The Geomorphology of the Great Barrier Reef
Development, Diversity, and Change
By David Hopley, Scott G. Smithers, and Kevin E. Parnell, Cambridge University Press, 2007, 546 pages, ISBN 9780521853026, Hardcover, $150 US REVIEWED BY NICK HARVEY The Geomorphology of the Great Barrier Reef by David Hopley, Scott G. Smithers, and Kevin E. Parnell was preceded 25 years ago by Hopley’s landmark book on the same topic. The first book filled a void in terms of Quaternary reef science at the time, and the recent volume provides a fresh perspective on the complexity, diversity, and volume of geomorphological research undertaken on the Great Barrier Reef (GBR) over the last 25 years. To complete this task, Hopley teamed up with two other coastal geomorphologists, Smithers and Parnell, both based at James Cook University in North Queensland. The three authors have extensive experience in reef research and are well qualified to write this book. The book is aimed at “academic researchers in geomorphology and oceanography” and is also intended to appeal “to graduate students in related fields.” The 468-page text is organized into 13 well-illustrated chapters that include over 150 black-and-white line diagrams and photographs. Although the diagrams are well drawn and clear, many of them, and most of the photographs, would have benefited considerably from being reproduced in color (I have seen some of the original photographs, which are quite spectacular). This publishing
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decision was undoubtedly cost-related. The book’s chapters are basically organized into three groups. The first group of four chapters provides the background to the geomorphology of the GBR including a historical perspective on previous research, the geological background, the impact of Quaternary sea-level changes, and the influence of oceanography, hydrodynamics, climate, and water quality. The next group of six chapters (5–10) takes a spatial approach in terms of an overall analysis of reef and island morphology (Chapter 5), and also deals with different areas of the reef in separate chapters such as those treating the mid-shelf reefs (Chapter 8) and the reef islands (Chapter 10). The final group of three chapters (11–13) synthesizes some of the earlier material and discusses it in a broader context. For example, Chapter 11 compares processes and rates from all the reef types and then puts them in context with examples from reefs located elsewhere. Chapter 13 summarizes the usefulness of geomorphology in GBR management. The discussion on the foundations of the reef (Chapter 2) shows that the modern GBR is one of the world’s youngest reef systems and that the major reef-building turn-on event occurred between 452 and 365 thousand years ago. However, the geomorphological characteristics of the GBR are mostly related to the last glacial period lasting for around 100 thousand years when the reef was exposed and subsequently drowned rapidly during the Holocene sea-level transgression. Chapter 3 goes into some
detail regarding the importance of sea-level fluctuations in controlling reef growth, and it points out that the GBR was subject to long periods of subaerial exposure with only relatively short intervening periods of reef construction. This chapter also provides a detailed discussion on the debate around Holocene sea-level curves for the GBR region, in particular the issues of whether there was a smooth or pulsed sea-level rise, the date at which modern sea level was reached, the influence of hydro-isostasy, and the complications of using sea-level data from different sea-level indicators and from different parts of the GBR. The next chapter, which outlines the importance of climatological and hydrodynamic influences on the GBR, comments that the modern debate on climate-change impacts needs to be in the context of the variability of the last few hundred years when climatic cycles such as the El Niño Southern Oscillation (ENSO) have been important factors. Similarly, the chapter notes the lack of Category 5 cyclones in the twentieth century compared to severe cyclogenesis in the nineteenth century based on
This article has been published in Oceanography, Volume 21, Number 1, a quarterly journal of The Oceanography Society. Copyright 2008 by The Oceanography Society. All rights reserved. Permission is granted to copy this article for use in teaching and research. Republication, systemmatic reproduction, or collective redistirbution of any portion of this article by photocopy machine, reposting, or other means is permitted only with the approval of The Oceanography Society. Send all correspondence to: info@tos.org or Th e Oceanography Society, PO Box 1931, Rockville, MD 20849-1931, USA.
B o o k R eviews
geomorphological evidence. This observation illustrates well the importance of geomorphological data to extend the historical record and avoid misinterpretations based on the relatively short instrumental record. Chapter 4 also provides an overview of water, sediment, and nutrient impacts on the GBR. Chapter 5 is the first of six chapters that provides a spatial approach to explaining patterns of reef morphology throughout the GBR region. This chapter goes into some detail, supplying reef and reef-island statistics, and descriptions of classification and distribution of reefs by type (e.g., crescentic or ribbon reefs). The chapter demonstrates the nonrandomness of reef type distribution and sets the scene for the following five chapters, which examine reef evolution of: non-reefal areas (Chapter 6); fringing and nearshore reefs (Chapter 7); mid-shelf reefs (Chapter 8); outer-shelf reefs (Chapter 9); and the islands (Chapter 10). Each chapter has a different focus, such as the substrate and deposits of fringing reefs in Chapter 7, and the shelf-edge morphology of and tectonic influences on the outer-shelf reefs in Chapter 9. Chapters 11 and 12 take a more holistic approach to GBR evolution by discussing data from all the reefs in the GBR to provide a better understanding of rates of geomorphological processes across the GBR and also in context of other reefs in different parts of the world. For example, Chapter 11 examines variations in the depth to the antecedent surface on the GBR (4–28 meters) and notes the similar depth range of this antecedent surface for other Australian reefs and also for Pacific atolls. This chapter discusses models of reef growth
in response to different rates of sea-level rise and the different growth rates for various reef facies. In particular, it notes the importance of the antecedent surface structure for the take-off rate and timing of Holocene reef growth but stresses the importance of the relative sea-level curve in influencing reef facies, growth rates, and age of the near-surface reef. Here, the chapter shows how the reef reaches optimal vertical growth rates of ~ 8 mm per year at water depths of 12 to 15 meters and discusses how various reefs in the GBR either kept up with sea-level rise or got left behind and managed to catch up later after sea level had stabilized. This discussion is important when considering future reef response to projected sea-level rise associated with climate change. The chapter is also important for its comparison between the GBR, Indo-Pacific atolls, Pacific barrier and fringing reefs, Indian Ocean reefs, and Caribbean reefs. The following chapter (12) then provides a synthesis of the Holocene evolution of the GBR by discussing key
upcoming
stages, such as the glacial maximum low sea level, the early sea-level transgression, the start of the Holocene, the final stage of the transgression, and then the mid-to-late Holocene. This chapter paints a picture of what the continental shelf would have looked like at various stages through the Holocene and notes that Aboriginal people in Australia were present throughout the flooding of the continental shelf and the creation of the modern GBR. The final chapter focuses on the importance of understanding geomorphological processes for management and conservation of the GBR. It is unfortunate that its running header emphasizes “Geomorphology’s contribution to the problems of the Great Barrier Reef ” rather than the importance of geomorphological knowledge to understanding and solving the problems. This chapter provides useful data on reef islands, sediments, nutrients, geomorphology, and conservation, but notes that geomorphological criteria have mostly been given a low status in the manage-
BOOK Reviews
Ebb and Flow: Tides and Life on our Planet by Tom Koppel, The Dundern Group, 292 pages Lagrangian Analysis and Prediction of Coastal and Ocean Dynamics by A. Griffa, A.D. Kirwan Jr., A.J. Mariano, T. Özgökmen, and T. Rossby, Cambridge University Press, 487 pages Climate Change: A Multidisciplinary Approach by William James Burroughs, Cambridge University Press, 378 pages. Arc Marine: GIS for a Blue Planet by Dawn J. Wright, Michael J. Blongewicz, Patrick N. Halpin, and Joe Breman, ESRI Press, 216 pages
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ment of the GBR compared with many terrestrial national parks. The final part of this chapter reflects on the importance of global climate change and the impact of projected sea-level rise on the GBR from a geomorphological perspective. This discussion is very relevant for the current global debate on the impacts of climate change such as the Fourth Assessment of the Intergovernmental Panel on Climate Change (IPCC), in particular the report from Working Group II (Parry et al., 2007). At the regional level, this issue is also addressed in the recent volume on Climate Change and the Great Barrier Reef (Johnson and Marshall, 2007), which incorporates a detailed discussion on potential geo-
morphological impacts resulting from climate change on the GBR. Overall, I think the book is an excellent synthesis of current knowledge on the geomorphology of the Great Barrier Reef. While I agree with the authors that understanding geomorphological reef processes is very important in the management of the GBR, I don’t think that this book alone will convince managers of that need because it is largely written for a different target audience. However, the book will undoubtedly become an essential reference for reef researchers and graduate students, and I give it my strongest endorsement. I congratulate the three authors on producing such a comprehensive text.
N ick H arvey (nicholas.harvey@ adelaide.edu.au) is the Executive Dean, Faculty of Humanities and Social Sciences, and Professor, Geography and Environmental Studies, The University of Adelaide, South Australia.
REFERENCE S Parry, M.L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.D. Hansen, eds. 2007. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK, 1000 pp. Johnson, J.E., and P.A. Marshall, eds. 2007. Climate Change and the Great Barrier Reef: A Vulnerability Assessment. Great Barrier Reef Marine Park Authority and Australian Greenhouse Office. 818 pp.
The Unnatural History of the Sea We learn from history that we do not learn from history. —Georg Wilhelm Friedrich Hegel (1770–1831)
By Callum M. Roberts, Island Press, 2007, 435 pages, ISBN 9781597261029, Hardcover, $28.00 US REVIEWED BY ANDREW J. READ On June 15, 2006, President George W. Bush created the world’s largest fully protected marine reserve, the Papahānaumokuākea Marine National Monument in the Northwestern Hawaiian Islands (NWHI). Established by Presidential proclamation, the monument is the largest conservation area in the United States. In his proclamation speech, the president noted that, “our duty is to use the land and seas wisely, or
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sometimes not use them at all.” Coming, as it did, from a president not known for his sensitivity to environmental issues, the establishment of the Papahānaumokuākea Marine National Monument was a major victory for the conservation of marine ecosystems. Commercial fisheries, and other forms of resource extraction, are to be banned from the monument, providing an unparalleled level of protection to the fragile coral reef ecosystems of the NWHI. Coral reefs are often described as the rainforests of the sea because of their biodiversity and, in some areas, high levels of endemism. Throughout the world ocean, coral
reefs are in decline, due to the synergistic effects of overfishing, coastal development, and climate change. One of the most pervasive threats is overfishing, particularly of large, predatory fishes. In one stroke of his pen, President Bush eliminated this threat to the extensive
coral reef systems in the NWHI. But what of coral reef systems elsewhere in the world? And what about the effects of fishing on other, less-celebrated marine ecosystems? To answer these questions, Callum Roberts has written The Unnatural History of the Sea, which he describes as “…an account of the history of fishing and the effects it has had on the sea.” The book is encyclopedic in scope, starting with the earliest accounts of fishing in the medieval period and continuing to the present. Roberts covers the history of European and North American harvests of whales, seals, sea turtles, oysters, and fish and the effect of these removals on marine ecosystems. The history of many fisheries, as seen through Roberts’ long historical lens, is depressingly familiar. The initial discovery of a new resource is followed by a rapid and profitable harvest expansion, which leads to overcapitalization, excess harvesting capacity, and eventual collapse of both the resource and the fishery. Roberts argues, correctly in my view, that to fully understand the effects of marine fisheries, we need to compare the current status of marine ecosystems with their structures and compositions prior to exploitation. But this is a difficult task, as most marine ecosystems were first exploited long before the fields of marine ecology and fisheries biology were conceived. Intensive fisheries have existed in Europe for centuries, but systematic observations of fisheries and fish populations (using fisheries-independent data) began only at the dawn of the twentieth century. Thus, when we examine trend data on the abundance of an exploited population, the starting point of our time series may not be representa-
tive of pre-exploitation conditions. This gap in our knowledge is exacerbated by the problem of shifting baselines, a term coined by Daniel Pauly of the University of British Columbia, which describes the tendency of each scientist to evaluate the degradation of marine ecosystems over her or his lifetime, thus ratcheting down expectations of ecosystem structure and function. One of the great strengths of The Unnatural History of the Sea is the use of older sources. The first third of this book, entitled “Explorers and Exploiters in the Age of Plenty,” is replete with citations to antique volumes. In the preface, Roberts admits to “an incurable passion for dusty, ancient tomes,” and the reader is all the better for his obsession. Later in the book, Roberts describes some of the first reviews of the ecological effects of commercial fishing, including a British Royal Commission appointed to examine the effects of bottom trawling in 1863. The excerpts of the Commission report will make sadly familiar reading to anyone acquainted with today’s battles over fisheries conservation in Europe or North America. Any book of this scope will contain some shortcomings and a few errors, and The Unnatural History of the Sea is no exception. Roberts does not give much consideration to opposing points of view and occasionally presents controversial hypotheses without an adequate explanation of the uncertainty associated with these ideas. Nevertheless, the book is a call to action rather than a dry, scholarly account of divergent viewpoints, and I have no quarrel with any of Roberts’ fundamental conclusions. In the last third of the book, Roberts lays out a series of recommendations
for the reform of fisheries management. He does so in a nontechnical and very accessible fashion, in keeping with the rest of the book. He identifies seven specific areas of reform that he believes are necessary to create sustainable (and more profitable) fisheries: (1) reduce the amount of fishing, (2) eliminate risky decisions, (3) eliminate catch quotas, (4) require fishers to keep what they catch, (5) use the best available fishing technology to reduce bycatch, (6) ban or restrict the most damaging fishing gear, and (7) implement extensive networks of marine reserves that are off limits to fishing. Roberts is best known for his work on marine reserves and he makes a strong argument for their efficacy in improving fish yields and conserving biodiversity. I read Callum Roberts’ book while taking a graduate class in Marine Conservation Biology to Midway Atoll in the newly created Papahānaumokuākea Marine National Monument. After the experience of snorkeling in a small marine reserve near Honolulu, my students and I were amazed to see the abundance and size of reef fish at Midway. It was a profound experience to swim alongside enormous jacks and through huge schools of goatfish. Perhaps Roberts’ book, and his optimism, will help to prove Hegel wrong. I hope so. ANDREW J. READ (aread@duke.edu) is Rachel Carson Associate Professor of Marine Conservation Biology, Nicholas School of the Environment and Earth Sciences, Duke University, Beaufort, NC, USA.
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Fundamentals of Geophysical Fluid Dynamics By James C. McWilliams, Cambridge University Press, 2006, 266 pages, ISBN 9780521856379, Hardcover, $79 US Reviewed by Christopher A. Edwards Fundamentals of Geophysical Fluid Dynamics is a new textbook that provides an introduction to the basic dynamics governing fluid motion in a rotating system. This book is designed for first-year graduate students and assumes background knowledge of multivariable calculus, partial differential equations, and classical mechanics. It would also be helpful if a student had previously studied nonrotational fluid dynamics and more general phenomenology of the ocean and atmosphere. The text is divided into six chapters. A very short introduction sets the broader context for the book’s subject. The second chapter presents a limited discussion of the basic equations that govern fluid dynamics, for example, those for conservation of momentum and kinetic and potential energy, and it introduces concepts of divergence, circulation, and vorticity. This chapter also provides relevant fundamentals, such as the equations of state and observed stratification for the ocean and the atmosphere. The final section of this chapter focuses on the influence of rotation, introducing geostrophic balance and including a valuable discussion of scaling to identify appropriate limits for approximations.
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The third chapter, entitled “Barotropic and Vortex Dynamics,” addresses twodimensional motion in the horizontal plane only. This chapter begins with the barotropic equations and defines the appropriate forms of the vorticity equation, potential vorticity, and streamfunction. By reintroducing geostrophy and extending the discussion to gradient-wind balance, the author prepares for an extensive discussion of stationary vortex flow and movement of multiple vortices. The chapter includes a section on barotropic and centrifugal instability, and concludes with a section on two-dimensional turbulence, with a concise discussion of the energy and enstrophy cascades. This chapter’s emphasis on vortex processes is excellent and unique among existing geophysical fluid dynamics texts. Providing this emphasis adds meaningfully to existing resources for students with material that extends easily across multiple geophysical systems. The topic of Chapter 4 is rotating shallow-water and wave dynamics. It begins with classical discussions of linear wave solutions and geostrophic adjustment, but then expands into nonlinear wave steepening leading to wave breaking. After an introduction to quasigeostrophy, the chapter discusses Rossby waves and ends with mechanisms for their generation. In general, the author very clearly does not try to exhaustively cover all aspects of geophysical fluid dynamics, particularly when a subject is discussed extensively in
other texts. Rather, he includes sufficient information to make this text (and associated course) self-contained, and directs interested readers to other references for further study. The author’s treatment of linear waves in geophysical systems is an excellent example. The text solidly addresses many introductory aspects and then moves on to important extensions, for example, nonlinear bores and the coupling of vortices on the beta-plane to Rossby wave modes, which are not covered in commonly used geophysical fluid dynamics texts. Chapter 5 introduces baroclinic motion with layered hydrostatic models. The chapter’s central topic, baroclinic instability, is covered in two parts. The first part is an analytical treatment of two-layer flow, described using a normal-mode approach. The second part describes the processes resulting from instability of a three-layer zonal jet. This section draws heavily on numerical experiments carried out by the author decades ago, but provides useful, intuition-building ideas about eddymean flow interaction and along- and cross-jet balances.
The final chapter focuses on boundary layers and the physics of ocean gyres. It derives appropriate dynamical approximations for atmospheric planetary boundary layers and surface and bottom boundary layers in the ocean. There is a subsequent discussion of classical winddriven ocean gyres. Both of these sections include interesting and important material focused on numerical support for the analytical treatments provided. In particular, there is a discussion of direct numerical simulations to test the validity of Ekman theory. In addition, the author uses scaling arguments to alert the student that real ocean gyres are more nonlinear than classical theory demands. He presents numerical experiments to reveal the influence of such nonlinearity. Overall, this textbook is extremely successful as a reference for an introductory graduate course. It balances two goals: discussing a wide range of interesting topics to engage the student reader and providing sufficient depth to offer students a rigorous foundation. By presenting relevant images of oceanic or atmospheric features, each chapter begins with classical material for which analytic approaches apply; each subject ends with more realistic, nonlinear regimes explored usually using idealized numerical output for phenomenological description or further analysis. There is some uneven treatment, for example, the discussion of the rotational coordinate transformation and the introduction to the N-layer system, but these areas are very few in number. The book’s scope is limited, omitting, for example, dynamics of internal waves in a continuously stratified medium, but it includes more than enough material for an introductory course—which is its intent. The
book is systematically organized, and the exposition is extremely clear and chock full of short, effective definitions and illuminating descriptions of important geophysical processes. On top of this, the text includes a collection of useful and challenging problems that are perfect for a class. These problems fill out derivations not offered in the text and also extend material and ideas brought forth within the chapters. Their inclusion further helps make this text an excellent teaching resource. In summary, Fundamentals of Geophysical Fluid Dynamics is a valuable addition to the existing collection of texts in this field. It is a well-written, concisely worded, self-contained introduction, emphasizing material, such as vortex motion, not central to other texts of its type. It will be useful as a study guide to incoming graduate students as well as an occasional reference for more advanced researchers in the field. Christopher A. Edwards (cedwards@ucsc. edu) is Assistant Professor, Ocean Sciences Department, University of California, Santa Cruz, CA, USA.
Upcoming Special-Issue Topics Vol. 21, No. 2, June 2008 Celebrating 50 Years of International Partnerships in Ocean Research Guest Editor: Peter Ranelli, NATO Undersea Research Centre Vol. 21, No. 3, September 2008 20th Anniversary of The Oceanography Society Guest Editor: Melbourne Briscoe, founding Secretary of TOS Vol. 21, No. 4, December 2008 Coastal Ocean Processes Guest Editor: Richard Jahnke, Skidaway Institute of Oceanography Vol. 22, No. 1, March 2009 HERMES: Hotspot Ecosystem Research on the Margins of European Seas Guest Editors: TBN Vol. 22, No. 2, June 2009 Tenth Anniversary of the National Oceanographic Partnership Program Guest Editors: Eric Lindstrom, National Aeronautics and Space Administration; Jim Kendall, Minerals Management Service; and Ben Chicoski, Consortium for Ocean Leadership Vol. 22, No. 3, September 2009 The Revolution in Global Ocean Forecasting – GODAE: 10 Years of Achievement Guest Editors: Mike Bell, National Centre for Ocean Forecasting, and Pierre-Yves Le Traon, IFREMER Vol. 22, No. 4, December 2009 Ocean Acidification Guest Editor: Richard Feely, National Oceanic and Atmospheric Administration
Future Topic Future of Satellite Oceanography
The editorial staff also encourages unsolicited manuscripts on other oceanography themes for consideration and publication under the Regular Features banner.
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