Aspects of the limnology of Yeppen Yeppen Lagoon, central Queensland

Abstract

Aspects of the morphometry and physical and chemical limnology of Yeppen Yeppen Lagoon, in tropical Australia, have been investigated. The lagoon is a channel billabong lying in the old bed of the Fitzroy River. It has a relatively small, shallow and elongated basin. Seasonal variations in water temperature, light regime, oxygen concentration, pH and conductivity suggest that the lagoon exhibits a warm monomictic pattern of thermal stratification rather than a continuous warm polymictic one. The annual heat budget was 3294 calories cm^-2 year^-1. Maximum work of the wind was 238.8 g-cm cm^-2, and maximum stability was 34.5 g-cm cm-2. Despite the apparently low stability of stratification, the lagoon remained thermally stratified for much of the year. Analysis of wind-distributed heat suggested that slow mixing was taking place even during periods of relatively high stability, although this mixing was insufficient to reoxygenate the hypolimnion, which remained anoxic for much of the year. Yeppen Yeppen Lagoon is likely to prove eutrophic, and it is suggested that primary productivity will be high because a large volume of the lagoon's water is well lit and a large sediment surface area is in contact with the epilimnion. Notes on the biota of Yeppen Yeppen Lagoon are also given.