MEPS 309:93-105 (2006)  -  doi:10.3354/meps309093

Spatial patterns of aerobic and anaerobic mineralization rates and oxygen penetration dynamics in coral reef sediments

Ursula Werner1,*, Paul Bird2, Christian Wild1, Timothy Ferdelman1, Lubos Polerecky1, Gabriele Eickert1, Ron Jonstone2, Ove Hoegh-Guldberg2, Dirk de Beer1

1Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany
2Centre for Marine Studies, The University of Queensland, Brisbane, Queensland 4072, Australia

ABSTRACT: Oxygen consumption rates (OCR), aerobic mineralization and sulfate reduction rates (SRR) were studied in the permeable carbonate reef sediments of Heron Reef, Australia. We selected 4 stations with different hydrodynamic regimes for this study. In situ oxygen penetration into the sediments was measured with an autonomous microsensor profiler. Areal OCR were quantified from the measured oxygen penetration depth and volumetric OCR. Oxygen penetration and dynamics (median penetration depths at the 4 stations ranged between 0.3 and 2.2 cm), OCR (median 57 to 196 mmol C m–2 d–1), aerobic mineralization (median 24 to 176 mmol C m–2 d–1) and SRR (median 9 to 42 mmol C m–2 d–1) were highly variable between sites. The supply of oxygen by pore water advection was a major cause for high mineralization rates by stimulating aerobic mineralization at all sites. However, estimated bottom water filtration rates could not explain the differences in volumetric OCR and SRR between the 4 stations. This suggests that local mineralization rates are additionally controlled by factors other than current driven pore water advection, e.g. by the distribution of the benthic fauna or by local differences in labile organic carbon supply from sources such as benthic photosynthesis. Carbon mineralization rates were among the highest reported for coral reef sediments, stressing the role of these sediments in the functioning of the reef ecosystem.

KEY WORDS: Coral reef · Permeable sands · Oxygen consumption · Sulfate reduction · Microsensors · In situ measurements

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