title: The Link between Microbial Diversity and Nitrogen Cycling in Marine Sediments Is Modulated by Macrofaunal Bioturbation.
abstract: OBJECTIVE
  The marine benthic nitrogen cycle is affected by both the presence and activity of macrofauna and the diversity of N-cycling microbes. However, integrated research simultaneously investigating macrofauna, microbes and N-cycling is lacking. We investigated spatio-temporal patterns in microbial community composition and diversity, macrofaunal abundance and their sediment reworking activity, and N-cycling in seven subtidal stations in the Southern North Sea.
  Our results indicated that bacteria (total and β-AOB) showed more spatio-temporal variation than archaea (total and AOA) as sedimentation of organic matter and the subsequent changes in the environment had a stronger impact on their community composition and diversity indices in our study area. However, spatio-temporal patterns of total bacterial and β-AOB communities were different and related to the availability of ammonium for the autotrophic β-AOB. Highest bacterial richness and diversity were observed in June at the timing of the phytoplankton bloom deposition, while richness of β-AOB as well as AOA peaked in September. Total archaeal community showed no temporal variation in diversity indices.
  Distance based linear models revealed that, independent from the effect of grain size and the quality and quantity of sediment organic matter, nitrification and N-mineralization were affected by respectively the diversity of metabolically active β-AOB and AOA, and the total bacteria, near the sediment-water interface. Separate models demonstrated a significant and independent effect of macrofaunal activities on community composition and richness of total bacteria, and diversity indices of metabolically active AOA. Diversity of β-AOB was significantly affected by macrofaunal abundance. Our results support the link between microbial biodiversity and ecosystem functioning in marine sediments, and provided broad correlative support for the hypothesis that this relationship is modulated by macrofaunal activity. We hypothesized that the latter effect can be explained by their bioturbating and bio-irrigating activities, increasing the spatial complexity of the biogeochemical environment.
authors.affiliation: Marine Biology Research Group, Biology Department, Ghent University, Ghent, Belgium; CeMoFE, Ghent University, Ghent, Belgium.
authors.forename: Maryam
authors.initials: M
authors.lastname: Yazdani Foshtomi
authors.affiliation: Marine Biology Research Group, Biology Department, Ghent University, Ghent, Belgium.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Braeckman
authors.affiliation: Marine Biology Research Group, Biology Department, Ghent University, Ghent, Belgium.
authors.forename: Sofie
authors.initials: S
authors.lastname: Derycke
authors.affiliation: The Food and Environment Research Agency, Sand Hutton, York, United Kingdom.
authors.forename: Melanie
authors.initials: M
authors.lastname: Sapp
authors.affiliation: Marine Biology Research Group, Biology Department, Ghent University, Ghent, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Van Gansbeke
authors.affiliation: Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Sabbe
authors.affiliation: CeMoFE, Ghent University, Ghent, Belgium; Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.
authors.forename: Anne
authors.initials: A
authors.lastname: Willems
authors.affiliation: Marine Biology Research Group, Biology Department, Ghent University, Ghent, Belgium.
authors.forename: Magda
authors.initials: M
authors.lastname: Vincx
authors.affiliation: Marine Biology Research Group, Biology Department, Ghent University, Ghent, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Vanaverbeke
mesh_terms: D019015:Geologic Sediments / Q000382:microbiology*; D008386:Marine Biology; D064307:Microbiota; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D009584:Nitrogen