Uptake and resource allocation of ammonium and nitrate in temperate seagrasses Posidonia and Amphibolis

Sasi Nayar, G Collings, D Miller, S Bryars, A Cheshire

    Research output: Contribution to journalArticlepeer-review

    12 Citations (Scopus)

    Abstract

    Ecologically relevant estimates of seasonal variability in nitrogen uptake and allocation in two species of temperate seagrasses were obtained using in situ isotope-labelling approach. Significantly higher uptake rates of ammonium by leaves, roots and epiphytes of Amphibolis than Posidonia were observed. Overall, root uptake rates were lower than other components. Effect of season was not significant for leaves, roots or epiphytes of the two species. However, plankton uptake varied seasonally with higher rates in winter (0.98mgNg-1DWh-1). In contrast, nitrate uptake rates for various components were significantly affected by seasons. Uptake rates by plankton were highest ranging from 0.003mgNg-1DWh-1 (summer, Amphibolis) to 0.69mgNg-1DWh-1 (winter, Posidonia). Uptake of nitrate by roots was negligible. Biotic uptake rates for nitrate were an order of magnitude slower than ammonium, demonstrating an affinity for ammonium over nitrate as a preferred inorganic nitrogen source. Adelaide coastal waters have lost over 5000ha of seagrasses, much of this attributed to nutrient inputs from wastewater, industrial and stormwater. Managing these inputs into future requires better understanding of the fate of nutrients, particularly biological uptake. This study attempts to quantify uptake rates of nitrogen by seagrasses.

    Original languageEnglish
    Pages (from-to)1502-1511
    Number of pages10
    JournalMarine Pollution Bulletin
    Volume60
    Issue number9
    DOIs
    Publication statusPublished - Sep 2010

    Keywords

    • Adelaide coastal waters
    • Epiphytes
    • Nutrient resource allocation
    • Nutrient uptake
    • Phytoplankton
    • Seagrass

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