Effects of salinity on leaf breakdown: Dryland salinity versus salinity from a coalmine

Felix Sauer, Mirco Bundschuh, Jochen Zubrod, Ralf Schafer, Kristie Thompson, Ben KEFFORD

    Research output: Contribution to journalArticle

    21 Citations (Scopus)

    Abstract

    Salinization of freshwater ecosystems as a result of human activities represents a global threat for ecosystems’ integrity. Whether different sources of salinity with their differing ionic compositions lead to variable effects in ecosystem functioning is unknown. Therefore, the present study assessed the impact of dryland- (50 μS/cm to 11,000 μS/cm) and coalmine-induced (100 μS/cm to 2400 μS/cm) salinization on the leaf litter breakdown, with focus on microorganisms as main decomposer, in two catchments in New South Wales, Australia. The breakdown of Eucalyptus camaldulensis leaves decreased with increasing salinity by up to a factor of three. Coalmine salinity, which is characterised by a higher share of bicarbonates, had a slightly but consistently higher breakdown rate at a given salinity relative to dryland salinity, which is characterised by ionic proportions similar to sea water. Complementary laboratory experiments supported the stimulatory impact of sodium bicarbonates on leaf breakdown when compared to sodium chloride or artificial sea salt. Furthermore, microbial inoculum from a high salinity site (11,000 μS/cm) yielded lower leaf breakdown at lower salinity relative to inoculum from a low salinity site (50 μS/cm). Conversely, inoculum from the high salinity site was less sensitive towards increasing salinity levels relative to inoculum from the low salinity site. The effects of the different inoculum were the same regardless of salt source (sodium bicarbonate, sodium chloride and artificial sea salt). Finally, the microorganism-mediated leaf litter breakdown was most efficient at intermediate salinity levels (≈500 μS/cm). The present study thus points to severe implications of increasing salinity intensities on the ecosystem function of leaf litter breakdown, while the underlying processes need further scrutiny
    Original languageEnglish
    Pages (from-to)425-432
    Number of pages8
    JournalAcquayic Toxicology
    Volume177
    DOIs
    Publication statusPublished - 2016

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