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Coccolithophore assemblages of a 9 000 year old marine sediment core from a climate hotspot in Tasmania, southeast Australia

Created 23/06/2025

Updated 23/06/2025

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Predicting phytoplankton impacts in response to a changing climate on Tasmania's east coast is presently based on short-term plankton data sets (~75 years). However, given the vital contribution coccolithophores make to oceanic carbon pumps, it is crucial to understand longer-term assemblage trends better. Here, we expand the archive of calcareous nannoplankton in southeast Australian waters by analysing coccolithophore microfossils in a ~2.68m long marine sediment core from the climate hotspot of Maria Island, Tasmania, using polarising light and scanning electron microscopy techniques in combination with analysis of sedimentary ancient DNA (sedaDNA). Coccolith assemblages at this site represent the complex interplay between the East Australian Current, Subantarctic incursions, and the hydrodynamics driving Subtropical Front positioning. Microfossil analysis revealed a shift from a cold to warm-adapted assemblage ~8 200 years BP, expressed by a striking transition from assemblages dominated by the cold-water species Gephyrocapsa muellerae to warmer water species Emiliania huxleyi. This transition compares with similar occurrences in the literature at ~11 000 years reported in the Southern Ocean and 12 000 years in the Tasman Sea, reflecting a broad shift of the Subtropical Front. E. huxleyi microfossils displayed the highest relative abundance, but less abundant larger taxa (including Calcidiscus, Coccolithus, Helicosphaera) accounted for >50% of coccolith CaCO3 sequestration, indicating large densely calcified species do the 'heavy-lifting' in terms of carbon cycling within mixed coccolithophore assemblages. Analysis of sedaDNA showed coccolithophores comprised the largest number of eukaryote molecular sequences recovered (~44%), far exceeding diatoms and dinoflagellates.

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Field Value
Title Coccolithophore assemblages of a 9 000 year old marine sediment core from a climate hotspot in Tasmania, southeast Australia
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/cf331bc3-34ef-4ba7-80fc-9e67480321bc
Contact Point
Australian Ocean Data Network
bradley.paine@utas.edu.au
Reference Period 01/05/2018 - 15/05/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
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Data Portal Australian Oceans Data Network

Data Source

This dataset was originally found on Australian Oceans Data Network "Coccolithophore assemblages of a 9 000 year old marine sediment core from a climate hotspot in Tasmania, southeast Australia". Please visit the source to access the original metadata of the dataset:
https://catalogue.aodn.org.au/geonetwork/srv/eng/csw/dataset/coccolithophore-assemblages-of-a-9-000-year-old-marine-sediment-core-from-a-climate-hotspot-in-