Diurnal fluctuations in primary production in shallow waters off south-western Australia

Florence Isabelle Verspecht, Charitha Pattiaratchi, Anya Waite

    Research output: Contribution to conferenceAbstract


    Research into aspects of the variability of marine production on a spectrum of spatial and temporal scales has highlighted the lack of understanding of planktonic responses at the smaller, higher frequency scales of perturbation. Here, the physical processes controlling diurnal fluctuations in primary production are investigated and the biological effects of wind-driven mixing in the oligotrophic waters off south-western Australia are characterized. The coast of Western Australia experiences a diel cycle of mixing and stratification, recorded in various other field studies including Wilson Inlet, Whitfords Lagoon and Cockburn Sound. Stratification and vertical mixing affect the movement of phytoplankton through the water column, and consequently the irradiances they experience. Previous studies have shown that neither stabilization nor destabilization of the water column favours production and that frequent alternation in the physical stability of the water column is conducive to enhancing primary production. Phytoplankton responses differ according to the intensity and persistence of this mechanical energy input. The aim of this study is to determine whether local wind-mixing augments the potential for production in the nearshore zone through varying of the light and nutrient climate that phytoplankton experience. Experiments have thus been conducted in the lagoonal waters off the south-west coast to characterize the physical stability of the water column, biological response and nutrient status for three sites with varying exposures. High frequency time- series were obtained during summer and winter for chlorophyll a, fluorescence, dissolved oxygen, temperature, conductivity, light and current data. Primary production was estimated through carbon uptake experiments with one hour in situ incubations and photosynthetic efficiency was estimated using high frequency pulse amplitude modulated (PAM) fluorescence measurements. Preliminary results will be discussed in the context of a highly dynamic coupled biophysical environment.
    Original languageEnglish
    Number of pages1
    Publication statusPublished - 2005
    EventIndian Ocean Marine Environmental Conference: Linking science, engineering and management - Perth Convention Exhibition Centre, Perth, Australia
    Duration: 14 Feb 200518 Feb 2005


    ConferenceIndian Ocean Marine Environmental Conference


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