[B-PT02_1PM1] Biocalcification and the Geochemistry of Proxies

[BPT02-18] Potentials and challenges on the use of environmental DNA to reconstruct deep-sea ecosphere and environmental changes.

*Frederic SINNIGER¹, Hiroyuki YAMAMOTO¹, Saki HARII², Hideto TAKAMI¹, Kenshiro OSHIMA³, Simon CREER⁴, Gary CARVALHO⁴, Jan PAWLOWSKI⁵ (1.Japan Agency for Marine Science and Technology, 2.University of the Ryukyus, 3.University of Tokyo, 4.Bangor University, 5.University of Geneva)

Keywords:Deep Sea, Environmental DNA, Biodiversity, Sediment, Hydrothermal vent

Deep sea is one of the most difficult to access environment, and consequently one of the most poorly known. However, deep-sea sediments and the organisms inhabiting this environment play a crucial role in the oceans geochemical cycles. Benthic communities are often well adapted to their local environment and therefore can reflect accurately the present conditions but also can provide insights into the past history of environmental changes. Unfortunately, except for a few specific taxa, most knowledge on deep-sea biodiversity is still missing. Deep-sea fauna is very patchy and rarity of most taxa adds to the sampling difficulty using traditional methods. Environmental DNA (eDNA) presents the advantage not to rely only on living organisms present in the sample. The presence of a species in an environment can also be detected using trace DNA left by the organism in the sediments (fragment of dead organisms, fecal pellets, etc). Recent development of DNA sequencing technologies led to promising results in the large-scale exploration of biodiversity from deep-sea environments based on eDNA using environmental DNA. Here we will examine the use of environmental DNA as a proxy to reconstruct deep-sea communities and estimate environmental conditions in the deep-sea ecosphere. We will present data obtained from deep-sea (500-9000 m) around Japan as well as from worldwide deep-sea oceans to explore the potential use of eDNA as a proxy at various geographical and historical scales and levels of resolution. The data obtained from Iheya North vent field in the Okinawa Trough allowed us to compare the signal of eDNA along extreme environmental gradients at a very restricted geographical scale, while worldwide deep-sea eDNA survey provided us with information of on the global deep-sea environment history and colonisation. Potential of eDNA obtained from sediments to obtain information on water column processes such as plankton blooms will also be discussed.