Biodiversity of the Southern Ocean

Biodiversity of the Southern Ocean

Series Editor Françoise Gaill Biodiversity of the Southern Ocean Bruno David Thomas Saucède

First published 2015 in Great Britain and the United States by ISTE Press Ltd and Elsevier Ltd Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address: ISTE Press Ltd Elsevier Ltd 27-37 St George s Road The Boulevard, Langford Lane London SW19 4EU Kidlington, Oxford, OX5 1GB UK UK www.iste.co.uk www.elsevier.com Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. For information on all our publications visit our website at http://store.elsevier.com/ ISTE Press Ltd 2015 The rights of Bruno David and Thomas Saucède to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988. British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress ISBN 978-1-78548-047-8 Printed and bound in the UK and US

Preface This book is intended for readers curious to learn more about the vast ocean surrounding the most isolated and inhospitable continent on the planet, the Southern Ocean. This ocean, which is isolated geographically (in a near polar position at the end of the Earth), climatically (icy cold and prone to violent storms) and oceanographically (currents and fronts between water masses form invisible yet effective borders), has very distinct characteristics, as the result of a history that began around 150 million years ago. These characteristics are not without consequences for the evolution and ecology of the biodiversity it supports, a much richer and more bountiful biodiversity than initially expected. Today, this southern biodiversity, untouched by human presence for so long, must in its turn face global climate change. Unable to migrate further south, how will it react and cope? These are the unique aspects that we have chosen to highlight in this book. The writing of this book owes much to our frequent visits to southern regions and to the exciting expeditions we have taken part in. Research missions to the Southern Ocean are, by their very nature, and of necessity, collaborative adventures. This work has drawn unreservedly on the lessons learned and the experience gained over time through contact with our colleagues and all those who participated in these scientific missions. Some will undoubtedly recognize themselves in the following pages. Such missions are only possible because major projects allow significant infrastructure to be made accessible to all researchers. We would like to thank the French Polar Institute (IPEV), the French Southern and Antarctic Lands (TAAF), the Alfred Wegener Institute (AWI), the British Antarctic Survey (BAS), the Chilean Antarctic Institute (INACH) and the Scientific Committee on Antarctic Research (SCAR).

x Biodiversity of the Southern Ocean Finally, we would like to express our deepest gratitude to Clément Blondel, Gilles Boeuf, Carmela Chateau, John Dolan, Guillaume Lecointre, Yvon Le Maho, Rich Mooi, Sébastien Motreuil, Pascal Neige and Catherine Ozouf-Costaz for their support during the writing of this book. Bruno DAVID Thomas SAUCÈDE Dijon August 2015

Introduction Antarctica is a vast white desert. Completely inhospitable, it is devoid of almost all life. Microorganisms alone live in the ice, while discrete plant forms, such as mosses and lichens, cling to the few available rocky surfaces. On the fringes of the continent, there are some impressive, albeit rather scattered, penguin colonies (see Figure I.1). Some other birds and a few marine mammals have also found shelter there. In contrast to this icy solitude, the marine waters bordering the continent host a rich and abundant biodiversity. The Southern Ocean teems with marine life, hidden beneath the surface, colonizing the seabed or living under the ice, while billions of organisms thrive in the water column. The marine ecosystems of the Southern Ocean, so difficult to explore because of its remoteness and extreme climate, are amongst the Earth s most unusual yet least known ecosystems. What is known about the evolutionary history of this southern biodiversity? How did it originate and develop? What are its characteristics? What factors govern its distribution and abundance? Research in this area has progressed significantly over recent years, driven by new investigative methods, improved sensor equipment and stronger modeling approaches, which provide ever more pertinent answers to such questions (Figure I.2). The Southern Ocean (sometimes incorrectly called the Antarctic Ocean) surrounds the entire Antarctic continent and is over 15,000 kilometers in circumference. Greater in length than from Norway to the Cape of Good Hope in the Atlantic, it covers 35 million square kilometers (see Figure A.1 in the Appendix for a map of the region, with the names of the key geographical areas). Isolated in the south of the planet by a large circular current, wracked by almost permanent storms and mostly covered by ice, it shelters an abundance of life with singular characteristics: marked endemism, organisms with slow metabolisms, some with longer lifespans, gigantism, absence of larval developmental stages, etc. These many distinctive features make this ocean a remarkable natural laboratory, where adaptive, evolutionary and ecological processes can be seen at work, in unusual