Category: JAMSTEC

New paper presents a new deep-sea fluid sampler

New co-authored paper (with Shinsuke Kawagucci and other colleagues) is now officially published in the Open Access journal Frontiers in Earth Sciences! Available from: http://journal.frontiersin.org/article/10.3389/feart.2017.00045/full/

Long story short, we developed a new water sampler for collecting hydrothermal fluid and other geofluids in the deep-sea. This new sampler, the “WHATS-III”, is capable of pressure-tight, flow-through sampling of four independent geofluids per submersible dive. We also present real data collected during field tests carried out in hydrothermal vents of the Indian Ocean and Okinawa Trough.

Overview of the WHATS-3 Sampler

  • Miyazaki J, Makabe A, Matsui Y, Ebina N, Tsutsumi S, Ishibashi J, Chen C, Kaneko S, Takai K, Kawagucci S (2017). WHATS-3: An improved flow-through gas-tight fluid sampler for deep-sea geofluid research. Frontiers in Earth Science, 5: 45. https://doi.org/10.3389/feart.2017.00045

New paper shows a vent squat lobster actively cultivates its epibionts!

A co-authored paper about the mechanism of symbiosis in a deep-sea vent crustacean is now published in the journal “Deep Sea Research Part I”: https://authors.elsevier.com/c/1Vm3k3RueHIHRB . Shinkaia crosnieri Baba & Williams, 1998 is a vent-endemic squat lobster with dense setae / hair on its ventral surface. Much like its distant (convergently evolved) cousin, the “yeti-crab” Kiwa, these setae are full of epibiotic bacteria. Recently, S. crosnieri became the first vent animal where the nutritional reliance on epibiotic bacteria was experimentally demonstrated. In this study, we take a step further and show that S. crosnieri actively utilises and produces water current that significantly increases the productivity (chemosynthetic activity) of its epibionts. This means the squat lobster is actively cultivating / farming its own food — the first example of such behavioural adaptation demonstrated among epibiont-hosting animals inhabiting chemosynthetic ecosystems.

Dense ventral setae of S. crosnieri (left) and epibionts on the setae (right)

Through a series of experiments measuring the rate of chemosynthesis (sulfide consumption rate), it was revealed that the rate in epibionts significantly increased when water current was produced. Then, living S. crosnieri individuals were shown to produce an endogenous water flow to the ventral setae through elegant current visualisation using fluorescent particles. Finally, behavioral experiment indicated that S. crosnieri likely exhibit rheotaxis in its natural habitat, meaning it uses existing water current in addition to self-generated ones to increase the productivity of its epibionts = food.

Endogenous water flow generated by S. crosnieri, left: artist’s impression (by Emi Hada) and right: visualisation of the actual current speed generated

Watsuji T, Tsubaki R, Chen C, Nagai Y, Nakagawa S, Yamamoto M, Nishiura D, Toyofuku T, Takai K (2017). Cultivation mutualism between a deep-sea vent galatheid crab and chemosynthetic epibionts. Deep-Sea Research Part I: Oceanographic Research Papers, 127: 13-20. DOI: 10.1016/j.dsr.2017.04.012

58th MEXT “Science and Technology Week” pamphlet

A photo I took aboard the JAMSTEC submersible “SHINKAI 6500“ is chosen as the cover of the 58th MEXT “Science and Technology Week” pamphlet. This photograph will be exhibited at the “Beauty” Panel Exhibition during the week (April 17-23, 2017). The “SHINKAI 6500″ is one of only six currently operational science manned deep-submergence vehicles capable of diving to extreme depths over 2000 m deep. For more information: http://stw.mext.go.jp/index.html

The eccentric world of molluscs

An image I produced was selected to be the JAMSTEC Image of the Week. http://www.jamstec.go.jp/e/hot_pictures/?494

The molluscs are invertebrates belonging to the phylum Mollusca, a highly diverse group of animals. With approximately 100,000 species, Mollusca is second largest animal phylum only after arthropods (including insects), and the most species rich in the marine realm. From their initial appearance in the Cambrian, molluscs have adapted to various aquatic and terrestrial environments through their evolutionary history, resulting in their amazingly disparate morphology within a single phylum. How did peculiar molluscs such as the iron-coated ‘scaly-foot gastropod’ Chrysomallon squamiferum (centre) from deep-sea hydrothermal vents and the eight-plated chiton Craspedochiton producta (bottom right) inhabiting shallow rocky shores evolve to adapt to their environment, and how did they achieve their strange morphological forms? Our research at JAMSTEC combines morphological (e.g., histology, dissection, microscopy) and genetic (e.g., phylogeny, population genetics) methodologies in an attempt to understand the life history and evolutionary biology of these remarkable animals.