple oscillation for all stations. Salinity of surface water fluctuated more sharply than bottom water salinity. In general, dissolved oxygen values showed an inverse correlation with values of salinity and temperature. Relatively low oxygen during May at the surface appeared to be due to upwelling. Transparency of water was high during summer months and low during south west monsoon season. The waters very near to the shore were more turbid than the waters farther away. Generally, surface currents were directed towards north during March and towards south during August.