Late Holocene environmental change of Te Whakaraupō | Lyttelton Harbour, New Zealand

Due to the increasing impacts of climate change, global sea levels and ocean temperatures have been rapidly increasing. One region which will be affected by these increased sea levels are the bays of Horomaka | Banks Peninsula on the east coast of the South Island, New Zealand. Horomaka is a poorly understood landscape that has been highly modified by human land management in both Māori and European times. This research will investigate the interactions between changes in the coastal system and the surrounding catchments which are deeply incised valleys in the flanks of an old volcanic complex. The work focusses on three locations: Te Whakaraupō | Lyttelton Harbour, Kawatea | Okains Bay and Te Wairewa | Lake Forsyth and uses a combination of micro-fossil, geochemical and sedimentological proxies to decipher ecological, hydrological and anthropomorphic changes in these catchments. Here we present our preliminary findings from Te Whakaraupō | Lyttelton Harbour, where a 3.4 m shallow marine sediment core was collected from the mudflats of the innermost harbour. Foraminiferal records indicate a rapid infilling of the harbour with a shift in conditions from low intertidal to high intertidal to present day salt marsh. This change in sedimentation is reflected in our X-ray Fluorescence results, which show increased variability in terrigenous sediment and organic content at the top of the record. This research presents the first of its kind in Horomaka to reconstruct past environmental conditions over time. Future research will include pollen and micro-charcoal analyses and grain size analysis to amplify the palaeoenvironmental data. This research will develop key information on changes in both marine and terrestrial environmental change and sedimentation rates over the late Holocene, which will help inform the management response to enhanced climate change and urban development in the harbour.

Keywords

Climates, Sea level, New Zealand, Bays, Valleys, Ecological balance, X-ray fluorescence analysis, Harbors

Citation

Hanson, J., Reid, C., Prebble, M., Shulmeister, J., Moy, C., Zawadzki, A., & Hua, Q. (2022). Late Holocene environmental change of Te Whakaraupō | Lyttelton Harbour, New Zealand. Paper presented to the AQUA 2022 Conference, 6-8th December, Adelaide (pp. 54-55). Retrieved from: https://aqua.org.au/conference/aqua-2022/aqua-2022-conference-program-and-abstracts/

URI

https://aqua.org.au/conference/aqua-2022/aqua-2022-conference-program-and-abstracts/
https://apo.ansto.gov.au/dspace/handle/10238/14764

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