Photographic Identification Guide to Larvae at Hydrothermal Vents by Susan W

Woods Hole Oceanographic Institution Technical Report :: June 2009 :: WHOI-2009-05 Photographic identification guide to larvae at hydrothermal vents by Susan W. Mills, Stace E. Beaulieu and Lauren S. Mullineaux Woods Hole Oceanographic Institution Funding provided by NSF grants OCE-9619605, OCE-9712233, OCE-0424593 and ATM-0428122 and ChEss Grant #WHOI 1334800. Approved for public release; distribution unlimited. Table of Contents Foreward �� 2 Unknown neomphalid W� �� 55 Acknowledgements �� 2 Melanodrymia aurantiaca �� 57 Introduction� � � � � � � � � � � � � � � � � � � � � � � � � � � � �3 Unknown ?neomphalid 290µm �� 59 Methods� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �3 Rhynchopelta concentrica � � � � � � � � � � � � � � � � �61 Using This Guide� � � � � � � � � � � � � � � � � � � � � � � � �5 Ctenopelta porifera �� 63 Terminology� � � � � � � � � � � � � � � � � � � � � � � � � � � � �6 Bathymargarites symplector �� 65 Gastropoda �� 9 Laeviphitus sp.. � � � � � � � � � � � � � � � � � � � � � � � �67 Gorgoleptis spiralis� � � � � � � � � � � � � � � � � � � � � � �9 Phymorhynchus sp� � � � � � � � � � � � � � � � � � � � � �69 “Pointy apex” � � � � � � � � � � � � � � � � � � � � � � � � �11 Bivalvia �� 71 Unknown benthic sp� A� �� 13 Bathymodiolus thermophilus � � � � � � � � � � � � � �71 Unknown neomphalid 5 �� 15 Bathypecten vulcani� � � � � � � � � � � � � � � � � � � � �73 Lepetodrilus spp..� � � � � � � � � � � � � � � � � � � � � � �17 Polychaeta �� 75 Clypeosectus delectus �� 19 Amphisamytha galapagensis �� 75 Gorgoleptis emarginatus� � � � � � � � � � � � � � � � � �21 Archinome rosacea � � � � � � � � � � � � � � � � � � � � � �77 Gorgoleptis sp� 3�� 23 “Chaetosphaerids” � �� 79 Unknown 7.. �� 25 Glycera sp.. � � � � � � � � � � � � � � � � � � � � � � � � � � �81 Lepetodrilus-like protoconchs �� 27 Nectochaetes� � � � � � � � � � � � � � � � � � � � � � � � � �83 Unknown 8.. �� 29 Nereis sp.. � � � � � � � � � � � � � � � � � � � � � � � � � � � �85 Unknown 9� �� 31 Ophryotrocha sp�� 87 Echinopelta fistulosa� � � � � � � � � � � � � � � � � � � � �33 Polynoids�� 89 Peltospira spp.�� 35 Unknown polychaete A� �� 91 Lirapex granularis � � � � � � � � � � � � � � � � � � � � � �37 Unknown polychaete B� � � � � � � � � � � � � � � � � �93 Unknown peltospirid 240µm � � � � � � � � � � � � �39 Crustacea � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �95 Unknown neomphalid B�� 41 Barnacle cyprids� �� 95 Cyathermia naticoides �� 43 Bythograea microps� �� 97 Neomphalus fretterae� � � � � � � � � � � � � � � � � � � �45 Bythograea thermydron �� 99 Melanodrymia ?galeronae �� 47 Foraminifera �� 101 Neolepetopsis spp�� 49 ?Tretomphalus sp.. � � � � � � � � � � � � � � � � � � � � � 101 Pachydermia laevis �� 51 Literature Cited � � � � � � � � � � � � � � � � � � � � � � � �102 Eulepetopsis vitrea � � � � � � � � � � � � � � � � � � � � � �53 Taxonomic Index � � � � � � � � � � � � � � � � � � � � � � �104 1 Foreward The purpose of this guide is to assist researchers in the pictures were taken by Stace Beaulieu and SEM’s by identification of larvae of benthic invertebrates at hy- Susan Mills and Diane Adams� drothermal vents� Our work is based on plankton sam- pling at the East Pacific Rise 9-10°N vent field from Although our own samples are limited to the EPR 1991-2007, supplemented by benthic collections of 9-10°N site, we would like to expand this guide by in- juveniles� In addition to images and descriptions of cluding additional species from other areas� This guide the species, we included frequency data from large- is also available online at: volume plankton pump samples taken between 1998 http://www.whoi.edu/vent-larval-id/ and 2004 and time-series sediment trap samples from 2004-2005� The online version includes links to ChEssBase and the Ocean Biogeographic Information System (OBIS)� This guide is divided into five sections: Gastropoda, Please contact Susan Mills (smills@whoi�edu) or Stace Bivalvia, Polychaeta, Arthropoda and other miscella- Beaulieu (stace@whoi�edu) if you have photos you neous taxa� All except the gastropods are in alphabeti- would like to have included on the website� cal order within a section� Since size is an important characteristic in species determinations in gastropod This guide is intended to serve as a companion to the protoconchs, we have put them in order of ascending Handbook of Deep-Sea Hydrothermal Vent Fauna size� An alphabetical index is included at the end of the (Desbruyeres, et al�, 2006), which provides photo- guide� Except where otherwise stated, light microscope graphs and descriptions of the adult forms� Acknowledgements We are indebted to the taxonomists who described This work was funded by NSF grants OCE-9619605 these species, whose papers appear in the Literature to L� Mullineaux, D� Manahan and C� Young, OCE- Cited section� In the case of the gastropods, they of- 9712233 to L� Mullineaux, C� Fisher and C� Peter- ten included SEM’s of the larval shells, which greatly son, OCE-0424593 to L� Mullineaux, A� Thurnherr, assisted us in assembling this guide� In particular, we J� Ledwell, D� McGillicuddy and W� Lavelle, ATM- would like to thank Anders Warén for assistance with 0428122 to H� Singh, T� Shank, L� Mullineaux, M� identifications of larval and juvenile gastropods and for Neubert and others, by a WHOI Deep Ocean Explora- advice on mounting specimens for SEM� In addition, tion Institute grant to L� Mullineaux and S� Beaulieu we thank Stacy Kim, Pat McMillan, Anne Beaudreau, and by a grant from the ChEss project of the Census of Andrew Sweetman, and Diane Adams for help in learn- Marine Life to L� Mullineaux, S� Beaulieu and S� Mills� ing how to distinguish larval gastropods� 2 Introduction For animals living on the seafloor, a planktonic larval plankton compared to typical deep-sea habitats� In ad- stage is a critical phase of the life cycle� Larval disper- dition, a large portion of hydrothermal vent commu- sal provides ecological and genetic connections among nities can be comprised of gastropods, which can, in communities in patchy habitats such as hydrothermal many cases, be identified by protoconch morphology� vents� Temporal variation in larval supply to benthic For example, gastropod larvae collected near hydro- communities can lead to fluctuations in the size and thermal vents in the eastern Pacific have been identified genetic composition of adult populations� On long morphologically under light and electron microscopy time scales, barriers to dispersal can lead to speciation (Mullineaux et al�, 1996)� and are thought to be fundamental factors in generat- ing biogeographic patterns and regional biodiversity� Since the discovery of hydrothermal vents thirty years Despite the importance of the larval phase, very little ago, researchers have been collecting larvae in studies is known about larval dispersal in the deep sea, even to explain the colonization of these oases in the deep at hydrothermal vents where the habitat is patchy and (e�g� Lutz et al� 1984, Turner et al� 1985, Kim and Mul- transient, and larval exchange critical to the survival of lineaux 1998)� Recent emphasis has been placed on endemic species� time-series collections of larvae in multi-disciplinary studies of larval dispersal and supply to vent communi- General difficulties of larval identification for deep- ties, such as the LADDER project at the East Pacific sea studies include the scarcity of larvae in plankton Rise (http://www�whoi�edu/projects/LADDER/)� The samples, the fact that the adults may be unknown, and purpose of this photographic identification guide is the difficulty of matching larval morphotypes to adult to serve researchers studying hydrothermal vent larvae forms� However, some hydrothermal vent habitats have in previously collected and future samples� The pho- well-characterized benthic communities with relatively tographs may also be useful to those studying newly low species diversity and relatively high biomass and settled colonists� fecundity, resulting in large numbers of larvae in the Methods Collection and preservation of larvae 1-day periods (McLane Large Volume Water Transfer For this first edition of the identification guide, lar- System WTS-LV50;

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