Temporal and Spatial Variations of Bacterial and Faunal Communities Associated with Deep-Sea Wood Falls

PLoS One. 2017 Jan 25;12(1):e0169906. doi: 10.1371/journal.pone.0169906. eCollection 2017.

Abstract

Sinking of large organic food falls i.e. kelp, wood and whale carcasses to the oligotrophic deep-sea floor promotes the establishment of locally highly productive and diverse ecosystems, often with specifically adapted benthic communities. However, the fragmented spatial distribution and small area poses challenges for the dispersal of their microbial and faunal communities. Our study focused on the temporal dynamics and spatial distributions of sunken wood bacterial communities, which were deployed in the vicinity of different cold seeps in the Eastern Mediterranean and the Norwegian deep-seas. By combining fingerprinting of bacterial communities by ARISA and 454 sequencing with in situ and ex situ biogeochemical measurements, we show that sunken wood logs have a locally confined long-term impact (> 3y) on the sediment geochemistry and community structure. We confirm previous hypotheses of different successional stages in wood degradation including a sulphophilic one, attracting chemosynthetic fauna from nearby seep systems. Wood experiments deployed at similar water depths (1100-1700 m), but in hydrographically different oceanic regions harbored different wood-boring bivalves, opportunistic faunal communities, and chemosynthetic species. Similarly, bacterial communities on sunken wood logs were more similar within one geographic region than between different seas. Diverse sulphate-reducing bacteria of the Deltaproteobacteria, the sulphide-oxidizing bacteria Sulfurovum as well as members of the Acidimicrobiia and Bacteroidia dominated the wood falls in the Eastern Mediterranean, while Alphaproteobacteria and Flavobacteriia colonized the Norwegian Sea wood logs. Fauna and bacterial wood-associated communities changed between 1 to 3 years of immersion, with sulphate-reducers and sulphide-oxidizers increasing in proportion, and putative cellulose degraders decreasing with time. Only 6% of all bacterial genera, comprising the core community, were found at any time on the Eastern Mediterranean sunken wooden logs. This study suggests that biogeography and succession play an important role for the composition of bacteria and fauna of wood-associated communities, and that wood can act as stepping-stones for seep biota.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Atlantic Ocean
  • Bacteria / classification
  • Bacteria / genetics
  • Bacteria / isolation & purification*
  • Biota*
  • Bivalvia*
  • DNA, Bacterial / analysis
  • Diffusion
  • Ecosystem
  • Mediterranean Sea
  • Methane / metabolism
  • Mollusca
  • Oxygen / analysis
  • Sea Urchins*
  • Seawater / microbiology*
  • Sequence Analysis, DNA
  • Sulfates / metabolism
  • Time Factors
  • Water Microbiology*
  • Wood / microbiology*

Substances

  • DNA, Bacterial
  • Sulfates
  • Methane
  • Oxygen

Grants and funding

This study was funded by the MPG-CNRS GDRE „Diversity, establishment and function of organisms associated with marine wood falls – DIWOOD”, the EU FP7 HERMIONE (Hotspot Ecosystem Research and Man’s Impact on European Seas, grant agreement no. 226354) project, the Research Center/Cluster of Excellence ‘The Ocean in the Earth System’ (MARUM, University Bremen), and the DFG (METEOR/MERIAN expeditions). This study contributes to the project ABYSS funded by the European Research Council Advanced Investigator Grant 294757 to AB. Additional resources were provided by the Leibniz programme of the DFG to AB, by the Helmholtz Association and the Max Planck Society. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.