Shallow lakes are often highly productive ecosystems that provide important habitats for aquatic flora and fauna and have many societal values, including cultural significance, recreational uses (e.g. angling) and the provision of water for commercial purposes. Depending on their geomorphology and regional setting (prevailing climate, catchment size, etc.), the ecological characteristics of these lentic systems may vary substantially due to the influence of water level fluctuations.
We provide an overview of the eco-hydrological science that has been undertaken over 30+ years to support water planning in the interconnected Lake Crescent and Lake Sorell, Tasmania, Australia. Three components of the lakes that are strongly influenced by water levels have been focused upon: (1) water clarity, (2) floral communities in littoral wetlands, and (3) recruitment and abundance of populations of the threatened fish species, golden galaxias (Galaxias auratus). The initial research identified important water level thresholds for maintaining these lake components in desirable states. Subsequently, these lake components were monitored through record low water levels associated with the Millennium Drought and high water levels during following wet years. The results were used to re-examine the early predictions, further understanding of eco-hydrological relationships and refine recommendations for water planning. While challenging, the inherent ecological and hydrological variability of shallow lakes needs to be accounted for in their management. This body of work in lakes Crescent and Sorell provides an important case study for the management of temperate shallow lakes in the Southern Hemisphere.