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 mu S/cm to 11,000 mu S/cm) and coalmine-induced (100 mu S/cm to 2400 mu S/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 dry land 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 mu S/cm) yielded lower leaf breakdown at lower salinity relative to inoculum from a low salinity site (50 mu S/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 (approximate to 500 mu S/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. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.

Keywords

Microorganisms; Freshwater; Salinization; Leaf breakdown; Major ions

Published in

Aquatic Toxicology
2016, Volume: 177, pages: 425-432
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Bundschuh, Mirco

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • University of Koblenz-Landau

Sustainable Development Goals

SDG15 Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


UKÄ Subject classification

Other Natural Sciences not elsewhere specified


Publication identifier

DOI: https://doi.org/10.1016/j.aquatox.2016.06.014

Permanent link to this page (URI)

https://res.slu.se/id/publ/80848