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Coral taxonomy has entered a historical phase where nomenclatorial uncertainty is rapidly increasing. The fundamental cause is mandatory adherence to historical monographs that lack essential information of all sorts, and also to type specimens, if they exist at all, that are commonly unrecognizable fragments or are uncharacteristic of the species they are believed to represent. Historical problems, including incorrect subsequent type species designations, also create uncertainty for many well-established genera. The advent of in situ studies in the 1970s revealed these issues; now molecular technology is again changing the taxonomic landscape. The competing methodologies involved must be seen in context if they are to avoid becoming an additional basis for continuing nomenclatorial instability. To prevent this happening, the International Commission on Zoological Nomenclature (ICZN) will need to focus on rules that consolidate well-established nomenclature and allow for the designation of new type specimens that are unambiguous, and which include both skeletal material and soft tissue for molecular study. Taxonomic and biogeographic findings have now become linked, with molecular methodologies providing the capacity to re-visit past taxonomic decisions, and to extend both taxonomy and biogeography into the realm of evolutionary theory. It is proposed that most species will ultimately be seen as operational taxonomic units that are human rather than natural constructs, which in consequence will always have fuzzy morphological, genetic, and distribution boundaries. The pathway ahead calls for the integration of morphological and molecular taxonomies, and for website delivery of information that crosses current discipline boundaries.

The conservation status of 845 zooxanthellate reef-building coral species was assessed by using International Union for Conservation of Nature Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds that of most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories, whereas the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures.

Temperature-induced mass coral bleaching causing mortality on a wide geographic scale started when atmospheric CO(2) levels exceeded approximately 320 ppm. When CO(2) levels reached approximately 340 ppm, sporadic but highly destructive mass bleaching occurred in most reefs world-wide, often associated with El Niño events. Recovery was dependent on the vulnerability of individual reef areas and on the reef's previous history and resilience. At today's level of approximately 387 ppm, allowing a lag-time of 10 years for sea temperatures to respond, most reefs world-wide are committed to an irreversible decline. Mass bleaching will in future become annual, departing from the 4 to 7 years return-time of El Niño events. Bleaching will be exacerbated by the effects of degraded water-quality and increased severe weather events. In addition, the progressive onset of ocean acidification will cause reduction of coral growth and retardation of the growth of high magnesium calcite-secreting coralline algae. If CO(2) levels are allowed to reach 450 ppm (due to occur by 2030-2040 at the current rates), reefs will be in rapid and terminal decline world-wide from multiple synergies arising from mass bleaching, ocean acidification, and other environmental impacts. Damage to shallow reef communities will become extensive with consequent reduction of biodiversity followed by extinctions. Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity. There will be knock-on effects to ecosystems associated with reefs, and to other pelagic and benthic ecosystems. Should CO(2) levels reach 600 ppm reefs will be eroding geological structures with populations of surviving biota restricted to refuges. Domino effects will follow, affecting many other marine ecosystems. This is likely to have been the path of great mass extinctions of the past, adding to the case that anthropogenic CO(2) emissions could trigger the Earth's sixth mass extinction.

Spatial analyses of coral distributions at spe- cies level delineate the Coral Triangle and provide new insights into patterns of diversity and endemism around the globe. This study shows that the Coral Triangle, an area extending from the Philippines to the Solomon Islands, has 605 zooxanthellate corals including 15 re- gional endemics. This amounts to 76% of the world's total species complement, giving this province the world's highest conservation priority. Within the Coral Triangle, highest richness resides in the Bird's Head Peninsula of Indonesian Papua which hosts 574 species, with indi- vidual reefs supporting up to 280 species ha -1 . Reasons for the exceptional richness of the Coral Triangle include the geological setting, physical environment and an ar- ray of ecological processes. These findings, supported by parallel distributions of reef fishes and other taxa, provide a clear scientific justification for the Coral Triangle Ini- tiative, arguably one of the world's most significant reef conservation undertakings.

The five mass extinction events that the earth has so far experienced have impacted coral reefs as much or more than any other major ecosystem. Each has left the Earth without living reefs for at least four million years, intervals so great that they are commonly referred to as ‘reef gaps’ (geological intervals where there are no remnants of what might have been living reefs). The causes attributed to each mass extinction are reviewed and summarised. When these causes and the reef gaps that follow them are examined in the light of the biology of extant corals and their Pleistocene history, most can be discarded. Causes are divided into (1) those which are independent of the carbon cycle: direct physical destruction from bolides, ‘nuclear winters’ induced by dust clouds, sea-level changes, loss of area during sea-level regressions, loss of biodiversity, low and high temperatures, salinity, diseases and toxins and extraterrestrial events and (2) those linked to the carbon cycle: acid rain, hydrogen sulphide, oxygen and anoxia, methane, carbon dioxide, changes in ocean chemistry and pH. By process of elimination, primary causes of mass extinctions are linked in various ways to the carbon cycle in general and ocean chemistry in particular with clear association with atmospheric carbon dioxide levels. The prospect of ocean acidification is potentially the most serious of all predicted outcomes of anthropogenic carbon dioxide increase. This study concludes that acidification has the potential to trigger a sixth mass extinction event and to do so independently of anthropogenic extinctions that are currently taking place.

Recipients of Darwin Medals from the International Society of Reef Studies are requested to write an overview of the work that led to their award. This account is a personal perspective of thirty-five years work on corals. The fields of taxonomy, biogeography, palaeontology, molecular biology, and evolution are presented in an historical context. Emphasis is given to the changing relevance of these fields to today’s world of information technology and the ever-increasing conservation needs.

One of the key issues in coral evolutionary biology is the significance of interspecific hybridisation in shaping modern reef corals. Despite this, few detailed studies of speciation and evolution exist for scleractinians. We examined molecular relationships among 25 species of the species-rich scleractinian genus Montipora sampled from Irian Jaya (Indonesia) and Magnetic Island (central Great Barrier Reef) using a nuclear and mitochondrial marker. Mitochondrial DNA (mtDNA) haplotypes are shared among several species and at least four species are not monophyletic based on the nuclear intron sequences. Moreover, although the mtDNA and nuclear trees have similar topologies, there are several important inconsistencies. These results, in combination with the observation of simultaneous spawning of and in vitro cross-fertility between some Montipora species, suggest that occasional gene exchange through interspecific hybridisation occurs between a small number of species in this coral genus. Little correlation was observed between morphological and molecular relationships.

This article is a summary of the main points about the evolution of corals put forward in Veron (1995). The main points presented are first, a family tree of the Scleractinia; second, an analysis of genera and their present-day global distributions, age patterns and diversity, including the Cenozoic fossil record; third, coral species and their global distributions, species determination in fossils of Pliocene to Recent age, their geologic history and geographic characteristics; fourth, the theoretical aspects of coral evolution based on surface circulation vicariance, reticulate evolution, and the nature and origin of species. For non-biologists, important concepts and terms are noted in bold and are defined in a glossary at the end of the text.

Coral reef geomorphology and community composition were investigated in the tropical northeastern Pacific during April 1994. Three areas were surveyed in the Revillagigedo Islands (Mexico), and an intensive study was conducted on Clipperton Atoll (1,300 km SW of Acapulco), including macro-scale surface circulation, sea surface temperature (SST) climatology, geomorphology, coral community structure, zonation, and biogeography. Satellite-tracked drifter buoys from 1979–1993 demonstrated complex patterns of surface circulation with dominantly easterly flow (North Equatorial Counter Current, NECC), but also westerly currents (South Equatorial Current, SEC) that could transport propagules to Clipperton from both central and eastern Pacific regions. The northernmost latitude reached by the NECC is not influenced by El Nino-Southern Oscillation (ENSO) events, but easterly flow velocity evidently is accelerated at such times. Maximum NECC flow rates indicate that the eastern Pacific barrier can be bridged in 60 to 120 days. SST anomalies at Clipperton occur during ENSO events and were greater at Clipperton in 1987 than during 1982–1983. Shallow (15–18 m)and deep (50–58 m) terraces are present around most of Clipperton, probably representing Modern and late Pleistocene sea level stands. Although Clipperton is a well developed atoll with high coral cover, the reef-building fauna is depauperate, consisting of only 7 species of scleractinian corals belonging to the generaPocillopora, Porites, Pavona andLeptoseris, and 1 species of hydrocoral in the genusMillepora. The identities of the one Pocilpopora species and one of the twoPorites species are still unknown. Two of the remaining scleractinians (Pavona minuta, Leptoseris scabra) and the hydrocoral (Millepora exaesa), all formerly known from central and western Pacific localities, represent new eastern Pacific records. Scleractinian corals predominate (10–100% cover) over insular shelf depths of 8 to 60m, and crustose coralline algae are dominant (5–40% cover) from 0.5 to 7m. Spur and groove features, constructed of alternating frameworks ofPocillopora andPorites, and veneered with crustose coralline algae, are generally well developed around most atoll exposures. Although crustose coralline algae predominate in the breaker zone (with up to 100% cover), a prominent algal ridge is absent with only a slight buildup (ca. 10 cm) to seaward. Frequent grazing by the pufferfishArothron meleagris results in the removal of large amounts of live tissue and skeleton fromPorites lobata. Acanthaster planci is present, but rare. The grazing of large diadematid sea urchins, (2 species each ofDiadema andEchinothrix) on dead corals cause extensive erosion in some areas. Large numbers of corals on the 15–18 m terrace had recently suffered partial (P. lobata, 60–70% maximum of all colonies sampled) or total (Pocillopora sp., 80% maximum) mortality. The lengths of regenerating knobs and the rates of linear skeletal growth inP. lobata, determined by sclerochronologic analysis, indicated a period of stress during 1987. Massive skeletal growth is significantly higher at intermediate (16–17 m) than shallow (6–8 m) depths with mean extension rates of 1.5 mm yr−1 inP. lobata and 1.4 mm yr−1 inP. minuta at intermediate depths. Skeletal growth inP. lobata was depressed during the 1987 El Nifio event at Clipperton. The branching coralPocillopora sp. demonstrated high and similar skeletal growth rates at both shallow (25.4 mm yr−1) and intermediate (26.5 mm yr−1) depths. The presence of widely distributed Indo-Pacific zooxanthellate corals at Clipperton and the Revillagigedo Islands indicates that these NE Pacific Islands probably serve as a stepping stone for dispersal into the far eastern Pacific region.

Electrophoretic surveys of 13 enzyme-coding loci distinguished unambiguously five morphologically defined species of Porites and two species of Goniopora. Each species was identifiable solely by unique, qualitative banding patterns at 1–6 loci. Genetic distances give preliminary estimates that these Porites species diverged from common ancestors 8–22 Ma during the Miocene, and that the two Goniopora species diverged about 3.5 Ma in the Pliocene, assuming Porites evolved from Goniopora 55 million years ago (Ma).

Spatial analyses of coral distributions at species level delineate the Coral Triangle and provide new insights into patterns of diversity and endemism around the globe. This study shows that the Coral Triangle, an area extending from the Philippines to the Solomon Islands, has 605 zooxanthellate corals including 15 regional endemics. This amounts to 76% of the world’s total species complement, giving this province the world’s highest conservation priority. Within the Coral Triangle, highest richness resides in the Bird’s Head Peninsula of Indonesian Papua, which hosts 574 species, with individual reefs supporting up to 280 species ha−1. The Red Sea/Arabian region, with 364 species and 27 regional endemics, has the second highest conservation priority. Reasons for the exceptional richness of the Coral Triangle include the geological setting, physical environment, and an array of ecological and evolutionary processes. These findings, supported by parallel distributions of reef fishes and other taxa, provide a clear scientific justification for the Coral Triangle Initiative, arguably one of the world’s most significant reef conservation undertakings.

Results of a long-term study of the taxonomy, distribution and abundance of the hermatypic corals of the Ryukyu Is. and mainland Japan indicate that the present high diversity is threatened by a quantitative and qualitative decrease in available habitat caused by Acanthaster planci predation and human-induced environmental deterioration. Ninety-eight sites were studied, allowing detailed comparison between the three main groups of the Ryukyu Is. (Yaeyama, Okinawa and Amami Groups) and seven principal coral regions of mainland Japan (Tanegashima, Amakusa Is., the Tosashimizu and Kushimoto regions, and the Shirahama, Izu and Tateyama Peninsulas). Within this area, 400 species have been recorded and 9 additional species are recorded from the literature, from additional localities, or with doubt, from the Ryukyu Is. In non-mutually exclusive distribution and abundance categories for the Ryukyu Is. and mainland Japan: 129 species are common in at least some Japanese localities; 24 are widely dispersed within the Indo-Pacific, but occur in small, perhaps disjunct populations in Japan; 149 are uncommon throughout their Indo-west Pacific distribution ranges including Japan; 38 are restricted to the Yaeyama Group where all but three are uncommon or rare; 69 purely reefal (Ryukyu Is.) species are rare; 17 are rare in the Ryukyu Is. but are relatively common in mainaland locations; and 8 species appear to be endemic to mainland Japan and adjacent Asian countries. Some 37% of all Japanese hermatypic corals are uncommon throughout their range in Japan and are at some risk of regional extinction, 29% of others are rare and at substantial risk as they occur only in very limited areas of high diversity or in species-specific refuges. These sites are dientified. Of the 8 endemic species, 5 are primarily restricted to species-specific refuges. These data indicate an unstable situation. At least one third of all Japanese hermatypic species will eventually be at risk if the present causes of diversity decrease are not remedied.

Nucleotide sequences have been determined for 31 homologous 118 base-pair highly repeated DNA sequences from seven species ofAcropora. A matrix was constructed from the sequence data and subjected to phylogenetic analysis using heuristic search routines in the PAUP (phylogenetic analysis using parsimony) program, Version 3.0L. These analyses confirm a close relationship between two species of one subgeneric group (A. pulchra andA. millepora), but identify a division in a group of six species which is contrary to taxonomic groupings based on morphological criteria.

Two of the most abundant corals of the Great Barrier Reef Acropora cuneata and Acropora palifera, can be distinguished reliably by conventional taxonomic methods only if large specimens of both species are collected from the same uniform biotope. In this study gross and microscopic examination of the corallite structures of large coralla, collected from a reef crest biotope, were used to confirm the assignment of these specific names to two electrophoretically distinct groups of corals. Identifications based on genetic and morphological data gathered from small fragments of coralla collected from five different sites were in agreement for two sites within which skeletal data were adequate for taxonomic purposes (i.e. one reef crest and one outer lagoon site). However, specimens collected from the other three sites could be identified reliably only by using the electrophoretic data. These results confirm that small fragments from diverse habitats may not be adequate for morphologically based identification. The application of electrophoretic identifications to the results of an earlier electrophoretic survey of 76 sites on 11 reefs revealed that, although A. palifera and A. cuneata frequently co-occur, they have significantly different habitat distributions. Acropora cuneata is more commonly associated with high energy environments such as the reef crest, whereas A. palifera occurs most commonly in the sheltered reef lagoons and on the deeper reef slopes.

Coral reefs are the most biologically diverse of shallow water marine ecosystems but are being degraded worldwide by human activities and climate warming. Analyses of the geographic ranges of 3235 species of reef fish, corals, snails, and lobsters revealed that between 7.2% and 53.6% of each taxon have highly restricted ranges, rendering them vulnerable to extinction. Restricted-range species are clustered into centers of endemism, like those described for terrestrial taxa. The 10 richest centers of endemism cover 15.8% of the world's coral reefs (0.012% of the oceans) but include between 44.8 and 54.2% of the restricted-range species. Many occur in regions where reefs are being severely affected by people, potentially leading to numerous extinctions. Threatened centers of endemism are major biodiversity hotspots, and conservation efforts targeted toward them could help avert the loss of tropical reef biodiversity.

Existing marine reserves are largely ineffective and as a whole remain insufficient for the protection of coral reef diversity.

In their report “regional-scale assembly rules and biodiversity of coral reefs” (25 May, p. [1532][1]), David R. Bellwood and Terry P. Hughes make several statements that warrant rebuttal. First, they say that “our understanding of regional-scale patters of biodiversity on coral reefs…has

Reef Evolution . Rachel Wood. Oxford University Press, Oxford, 1999. 426 pp. $100, £55. ISBN 0-19-854999-7. Paper, $37.50, £22.50. ISBN 0-19-857784-2. Wood's overview of reef processes, primarily from a geological perspective, provides an admirable synthesis that will have a substantial impact on all who study reefs, biologists and geologists alike.

The basement and much of the volume of the northern barrier reefs are Miocene in age. Formation of the ancestral northern barrier reefs was greatly affected by late Miocene crustal instability associated with formation of the Papuan Basin. Present physiographic features are primarily the product of Quaternary eustatic changes. Present morphologies of the deltaic and far northern dissected reefs are discussed in relation to what is known of the geological history of the area.

Ribbon reef is a general term applied to most of the shelf-edge reefs of the Northern Region. The principal morphological characters of these reefs are described from aerial photographs. Their position in relation to the Queensland Trench is described from direct observation with the use of Scuba and from soundings. The depth and position of major reef zones and their substrates and dominant biota are described from transects of Tijou and Great Detached reefs.

The outer barrier reefs north of the ribbon reefs are composed of two distinctly different reef types, here called ‘deltaic’ reefs and far northern ‘dissected’ reefs. Two reefs of each of these types are described. The deltaic reef system is composed of 96 km of reef front characterized by the presence of regular, well defined channels containing very strong tidal currents, and also by the presence of a deltaic pattern at the reef back. The dissected reefs are the northernmost of the barrier reefs. They are composed of many small E-W elongate reefs interspersed by many wide channels. Both reef types are part of the one structure, their differing surface morphologies being attributed to bathymetric and hydrodynamic factors of the present and of the past.

Coral reef ecosystems are seriously threatened by changing conditions in the ocean. Although many factors are implicated, climate change has emerged as a dominant and rapidly growing threat. Developing a long-term strategic plan for the conservation of coral reefs is urgently needed yet is complicated by significant uncertainty associated with climate change impacts on coral reef ecosystems. We use Modern Portfolio Theory to identify coral reef locations globally that, in the absence of other impacts, are likely to have a heightened chance of surviving projected climate changes relative to other reefs. Long-term planning that is robust to uncertainty in future conditions provides an objective and transparent framework for guiding conservation action and strategic investment. These locations constitute important opportunities for novel conservation investments to secure less vulnerable yet well-connected coral reefs that may, in turn, help to repopulate degraded areas in the event that the climate has stabilized.

Activity influences evaporative rate and the only valid way of comparing rates of loss among individuals is to compare standard rates of loss (SRL), i.e. the rate of loss of inactive animals. Body size probably influences interspecific differences in SRL and survival time, but because of the operation of size-independent influences, is evident only when size differences are large. The chief mode of adaptation to xeric habitats is a reduction in SRL; lizards from habitats differing in degree of aridity had similar water contents and vital limits of water loss.

Sphenomorphus quoyii is found near streams in a wide variety of climates; the animals of the present study were from the New England Plateau. In this area minimum winter air and soil temperatures frequently go below 0?C. There is a hibernation period from May to September (inclusive). Testis weights begin increasing in April and continue to do so throughout the hibernation period reaching a maximum by the September emergence. Ovary weights also begin increasing before the hibernation period and continue increasing until the ova are released into the oviduct in October. Seasonal variation is found in the number of relatively ripe ova, in ovum diameters and in oviduct diameters. Oviduct diameter varies with snout-vent length; there is no sharp distinction in size between oviducts which contained embryos the previous year and those which did not. From two to seven young are born in December or January. The sex ratio is skewed towards females except for a period of approximately one month after emergence from hibernation. * * * Sphenomorphus quoyii is distributed along the coastline of eastern and southeastern Aus- tralia and inland into the high altitude area of the Great Dividing Range. Lizards used in this study were all taken from Boorolong Creek, Dumaresq Creek or their smaller tributary creeks near Armi- dale, New South Wales (an area of 9 x 6 miles). This area, part of the New England Plateau, has an altitude of approximately 3,000 to 3,500 feet. Maximum and minimum environmental tempera- tures for 1967 and 1968, recorded at the University of New England, 14 miles from the study area, showed great seasonal fluctuation, minimum air temperatures frequently going below -5?C, the lowest reading being -7.6?C. Minimum soil temperatures at depths of 5 and 10 cm were as low as -0.7 and 1.1?C respectively. Summers were relatively hot with air and soil temperatures at 5 and 10 cm depth reaching maxima of 32.2, 40.2 and 36.2?C respectively. S. quoyii avoids very cold conditions by hibernating during the winter months of May to September (Veron, in prep.).