Macrofauna regulate heterotrophic bacterial carbon and nitrogen incorporation in low-oxygen sediments

William R. Hunter*, Bart Veuger, Ursula Witte

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)
184 Downloads (Pure)

Abstract

Oxygen minimum zones (OMZs) currently impinge upon >1 million km 2 of sea floor and are predicted to expand with climate change. We investigated how changes in oxygen availability, macrofaunal biomass and retention of labile organic matter (OM) regulate heterotrophic bacterial C and N incorporation in the sediments of the OMZ-impacted Indian continental margin (540-1100 m; O 2 0.35-15 μmol l 1). In situ pulse-chase experiments traced 13 C: 15 N-labelled phytodetritus into bulk sediment OM and hydrolysable amino acids, including the bacterial biomarker D-alanine. Where oxygen availability was lowest (O 2 0.35 μmol l 1), metazoan macrofauna were absent and bacteria assimilated 30-90% of the labelled phytodetritus within the sediment. At higher oxygen levels (O 2 2-15 μmol l 1) the macrofaunal presence and lower phytodetritus retention with the sediment occur concomitantly, and bacterial phytodetrital incorporation was reduced and retarded. Bacterial C and N incorporation exhibited a significant negative relationship with macrofaunal biomass across the OMZ. We hypothesise that fauna-bacterial interactions significantly influence OM recycling in low-oxygen sediments and need to be considered when assessing the consequences of global change on biogeochemical cycles.

Original languageEnglish
Pages (from-to)2140-2151
Number of pages12
JournalThe ISME Journal
Volume6
Issue number11
Early online date17 May 2012
DOIs
Publication statusPublished - 01 Nov 2012
Externally publishedYes

Keywords

  • bacteria
  • C:N coupling
  • hydrolysable amino acids
  • macrofauna
  • oxygen minimum zone
  • sediment

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Microbiology

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