Exploration and characterisation of hydrothermal vent communities using ultrasequencing of environmental DNA.

Chemosynthetic environments in the deep sea harbour highly specialised communities. Those communities are often dominated by a few characteristic species. While the dominant macrofaunal species received lots of attention from the scientific community, other groups such as the meiofauna remain largely unknown. Meiofauna has been reported to be rare or less diverse in chemosynthetic environments such as hydrothermal vents compared to bathyal or abyssal plains. This is likely explained by the little availability of sediments samples as well as environmental characteristics of hydrothermal vents ecosystem. In shallow environments, meiobenthic communities have been shown to be sensitive to a variety of environmental parameters. In response to the steep gradients in multiple environmental parameters encountered in hydrothermal vents fields, it is expected that the patterns of meiobenthic communities will be complex and reflecting such environmental changes accurately. However, low abundance of organisms and difficulty to collect samples from these environments are a major issue towards the investigation of meiofaunal diversity and biogeographical patterns.
Metagenetics is the part of metagenomics consisting in sequencing one homologous marker from environmental DNA. This method offers new perspectives to investigate the taxonomic composition of the communities inhabiting ocean seafloor. In comparison to more traditional methods based on sorting of organisms, environmental DNA allows to detect rare species in an environment, even if only fragment of organisms or DNA are present in the sampled sediments. Moreover, metagenetics approach allows the estimation of taxonomic richness and distribution across multiple phyla in parallel.
Our study focused on environmental DNA extracted from sediments samples collected in the Iheya North hydrothermal vent field in the Okinawa Through. In 2012, eight sediment cores were obtained from 3 sites within the vent field. One is located near a site of active hydrothermal venting, while the other two sites are distant from the active vent. The core samples were sliced in five layers of 1cm thickness, and three replicates were sub-sampled from each layer. Environmental DNA was extracted independently from less than 1 g sediments from each replicate. Here we will present the preliminary results obtained from the sequence data of this environmental DNA, and compare them with information obtained from other biogeographic areas as well as from sorted subsamples. We will then discuss on the usefulness of this metagenetic protocol to determine the diversity of meiobenthic community in hydrothermal vents in comparison to other deep-sea environments.

Your format preference:: 
Oral Presentation
Would you be interested in publishing this conference paper in a special issue of Marine Ecology?: 
Yes
First Name: 
Frederic
Last Name: 
Sinniger
Telephone: 
+81 80 1748 9097
Affiliation: 
Submarine Resources Research Project, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
First Name: 
Hiromi
Last Name: 
Watanabe
Affiliation: 
Submarine Resources Research Project, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
First Name: 
HIroyuki
Last Name: 
Yamamoto
Affiliation: 
Submarine Resources Research Project, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
Choose keywords that are most applicable to your abstract. (Three maximum.): 
Biogeography
Distribution and abundance
Human Impacts / Conservation
Abstract ID: 
CBE5-154