Salinity and Oxygen Concentrations
In summer, the salinity levels of both surface and bottom waters in the north and south of Oyster Harbour are close to being at marine levels. The average dissolved oxygen values were in the healthy range. Bottom dissolved oxygen was slightly lower, particularly in the north of the harbour. This is due to the breakdown of organic matter, which consumes oxygen – a typical process in most estuarine ecosystems.
Winter salinities were slightly lower in the surface waters and varied more, due to the influence of fresher river inflows, yet remained in the ‘saline’ zone. This indicates river inflows have a relatively small impact on salinity. Average oxygen concentrations were well within the healthy range throughout the period.
Oxygen concentrations and salinity are related to stratification. Find out about stratification and how it impacts estuary health here.