Microbial assemblages on a cold-water coral mound at the SE Rockall Bank (NE Atlantic): interactions with hydrography and topography

Abstract

This study characterizes the microbial community composition over Haas Mound, one of the most prominent cold-water coral mounds of the Logachev Mound province (Rockall Bank, NE Atlantic). We outline patterns of distribution vertically -from the seafloor to the water column -and laterally -across the mound -and couple these to mound topography and hydrography. Samples of water, sediment and Lophelia pertusa were collected in 2012 and 2013 from locations that were chosen based on high definition video surveys. Temperature and current measurements were obtained at two sites at the summit and foot of Haas Mound to study near-bed hydrodynamic conditions. Overlaying water was collected from depths of 400 m as well as 5 and 10 m above the bottom using a CTD/Rosette system. Near-bottom water, sediment and L. pertusa mucus and skeleton samples were obtained with a box corer. Of all these biotopes, Roche GS-FLX amplicon sequencing targeting both Bacteria and Archaea was carried out, augmenting our understanding of deep sea microbial consortia. The pattern of similarities between samples, visualized by multi-dimensional scaling (MDS), indicates a strong link between the distribution of microbes and the specific biotopes. The microbial operational taxonomic unit (OTU) diversity was the highest in near-bottom water, which was sampled in the coral framework. For the first time, Thaumarchaeota marine group I (MGI) were found in L. pertusa mucus; Endozoicomonas was detected in skeleton, mucus and near-bottom water, whereas Mycoplasma was only detected in skeleton and near-bottom water, however not in mucus. Analysis of similarities (ANOSIM) indicates that overlaying water is well-mixed at 400 m depth but less so at 5 and 10 m above the bottom, where the composition of microbial communities differed significantly between summit, slope and off-mound. At all locations, the near-bottom water differed significantly from water at 5 m above the bottom, illustrating that the near-bottom water in between the coral framework represents a separate microbial habitat. Furthermore, the observed spatial heterogeneity in microbial communities is discussed in relation to environmental conditions. Published by CopernicusPublications on behalf of the European Geosciences Union. J. D. L. van Bleijswijk et al.: Microbial assemblages on a cold-water coral mound 1000 m 12 9 11 8 24 15 25 46 72 lander

Distinguishing between Microbial Habitats Unravels Ecological Complexity in Coral Microbiomes

“…Sequences belonging to the Holophagae class have only otherwise been recovered from the skeleton and mucus of cold water corals (34). Acidobacteria are common associates of soil environments, but investigations into specific Acidobacteria within the family Holophagae have revealed this class to be ecologically diverse, including both marine isolates (35) as well as plant symbionts (36).…”

“…“ Ca. Actinomarina” bacteria are generally very small cells (volume of ~0.013 µm 3 ), and the genetic material has very low GC content (33%) (34). In addition, “ Ca.…”

Cable Bacteria and the Bioelectrochemical Snorkel: The Natural and Engineered Facets Playing a Role in Hydrocarbons Degradation in Marine Sediments

“…Some recent studies reported the occurrence of members of this genus in marine environments like cold-water coral reefs as hotspots of carbon mineralization (Van Oevelen et al, 2009; Rovelli et al, 2015; Van Bleijswijk et al, 2015). …”

On the influence of cold‐water coral mound size on flow hydrodynamics, and vice versa

“…The focus is on the northwest European shelf, known for hosting several CWC mound clusters (or provinces) along the continental slopes [Roberts et al, 2008;White and Dorschel, 2010]. Geological evidence exists of successive mound growth in the area over the past 2.6 Ma [Thierens et al, 2010]. From a physical point of view, this region is also known for its "extraordinary" tidal currents [Moray, 1665;Cartwright, 1969] resulting from the diurnal tidal waves being trapped and driven to resonance by the topographical features [Longuet-Higgins, 1968;Huthnance, 1974;Pingree and Griffiths, 1984].…”