Ecosystems of the world 25: Coral reefs

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not include multiple regression, analysis of covariance and methods for handling repeated measures. In missing out these statistical techniques, the authors fail to appreciate that the data collected by field biologists today often involve measurements of many different behavioural and ecological traits of the individuals in a population over long periods, and that the questions they attempt to answer require sophisticated statistics. This is well illustrated

by the fact that 19 out of 23 papers in the February 1991 issue of Journal of Animal Ecology used statistics (primarily multiple regression) not covered in Practical Statistics for Field Biology. In summary, Practical Statistics for Field Biology is an excellent introductory text for first and second year undergraduate courses in biology. However, students doing Honours projects or PhD theses or established research workers should continue to

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use Sokal and Rohlf’ or similar advanced texts, at least until the authors produce Further Statistics for Field Biology. S. Albon ZoologyDept, Uwersity of Cambridge, Dowmng St, Cambridge CB2 3EJ, UK Reference 1 Sokal, R.R. and Rohlf, F.J. (19811 Biometry (2nd edn), Freeman

CoralReefEcology Ecosystemsof the World 25: Coral Reefs edited by Z. Dubinsky, Elsevier, 1991. $22O.OO/Dfl.385.00 hbk (xi + 550 pages) ISBN 0 444 87392 9 Just over 20 years ago, a substantial proportion of coral reef science could be effectively reviewed in a single landmark paper’. This is no longer a realistic possibility. Scientific work on coral reefs has increased so much, especially in Australia, that whole volumes like this one are now needed to convey what is happening. Unfortunately, the faster a subject is moving, and the more publications it generates, the harder it becomes to organize and produce a useful review volume in a short time. Thus, the 1991 publication date of Ecosystems 25 is belied by the lack of any cited references more recent than 1986. This need not have mattered greatly, since reviews and syntheses can still be of value long after they were written, and not just for historical reasons. The critical question is whether the subject has developed significantly, or its emphasis shifted dramatically, since a review was written. The mid-1980s vintage of Ecosystems 25 is just too early to reflect the interesting stage that coral reef science now seems to have reached. Broad themes are emerging more clearly and the subject is developing particular foci, whereas this book notably lacks thematic cohesion. There is neither a framework set out in an opening chapter that relates its contents to ecosystem theory and concepts nor any particular connecting themes picked out by the editors. The only chapter that attempts a unifying thematic treatment is the final one by Endean and Cameron: they draw attention to a number of important questions about taxonomic richness and community structure, but do not always support their contentions with data, and their preoccupation 410

with replacing the r-K concept with something that seems to be very similar was surely answered in advance by Southwood2. This volume essentially consists of a series of chapters by leading specialists on important details of reef biology, many of them valuable and interesting in their own right (e.g. Harrison and Wallace on reproduction, dispersal and recruitment of corals). Moreover, while the volume overall lacks an obvious framework, individual authors have in some cases helpfully provided one within their own subject matter (e.g. Andrews and Pickard on physical oceanography). Unfortunately, this kind of approach (framework plus data review) is not consistently adopted by all the authors, and some chapters, such as Berner’s eight pages on algae (excluding references), are surprisingly thin. It is almost a cliche that algae are probably of greater bulk importance on coral reefs than the corals themselves. All this leaves us with a somewhat incomplete and patchy reference work that is still useful at the detailed level (I am pleased to have a copy myself), so long as its price and its manuscript date (rather than publication date) are borne in mind. For years, many ideas about the coral reef ecosystem were well ahead of the data needed to test them properly, while others rested on a surprisingly small number of elegant and famous studies of particular details or locations. Increased effort overthelast ISyearsorso hasgreatly changed this, though until the last few years progress has been channelled into seemingly disconnected topics - worthy studies in search of a grander context. The belief held by some of us that geologists and biologists should be able to commune together about the coral reef ecosystem was beginning to feel more like

an anachronistic ideal than a vision of the future. Typically, at coral reef geologically focused congresses, sessions have been run concurrently with biological ones, so pre-empting useful exchange, whilst here in Ecosystems25, thegeological dimension is virtually absent. Now at last there are indications of change, as can be discerned in the proceedings of the last coral reef congress3 and in the prospectus for the next one. In particular, the question increasingly discussed is now whether reefs are ecosystems that are stable or unstable, robust or fragile. These are heavily subjective concepts made more so by their underlying link with the difficult and confused idea of stress. In fairness, stress is considered in Ecosysrems25 by Grigg and Dollar, though their chapter is relatively short and considers only the most immediate biological issues. In practice, it is also necessary to take into account the familiar problems of time scales and rates of change. Thus the biologist, working within the time scale of direct human observation, sees cyclones, oil spills, El Nirio southern oscillations, Acanthaster plagues and global warming as destructive factors indicative of fragility and instability. On the other hand, the geologist, work ing with a much longer time scale, finds that coral assemblages on reefs have remained remarkably constant in mode and composition over surprisingly long periods of geological time, notwithstanding spectacular changes of climate and sea level on a much larger scale than anything currently predicted for present global warming (G.J.H. McCall et al., sub. mitted). Yet, there was also a substantial and unexplained change in assemblages around the end of the Tertiary. Thus, geology should provide a unique perspective that can help to qualify, and perhaps even

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quantify, the topical notions of stability and stress, and there is a definite intellectual thread that connects environmental monitoring at one extreme with reef palaeocology at the other. The problem for a satisfactory ‘ecosystem theory’ of coral reefs is to distinguish, operationally and conceptually, the transient and the local from the irreversible and the global. From this question of stability, fragility and stress, it is natural to go on to consider the matter of whether reefs ‘keep up, catch up or give up’ with relative rises in sea level4 or, in the most general, potentially unifying, sense, what ‘turns them on or ~ff’~. In other words, what controls the initiation, maintenance and demise of coral reef ecosystems (again, on all time scales)? Currently, the most widely influential works in this area are those of Birkeland6 and Hallock and Schlager’, who have drawn attention to the possible controlling role of nutrient limitation on reef ecosystems in both the present and past, although their key papers are too recent to have made any impact on Ecosystems 25. However, D’Elia and Wiebe do address this subject and their chapter, read with hindsight, conveys the kind of problems that need to be solved if the nutrientlimitation hypothesis is to be properly tested-it would be interesting to know how they would have written it now. The nutrient-limitation hypothesis reveals possible multidisciplinary links from microscopic to megascopic levels, starting on the cellular scale with the nature of algal symbiosis in reef organisms, especially corals (usefully reviewed in Ecosystems 25 by Muscatine), and proceeding through the trophic biogeography of reefs and the consequences of human pollution (eutrophication) to changes in the geochemical composition of atmosphere and ocean through geological time and their possible influence on reef building and limestone deposition. Certainly, the geologists have not been slow to see the wider implication@ but it is early days and it will be important and exciting to develop rigorous approaches for testing the hypothesis. Nutrient limitation is precisely the kind of unifying, multidisciplinary problem that coral reef studies have needed. It is a far-fromsettled question that promises to run for a while yet. Brian R. Rosen Deptof Palaeontology, The NaturalHistory Museum, CromwellRoad,LondonSW758D. UK

References 1 Stoddart, D.R. (1969) Biol. Rev. 44, 433-498 2 Southwood, T.R.E. (1977) J. Anim. Ecol. 46,337-365 3 Choat, J.H. et al., eds (1988) Proceedings of the Sixth International Coral Reef Symposium, Townsville, Australia, James Cook University 4 Neumann, AC. and Macintyre, I. (1985) Proceedings of the Fifth International Coral Reef Congress, Tahiti (Vol. 3) (Delesalle, B. eta/., eds), pp. 105-110,

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5 Buddemeier, R.W. and Hopley, D. (1988) Proceedings of the Sixth International Coral Reef Symposium, Townsville, Australia (Vol. 1) (Choat, J.H. et al., eds), pp. 253-261, James Cook University 6 Birkeland, C. (1988) Proceedings of the Sixth International Coral Reef Symposium, Townsville, Australia (Vol. 1) (Cheat, J.H. et a/., eds), pp. 21 l-220, James Cook University 7 Hallock, P. and Schlager, W. (1986) Palaios 1,389-398 6 Cowen, R. (1988) Palaios 3, 221-227

Parasites for All Bird-Parasite Interactions: Ecology, Evolution and Behaviour edited by J.E. Loye and M. Zuk, Oxford University Press/OUP USA, 1997. f37.50 hbk (xv + 406 pages) ISBN 0 19 857738 9 ‘With this volume a paradigm is born: parasites are likely to play a role in practically every aspect of the evolutionary biology of birds, and probably vertebrates in general.’ Heady stuff, and it’s not even dustjacket rhetoric. That opening line from Peter Price’s preface to this 21chapter,41-authorvolumeaptlysummarizes the euphoria evident in almost every chapter. Recognizing that the ecology of parasitism in wild vertebrate populations has been overlooked, these authors are enthusiastically rushing to fill the gap. The issues they explore are diverse (indeed, the only common thread in thisvolume is the taxonomicgroup of the hosts). Do parasites have an impact on host fitness (that is, are parasites actually parasites)? If they do, are they regulating host population sizes? Are they responsible for some host adaptations? What about the ecology of the parasites themselves? And do hosts impose selection for parasite adaptations? For the most part, this book does not contain general answers to these questions (a reflection of the infancy of the field, as the editors point out), but rather a series of largely empirical studies of host-parasite systems from the field and laboratory involving a wide range of parasites (ectoparasites, blood protozoa, fly larvae, viruses and worms). For the most part, the data are new, and by pulling together articles that would normally appear in a wide range of specialist journals, the editors have created something of a benchmark. There is clearly sufficient knowledge of the basic biology of bird-parasite interactions (ably

summarized here) to go beyond exploratory field studies. Relatively few chapters make exciting reading for those who are not avian-parasite specialists, but those few describe manipulations of parasite burdens in field populations, and set the standards for future studies. One general conclusion does emerge: parasites can be nasty in the wild. Because it is often unclear whether high parasite burdens are a cause or a consequence of lower host fitness, and because sampling procedures may be biased by the health of animals, experimental manipulation of parasite densities is usually the only way of convincingly demonstrating parasite-induced reductions in host fitness. Together with studies published elsewhere’,*, this volume shows that there is now little doubt that parasitescan havesignificant impact on host fitness in the wild. This battery of evidence should finally lay to rest the infamous conventional wisdom of parasitologists that parasites always evolve towards avirulence. But the evolutionary and ecological consequences of this reduced fitness have proved much more elusive. Only one study in this book (Hudson and Dobson on the trichostrongylid nematodes of red grouse) provides more than suggestive evidence for the regulating role of parasites on host populations. And while an intimidating number of host traits are attributed to parasite-imposed selection (habitat selection, timing of breeding season, second broods, reproductive synchrony, nest sanitation, preening behaviour, mate choice, etc.) only a few studies have begun to provide convincing evidence that these traits are adaptive in the presence of parasites, let alone antiparasite adaptations. One of these is Clark’s elegant study of the use by birds of natural insecticides for nest sanitation. The 411