Coral Reef Fauna Research Articles

Differential Responses of Emergent Intertidal Coral Reef Fauna to a Large-Scale El-Niño Southern Oscillation Event: Sponge and Coral Resilience

There is a paucity of information on the impacts of the 1997–8 El Niño event and subsequent climatic episodes on emergent intertidal coral reef assemblages. Given the environmental variability intertidal reefs experience, such reefs may potentially be more resilient to climatic events and provide important insights into the adaptation of reef fauna to future ocean warming. Here we report the results of a 17-year (1995–2011) biodiversity survey of four emergent coral reef ecosystems in Bahia, Brazil, to assess the impact of a major El Niño event on the reef fauna, and determine any subsequent recovery. The densities of two species of coral, Favia gravida and Siderastrea stellata, did not vary significantly across the survey period, indicating a high degree of tolerance to the El Niño associated stress. However, there were marked decreases in the diversity of other taxa. Molluscs, bryozoans and ascidians suffered severe declines in diversity and abundance and had not recovered to pre-El Niño levels by the end of the study. Echinoderms were reduced to a single species in 1999, Echinometra lucunter, although diversity levels had recovered by 2002. Sponge assemblages were not impacted by the 1997–8 event and their densities had increased by the study end. Multivariate analysis indicated that a stable invertebrate community had re-established on the reefs after the El Niño event, but it has a different overall composition to the pre-El Niño community. It is unclear if community recovery will continue given more time, but our study highlights that any increase in the frequency of large-scale climatic events to more than one a decade is likely to result in a persistent lower-diversity state. Our results also suggest some coral and sponge species are particularly resilient to the El Niño-associated stress and therefore represent suitable models to investigate temperature adaptation in reef organisms.

Resilience to Disturbance Despite Limited Dispersal and Self-Recruitment in Tropical Barrel Sponges: Implications for Conservation and Management

While estimates of connectivity are important for effective management, few such estimates are available for reef invertebrates other than for corals. Barrel sponges are one of the largest and most conspicuous members of the coral reef fauna across the Indo-Pacific and given their large size, longevity and ability to process large volumes of water, they have a major role in reef functioning. Here we used a panel of microsatellite markers to characterise the genetic structure of two barrel sponge species, Xestospongia testudinaria and a currently undescribed Xestospongia species. We sampled across seven populations in the Wakatobi Marine National Park, SE Sulawesi (Indonesia) spanning a spatial scale of approximately 2 to 70 km, and present the first estimates of demographic connectivity for coral reef sponges. Genetic analyses showed high levels of genetic differentiation between all populations for both species, but contrasting patterns of genetic structuring for the two species. Autocorrelation analyses showed the likely dispersal distances of both species to be in the order of 60 and 140 m for Xestopongia sp. and Xestospongia testudinaria, respectively, which was supported by assignment tests that showed high levels of self-recruitment (>80%). We also found consistently high inbreeding coefficients across all populations for both species. Our study highlights the potential susceptibility of barrel sponges to environmental perturbations because they are generally long-lived, slow growing, have small population sizes and are likely to be reliant on self-recruitment. Surprisingly, despite these features we actually found the highest abundance of both barrel sponge species (although they were generally smaller) at a site that has been severely impacted by humans over the last fifty years. This suggests that barrel sponges exhibit environmental adaptation to declining environmental quality and has important implications for the management and conservation of these important reef species.

Reduced Diversity and High Sponge Abundance on a Sedimented Indo-Pacific Reef System: Implications for Future Changes in Environmental Quality

Although coral reef health across the globe is declining as a result of anthropogenic impacts, relatively little is known of how environmental variability influences reef organisms other than corals and fish. Sponges are an important component of coral reef fauna that perform many important functional roles and changes in their abundance and diversity as a result of environmental change has the potential to affect overall reef ecosystem functioning. In this study, we examined patterns of sponge biodiversity and abundance across a range of environments to assess the potential key drivers of differences in benthic community structure. We found that sponge assemblages were significantly different across the study sites, but were dominated by one species Lamellodysidea herbacea (42% of all sponges patches recorded) and that the differential rate of sediment deposition was the most important variable driving differences in abundance patterns. Lamellodysidea herbacea abundance was positively associated with sedimentation rates, while total sponge abundance excluding Lamellodysidea herbacea was negatively associated with rates of sedimentation. Overall variation in sponge assemblage composition was correlated with a number of variables although each variable explained only a small amount of the overall variation. Although sponge abundance remained similar across environments, diversity was negatively affected by sedimentation, with the most sedimented sites being dominated by a single sponge species. Our study shows how some sponge species are able to tolerate high levels of sediment and that any transition of coral reefs to more sedimented states may result in a shift to a low diversity sponge dominated system, which is likely to have subsequent effects on ecosystem functioning.

Isolation and characterisation of twelve polymorphic microsatellite markers for Xestospongia spp. and their use for confirming species identity

Barrel sponges are one of the largest and most conspicuous members of the coral reef fauna across the Indo-Pacific that are under threat from habitat degradation. Twelve novel microsatellite markers were developed for Xestospongia testudinaria from 454 sequence data and scored across 47 individual barrel sponges collected from the Sampela reef in the Wakatobi Marine National Park, Indonesia. All loci except one was polymorphic with the number of alleles per locus ranging from 5 to 24. Observed heterozygosity ranged from 0.08 to 0.77 and FIS values ranged from −1.61 to 0.77, with the majority of loci being in Hardy–Weinberg equilibrium (HWE). We then tested our markers on 28 likely Xestospongia bergquistia specimens from the same reef. Observed heterozygosity ranged from 0.23 to 0.593 and FIS values ranged from −0.078 to 0.373; all but two loci were in HWE. Furthermore, we confirmed the differentiation of these two species by Principle Coordinate Analysis and Analysis of Molecular Variance. These markers will be useful for a range of future fine-scale population genetics studies for these two important reef species.

Validation of internal reference genes for gene expression analysis in Montipora digitata, Pocillopora damicornis and Acropora nasuta by quantitative real-time PCR

Abstract The highest concentrations of Indo-Pacificreef coral species occur in the Coral Triangle (CT). A large part of the CT is bordering the edge of the Sunda Shelf, with the highest species richness to the north and east of the Sunda Shelf, including parts of Malaysia, Indonesia, the Philippines, Papua New Guinea, Timor Leste, and the Solomons. Within eastern Indonesia also differences in coral reef fauna can be observed, e.g. between Sulawesi and West Papua. There is no relation with Wallace’s Line or with Wallacea, the area in between the Sunda and Sahul shelves, which both relate to terrestrial biogeography. The west-east variation in marine species diversity can be explained hypothetically in four ways. The CT has more species because of (1) plate tectonics; (2) a higher species survival during the Last Glacial Maximum (LGM); (3) higher habitat variability, especially from near-shore (shallow, sheltered, murky water) to offshore (deep, ex-posed clear water); (4) inter-oceanic currents running in north-south direction between the Pacificand the Indian Ocean, such as the Indonesian Through Flow (ITF), pre-venting connections between west and east. Future re-search should give more insight in the relative im portance of these four factors and whether there are clear-cut lines of division or zones of transition with ever-changing species compositions.

Revealing the Appetite of the Marine Aquarium Fish Trade: The Volume and Biodiversity of Fish Imported into the United States

The aquarium trade and other wildlife consumers are at a crossroads forced by threats from global climate change and other anthropogenic stressors that have weakened coastal ecosystems. While the wildlife trade may put additional stress on coral reefs, it brings income into impoverished parts of the world and may stimulate interest in marine conservation. To better understand the influence of the trade, we must first be able to quantify coral reef fauna moving through it. Herein, we discuss the lack of a data system for monitoring the wildlife aquarium trade and analyze problems that arise when trying to monitor the trade using a system not specifically designed for this purpose. To do this, we examined an entire year of import records of marine tropical fish entering the United States in detail, and discuss the relationship between trade volume, biodiversity and introduction of non-native marine fishes. Our analyses showed that biodiversity levels are higher than previous estimates. Additionally, more than half of government importation forms have numerical or other reporting discrepancies resulting in the overestimation of trade volumes by 27%. While some commonly imported species have been introduced into the coastal waters of the USA (as expected), we also found that some uncommon species in the trade have also been introduced. This is the first study of aquarium trade imports to compare commercial invoices to government forms and provides a means to, routinely and in real time, examine the biodiversity of the trade in coral reef wildlife species.

Biodiversity of foraminifera from Late Pleistocene to Holocene coral reefs, South Sinai, Egypt

Tropical coral reefs are among the most diverse marine ecosystems. In order to better understand temporal and spatial variation in late Quaternary biodiversity, foraminiferal faunas of two fossil, raised reef terraces at the southern Sinai Peninsula were studied and compared to modern coral reef faunas. Eleven U-series dates of shell fragments of the giant clam Tridacna sp. indicates deposition largely during marine isotope stage 5 (MIS 5), 77–129 kyr BP, for the two raised terraces. In these terraces, Amphistegina (A. lessonii and A. lobifera) dominates the five fossil foraminiferal associations. The fossil reef-flat association 1 has common Gypsina plana, Homotrema rubra and Acervulina spp., and fossil reef-flat association 2 consists of Amphistegina spp. Of the three fossil fore-reef associations, one has abundant porcelaneous taxa including Sorites, Amphisorus, Peneroplis and Borelis, one has a mix of porcelaneous taxa and attached-arborescent taxa (Homotrema and Placopsilina) and one has abundant attached and arborescent taxa (Miniacina, Gypsina, Acervulina and Planogypsina). The modern fringing reef is dominated by porcelaneous foraminifera, and three modern associations are identified. These include a lagoonal association with abundant Peneroplis pertusus, a reef-flat association dominated by Sorites orbiculus and a fore-reef association with porcelaneous taxa plus common H. rubra, Amphistegina lessonii and A. lobifera. Based on our data and including additional published information on regional biodiversity it appears that during MIS 5 foraminiferal biodiversity was higher and community structure was different than within the modern reefs. These data and regional paleo-climate patterns indicate that oceanographic conditions in the Red Sea were probably closer to normal marine conditions during the last interglacial than they are today.

Faune corallienne des récifs toarciens du Moyen Atlas marocain, première approche

Abstract Des récifs ont été décrits dans le Toarcien supérieur du Moyen Atlas Marocain [Elmi et al., 2002]. Ils sont localisés dans le synclinal de Awragh-Afennourir (Moyen Atlas occidental) immédiatement au sud du Moyen Atlas tabulaire. Ce sont des biohermes placés au sommet de blocs basculés. Leur épaisseur varie de 1 à 12 m. Ils reposent sur une formation datée de la zone à Levisoni, sous zone à Gemma et sont couverts par des sédiments appartenant à la partie supérieure de la zone à Meneghini. Leur paléolatitude était de 18°N. Un ensemble de 18 échantillons de coraux collectés par S. Elmi sont ici analysés. Ils constituent un témoignage exceptionnel de faune corallienne récifale pour cet étage. Les taxons appartenant aux genres Cladophyllia, Diplocoenia ?, Montlivaltia (deux espèces), Thecosmilia (deux espèces), Isastrea ?, Latomeandra, Periseris, Microphyllia (trois espèces), et Proleptophyllia (deux espèces), ont été identifiés. La faune inclut 12 formes coloniales et 7 solitaires. Parmi les spécimens coloniaux, les formes méandroïdes avec un haut niveau d’intégration colonial sont bien représentées et fournissent un argument fort pour la présence de zooxanthelles symbiotiques. L’examen des textures micritiques et des croûtes microbialitiques, associé avec le développement important des microarchitectures pennulaires suggèrent un récif sous le niveau d’action des vagues de beau temps et des eaux plutôt mésotrophiques. Les coraux, leur forme et leur diversité, permettent de diagnostiquer des récifs de zone photique, à une profondeur et une latitude optimale. Les extensions stratigraphiques de plusieurs genres sont agrandies : nouvelle première occurrence pour Cladophyllia, Latomeandra et Periseris (peut être aussi Diplocoenia) et nouvelle dernière occurrence pour Proleptophyllia classiquement considéré comme Pliensbachien. La seule monographie disponible à caractère général sur les coraux du Lias du Maroc [Beauvais, 1986] identifie 15 taxons génériques pour le Toarcien. Tous proviennent du Haut Atlas et seulement 3 taxons sont communs avec les résultats présentés ici. La vue générale est celle d’une faune qui ressemble davantage à celle des communautés récifales du Dogger qu’à celle du Pliensbachien.

Cenozoic Diversification and Extinction Patterns in Caribbean Reef Corals: A Review

Statistical analyses of occurrence data based on collections made from scattered Caribbean sections over the past 20 years indicate that turnover occurred in the Caribbean reef coral fauna between the late Miocene and early Pleistocene. The collections have been identified using standardized procedures, and age-dates assigned using high-resolution chronostratigraphic methods. During turnover, ~80% of the > 100 species and 17 of the 41 genera that were living in the Caribbean during the early Pliocene became extinct, and > 60% of the species now living in the Caribbean originated. Turnover involved increased speciation beginning in the late Miocene and ended with a pulse of extinction in Plio-Pleistocene time. Turnover was preceded by faunal collapse during the late Oligocene to early Miocene, and it was followed by stasis during the late Pleistocene to Recent. During these preceding and succeeding intervals, reef development was at a maximum, although reef coral diversity was relatively low. As a consequence of origination preceding extinction during turnover, most modern Caribbean reef coral species originated before the Plio-Pleistocene peak of extinction, under quite different ecological conditions from those in which they have lived over the past million years. The unusual relationship between origination and extinction may have been caused by changes in productivity associated with emergence of the Central American Isthmus, followed by the onset of Northern Hemisphere glaciation.During turnover, faunal change was stepwise or gradual. Local assemblages consisted of a mix of extinct and living species, which varied in composition but not in richness. Important reef dominants such as Acropora palmata and A. cervicornis arose in the southern Caribbean and appear to have migrated northward. Faunal change took place in shallow exposed environments, before it occurred in deep protected environments that served as refuges. Plio-Pleistocene extinction was selective for corals with small colonies, and resulted in a faunal shift to the large, fast-growing species that dominate Caribbean reefs today.

Multi-Locus Phylogeny of Sponge-Dwelling Snapping Shrimp (Caridea: Alpheidae: Synalpheus) Supports Morphology-Based Species Concepts

Alpheid snapping shrimp are one of the most diverse groups of coral-reef fauna, and sponge-dwelling shrimp in the genus Synalpheus (gambarelloides species group) have in particular become a model system for studying the evolution of social biology and host use in marine invertebrates. Despite recent advances in understanding the evolution and systematics of Synalpheus, the taxonomy and phylogenetic relationships within this group remain challenging. More than 20 new species in the S. gambarelloides species group have been described over the past two decades, primarily within several cryptic species complexes, which has doubled the known diversity of this group in the West Atlantic. Here we construct a new phylogenetic tree describing relationships between 40 different species from the S. gambarelloides-group (119 individuals from across the Caribbean), using a combined dataset consisting of two mitochondrial loci (16S and COI), one nuclear protein-coding gene (elongation-factor 2), and 33 morphological characters. Putative conspecific specimens of Synalpheus from multiple locations across the Caribbean were always monophyletic (with one exception), providing strong support for the validity of species concepts based on morphology. Our study also provides further evidence for the monophyly of the S. gambarelloides-group in the Caribbean, resolves the molecular relationships within many recently described species complexes, and provides a new phylogenetic framework for future evolutionary studies of this group.

Incongruence between the distribution of a common coral reef sponge and photosynthesis

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 423:95-100 (2011) - DOI: https://doi.org/10.3354/meps08886 Incongruence between the distribution of a common coral reef sponge and photosynthesis R. J. Bannister1,2,6,*, M. O. Hoogenboom3, K. R. N. Anthony4, C. N. Battershill2,5, S. Whalan1, N. S. Webster5, R. de Nys1,2 1School of Marine and Tropical Biology, and 2AIMS@JCU Tropical Aquaculture Program, James Cook University, Townsville, Queensland 4811, Australia 3Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK 4Center for Marine Studies, University of Queensland, St Lucia, Queensland 4072, Australia 5Australian Institute of Marine Science, PMB 3, Townsville, Queensland 4810, Australia 6Present address: Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway *Email: raymond.bannister@imr.no ABSTRACT: Symbiosis between coral reef fauna and microorganisms drives the growth, maintenance and diversity of coral reef habitats. Sponges, a key faunal component of coral reefs, form complex symbiotic relationships with microorganisms which may supply over half of their nutritional requirements through photosynthesis. The habitat distribution of the coral reef sponge Rhopaloeides odorabile correlates with light availability, suggestive of photosynthesis. The present study directly investigated the hypothesis that habitat distribution of R. odorabile is correlated with photosynthesis. Results of photorespirometry trials of 30 ind. exposed to light intensities between 0 and 900 µmol photons m–2 s–1 showed no evidence of photosynthesis. Furthermore, no photopigments were present in these sponges and no cyanobacteria could be detected within the tissue. These results did not vary between sponges collected from nutrient rich inner- and mid-shelf reefs, or from oligotrophic outer-shelf reefs. These findings demonstrate that R. odorabile is not a phototrophic sponge and that habitat distributions clearly correlated with light can be due to factors other than photosynthesis. KEY WORDS: Symbiosis · Photosynthesis · Porifera · Rhopaloeides odorabile · Great Barrier Reef · Cyanobacteria Full text in pdf format PreviousNextCite this article as: Bannister RJ, Hoogenboom MO, Anthony KRN, Battershill CN, Whalan S, Webster NS, de Nys R (2011) Incongruence between the distribution of a common coral reef sponge and photosynthesis. Mar Ecol Prog Ser 423:95-100. https://doi.org/10.3354/meps08886 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 423. Online publication date: February 10, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Tempering Expectations of Recovery for Previously Exploited Populations in a Fully Protected Marine Reserve

Centuries of resource extraction have impacted coral reef ecosystems worldwide. In response, area and fishery closures are often enacted to restore previously exploited populations and reestablish diminished ecosystem function. During the 19th and 20th centuries, monk seals, pearl oysters, and two lobster species were overharvested in the Northwestern Hawaiian Islands, now managed as the Papahānaumokuākea Marine National Monument, one of the largest conservation areas in the world. Despite years of protection, these taxa have failed to recover. Here, we review each case, discussing possible factors that limit population growth, including: Allee effects, interspecific interactions, and time lags. Additionally, large-scale climate changes may have altered the overall productivity of the system. We conclude that overfishing of coral reef fauna may have broad and lasting results; once lost, valuable resources and services do not quickly rebound to pre-exploitation levels. In such instances, management options may be limited to difficult choices: waiting hundreds of years for recovery, actively restoring populations, or accepting the new, often less desirable, alternate state.

Diversity and abundance of sponges in bathyal coral reefs of Rockall Bank, NE Atlantic, from boxcore samples

Recent (2004) boxcoring on the SW Rockall Bank, west of Ireland (approx. 55°N 15°W, depths between 557 and 1407 m) yielded 95 species of sponges in 20 boxcore attempts. There are no published reports of Rockall Bank coral reef sponge fauna, but comparison with trawl and dredge efforts in neighbouring parts of the NE Atlantic (east of Rockall Trench, off the Scottish coasts) made in the late 19th and early 20th century leads to the conclusion that our boxcoring efforts yielded similar numbers of species as these more elaborate collecting programs. Numbers of specimens for all boxcore samples combined was 466, together occupying a total volume of approx. 3.38 l, based on length x width x height measurements of all individuals. These results indicate a generally low biomass of sponges contributing to the deep water coral reef fauna. Species composition in this bathyal habitat shows a high heterogeneity (Eveness J’: 0.81–0.97) and the majority of sponge individuals does not exceed 1 cm3 in volume. Nevertheless, high densities of a large hexactinellid species, Asconema aff. setubalense (up to 30 cm in height), were encountered locally. Sponge community analysis showed that there was no clear correlation between coral cover and sponge diversity, and only a weak correlation between coral cover and abundance and volume of sponges. This, combined with the overall very small size of the sponges, suggests that substratum is not a limiting factor for their occurrence.

Diversification of a New Atlantic Clade of Scleractinian Reef Corals: Insights from Phylogenetic Analysis of Morphologic and Molecular Data

Recent molecular analyses of the traditional scleractinian suborder Faviina have revealed a new Atlantic clade of reef corals, which disagrees with traditional classification. The new clade contradicts long-held notions of Cenozoic diversification being concentrated in the Pacific, and of Atlantic species bearing close evolutionary relationships with Pacific species. In the present paper, we outline an approach for integrating molecular, morphologic, and fossil data, which will allow future examination of the timing and phylogenetic context of the divergence of the new Atlantic clade. Our analyses are preliminary and focus on 17 genetically characterized species within the new Atlantic clade. The molecular dataset consists of 630 base pairs from the COI gene and 1143 base pairs from the cytB gene. The morphologic dataset consists of 25 traditional morphologic characters (86 states) in 57 species (23 extant and 32 extinct). Phylogenetic analyses are first performed separately on the molecular and morphologic (extant taxa only) datasets. Subsequent phylogenetic analyses involve adding fossil taxa to the morphologic dataset and performing a combined analysis for extant taxa.The results of both molecular and morphologic phylogenetic analyses disagree with traditional classification. They also disagree with each other, indicating the two datasets provide different phylogenetic signals and are informative at different taxonomic levels. Molecular trees for the mitochondrial genes analyzed have higher bootstrap support for deeper nodes in the tree; morphologic trees have higher bootstrap support near branch tips. The addition of fossils to the morphologic dataset does not improve resolution within phylogenetic trees, but it does indicate that all of the major subclades within the new Atlantic clade originated prior to middle Eocene time. The pulse of origination associated with Plio-Pleistocene faunal turnover involved speciation within well-established clades. Examination of the geographic distributions of the taxa within each of the four resulting trees indicates that the origin of the Brazilian reef coral fauna involved more than one separate dispersal event or that the fauna may be descended from a larger Mio-Pliocene Atlantic (Caribbean to Brazil) species pool, portions of which have subsequently become extinct. Because of the complex nature of scleractinian evolution (involving possible hybridization), we advocate using a phylogenetic approach that compares multiple independent datasets, including datasets that are currently being developed for new microstructural characters.

Fishes of the Dampier Archipelago, Western Australia

The shallow-water fish fauna of the Dampier Archipelago (to a depth of 30 m), which now totals 650 species, consists of a rich coral reef fauna (465 species), a moderate mangrove one (116 species), smaller numbers of soft bottom inhabitants (106 species) and a relatively low number of pelagic species (67). The outer islands are inhabited predominantly by coral reef fishes whereas inner areas close to the mainland are occupied by mangrove and silty-bottom dwellers. The inter-island passages have a relatively rich soft bottom fauna. Species diversity is at its highest in areas of high topographic diversity, the area with the highest diversities lying along the exposed northern perimeter of the archipelago. These more off-shore areas are apparently under the direct influence of the off-shore flowing, warm Leeuwin Current, where water clarity is high and propagules from upstream locations, such as the Rowley Shoals, are deposited. The more in-shore areas are affected by high turbidity resulting from mangrove communities and high freshwater runoff during cyclonic events. The fish fauna of the archipelago is closely related to that occurring at the more off-shore Monte Bello Islands, but is noticeably less diverse than the islands of the West Pilbara region to the south. Some elements of the Kimberley fish fauna also inhabit the archipelago.

Phylogenetic evidence for an ancient rapid radiation of Caribbean sponge-dwelling snapping shrimps ( Synalpheus)

A common challenge in reconstructing phylogenies involves a high frequency of short internal branches, which makes basal relationships difficult to resolve. Often it is not clear whether this pattern results from insufficient or inappropriate data, versus from a rapid evolutionary radiation. The snapping shrimp genus Synalpheus, which contains in excess of 100 species and is a prominent component of coral-reef faunas worldwide, provides an example. Its taxonomy has long been problematic due to the subtlety of diagnostic characters and apparently widespread variability within species. Here we use partial mt COI and 16S rRNA sequences and morphological characters to reconstruct relationships among 31 species in the morphologically well-defined gambarelloides species group, a putative clade of obligate sponge associates that is mostly endemic to the Caribbean and contains the only known eusocial marine animals. Analysis of the combined data produced a single tree with good support for many terminal clades and for relationships with outgroups, but poor support for branches near the base of the gambarelloides group. Most basal branches are extremely short and terminal branches are long, suggesting a relatively ancient, but rapid radiation of the gambarelloides group. This hypothesis is supported by significant departure from a null model of temporally random cladogenesis. Calibration of divergence times among gambarelloides-group species using data from three geminate pairs of Synalpheus species separated by the isthmus of Panamá suggests a major radiation between ∼5 and 7 Mya, a few My before final closure of the Panamanian seaway during a period of spreading carbonate environments in the Caribbean; a second, smaller radiation occurred ∼4 Mya. This molecular evidence for a rapid radiation among Caribbean marine organisms in the late Miocene/early Pliocene is strikingly similar to patterns documented from fossil data for several other Caribbean reef-associated invertebrate taxa. The similar patterns and timing of cladogenesis evidenced by molecular and fossil data for different Caribbean and East Pacific taxa suggests that the radiation involved a wide range of organisms, and strengthens the case that poor basal resolution in the gambarelloides group of Synalpheus reflects a real evolutionary phenomenon. The rapid radiation also helps explain the historical difficulty of diagnosing species in Synalpheus.

Historical biogeography of Indo‐western Pacific coral reef biota: is the Indonesian region a centre of origin?

AimTo apply the modern theory of vicariant biogeography to the study of evolution of the coral reef fauna in the Indo‐western Pacific region.LocationIndian and western Pacific Oceans.MethodsUse of taxa ladograms and Brooks Parsimony Analysis to reconstruct relationships between geographical areas.ResultsThe analysis seems to indicate that the Indonesian region, long stated to be a `centre of origin' for most of the Indo‐West Pacific marine fauna, is a very derived area in the general area cladogram; and that most of the lineages may have originated in the western Indian Ocean, Australia, or the South‐western Pacific (probably from lineages that had remained isolated after the breakup of the Gondwanan supercontinent, or because of the movement of island arcs). A series of events that fragmented an originally widespread biota seems to be highly congruent with geological events that caused the break up of Gondwanaland.Main conclusionsContrary to several previous claims, based mostly on descriptive, rather than analytical, studies, most lineages of coral reef fauna inhabiting the Indo‐western Pacific region probably originated through vicariant events associated with, and following the break up of Gondwana. A general pattern of biotic distribution that is highly congruent with geological data shows that even if long range dispersal and sympatric speciation may in some cases have taken place, they have not probably been the predominant mechanism of speciation in the clades examined.

REDESCRIPTION OF PHYLLIDIOPSIS SINAIENSIS (YONOW, 1988) (NUDIBRANCHIA: DORIDOIDEA: PHYLLIDIIDAE), WITH A REVIEW OF THE RED SEA PHYLLIDIIDAE

Phyllidiopsis sinaiensis (Yonow, 1988), of which only one single preserved specimen had been known, was rediscovered in the northern Red Sea. The dorsal colour-pattern of living individuals is presented for the first time, and the anatomy of P. sinaiensis is described in detail. Major features of the holotype previously used to characterise the species are shown to be artifacts. Principal distinguishing characters of P. sinaiensis include the central tubercle ridge, large and multicompound, broad based, pink tubercles, bicoloured black and pink rhinophores, the very elongate muscular oesophageal segment, the distinct stomach and the extremely long, convoluted prostate that is bound together by connective tissue. In some specimens, the bases of the tubercles may fuse leading to a predominantely pink dorsum with only a few black lines. Phyllidiopsis sinaiensis appears to be among the most common nudibranchs in the Gulf of Aqaba. The fact that it has not been reported since its original collection in 1980 can be explained by being confused with the externally similar, well-known species Phyllidiella pustulosa (Cuvier, 1804). A review of the phyllidiid fauna of the Red Sea reveals eleven valid species that can all be identified with the key presented herein. With four out of eleven species, phyllidiid endemism (36%) is high in the Red Sea. This is in contrast to recent palaeobiological hypotheses of a post-glacial origin of the Red Sea coral reef fauna.

Unexpected richness of reef corals near the southern Amazon River mouth

Manoel Luis Reefs (00° 52’ S, 44° 15’W),located 180 km north of Sao Luis, offMaranhao State, represent the northernmostoutpost of the Brazilian reef coral fauna, andthe closest well-developed reefs to theAmazon River mouth (Figure 1). In July1998, during a reef fish survey along theBrazilian coast, we found a surprising richness of corals and other reef associatedorganisms in the area, including nine speciesof reef corals and two milleporans, six ofwhich were not previously reported for theNorthern coast of Brazil (Belem et al. 1986,Veron 1996). Despite its proximity to the Amazon Rivermouth, the West flowing Equatorial Currentprovides the region with clear and salinewater. The tidal range is about 6.5 m andvisibility ranged between 20 and 30 m duringour 12 day visit. The reef is approximately y-shaped, with about 10 km in its SE-NEaxis (Figure 1). It is constituted by approximately circular pinnacles, ranging from 50 to 300 m in diameter.The pinnacles rise from 25–30 m depth to near the surface, the tops of some being exposed on the lowesttides. Superimposed coralline algal crusts constitute the framework of the reef, which is sparsely covered withcolonies of Agaricia fragilis(Dana), Favia gravidaVerrill, Madracis decactis(Lyman), Meandrina brazilien-sisMilne Edwards & Haime, Montastraea cavernosa(Linne), Mussismilia hispida(Verrill), Poritescf. ast-reoidesLamarck, Scolymia wellsiLaborel, Siderastrea stellataVerrill, Millepora alcicornis(Linne) and abizarre sub-massive form of Millepora,possibly a new species. Fifty-five percent of the reef coral fauna surveyed iscomposed of species widely distributed in the Western Atlantic and 45 % of Brazilian endemics (Belem et al.1986, Hetzel and Castro 1994). At the time of our visit all coral species were bleached. The Manoel Luis Reefs region, due to its proximity to the Amazon River, may play a major role in geneflow between northern and southern Western Atlantic reef fauna. The presence and great abundance ofCaribbean reef organisms which do not occur along the eastern coast of South America, such as the purple reeffish Chromis scotti,provide additional evidence that the Manoel Luis Reefs may be one of the main faunalstepping stones between the Caribbean and the Brazilian coast (Collette & Rutzler 1977).

Origination preceding extinction during late Cenozoic turnover of Caribbean reefs

AbstractStatistical analyses of occurrence data derived from new collections through scattered Caribbean sections indicate that increased speciation preceded a pulse of extinction during regional turnover of the Caribbean reef coral fauna in Plio-Pleistocene time. The data are based on samples that were newly collected and identified to species using standardized procedures. Age-dates were assigned using high-resolution chronostratigraphic methods. The results show that coral species with a wide range of ecological traits originated and were added to the species pool as much as 1–2 million years before extinction peaked at the end of the turnover interval. Local assemblages consisted of a mix of extinct and living species, which varied in composition but not in richness. Extinction was selective and resulted in a faunal shift to the large, fast-growing species that dominate Caribbean reefs today. The unusual relationship between origination and extinction may have been caused by changes in oceanic circulation associated with emergence of the Central American Isthmus, followed by the onset of Northern Hemisphere glaciation. The pattern of origination preceding extinction may have been responsible for the stability of reef ecosystems during the intense climatic fluctuations of the late Pleistocene, and for the composition and structure of modern Caribbean reef ecosystems.