The effect of sediment grain properties and porewater flow on microbial abundance and respiration in permeable sediments


Contact
moritz.holtappels [ at ] awi.de

Abstract

Sandy sediments cover 50–60% of the continental shelves and are highly efficient bioreactors in which organic carbon is remineralized and inorganic nitrogen is reduced to N2. As such they seem to play an important role, buffering the open ocean from anthropogenic nitrogen inputs and likely remineralizing the vast amounts of organic matter formed in the highly productive surface waters. To date however, little is known about the interrelation between porewater transport, grain properties and microbial colonization and the consequences for remineralization rates in sandy sediments. To constrain the effect of theses factors on remineralization in silicate sands, we incubated North Sea sediments in flow-through reactors after separating into five different grain size fractions. Bulk sediment and sediment grain properties were measured along with microbial colonization and cell abundances, oxygen consumption and denitrification rates. Volumetric oxygen consumption ranged from 14 to 77 µmol O2 l−1 h−1 while nitrogen-loss via denitrification was between 3.7 and 8.4 µmol N l−1 h−1. Oxygen consumption and denitrification rates were linearly correlated to the microbial cell abundances, which ranged from 2.9 to 5.4·108 cells cm−3. We found, that cell abundance and consumption rates in sandy sediments are influenced (i) by the surface area available for microbial colonization and (ii) by the exposure of these surfaces to the solute-supplying porewater flow. While protective structures such as cracks and depressions promote microbial colonization, the oxygen demand is only met by good ventilation of these structures, which is supported by a high sphericity of the grains. Based on our results, spherical sand grains with small depressions, i.e. golf ball like structures, provide the optimal supporting mineral structure for microorganisms on continental shelves.



Item Type
Article
Authors
Divisions
Primary Division
Programs
Primary Topic
Publication Status
Published
Eprint ID
51305
DOI 10.1038/s41598-020-60557-7

Cite as
Ahmerkamp, S. , Marchant, H. K. , Peng, C. , Probandt, D. , Littmann, S. , Kuypers, M. M. M. and Holtappels, M. (2020): The effect of sediment grain properties and porewater flow on microbial abundance and respiration in permeable sediments , Scientific Reports, 10 (1) . doi: 10.1038/s41598-020-60557-7


Download
[thumbnail of Ahmerkamp_2020_The-effect-of-sediment-grain-properties-and-porewater-flow-on-microbial-abundance-and-repiration-in-permeable-sediments.pdf]
Preview
PDF
Ahmerkamp_2020_The-effect-of-sediment-grain-properties-and-porewater-flow-on-microbial-abundance-and-repiration-in-permeable-sediments.pdf

Download (2MB) | Preview

Share
Add to AnyAdd to TwitterAdd to FacebookAdd to LinkedinAdd to PinterestAdd to Email


Citation

Geographical region

Research Platforms

Campaigns
HE > 420-439 > 432


Actions
Edit Item Edit Item