Sulfur cycling and seagrass (Posidonia oceanica) status in carbonate sediments

Marianne Holmer*, Carlos Duarte, Núria Marbá

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

Sulfur cycling was investigated in carbonate-rich and iron-poor sediments vegetated with Posidonia oceanica in oligotrophic Mediterranean around Mallorca Island, Spain, to quantify sulfate reduction and pools of sulfide in seagrass sediments. The oxygen penetration depth was low (< 4.5 mm) and sulfate reduction rates were relatively high (0.7-12 mmol m-2d-1). The total pools of reduced sulfides were remarkably low (< 5 mol S m -2) indicating a fast turnover of reduced sulfides in these iron-poor sediments. The sulfate reduction rates were generally higher in vegetated compared to bare sediments possible due to enhanced sedimentation of sestonic material inside the seagrass meadows. The sulfate reduction rates were positively correlated with the seasonal variation in water temperature and negatively correlated with the shoot density indicating that the microbial activity was controlled by temperature and release of oxygen from the roots. The pools of reduced sulfides were low in these iron-poor sediments leading to high oxygen consumption for reoxidation. The sediments were highly anoxic as shown by relatively low oxygen penetration depths (< 4.5 mm) in these low organic sediments. The net shoot recruitment rate was negative in sediments enriched with organic matter, suggesting that organic matter enrichment may be an important factor for seagrass status in these iron-depleted carbonate sediments.

Original languageEnglish (US)
Pages (from-to)223-239
Number of pages17
JournalBiogeochemistry
Volume66
Issue number3
DOIs
StatePublished - Dec 1 2003

Keywords

  • Carbonate sediments
  • Posidonia ocenica
  • Seagrass
  • Sulfate reduction rates
  • Sulfides

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology
  • Earth-Surface Processes

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