Author(s)

Z. SHARIP, M.R. HIPSEY, S.S. SCHOOLER & R.J. HOBBS

Abstract

This paper examines the spatial patterns of water exchange based on water temperature variation between littoral and pelagic zones and compares the patterns in a series of shallow lakes at different water levels. Exchange patterns were assessed by developing isotherms along the transects and estimating the surface energy budget using the vertical temperature profile and time-series measurements. Our results indicate the presence of density-driven flow induced by the differential temperature gradient between littoral areas, which are dominated by either floating-leaved or submerged vegetation, and the open pelagic region. Persistent stratification was noted in the narrower lakes, which was thought to be due to the presence of dense submerged vegetation that attenuate wind-driven turbulence. In addition, variation of thermal stratification and mixing dynamics between these lakes at different water levels has corresponding effects on the biological and chemical regimes. The circulation contributes to increased transport of the phosphate that could favour submerged species and subsequently induce shifts of macrophyte community composition. The results of this study have implications for the rehabilitation and management of lake ecosystems.

Keywords

convective circulation, density driven flow, floating-leaved plant, Lake Chini, shallow wetland, submerged macrophytes, thermal stratification, water exchange