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Groundwater-dependent ecology of the shoreline of the subtropical Lake St Lucia estuary

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Environmental Geology

Abstract

The ecology of the St Lucia estuary in South Africa is of unique international importance. During droughts the estuary experiences high salinities, with values above that of seawater. Ion-poor groundwater flowing into the estuary from prominent sand aquifers along its eastern shoreline forms low-salinity habitats for salt-sensitive biota. During droughts, plants and animals can take refuge in the groundwater discharge zone until the condition in the estuary regains tolerable salinity. Simulations of the groundwater discharge indicate that the flow can persist during droughts over at least a decade, and be of great important for the resilience of the estuary. Anthropogenic activities have reduced the river inflow and made the St Lucia estuary more sensitive to droughts. The groundwater has thereby become increasingly important for the estuary’s ecology. Protection of the groundwater discharge along the shoreline itself and actions to increase the groundwater recharge are therefore important management tasks.

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Acknowledgements

We want to thank the following institutions and persons: Financial funding was provided by the Norwegian Council for Higher Education’s Programme for Development Research and Education and from the Norwegian University of Life Sciences C. Fox and A. Myeza from KwaZulu-Natal Wildlife were responsible for measurements of groundwater levels and salinities in the field. They also helped to keep crocodiles and hippopotamuses away from our students during the work along the estuary shore.

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Authors and Affiliations

  1. KZN Wildlife, Private Bag X01, St Lucia, 3936, South Africa

    Ricky Taylor

  2. Department of Hydrology, University of Zululand, Private Bag X1001, Kwa-Dlangezwa, 3886, South Africa

    Bruce Kelbe

  3. Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway

    Ricky Taylor, Sylvi Haldorsen, Bente Wejden, Lars Været & Marianne B. Simonsen

  4. Council for Geoscience, P.O.Box 900, Pietermaritzburg, 3200, South Africa

    Greg A. Botha

  5. Nordre Skuterudvei 16, 1432, Ås, Norway

    Bente Wejden

  6. Norconsult AS, Vestfjordgaten 4, 1338, Sandvika, Norway

    Marianne B. Simonsen

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  1. Ricky Taylor
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  2. Bruce Kelbe
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  3. Sylvi Haldorsen
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  4. Greg A. Botha
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  5. Bente Wejden
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  6. Lars Været
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  7. Marianne B. Simonsen
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Correspondence to Ricky Taylor.

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Taylor, R., Kelbe, B., Haldorsen, S. et al. Groundwater-dependent ecology of the shoreline of the subtropical Lake St Lucia estuary. Environ Geol 49, 586–600 (2006). https://doi.org/10.1007/s00254-005-0095-y

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  • DOI: https://doi.org/10.1007/s00254-005-0095-y

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