Investigation of nutrient thresholds for ecological regime change in the Vasse-Wonnerup Estuary in south-Western Australia
Chambers, J., Wilson, C., Tulbure, M. and Clarke, A. (2011) Investigation of nutrient thresholds for ecological regime change in the Vasse-Wonnerup Estuary in south-Western Australia. In: 48th Annual Conference of the Australian Marine Science Association, 3 - 7 July, Fremantle, Western Australia.
Recent literature suggests that the initial concept of two contrasting ecological regimes (macrophyte or phytoplanktondominated) in nutrient-enriched shallow lakes should be extended, based on observations that such systems may be dominated by free-floating plants, submerged charophytes, submerged angiosperms, green algae or cyanobacteria at different points along a gradient of eutrophication. The implications of this for management and restoration are that different levels or thresholds of a controlling variable (such as nutrients) may be necessary to cause a shift in dominance depending on the characteristics of the dominant taxa. Each of the plant types listed above occur simultaneously in spring in different locations in the Vasse Wonnerup Estuary. This paper explores the drivers for dominance of different plant communities in these shallow waterbodies, focussing on potential thresholds (particularly total phosphorus concentrations and N:P ratios), that might explain the efficacy of nutrient reduction measures, the likelihood of catastrophic loss of macrophytes from the wetlands or guide restoration of macrophytes in currently phytoplankton-dominated systems.
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|Murdoch Affiliation:||School of Environmental Science|
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