Dynamic Modeling for Marine Conservation PDF
Preview Dynamic Modeling for Marine Conservation
Modeling Dynamic Systems Series Editors Matthias Ruth Bruce Hannon Springer Science+Business Media, LLC MODELINGDYNAMICSYSTEMS ModelingDynamicBiologicalSystems BruceHannonandMatthiasRuth ModelingDynamicEconomicSystems MatthiasRuthandBruceHannon DynamicModelingintheHealthSciences JamesL Hargrove ModelingandSimulationinScienceand MathematicsEducation WallaceFeurzeigandNancyRoberts. Editors DynamicModelingofEnvironmentalSystems MichaelL DeatonandJamesJ.Winebrake DynamicModeling,SecondEdition BruceHannon andMatthiasRuth ModelingDynamicClimateSystems WalterA.Robinson DynamicModelingforMarineConservation MatthiasRuthandJamesLindholm. Editors Formoreinformation,see: www.springer-ny.com/biology/moddysys Matthias Ruth James Lindholm Editors Dynamic Modeling for Marine Conservation With a Foreword by Elliott A. Norse With 212 Illustrations EXIRA MATERIALS extras.springer.com Springer Matthias Ruth ]ames Lindholm Environmental Program Stellwagen Bank National School of Public Affairs Marine Sanctuary Van Munching Hali 175 Edward Foster Road University of Maryland Scituate, MA 02066, USA College Park, MD 20742-1821, USA Series Editors Matthias Ruth Bruce Hannon Environmental Program Department of Geography School of Public Affairs 220 Davenport Hali, MC 150 Van Munching Hali University of Illinois University of Maryland Urbana, IL 61801, USA College Park, MD 20742-1821, USA Cover photograph: Kelp beds are extremely complex and critical marine habitats. Wise management of both kelp beds and the animals that depend on them is key to the future of our marine ecosystem. OAR!National Undersea Research Program (NURP) http://www.photolib.noaa.gov/nurp. Library of Congress Cataloging-in-Publication Data Dynamic modeling for marine conservation / editors, Matthias Ruth, ]ames Lindholm. p. cm. Includes bibliographical references (p. ) Additional material to this book can be downloaded from http://extras.springer.com. ISBN 978-1-4612-6544-3 ISBN 978-1-4613-0057-1 (eBook) DOI 10.1007/978-1-4613-0057-1 1. Conservation biology--Computer simulation. 2. Marine biological diversity conservation--Computer simulation. 1. Ruth, Matthias. II. Lindholm, ]ames, 1968- QH75 .D96 2001 333.91'6416'oOl3--dc21 2001032840 Printed on acid-free paper. © 2002 Springer Science+Business Media New York Originally published by Springer-Verlag New York Inc. in 2002 Softcover reprint of the hardcover lst edition 2002 AII rights reserved. This work consists of a printed book and a CD-ROM packaged with the book. The book and the CD-ROM may not be translated or copied in whole or in part with out the written permission of the publisher (Springer Science+ Business Media New York), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now know or here-after developed is forbidden. The CD-ROM contains the run-time version of the STELLA ®s oft ware. STELLA® software © 1985, 1987, 1988, STELLA® software© 1985, 1987, 1988, 1990-1997, 2000, 2001 by High Performance Systems, Inc. Ali rights reserved. STELLA® is a registered trademark of High Performance Systems, Inc. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely byanyone. Production coordinated by Impressions Book and ]ournal Services, Inc., and managed by Timothy A. Taylor; manufacturing supervised by]acqui Ashri. Typeset by Impressions Book and ]ournal Services, Inc., Madison, WI. 987654321 ISBN 978-1-4612-6544-3 SPIN 10841610 Foreword The oceans are shrinking. They're not literally shrinking; warming in the last century has actually expanded the sea enough to threaten low-lying coastal lands that are vul nerable to storm surge. During the same interval, however, events on land have increasingly affected the sea.Since in most ways the Earth isa closed system-a zero-sum planet in today's parlance-as terrestrial influence on the sea expands, the sea's influence on its own processes shrinks. Control of many crucial marine processes no longer resides within the sea. The evidence for this isabundant and, to anyone who islooking, unmis takable. In recent decades scientists have witnessed unprecedented pertur bations and increases in previously uncommon events that demonstrate growing terrestrial influences on the sea. Numerous marine species, from sea urchins to monk seals, have experienced devastating epidemics. The numberof harmful algalblooms and jellyfishpopulation explosions isrising An hypoxic "dead zone" in the Gulf of Mexico off the mouth of the Mississippi Rivernow appears each year and grows toencompass an area as largeas NewJersey. Live coral coverinshallow reefs inFlorida,Jamaica, the Maldivesand many other locations has severely declined. Deepwater reef building corals,once widely distributed,have disappeared throughout much of their ranges. Researchers have discovered high concentrations of persis tent organic pollutants in declining populations of beluga whales and polar bears,both high trophic levelpredators inmarine food webs. Populationsof once-abundant fishes, such as Atlantic cod in Newfoundland, Napoleon wrasse in Indonesia and bluefin tunas throughout temperate seas, have declined sharply. What is more, a new kind of disturbance occurring on a continent-sized scale is converting the formerly tranquil seabed as deep as 2,000meters into a biological wasteland. The common thread in all these and countless other cases is the un precedented expansion in the population, technology and economic activ ityof one terrestrial species. Humans are now so powerful that we are pro foundly affecting the Earth'sbiogeochemical cycles and biological diversity. Aswe have converted more and more of the terrestrial realm to suit our v vi Foreword needs, we have increasingly harmed the sea. One reason isthat, in a geo chemical sense, the sea is downhill from the land; far more nutrients and toxics flow from land to sea than vice versa. Moreover, the sea is where land-dwellers conduct the last great hunt for Earth's wildlife, our marine fisheries. Unfortunately, individuals, companies and governments seldom employ the precautionary principle (essentially,"Don't act unless you can be confi dent of doing no consequential harm") in dealing with the rest of the world. Thus, deciding to cease and reverse harm requires an after-the-fact understandingofhow we are affectingmarine processes.However, our un derstanding is complicated by statistical confounding, the difficultyin un raveling strands of cause and effectwhen many human activitiesare affect ing the sea concurrently. For example, we know that North Atlanticright whales are critically endangered even though whaling for them was banned more than 60 years ago. But is this because undersea noise pre vents them from finding mates, persistent organic pollutants reduce their reproductive success, the food webs that support them have been altered, they are experiencing demographic imbalances or inbreeding depression, some other agent that we haven't yet recognized is harming them, or all these factors in combination? In this and many other cases, itis difficultto reach sound conclusions, yet we desperately needmore insight to protect, restore and sustainably use the livingsea. In essence,humans are perform ing a vast unplanned and uncontrolled experiment on our planet's life support systems, and the fact that we are utterly dependent on their func tioning for our survivalsuggests the value of tools that help us understand key cause-effect relationships. Modelingthe dynamics ofsingle populations, interacting species, ecosys tems and human impacts is a powerful means of penetrating the haze caused by multiple variables behaving in different ways. Modeling allows marine conservationbiologists to describe components ofsystemsquantita tivelyand to assemble them into larger systems whose complexity exceeds our unassisted predictive capacity.Thus,itcan reveal results that we might not readily infer, results whose assumptions can be examined, challenged, modified and re-examined until they represent the broadest and deepest understanding we can create. Once modeling was done in the realm of in timidating mainframe computers and equally intimidating programming languages. Now the exponential increase of computing power and access to it has democratized modeling. At the same time, models have become more realisticand user-friendly,allowing a growing number of established scientists and students to use them to test hypotheses, explore dynamics and weigh sensitivities. Ofcourse,amodel isnot a panacea.Itisapotenttool inatimewhen the questions facing us are dauntingly complex and policy makers require timelyguidance. Amodel isasimplifiedvisionofnature, and itsvalidityde pends on the degree to which it identifies, portrays and connects relevant Foreword vii variables accurately. In a world where manifold consequences of our ter restrialspecies are effectivelyshrinking oceans and the rest of nature,mod eling could be crucial to protecting, restoring and sustainably using ourliv ing planet. The powerful yetaccessible modeling methods discussed in this book are a welcome step forward in marine conservation biology. ElliottA.Norse, President Marine Conservation Biology Institute October 17, 2000 Series Preface The world consists of many complex systems, ranging from our own bod ies to ecosystems to economic systems. Despite their diversity, complex systems have many structural and functional features in common that can be effectively modeled using powerful, user-friendly software. Asa result, virtually anyone can explore the nature of complex systems and their dy namical behaviorunder a range of assumptions and conditions.This ability to model dynamic systems isalready having a powerful influence on teach ing and studying complexity. The books in this series will promote this revolution in "systems think ing"by integrating computational skillsofnumeracyand dynamic modeling techniques into a variety of disciplines. The unifying theme across the se rieswillbe the power and simplicityof the model-building process,and all books are designed to engage readers in developing their own models for exploration of the dynamics of systems that are of interest to them. Modeling Dynamic Systems does not endorse any particular modeling paradigmor software.Rather,the volumes inthe series willemphasize sim plicityof learning, expressive power,and the speed of execution as priori ties that willfacilitatedeeper understanding ofsystems. MatthiasRuthand Bruce Hannon ix Acknowledgments Matthias Ruth and James Lindholm thank the Pew Charitable Trusts, the Kendall Foundation, the Mudge Foundation, and the National Undersea Research Center at the Universityof Connecticut for their support of work on this book and research related to it. Ms. Sara Schaub of the National Undersea Research Center at the Uni versity of Connecticut contributed significantly to the preparation of the glossary. DevelopmentofChapter 10byAndrew M.Lohrerand RobertB.Whitlatch was in part supported by a grant form the NationalScienceFoundation. RoelofM.]. Boumans and Pamela M. Behm thank Dr. Frederick T. Short and Dr. David M. Burdick of the Jackson Estuarine Laboratory (University of New Hampshire) for their invaluable expertise in the field of eelgrass ecology. They also thank the numerous students at the University of New Hampshire who have contributed to this project. Mark Maguire and Matthias Ruth thank Yamiery Vanessa Puchi for her contributions to Chapter 11. RichardLangton and SallySherman acknowledge the financial supportof the state of Maine and the Sportsfish Restoration Actwhile conducting this study. Peter Austerwas supported by the National Undersea Research Center at the Universityof Connecticut, Stellwagen Bank National Marine Sanctuary, and the USGeological Survey. Denise Johnston, Chris Soderquist and Donella Meadows wish to thank the many people who have contributed to the project on which Chapter 18 reports. Rockefeller Brothers Fund, C.S. Mott Foundation and Wallace Global Fund provided the funds necessary to research the system and build the model. Special thanks goes to the many people who have shared their time and expertise, particularly Jason Clay at World Wildlife Fund, Peter Riggs at Rockefeller Brothers Fund, and John Ward at National Marine Fisheries Service. Matthias Ruth James Lindholm xi Contents Foreword v Series Preface ix Acknowledgments xi Contributors xix Part 1. Concepts and Techniques 1 1. Introduction 3 MATIHIAS RUTH ANDJAMES LINDHOLM 1.1 Dynamic Modeling for Marine Conservation 3 1.2 What Is Conservation Biology? 5 1.3 Why Marine Conservation? 8 1.4 What Is Dynamic Modeling? 9 1.5 Using Dynamic Modeling to Generate Consensus 12 1.6 Overview 17 1.7 Questions and Tasks 20 2. Modeling in STELLA 21 MAITHIAS RUTH ANDJAMES LINDHOLM 2.1 Basic Population Model 21 2.2 Closing a Model 27 2.3 STELLA's Numeric Solution Techniques 32 2.4 Sources of Model Errors 37 2.5 Guidelines for the Development of a Dynamic Model 40 2.6 Questions and Tasks 41 3. Predator-Prey Dynamics 43 MAITHIAS RUTH ANDJAMES LINDHOLM 3.1 Humpback Whales and Sand Lance 43 3.2 Sectors 49 3.3 Questions and Tasks 53 xiii
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