CIRCULATION IN WESTERN-PORT, VICTORIA, AS DEDUCED FROM SALINITY AND REACTIVE-SILICA DISTRIBUTIONS

The study of the hydrochemistry of Western Port began in June 1973 as part of the Westernport Bay Environmental Study. The objectives were to understand nutrient dynamics and to assist in formulation of management guidelines for the bay and for use in mathematical modelling, Parameters measured included: inorganic forms of nitrogen, reactive phosphorus, total phosphorus, chlorophylls, dissolved oxygen, particulate and total organic carbon, salinity and reactive silica. Detailed sampling of Western Port waters was carried out every three weeks throughout the four-year period. Initially a 48-station grid was used, but as the study progressed this was expanded to 62 stations and 26 shore locations. Analyses of detailed salinity and reactive-silica distributions have revealed the major features of water circulation. Water moves around French Island in a clockwise direction and some recycling occurs off Tortoise Head to form a complete loop. A clockwise movement exists in the Western Entrance Segment while a weak counter-clockwise movement exists in the Rhyll Segment. An exchange period of about twelve weeks is indicated for waters in the upper parts of Western Port. © 1979.