Understanding the impacts of multiple stressors and associated regime shifts in shallow wetlands

Jenny DAVIS

    Research output: A Conference proceeding or a Chapter in BookConference contribution

    Abstract

    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.
    Original languageEnglish
    Title of host publicationProceedings of the Symposium on Australia-China Wetland Network Research Partnership
    EditorsGiri Kattel
    Place of PublicationAustralia
    PublisherFederation University Australia
    Pages50-55
    Number of pages6
    Publication statusPublished - 2014
    EventSymposium on Australia-China Wetland Network Research Partnership - , China
    Duration: 23 Mar 201428 Mar 2014

    Conference

    ConferenceSymposium on Australia-China Wetland Network Research Partnership
    CountryChina
    Period23/03/1428/03/14

    Fingerprint

    wetland
    phytoplankton
    nutrient
    feedback mechanism
    phosphorus
    water
    wetland management
    salinity
    lake
    hysteresis
    water quality
    organic matter
    prediction

    Cite this

    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.
    DAVIS, Jenny. / Understanding the impacts of multiple stressors and associated regime shifts in shallow wetlands. Proceedings of the Symposium on Australia-China Wetland Network Research Partnership. editor / Giri Kattel. Australia : Federation University Australia, 2014. pp. 50-55
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    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. Federation University Australia, Australia, pp. 50-55, Symposium on Australia-China Wetland Network Research Partnership, China, 23/03/14.

    Understanding the impacts of multiple stressors and associated regime shifts in shallow wetlands. / DAVIS, Jenny.

    Proceedings of the Symposium on Australia-China Wetland Network Research Partnership. ed. / Giri Kattel. Australia : Federation University Australia, 2014. p. 50-55.

    Research output: A Conference proceeding or a Chapter in BookConference contribution

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    AB - 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.

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    DAVIS J. Understanding the impacts of multiple stressors and associated regime shifts in shallow wetlands. In Kattel G, editor, Proceedings of the Symposium on Australia-China Wetland Network Research Partnership. Australia: Federation University Australia. 2014. p. 50-55