The use of δ 15N signatures of translocated macroalgae to map coastal nutrient plumes: Improving species selection and spatial analysis of metropolitan datasets

Milena Fernandes, Simon Benger, S Sharma, Simon Gaylard, T Kildea, S Hoare, M. Braley, A Irving

    Research output: Contribution to journalArticle

    13 Citations (Scopus)

    Abstract

    The definition of the spatial footprint of land-derived nutrient plumes is a key element to the design of initiatives to combat eutrophication in urbanised coastal regions. These plumes, however, are difficult to monitor because of their inherent high-frequency temporal and spatial variability. Biomonitoring with macroalgae provides time-integration of bioavailable nitrogen inputs through the measurement of δ15N signatures in tissues, and adequate spatial coverage through translocation to desirable monitoring locations. In this study, we used laboratory incubations to compare three different species of macroalgae as bioindicators, and a field experiment to investigate the applicability of the technique for the large-scale mapping of nutrient plumes. Cladophora valonioides was selected for the field experiment as it showed rapid changes in δ15N values in the laboratory incubations, was abundant in shallow depths making collection cost-efficient, and had tough thalli capable of withstanding deployment in open water. Ecklonia radiata also performed well in the laboratory incubations, but field harvest from subtidal depths was comparatively more expensive. Ulva lactuca had fragile thalli, and large nitrogen reserves that acted to mask the isotopic signal of newly acquired nitrogen. Cladophora valonioides was translocated to 246 sites covering an area of ∼445 km2 along the highly urbanized temperate coast of Adelaide, South Australia. The resulting isotopic signatures of nitrogen in tissues were spatially interpolated to produce maps of land-derived nutrient plumes, to model probability and standard error in the predictive surface, and to optimize sampling design.

    Original languageEnglish
    Pages (from-to)2399-2410
    Number of pages12
    JournalJournal of Environmental Monitoring
    Volume14
    Issue number9
    DOIs
    Publication statusPublished - Sep 2012

    Fingerprint Dive into the research topics of 'The use of δ <sup>15</sup>N signatures of translocated macroalgae to map coastal nutrient plumes: Improving species selection and spatial analysis of metropolitan datasets'. Together they form a unique fingerprint.

  • Cite this