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Dr. Chong CHEN

Dr. Chong CHEN

Deep-sea biologist. Malacologist. Evolutionary biologist. "Mollusc collector", photographer.

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Gallery of Publications

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/<br /> <br /> 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. <br /> <br /> 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 co-authored paper (with Yanjie Zhang, Jin Sun, Hiromi Watanabe-Kayama and others) on the adaptation and evolution of deep-sea vent/seep scale worms (polynoid polychaetes) published in Scientific Reports! The article is open access and free to read here: http://www.nature.com/articles/srep46205<br /> <br /> Scale worms inhabit a great variety of environments ranging from very shallow water down to kilometres deep and are often an important member of chemosynthetic ecosystems such as vents, often living in close proximity to hot black smokers. In this study, we sequenced the transcriptomes of two deep-sea scale worms inhabiting hydrothermal vents and hydrocarbon seeps and one shallow water counterpart that was rather closely related. By comparing the three transcriptomes, we were able to elucidate selective amino acid usage, positively selected genes, highly expressed genes, and potentially duplicated genes, thereby shedding light on how the scale worms evolved to become successful members of deep-sea chemosynthetic communities. These are the first deep-sea scale worm transcriptomes ever reported. <br /> <br /> Most significant among our findings was the significance of genes related to haemoglobin. The two deep-sea polynoids chosen for this study, in the genera Branchipolynoe and Lepidonotopodium, are shown to have adopted different yet equally effective ways to cope with the oxygen-poor chemosynthetic ecosystems. Branchipolynoe rapidly evolved a novel tetra-domain haemoglobin which is highly effective in oxygen transport, whereas Lepidonotopodium increased the expression levels of standard single-domain haemoglobin to four times as high as Branchipolynoe. These results indicate that dealing with hypoxic environment is a key element in becoming successful in deep-sea vents and seeps. <br /> <br /> PS. I know this is not a mollusc paper, but I am interested in all cool animals especially when they have evolved key adaptations to live in weird environments! And the importance of haemoglobin is not limited to scale worms, but also applies to molluscs. <br /> <br /> Zhang Y [Yanjie], Sun J, Chen C, Watanabe HK, Feng D, Zhang Y [Yu], Chiu JMY, Qian P-Y, Qiu J-W (2017). Adaptation and evolution of polynoid scale-worms (Annelida: Polynoidae): insights from transcriptome comparison among two deep-sea and a shallow-water species. Scientific Reports, 7: 46205. http://doi.org/10.1038/srep46205
New paper dealing with a 'cryptic species complex' of chitons published in Marine Biodiversity! Open access, please read here: http://bit.ly/2okQQ56<br /> <br /> In this work, we present a case study of a total-evidence approach to resolving difficult and perplexing 'cryptic species complexes'. A Pacific shallow water polyplacophoran mollusc (chiton) Leptochiton rugatus (Carpenter in Pilsbry, 1892) is supposed to have a very wide range from Japan to Baja California, but has been previously suggested to comprise several cryptic species. Our genetic haplotype network using specimens across the range revealed four discrete clusters. Most strikingly, the haplotype of L. rugatus sensu stricto (California to Baja California) was very different in structure from that of the cluster ranging from the panhandle of Alaska to Oregon. The latter was found to have extremely high side fidelity and patchy distribution, and we present evidence that it is likely a brooder. The difference in life-history strategies between these two clusters account for the differences in their genetic structure. Although morphological differences were observed, these were minor and insufficient to guarantee each as species-level lineages alone. Only with the difference in life-history strategy could they be confidently recognised as separate species, the latter we described as L. cascadiensis sp. nov. after the Cascadia costal bioregion which it inhabits. <br /> <br /> Things without names are difficult to rationalise, and are difficult to conserve; assigning names to species is therefore critical to understanding and conserving biodiversity.This study shows that combining evidence from molecules, morphology, and importantly life-history, is key to untangling 'cryptic species complexes' which have become increasingly discovered in the recent years. The take-home message: if you want to solve cryptic species problems, don't forget to look at their way of life!<br /> <br /> This is my first time getting involved with describing a chiton, yay! Chitons are awesome. <br /> <br /> Sigwart JD, Chen C (2017). Brooding behaviour explains patchy distribution in a shallow-water invertebrate (Mollusca: Polyplacophora: Lepidopleurida). Marine Biodiversity, First Online, DOI: 10.1007/s12526-017-0688-1
New co-authored paper published today in The Nautilus! Read: http://bit.ly/2o07dEe <br /> <br /> We discuss the potential impacts of deep-sea mining to molluscan biodiversity, especially with regards to exploiting active hydrothermal sulfide deposits. Take the famous scaly-foot gastropod Chrysomallon squamiferum as an example – it is only known from three hydrothermal vents in the Indian Ocean, each around 0.003 sq km or half the size of a football field. Two of the three scaly-foot sites are already under active mining exploration licenses from the International Seabed Authority (ISA), to China (2011-2026) and Germany (2015-2030); the last one is in the Mauritius exclusive economic zone and therefore not under ISA jurisdiction. In fact, only 37 vent sites have been detected (4 actually visited) in the Indian Ocean (area approx.. 73,550,000 sq km) and their total area adds up to a mere 0.27 sq km (check out the infographics)! Many of these are also within the areas licenced for mining. These explorations are due to begin very soon and no conservation measures are in place or proposed, whereas many terrestrial mollusks such as the two-lipped door snail Alinda biplicata have extensive reserves dedicated to their conservation. Economic and political pressures to exploit deep-sea vents are advancing far quicker than our scientific understanding of these ecosystems that unique animals such as the scaly-foot call home, putting them at risk. Conservation measures for vent animals are urgently needed, and seem warranted given their tiny, disjunct areas of distribution. <br /> <br /> Please let me know if you would like a PDF copy, as usual. <br /> <br /> The original idea of this work was presented at the “Mollusks in Peril” 2016 Forum at the Bailey-Matthews National Shell Museum. <br /> <br /> Sigwart JS, Chen C, Marsh L (2017). Is mining the seabed bad for mollusks? The Nautilus 131(1): 43-50.
New first-authored paper published in BMC Evolutionary Biology ( http://bit.ly/3DGIGANTO ) reveals that two neomphaline hydrothermal vent gastropods, Gigantopelta and the 'scaly-foot' Chrysomallon, convergently evolved the peculiar adaptation of housing endosymbiotic bacteria in their much enlarged oesophageal gland. We first confirmed the existence of endosymbionts in Gigantopelta using Transmision Electron Microscopy (TEM), and then carried out serial sectioning and 3D reconstruction for a juvenile specimen of Gigantopelta chessoia along with dissections of the adult. These revealed many key anatomical differences with the 'scaly-foot gastropod' pointing towards two independent origins of a similar way of life, confirmed by a 5-gene phylogenetic reconstruction clearly showing that the two are not sister within the known members of Peltospiridae. By comparing Gigantopelta and Chrysomallon, we show that metazoans are capable of rapidly and repeatedly evolving equivalent anatomical adaptations and close-knit relationships with chemoautotrophic bacteria, achieving the same end-product through parallel evolutionary trajectories.<br /> <br /> The paper is open access and available freely: http://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-017-0917-z<br /> <br /> We also included an interactive 3D anatomical model of Gigantopelta, you only need a PDF reader to play around with it! Have fun! It is available here: https://static-content.springer.com/esm/art%3A10.1186%2Fs12862-017-0917-z/MediaObjects/12862_2017_917_MOESM1_ESM.pdf
A new first-authored paper (http://bit.ly/2g4qYmQ) has been published in Journal of the Marine Biological Association of the United Kingdom! This paper describes Provanna cingulata n. sp., from Shinkai Seep Field, a serpentinisation-hosted ecosystem 5700 m deep in the Mariana Trench. It is the deepest and largest member of genus Provanna, which is endemic to chemosynthetic ecosystems. Unlike most Provanna species which either have prominent lattice sculpture or completely smooth, this species is characterised by prominent spiral sculpture but lacking in axial sculpture. Please let me know if you would like to have a PDF copy :)
New co-authored paper published in the journal Geochemistry, Geophysics, Geosystems! Link: http://bit.ly/2dhKMSF <br /> <br /> This study reports three types of brucite-carbonate chimneys from the deepest known serpentinite-hosted vent in the world, the 5700 m deep Shinkai Seep Field in Mariana forearc. Although mainly a geochemistry/geology paper, the chimneys are inhabited by some megafaunal animals and brief descriptions of the colonies are included. Molluscs are also present, such as Provanna snails. The paper is open-access so anyone can read it for free! 🙂<br /> <br /> Okumura T, Ohara Y, Stern RJ, Yamanaka T, Onishi Y, Watanabe H, Chen C, Bloomer SH, Pujana I, Sakai S, Ishii T, Takai K (2016). Brucite chimney formation and carbonate alteration at the Shinkai 1 Seep Field, a serpentinite-hosted vent system in the Southern Mariana Forearc. Geochemistry, Geophysics, Geosystems, 75. DOI: 10.1002/2016GC006449
A new paper lead-authored by myself has been published today in Molluscan Research today ( http://bit.ly/Chen2016a )! The paper describeds a new species of Desbruyeresia (Gastropoda: Provannidae), Desbruyeresia chamorrensis Chen, Ogura & Okutani in Chen et al., 2016. The family Provannidae is only known from chemosynthetic ecosystems, and genus Desbruyeresia was so far restricted to hydrothermal vents. The present new species, however, was discovered from an alkaline serpentinite-hosted seep more than 2900m deep on the South Chamorro Seamount (13°47’N, 146°00’E), southeastern Mariana Forearc. It is a deposit feeder and only three specimens have been collected so far. It is distinguished from all other described congeners by having much more numerous (17–20) axial ribs on the teleoconch and a broad shell for the genus (shell width to height ratio 0.6–0.65). It was a great pleasure working with the eminent Japanese malacologist Prof. Takashi Okutani during the course of this project. Please let me know if you would like a copy in PDF :)<br /> <br /> Chen C, Ogura T, Hirayama H, Watanabe HK, Miyazki J, Okutani T (2016). First seep-dwelling Desbruyeresia (Gastropoda: Abyssochrysoidea) species discovered from a serpentinite-hosted seep in the southeastern Mariana Forearc. Molluscan Research. DOI:10.1080/13235818.2016.1172547
New lead-authored paper published in the Zoological Journal of the Linnean Society! This is the description of a brand new genus of large deep-sea hydrothermal vent snail, Gigantopelta. Two new species are described, G. chessoia from the Antarctic vents in the East Scotia Ridge and G. aegis from the Southwest Indian Ridge. Both are from bathyal depths exceeding -2500m, and are powered by chemosynthetic endosymbiont bacteria housed in the esophageal gland. They belong to the "hot-vent" family Peltospiridae in the clade Neomphalina, and being even larger (slightly, up to 45.7mm) than the 'scaly-foot gastropod', these are the largest neomphalines known to date. Hence "giganto", meaning "giant", derived from "Gigantes", the giants in Greek mythology. G. chessoia is a dominant species in East Scotia Ridge vents, the only truly Antarctic vents well-explored to date. G. aegis is especially interesting because both the shell and operculum are overlaid by a thick layer of iron oxide (i.e., rust), and thus it is another iron-armoured vent gastropod like the 'scaly-foot'. The operculum, especially, is so thickened that it is almost like a calcified one of a turbinid; hence the name "aegis", which refers to the mythical shield of Zeus and Athena. <br /> <br /> Please do let me know if you would like a copy of the full-text in PDF 🙂<br /> <br /> Chen C, Linse K, Roterman CN, Copley JT, Rogers AD (2015). A new genus of large hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae). Zoological Journal of the Linnean Society, 175 (2), 319-335.<br /> http://onlinelibrary.wiley.com/doi/10.1111/zoj.12279/abstract
A new lead-authored paper published today reveals the genetic connectivity among all three known populations of the 'scaly-foot gastropod' (Chrysomallon squamiferum). Especially noteworthy is the low connectivity indicated between the Southwest Indian Ridge and Central Indian Ridge, which has implications for upcoming seafloor mining already planned for the Southwest Indian Ridge. This study is the first to investigate connectivity between hydrothermal vents across two mid-ocean ridges in the Indian Ocean. Please let me know if you would like to have a copy :)<br /> <br /> Chen C, Copley JT, Linse K, Rogers AD (2015). Low connectivity between ‘scaly-foot gastropod’ (Mollusca: Peltospiridae) populations at hydrothermal vents on the Southwest Indian Ridge and the Central Indian Ridge. Organisms Diversity & Evolution, doi:10.1007/s13127-015-0224-8.
Internal organ systems of the 'scaly-foot gastropod' (Chrysomallon squamiferum) uncovered! A new lead-authored paper by myself is now published in the journal Frontiers in Zoology, where we used 3D tomographic reconstruction and traditional dissection to reveal its detailed anatomy. Among other extraordinary features, it has a gigantic 'dragon heart' occupying a whooping 4% of the body volume (mind you, the average heart volume in a human being is only 1.5%)!!!! The paper is open access and freely available online at: http://www.frontiersinzoology.com/content/12/1/13<br /> <br /> Chen C, Copley JT, Linse K, Rogers AD, Sigwart JD (2015). The heart of a dragon: 3D anatomical reconstruction of the ‘scaly-foot gastropod’ (Mollusca: Gastropoda: Neomphalina) reveals its extraordinary circulatory system. Frontiers in Zoology 12:13; doi:10.1186/s12983-015-0105-1.
A co-authored paper has just been published on the online journal PLOS ONE (http://bit.ly/1DCnBXW)! What happens to local ecosystem if you make an artificial hydrothermal vent by deep-sea drilling? We investigated this in Okinawa Trough, Japan by monitoring the benthic area across a 40-months period after a drilling event. Through quantifying the visible changes in benthos fauna we found many interesting facts such as Shinkaia crosnieri squat lobsters are able to literally migrate on foot from nearby vents, and also showed how various vent animals colonise the new habitat in this area. This is among the first research to elucidate the initial formation processes of deep-sea hydrothermal vent ecosystems, and provides key information for future ecosystem assessment in the event of deep-sea mining, for example. This research was done in collaboration with JAMSTEC in Japan and was lead-authored by Dr. Ryota Nakajima from there. The paper is open access and therefore freely available from the publisher's website: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0123095<br /> <br /> Nakajima R, Yamamoto H, Kawagucci S, Takaya Y, Nozaki T, Chen C, Fujikura K, Miwa T, Takai K (2015). Post-drilling changes in seabed landscape and megabenthos in a deep-sea hydrothermal system, the Iheya North field, Okinawa Trough. PLoS ONE, 10(4): e0123095, doi: 10.1371/journal.pone.0123095.
The iconic 'scaly-foot gastropod' from hydrothermal vents of Indian Ocean finally gets a name! The description paper I lead-authored is now published online in Journal of Molluscan Studies (Advanced access: http://bit.ly/1D52Svg). The 'scaly-foot gastropod' was given the name Chrysomallon squamiferum gen. et sp. nov., and its relationship to other neomphalines were explored using both morphological and molecular methods. Please let me know if you would like a copy in PDF! :)<br /> <br /> Chen C, Linse K, Copley JT, Rogers AD (2015). The 'scaly-foot gastropod': a new genus and species of hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae) from the Indian Ocean. Journal of Molluscan Studies. Advance Access published April 20, 2015, doi:10.1093/mollus/eyv013.
Co-authored paper published in the journal Deep Sea Research Part I! Not molluscs this time -- it is about life history traits of hydrothermal vent squat lobsters (Munidopsis spp.). Free access to the full-text online through this link: http://authors.elsevier.com/a/1Qgaw3RueHDJ1A. :)<br /> <br /> Nakamura M, Chen C, Mitarai S (2015). Insights into life-history traits of Munidopsis spp. (Anomura: Munidopsidae) from hydrothermal vent fields in the Okinawa Trough, in comparison with the existing data. Deep Sea Research Part I: Oceanographic Research Papers, 100: 48-53.
A paper I co-authored, "The mitochondrial genome of the deep-sea snail Provanna sp. (Gastropoda: Provannidae)", has been published in the journal Mitochondrial DNA (early online: http://dx.doi.org/10.3109/19401736.2014.1003827). :) Please do let me know if you are interested in a PDF copy.
A paper I lead authored, "How the mollusc got its scales: convergent evolution of the molluscan scleritome", is now published in the Biological Journal of the Linnean Society (early online, http://dx.doi.org/10.1111/bij.12462)! Please let me know if you would like to have a PDF copy :)
Paper published in the Venus volume 73 (1-2)! This includes the description of two new species of Chicomurex: C. globus Houart Moe & Chen, 2015 and C. pseudosuperbus Houart Moe & Chen 2015; and also reinstates the name C. gloriosus (Shikama, 1977) for the Philippines specimens previously referred to as C. venustulus (Rehder & Wilson, 1975), which is a different species restricted to the Marquesas Islands. Many thanks to Roland and Chris!! Please let me know if you would like a PDF copy.
(Note: this is an article from 2014, just uploading for the record)<br /> <br /> Co-authored publication published in Bulletin of Malacology, Taiwan! A new species of Chicomurex that was confused with C. superbus (Sowerby, 1889) in several publications is described from Taiwan and C. problematicus (Lan, 1981) is considered a junior subjective synonym of C. superbus. The holotypes of both C. superbus and C. problematicus are illustrated and C. superbus is redescribed.
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