Understanding the dynamics and drivers of regime change is essential for effective wetland management. Much evidence suggests that nutrient-enriched, shallow, permanent lakes and wetlands typically exist in either two alternative stable states or regimes: a clear-water state dominated by macroscopic plants or a turbid-water state dominated by microscopic phytoplankton. In European lakes, where phosphorus is often limiting, macroscopic plants typically dominate when total phosphorus (TP) is less than 50 µg L-1 and phytoplankton dominate when total phosphorus exceeds 150 µg L-1. Predicting which state will dominate between these two thresholds is more difficult because feedback mechanisms hinder macroscopic plants invading a phytoplankton-dominated system and vice versa. Hysteresis occurs because there is not a simple linear relationship between nutrient concentration and the abundance of phytoplankton or macroscopic plants. Non-linear dynamics prevail and regime change can only occur when nutrient thresholds and associated feedback mechanisms are overcome. Although nutrient-driven state changes are well documented, other state changes can be driven by water regime, salinity and organic matter loadings. Research on wetlands in south-western Australia indicated that a multi-state model was applicable to perennial salinised wetlands where salinity, rather than nutrient concentration, was the main water quality driver. The finding that a dual state model did not apply to Western Australian wetlands with a seasonal water regime indicated that water regime is also influential. Developing conceptual models of regime change provides a powerful tool for integrating data on physical, chemical and biological features of standing waters into concepts that can generate testable predictions and guide restoration activities.
|Title of host publication||Proceedings of the Symposium on Australia-China Wetland Network Research Partnership|
|Place of Publication||Australia|
|Publisher||Federation University Australia|
|Number of pages||6|
|Publication status||Published - 2014|
|Event||Symposium on Australia-China Wetland Network Research Partnership - , China|
Duration: 23 Mar 2014 → 28 Mar 2014
|Conference||Symposium on Australia-China Wetland Network Research Partnership|
|Period||23/03/14 → 28/03/14|
DAVIS, J. (2014). Understanding the impacts of multiple stressors and associated regime shifts in shallow wetlands. In G. Kattel (Ed.), Proceedings of the Symposium on Australia-China Wetland Network Research Partnership (pp. 50-55). Australia: Federation University Australia.