Population-specific shifts in viral and microbial abundance within a cryptic upwelling

James Paterson, Sasi Nayar, James Mitchell, Laurent Seuront

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)


    Coastal upwelling systems play an essential role in bringing cold and nutrient-rich water into the euphotic zone, hence enhancing the biological productivity of the world's oceans. We describe a "cryptic" upwelling occurring in South Australian waters, in which cold upwelled waters do not reach surface waters and do not exhibit a sea surface temperature (SST) signature. Due to the wide continental shelf (ca. 100 km), upwelled waters form a sub-surface cold water pool and are forced north-west after a secondary event. Using flow cytometry we investigated the abundance and composition of viruses, heterotrophic bacteria and pico-phytoplankton within upwelling affected and unaffected waters. Our results identified the presence of upwelled waters at and below the Deep-Chlorophyll Maximum (DCM), where water temperature was at least 4 °C colder than surface waters. In contrast to previous studies, no significant differences were observed between upwelled and non-upwelled waters for most individual viral, bacterial and pico-phytoplankton sub-groups. However, one viral, one bacterial and two pico-phytoplankton sub-groups were significantly more abundant at the DCM. This indicates the presence of depth- and population-specific shifts in abundance and potential niche partitioning of these cytometrically-defined sub-groups that may be related to their host organisms and/or resource availability.

    Original languageEnglish
    Pages (from-to)52-61
    Number of pages10
    JournalJournal of Marine Systems
    Publication statusPublished - Mar 2013


    • Bacteria
    • Coastal upwelling
    • Cryptic
    • Flow cytometry
    • Pico-phytoplankton
    • Viruses


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