Sedimentary Microbial Community Development from the Settlement of Water Column Particulate Matter
Abstract
Estuarine waters carry a high load of particulate matter, which is colonized by microbes that differ from those free-living in the water column. The transport of particles is a delivery mechanism of these microbes to new areas, including the seafloor. Sedimentary microbial communities differ from both free-living and particle-associated water column communities, even though settling particulate matter is the source of sea floor sediment. An experiment was designed to test how the sedimentation of particles and their associated microbes influences the development of the sedimentary microbial community. In this experiment, estuarine water was pumped through a low-flow system to allow the settlement of particles and the development of a sediment column over the course of two months. An additional treatment was tested by adding algae weekly to simulate algal bloom conditions. 16S rRNA gene amplicon sequencing indicated little difference between control and algal bloom conditions, though subtle differences with sediment depth were detected in both treatments, including an increase in the relative abundance of archaea with depth. The sedimentary communities were characteristic of natural estuarine sediments, and were significantly different from the water column microbial communities from which they came. Our results agree with previous findings that sedimentary microbial communities are seeded by the rare biosphere in particle-associated water column microbial communities and that particles are a delivery mechanism for sedimentary microbes, but also show that community development is not affected by ecological disturbances such as algal blooms, which alter the delivery of carbon and nutrients to the sediment. Metagenomic analyses additionally show little difference in metabolic potential between the treatments, though a difference in the taxonomic association of some genes, such as key nitrogen cycling genes, was observed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B23F2568Y
- Keywords:
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- 0456 Life in extreme environments;
- BIOGEOSCIENCESDE: 0460 Marine systems;
- BIOGEOSCIENCESDE: 4805 Biogeochemical cycles;
- processes;
- and modeling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 4840 Microbiology and microbial ecology;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL