Influence of local physical events on picophytoplankton spatial and temporal dynamics in South Australian continental shelf waters

Virginie Van Dongen-Vogels, Justin Seymour, John Middleton, Laurent Seuront, James Mitchell

    Research output: Contribution to journalArticle

    17 Citations (Scopus)

    Abstract

    We investigated the spacetime dynamics of picophytoplankton in South Australian continental shelf waters from February 2008 to January 2009, focusing on localized physical events. We discriminated six picophytoplankton populations by flow cytometry, including Synechococcus (SYN1, SYN2), Prochlorococcus (PROC1, PROC2) and small and large picoeukaryotes (EUKS, EUKL). Local physical events observed included downwelling and dense waters outflowing from a nearby gulf in winterearly spring 2008, upwelling in summer and early spring 2008 and eddy formation in January 2009. Each population responded differently to these events, which resulted in up to four orders of magnitude changes in their abundances. Population-specific hotspots reflected a succession of distinct dominant communities associated with the strength of upwelling events, changes in fluorescence maximum depths and local downwelling and mixing processes. The unexpected high abundances and local dominance of Prochlorococcus in summer reflected the possible influence of eastward and westward current transports and the presence of a High-Light (PROC1)- and Low-Light (PROC2)-adapted ecotypes. This study highlights the role of localized physical events in the dominance of all three picophytoplankton groups that may be critical for the high productivity of the study region, and suggests the importance of hydroclimatic forcing for inter-annual changes in picophytoplankton communities.

    Original languageEnglish
    Pages (from-to)1825-1841
    Number of pages17
    JournalJournal of Plankton Research
    Volume33
    Issue number12
    DOIs
    Publication statusPublished - Dec 2011

    Keywords

    • Chlorophyll fluorescence maximum
    • Coastal upwelling and downwelling
    • Picophytoplankton
    • South Australia
    • Spatial and temporal dynamics

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