Extinction rate, historical population structure and ecological role of the Caribbean monk seal

The productivity and biomass of pristine coral reef ecosystems is poorly understood, particularly in the Caribbean where communities have been impacted by overfishing and multiple other stressors over centuries. Using historical data on the spatial distribution and abundance of the extinct Caribbean monk seal (Monachus tropicalis), this study reconstructs the population size, structure and ecological role of this once common predator within coral reef communities, and provides evidence that historical reefs supported biomasses of fishes and invertebrates up to six times greater than those found on typical modern Caribbean reefs. An estimated 233,000-338,000 monk seals were distributed among 13 colonies across the Caribbean. The biomass of reef fishes and invertebrates required to support historical seal populations was 732-1018 gm(-2) of reefs, which exceeds that found on any Caribbean reef today and is comparable with those measured in remote Pacific reefs. Quantitative estimates of historically dense monk seal colonies and their consumption rates on pristine reefs provide concrete data on the magnitude of decline in animal biomass on Caribbean coral reefs. Realistic reconstruction of these past ecosystems is critical to understanding the profound and long-lasting effect of human hunting on the functioning of coral reef ecosystems.     

Can a thermally tolerant symbiont improve the future of Caribbean coral reefs?

The detrimental effect of climate change induced bleaching on Caribbean coral reefs has been widely documented in recent decades. Several studies have suggested that increases in the abundance of thermally tolerant endosymbionts may ameliorate the effect of climate change on reefs. Symbionts that confer tolerance to temperature also reduce the growth rate of their coral host. Here, we show, using a spatial ecosystem model, that an increment in the abundance of a thermally tolerant endosymbiont (D1a) is unlikely to ensure the persistence of Caribbean reefs, or to reduce their rate of decline, due to the concomitant reduction in growth rate under current thermal stress predictive scenarios. Furthermore, our results suggest that given the documented vital rates of D1a‐dominated corals, increasing dominance of D1a in coral hosts may have a detrimental effect by reducing the resilience of Caribbean reefs, and preventing their long‐term recovery. This is because Caribbean ecosystems appear to be highly sensitive to changes in the somatic growth rate of corals. Alternative outcomes might be expected in systems with different community‐level dynamics such as reefs in the Indo‐Pacific, where the ecological costs of reduced growth rate might be far smaller.     

Island biogeography of Caribbean coral reef fish

Aim The goal of our study was to test fundamental predictions of biogeographical theories in tropical reef fish assemblages, in particular relationships between fish species richness and island area, isolation and oceanographic variables (temperature and productivity) in the insular Caribbean. These analyses complement an analogous and more voluminous body of work from the tropical Indo‐Pacific. The Caribbean is more limited in area with smaller inter‐island distances than the Indo‐Pacific, providing a unique context to consider fundamental processes likely to affect richness patterns of reef fish. Location Caribbean Sea. Methods We compiled a set of data describing reef‐associated fish assemblages from 24 island nations across the Caribbean Sea, representing a wide range of isolation and varying in land area from 53 to 110,860 km². Regression‐based analyses compared the univariate and combined effects of island‐specific physical predictors on fish species richness. Results We found that diversity of reef‐associated fishes increases strongly with increasing island area and with decreasing isolation. Richness also increases with increasing nearshore productivity. Analyses of various subsets of the entire data set reveal the robustness of the richness data and biogeographical patterns. Main conclusions Within the relatively small and densely packed Caribbean basin, fish species richness fits the classical species–area relationship. Richness also was related negatively to isolation, suggesting direct effects of dispersal limitation in community assembly. Because oceanic productivity was correlated with isolation, however, the related effects of system‐wide productivity on richness cannot be disentangled. These results highlight fundamental mechanisms that underlie spatial patterns of biodiversity among Caribbean coral reefs, and which are probably also are functioning in the more widespread and heterogeneous reefs of the Indo‐Pacific.     

Low natural repopulation of marginal coral communities under the influence of upwelling

The study of coral repopulation in marginal communities may provide a useful analog for understanding the dynamics of coral reefs subjected to deleterious environmental changes. Repopulation of scleractinian reef corals may strongly impact the community structure on tropical reefs; however, the extent of this process on coral communities influenced by upwelling is unknown, especially in the Caribbean. In this study, the potential for natural repopulation of coral communities subjected to wind-driven upwelling was evaluated at three sites on the island of Cubagua, Venezuela. Coral spawning behavior was recorded and both larval settlement and juvenile abundance were estimated. Upwelling did not appear to affect coral spawning behavior, since at this locality spawning occurred at dates and times similar to those reported for well-developed reefs in the Caribbean. Also, juveniles produced by brooding corals were six times more abundant than those of broadcasting species, similar to patterns on other Caribbean reefs that are not under the influence of upwelling. By contrast, mean larval settlement (4 settlers m⁻²) and juvenile abundance (0.1 juveniles m⁻²) in Cubagua were both lower than those elsewhere in the Caribbean and on Pacific reefs. Thus, the potential for repopulation of these marginal communities seems lower than for well-developed coral reefs in other regions. These results suggest that more fully developed coral reefs also may have reduced repopulation potential, as they become influenced by suboptimal environmental conditions. Handling editor: I. Nagelkerken     

Human activities as a driver of spatial variation in the trophic structure of fish communities on Pacific coral reefs

Anthropogenic activities such as land‐use change, pollution and fishing impact the trophic structure of coral reef fishes, which can influence ecosystem health and function. Although these impacts may be ubiquitous, they are not consistent across the tropical Pacific Ocean. Using an extensive database of fish biomass sampled using underwater visual transects on coral reefs, we modelled the impact of human activities on food webs at Pacific‐wide and regional (1,000s–10,000s km) scales. We found significantly lower biomass of sharks and carnivores, where there were higher densities of human populations (hereafter referred to as human activity); however, these patterns were not spatially consistent as there were significant differences in the trophic structures of fishes among biogeographic regions. Additionally, we found significant changes in the benthic structure of reef environments, notably a decline in coral cover where there was more human activity. Direct human impacts were the strongest in the upper part of the food web, where we found that in a majority of the Pacific, the biomass of reef sharks and carnivores were significantly and negatively associated with human activity. Finally, although human‐induced stressors varied in strength and significance throughout the coral reef food web across the Pacific, socioeconomic variables explained more variation in reef fish trophic structure than habitat variables in a majority of the biogeographic regions. Notably, economic development (measured as GDP per capita) did not guarantee healthy reef ecosystems (high coral cover and greater fish biomass). Our results indicate that human activities are significantly shaping patterns of trophic structure of reef fishes in a spatially nonuniform manner across the Pacific Ocean, by altering processes that organize communities in both “top‐down” (fishing of predators) and “bottom‐up” (degradation of benthic communities) contexts.     

珊瑚礁生态系统病毒研究进展

病毒对珊瑚礁生态系统中的生物进化、生物地球化学循环、珊瑚疾病等方面具有重要的生态影响。随着珊瑚礁的全球性退化，病毒在珊瑚礁生态系统中的功能与危害日益显现。综述了珊瑚礁生态系统中病毒的研究现状与进展，包括：（1）珊瑚礁病毒的多样性与分布特征（水体、宿主、核心病毒组）；（2）珊瑚礁病毒的生态功能（感染方式、促进生物进化、生物地球化学循环）；（3）珊瑚礁病毒对全球气候变化的响应（热压力、珊瑚疾病）。总体而言，珊瑚礁生态系统具有极高的病毒多样性，所发现的60个科占已知所有病毒科数量的58%。珊瑚的核心病毒组主要由双链DNA病毒、单链DNA病毒、单链逆转录病毒所组成，珊瑚黏液层对病毒具有富集作用。"Piggyback-the-Winner"（依附-胜利）是病毒在珊瑚礁中主要的生物动力学模式，其可通过水平基因迁移的方式促进礁区生物进化。病毒可通过裂解细菌与浮游藻类的途径参与珊瑚礁的生物地球化学循环，尤其是碳循环与氮循环过程。此外，病毒还具有介导珊瑚热白化与直接引发珊瑚疾病的能力，这会影响珊瑚礁生态系统应对气候变化的适应性与恢复力。基于国际上的研究进展综述，结合南海珊瑚礁生态现状提出以下研究方向，以期促进我国珊瑚礁病毒学的发展：（1）开展南海珊瑚礁中病毒多样性的识别及其时-空分布特征研究；（2）探索病毒对南海珊瑚热白化、珊瑚疾病的介导作用及其与气候变化的关系；（3）揭示病毒对南海珊瑚礁生物地球化学循环的贡献。     

Patterns of Admixture and Population Structure in Native Populations of Northwest North America

The initial contact of European populations with indigenous populations of the Americas produced diverse admixture processes across North, Central, and South America. Recent studies have examined the genetic structure of indigenous populations of Latin America and the Caribbean and their admixed descendants, reporting on the genomic impact of the history of admixture with colonizing populations of European and African ancestry. However, relatively little genomic research has been conducted on admixture in indigenous North American populations. In this study, we analyze genomic data at 475,109 single-nucleotide polymorphisms sampled in indigenous peoples of the Pacific Northwest in British Columbia and Southeast Alaska, populations with a well-documented history of contact with European and Asian traders, fishermen, and contract laborers. We find that the indigenous populations of the Pacific Northwest have higher gene diversity than Latin American indigenous populations. Among the Pacific Northwest populations, interior groups provide more evidence for East Asian admixture, whereas coastal groups have higher levels of European admixture. In contrast with many Latin American indigenous populations, the variance of admixture is high in each of the Pacific Northwest indigenous populations, as expected for recent and ongoing admixture processes. The results reveal some similarities but notable differences between admixture patterns in the Pacific Northwest and those in Latin America, contributing to a more detailed understanding of the genomic consequences of European colonization events throughout the Americas.     

Reef sharks exhibit site-fidelity and higher relative abundance in marine reserves on the Mesoamerican Barrier Reef

Carcharhinid sharks can make up a large fraction of the top predators inhabiting tropical marine ecosystems and have declined in many regions due to intense fishing pressure. There is some support for the hypothesis that carcharhinid species that complete their life-cycle within coral reef ecosystems, hereafter referred to as “reef sharks”, are more abundant inside no-take marine reserves due to a reduction in fishing pressure (i.e., they benefit from marine reserves). Key predictions of this hypothesis are that (a) individual reef sharks exhibit high site-fidelity to these protected areas and (b) their relative abundance will generally be higher in these areas compared to fished reefs. To test this hypothesis for the first time in Caribbean coral reef ecosystems we combined acoustic monitoring and baited remote underwater video (BRUV) surveys to measure reef shark site-fidelity and relative abundance, respectively. We focused on the Caribbean reef shark (Carcharhinus perezi), the most common reef shark in the Western Atlantic, at Glover''s Reef Marine Reserve (GRMR), Belize. Acoustically tagged sharks (N = 34) were detected throughout the year at this location and exhibited strong site-fidelity. Shark presence or absence on 200 BRUVs deployed at GRMR and three other sites (another reserve site and two fished reefs) showed that the factor “marine reserve” had a significant positive effect on reef shark presence. We rejected environmental factors or site-environment interactions as predominant drivers of this pattern. These results are consistent with the hypothesis that marine reserves can benefit reef shark populations and we suggest new hypotheses to determine the underlying mechanism(s) involved: reduced fishing mortality or enhanced prey availability.     

Future habitat suitability for coral reef ecosystems under global warming and ocean acidification

Rising atmospheric CO₂ concentrations are placing spatially divergent stresses on the world's tropical coral reefs through increasing ocean surface temperatures and ocean acidification. We show how these two stressors combine to alter the global habitat suitability for shallow coral reef ecosystems, using statistical Bioclimatic Envelope Models rather than basing projections on any a priori assumptions of physiological tolerances or fixed thresholds. We apply two different modeling approaches (Maximum Entropy and Boosted Regression Trees) with two levels of complexity (one a simplified and reduced environmental variable version of the other). Our models project a marked temperature‐driven decline in habitat suitability for many of the most significant and bio‐diverse tropical coral regions, particularly in the central Indo‐Pacific. This is accompanied by a temperature‐driven poleward range expansion of favorable conditions accelerating up to 40–70 km per decade by 2070. We find that ocean acidification is less influential for determining future habitat suitability than warming, and its deleterious effects are centered evenly in both hemispheres between 5° and 20° latitude. Contrary to expectations, the combined impact of ocean surface temperature rise and acidification leads to little, if any, degradation in future habitat suitability across much of the Atlantic and areas currently considered ‘marginal’ for tropical corals, such as the eastern Equatorial Pacific. These results are consistent with fossil evidence of range expansions during past warm periods. In addition, the simplified models are particularly sensitive to short‐term temperature variations and their projections correlate well with reported locations of bleaching events. Our approach offers new insights into the relative impact of two global environmental pressures associated with rising atmospheric CO₂ on potential future habitats, but greater understanding of past and current controls on coral reef ecosystems is essential to their conservation and management under a changing climate.     

The Gondwanan and South American Episodes: Two Major and Unrelated Moments in the History of the South American Mammals

The first steps in the history of South American mammals took place ca. 130 Ma., when the South American plate, still connected to the Antarctic Peninsula, began to drift away from the African-Indian plate. Most of the Mesozoic history of South American mammals is still unknown, and we only have a few enigmatic taxa (i.e., a Jurassic Australosphenida and an Early Cretaceous Prototribosphenida) that pose more evolutionary and biogeographic questions than answers. The best-known Mesozoic, South American land-mammal fossils are from Late Cretaceous Patagonian beds. These fossils represent the last survivors of non- and pre-tribosphenic Pangaean lineages, all of them with varying endemic features: some with few advanced features (e.g., ?Eutriconodonta and “Symmetrodonta”), some very diversified as endemic groups (e.g., ?Docodonta Reigitheriidae), and others representing vicariant types of well known Laurasian Mesozoic lineages (e.g., Gondwanatheria as vicariant of Multituberculata). These endemic mammals lived as relicts (although advanced) of pangeic lineages when a primordial South American continent was still connected to the Antarctic Peninsula and, at the northern extreme, near the North American Plate. By the beginning of the Late Cretaceous, the volcanic and diastrophic processes that finally led to the differentiation of the Caribbean region and Central America built up transient geographic connections that permitted the initiation of an overland inter-American exchange that included, for example, dinosaurian titanosaurs from South America and hadrosaurs from North America. The immigration of other vertebrates followed the same route, for example, polydolopimorphian marsupials. These marsupials were assumed to have differentiated in South America prior to new discoveries from the North American Late Cretaceous. The complete extinction of endemic South American Mesozoic mammals by the Late Cretaceous-Early Paleocene, and the subsequent and in part coetaneous immigration of North American therians, respectively, represent two major moments in the history of South American mammals: a Gondwanan Episode and a South American Episode. The Gondwanan Episode was characterized by non- and pre-tribosphenic mammal lineages that descended from the Pangeic South American stage (but already with a pronounced Gondwanan accent, and wholly extinguished during the Late Cretaceous-Early Paleocene span). The South American Episode, in turn, was characterized only by therian mammals, mostly emigrated from the North American continent and already with a South American accent obtained through isolation. The southernmost extreme of South America (Patagonia) remained connected to the present Antarctic Peninsula at least up until about 30 Ma., and both provided the substratum where the primordial cladogenesis of “South American” mammals occurred. The resulting cladogenesis of South American therian mammals followed Gould's motto: early experimentation, later standardization. That is to say, early cladogenesis engendered a great variety of taxa with scarce morphological differentiation. After this early cladogenesis (Late Eocene-Early Oligocene), the variety of taxa became reduced, but each lineage became clearly recognizable distinctive by a constant morphologic pattern. At the same time, those mammals that underwent the “early experimentation” were part of communities dominated by archaic lineages (e.g., brachydont types among the native “ungulates”), whereas the subsequent communities were dominated by mammals of markedly “modern” stamp (e.g., protohypsodont types among the native “ungulates”). The Gondwanan and South American Episodes were separated by a critical latest Cretaceous-earliest Paleocene hiatus, it is as unknown as it is important in which South American land-mammal communities must have experienced extinction of the Gondwanan mammals and the arrival and radiation of the North American marsupials and placentals (with the probable exception of the xenarthrans, whose biogeographic origin is still unclear).     

Persistence and Change in Community Composition of Reef Corals through Present,Past, and Future Climates

The reduction in coral cover on many contemporary tropical reefs suggests a different set of coral community assemblages will dominate future reefs. To evaluate the capacity of reef corals to persist over various time scales, we examined coral community dynamics in contemporary, fossil, and simulated future coral reef ecosystems. Based on studies between 1987 and 2012 at two locations in the Caribbean, and between 1981 and 2013 at five locations in the Indo-Pacific, we show that many coral genera declined in abundance, some showed no change in abundance, and a few coral genera increased in abundance. Whether the abundance of a genus declined, increased, or was conserved, was independent of coral family. An analysis of fossil-reef communities in the Caribbean revealed changes in numerical dominance and relative abundances of coral genera, and demonstrated that neither dominance nor taxon was associated with persistence. As coral family was a poor predictor of performance on contemporary reefs, a trait-based, dynamic, multi-patch model was developed to explore the phenotypic basis of ecological performance in a warmer future. Sensitivity analyses revealed that upon exposure to thermal stress, thermal tolerance, growth rate, and longevity were the most important predictors of coral persistence. Together, our results underscore the high variation in the rates and direction of change in coral abundances on contemporary and fossil reefs. Given this variation, it remains possible that coral reefs will be populated by a subset of the present coral fauna in a future that is warmer than the recent past.     

Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005

Background

The rising temperature of the world''s oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin.

Methodology/Principal Findings

Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers'' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles.

Conclusions/Significance

Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch''s Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.     

Allelopathy in the tropical alga Lobophora variegata (Phaeophyceae): mechanistic basis for a phase shift on mesophotic coral reefs?

Macroalgal phase shifts on Caribbean reefs have been reported with increasing frequency, and recent reports of these changes on mesophotic coral reefs have raised questions regarding the mechanistic processes behind algal population expansions to deeper depths. The brown alga Lobophora variegata is a dominant species on many shallow and deep coral reefs of the Caribbean and Pacific, and it increased in percent cover (>50%) up to 61 m on Bahamian reefs following the invasion of the lionfish Pterois volitans. We examined the physiological and ecological constraints contributing to the spread of Lobophora on Bahamian reefs across a mesophotic depth gradient from 30 to 61 m, pre‐ and post‐lionfish invasion. Results indicate that there were no physiological limitations to the depth distribution of Lobophora within this range prior to the lionfish invasion. Herbivory by acanthurids and scarids in algal recruitment plots at mesophotic depths was higher prior to the lionfish invasion, and Lobophora chemical defenses were ineffective against an omnivorous fish species. In contrast, Lobophora exhibited significant allelopathic activity against the coral Montastraea cavernosa and the sponge Agelas clathrodes in laboratory assays. These data indicate that when lionfish predation on herbivorous fish released Lobophora from grazing pressure at depth, Lobophora expanded its benthic cover to a depth of 61 m, where it replaced the dominant coral and sponge species. Our results suggest that this chemically defended alga may out‐compete these species in situ, and that mesophotic reefs may be further impacted in the near future as Lobophora continues to expand to its compensation point.     

Neogene reef coral assemblages of the Bocas del Toro region, Panama: the rise of Acropora palmata

Temporal patterns are evaluated in Neogene reef coral assemblages from the Bocas del Toro Basin of Panama in order to understand how reef ecosystems respond to long-term environmental change. Analyses are based on a total of 1,702 zooxanthellate coral specimens collected from six coral-bearing units ranging in age from the earliest Late Miocene to the Early Pleistocene: (1) Valiente Formation (12–11 Ma), (2) Fish Hole Member of the Old Bank Formation (5.8–5.6 Ma), (3) La Gruta Member of the Isla Colon Formation (2.2–1.4 Ma), (4) Ground Creek Member of the Isla Colon Formation (2.2–1.4 Ma), (5) Mimitimbi Member of the Urracá Formation (1.2–0.8 Ma), and (6) Hill Point Member of the Urracá Formation (1.2–0.8 Ma). Over 100 coral species occur in the six units, with faunal assemblages ranging from less than 10% extant taxa (Valiente Formation) to over 85% extant taxa (Ground Creek Member). The collections provide new temporal constraints on the emergence of modern Caribbean reefs, with the La Gruta Member containing the earliest occurrence of large monospecific stands of the dominant Caribbean reef coral Acropora palmata, and the Urracá Formation containing the last fossil occurrences of 15 regionally extinct taxa. Canonical correspondence analysis of 41 Late Miocene to Recent reef coral assemblages from the Caribbean region suggests changes in community structure coincident with effective oceanic closure of the Central American Seaway (~3.5 Ma). These changes, including increased Acropora dominance, may have contributed to a protracted period of elevated extinction debt prior to the major peak in regional coral extinctions (~2–1 Ma).     

Benthic foraminiferal response to the emergence of the Isthmus of Panama and coincident paleoceanographic changes

Late Cenozoic benthic foraminiferal faunas from the Caribbean Deep Sea Drilling Project (DSDP) Site 502 (3052 m) and East Pacific DSDP Site 503 (3572 m) were analyzed to interpret bottom-water masses and paleoceanographic changes occurring as the Isthmus of Panama emerged. Major changes during the past 7 Myr occur at 6.7–6.2, 3.4, 2.0, and 1.1 Ma in the Caribbean and 6.7–6.4, 4.0–3.2, 2.1, 1.4, and 0.7 Ma in the Pacific. Prior to 6.7 Ma, benthic foraminiferal faunas at both sites indicate the presence of Antarctic Bottom Water (AABW). After 6.7 Ma benthic foraminiferal faunas indicate a shift to warmer water masses: North Atlantic Deep Water (NADW) in the Caribbean and Pacific Deep Water (PDW) in the Pacific. Flow of NADW may have continued across the rising sill between the Caribbean and Pacific until 5.6 Ma when the Pacific benthic foraminiferal faunas suggest a decrease in bottom-water temperatures. After 5.6 Ma deep-water to intermediate-water flow across the sill appears to have stopped as the bottom-water masses on either side of the sill diverge.The second change recorded by benthic foraminiferal faunas occurs at 3.4 Ma in the Caribbean and 4.0-3.2 Ma in the Pacific. At this time the Caribbean is flooded with cold AABW, which is either gradually warmed or is replaced by Glacial Bottom Water (GBW) at 2.0 Ma and by NADW at 1.1 Ma. These changes are related to global climatic events and to the depth of the sill between the Caribbean and Atlantic rather than the rising Isthmus of Panama. Benthic foraminiferal faunas at East Pacific Site 503 indicate a gradual change from cold PDW to warmer PDW between 4.0 and 3.2 Ma. The PDW is replaced by the warmer, poorly oxygenated PIW at 2.1 Ma. Although the PDW affects the faunas during colder intervals between 1.4 and 0.7 Ma, the PIW remains the principal bottom-water mass in the Guatemala Basin of the East Pacific.     

Global coral disease prevalence associated with sea temperature anomalies and local factors

Coral diseases are taking an increasing toll on coral reef structure and biodiversity and are important indicators of declining health in the oceans. We implemented standardized coral disease surveys to pinpoint hotspots of coral disease, reveal vulnerable coral families and test hypotheses about climate drivers from 39 locations worldwide. We analyzed a 3 yr study of coral disease prevalence to identify links between disease and a range of covariates, including thermal anomalies (from satellite data), location and coral cover, using a Generalized Linear Mixed Model. Prevalence of unhealthy corals, i.e. those with signs of known diseases or with other signs of compromised health, exceeded 10% on many reefs and ranged to over 50% on some. Disease prevalence exceeded 10% on 20% of Caribbean reefs and 2.7% of Pacific reefs surveyed. Within the same coral families across oceans, prevalence of unhealthy colonies was higher and some diseases were more common at sites in the Caribbean than those in the Pacific. The effects of high disease prevalence are potentially extensive given that the most affected coral families, the acroporids, faviids and siderastreids, are among the major reef-builders at these sites. The poritids and agaricids stood out in the Caribbean as being the most resistant to disease, even though these families were abundant in our surveys. Regional warm temperature anomalies were strongly correlated with high disease prevalence. The levels of disease reported here will provide a much-needed local reference point against which to compare future change.     

How will coral reef fish communities respond to climate-driven disturbances? Insight from landscape-scale perturbations

Global climate change is rapidly altering disturbance regimes in many ecosystems including coral reefs, yet the long-term impacts of these changes on ecosystem structure and function are difficult to predict. A major ecosystem service provided by coral reefs is the provisioning of physical habitat for other organisms, and consequently, many of the effects of climate change on coral reefs will be mediated by their impacts on habitat structure. Therefore, there is an urgent need to understand the independent and combined effects of coral mortality and loss of physical habitat on reef-associated biota. Here, we use a unique series of events affecting the coral reefs around the Pacific island of Moorea, French Polynesia to differentiate between the impacts of coral mortality and the degradation of physical habitat on the structure of reef fish communities. We found that, by removing large amounts of physical habitat, a tropical cyclone had larger impacts on reef fish communities than an outbreak of coral-eating sea stars that caused widespread coral mortality but left the physical structure intact. In addition, the impacts of declining structural complexity on reef fish assemblages accelerated as structure became increasingly rare. Structure provided by dead coral colonies can take up to decades to erode following coral mortality, and, consequently, our results suggest that predictions based on short-term studies are likely to grossly underestimate the long-term impacts of coral decline on reef fish communities.     

Around the world in 10 million years: biogeography of the nearly cosmopolitan true toads (Anura: Bufonidae)

Aim The species‐rich family of true toads (Anura: Bufonidae) has been the focus of several earlier studies investigating the biogeography of geographically widespread taxa. Herein, we employ newly developed Bayesian divergence estimate methods to investigate the biogeographical history of this group. Resulting age estimates are used to test several key temporal hypotheses including that the origin of the bufonid clade pre‐dates Gondwanan vicariance (~105 million years ago, Ma). Area cladograms are also invoked to investigate the geographical origin of the family. Location Worldwide, except the Australia–New Guinea plate, Madagascar and the Antarctic. Methods A phylogenetic hypothesis of the relationships among true toads was derived from analysis of 2521 bp of DNA data including fragments from three mitochondrial (12S, tRNA^val, 16S) and two nuclear (RAG‐1, CXCR‐4) genes. Analysis of multiple, unlinked loci with a Bayesian method for estimating divergence times allowed us to address the timing and biogeographical history of Bufonidae. Resulting divergence estimates permitted the investigation of alternative vicariance/dispersal scenarios that have been proposed for true toads. Results Our area cladogram resulting from phylogenetic analysis of DNA data supports a South American origin for Bufonidae. Divergence estimates indicate that the family originated earlier than had been suggested previously (78–99 Ma). The age of the enigmatic Caribbean clade was dated to the late Palaeocene–early Eocene. A return of bufonids to the New World in the Eocene was followed by rapid diversification and secondary expansion into South America by the early Oligocene (Rupelian). Main conclusions The South American origin of Bufonidae in the Upper Cretaceous was followed by relatively rapid expansion and radiation around the globe, ending with a return to the Americas via a Eurasian/North American land bridge in the Eocene. Though the exact route of this dispersal (Beringia or North Atlantic) remains unclear, an argument is made for the less frequently invoked North Atlantic connection. The origin of the enigmatic Caribbean lineage was found to be consistent with colonization following the bolide impact at the K/T boundary. These findings provide the first, firm foundation for understanding true toad divergence times and their truly remarkable and global radiation.     

The Great American Biotic Interchange revisited

The “Great American Biotic Interchange” (GABI) is regarded as a defining event in the biogeography of the Americas. It is hypothesized to have occurred when the Isthmus of Panama closed ca three million years ago (Ma), ending the isolation of South America and permitting the mixing of its biota with that of North America. This view of the GABI is based largely upon the animal fossil record, but recent molecular biogeographic studies of plants that show repeated instances of long‐distance dispersal over major oceanic barriers suggest that perhaps the land bridge provided by the isthmus may have been less necessary for plant migration. Here we show that plants have significantly earlier divergence time estimates than animals for historical migration events across the Isthmus of Panama region. This difference in timing indicates that plants had a greater propensity for dispersal over the isthmus before its closure compared with animals. The GABI was therefore asynchronous for plants and animals, which has fundamental implications for the historical assembly of tropical biomes in the most species‐rich forests on the planet.     

Phylogenetic relationships within Aglaopheniidae (Cnidaria,Hydrozoa) reveal unexpected generic diversity

Morphology can be misleading in the representation of phylogenetic relationships, especially in simple organisms like cnidarians and particularly in hydrozoans. These suspension feeders are widely distributed in many marine ecosystems, and the family Aglaopheniidae Marktanner‐Turneretscher, 1890 is among the most diverse and visible, especially on tropical coral reefs. The taxonomy of this family is based on morphological characters with emphasis on reproductive structures for the identification of genera. This study is the most comprehensive molecular phylogeny of the Aglaopheniidae to date, including six genera and 38 species, of which 13 were investigated for the first time and sampled on tropical coral reefs throughout the Indo‐Pacific region. For newly sampled individuals, we sequenced the 16S rRNA, the nuclear locus comprising the complete ITS1‐5.8S rRNA gene‐ITS2 and the first intron of the calmodulin nuclear gene. Phylogenetic analyses of the data revealed and confirmed a general polyphyly, or doubtful monophyly, of all sampled genera in tropical regions based on both the mitochondrial and nuclear markers. Our results revealed that several morphological characters used today are unsuited to resolve phylogenetic relationships between species and genera, as well as the high phyletic diversity within this family. Future revision of the classification of this family will require extensive geographic sampling and the use of an integrative approach.