Some Aspects of the Ecology of Lake Macquarie, N.S.W., with Regard to an Alleged Depletion of Fish. II. Hydrology

Abstract

Lake Macquarie is a marine-dominated drowned valley connected to the sea by a shallow narrow channel which damps tidal oscillations from 5 ft on the coast outside to about 3 in. in the like. Superimposed on the semi-diurnal tides are changes in level in response to changes both in the external daily mean sea-level and in the volume of fresh water discharge into the lake.

Temperature and chlorinity cycles are closely linked. Discharge from the creeks supplies phosphate but little nitrate for the lake. Prolonged heavy rainfall in both 1955 and 1956 produced stratification of the water associated with lowered oxygen tension in the underlying salt water. There is evidence of a wind-generated circulation within the lake.