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.     

Identifying multiple coral reef regimes and their drivers across the Hawaiian archipelago

Loss of coral reef resilience can lead to dramatic changes in benthic structure, often called regime shifts, which significantly alter ecosystem processes and functioning. In the face of global change and increasing direct human impacts, there is an urgent need to anticipate and prevent undesirable regime shifts and, conversely, to reverse shifts in already degraded reef systems. Such challenges require a better understanding of the human and natural drivers that support or undermine different reef regimes. The Hawaiian archipelago extends across a wide gradient of natural and anthropogenic conditions and provides us a unique opportunity to investigate the relationships between multiple reef regimes, their dynamics and potential drivers. We applied a combination of exploratory ordination methods and inferential statistics to one of the most comprehensive coral reef datasets available in order to detect, visualize and define potential multiple ecosystem regimes. This study demonstrates the existence of three distinct reef regimes dominated by hard corals, turf algae or macroalgae. Results from boosted regression trees show nonlinear patterns among predictors that help to explain the occurrence of these regimes, and highlight herbivore biomass as the key driver in addition to effluent, latitude and depth.     

An assessment of natural and human disturbance effects on Mexican ecosystems: current trends and research gaps

Mexico harbors more than 10% of the planet’s endemic species. However, the integrity and biodiversity of many ecosystems is experiencing rapid transformation under the influence of a wide array of human and natural disturbances. In order to disentangle the effects of human and natural disturbance regimes at different spatial and temporal scales, we selected six terrestrial (temperate montane forests, montane cloud forests, tropical rain forests, tropical semi-deciduous forests, tropical dry forests, and deserts) and four aquatic (coral reefs, mangrove forests, kelp forests and saline lakes) ecosystems. We used semi-quantitative statistical methods to assess (1) the most important agents of disturbance affecting the ecosystems, (2) the vulnerability of each ecosystem to anthropogenic and natural disturbance, and (3) the differences in ecosystem disturbance regimes and their resilience. Our analysis indicates a significant variation in ecological responses, recovery capacity, and resilience among ecosystems. The constant and widespread presence of human impacts on both terrestrial and aquatic ecosystems is reflected either in reduced area coverage for most systems, or reduced productivity and biodiversity, particularly in the case of fragile ecosystems (e.g., rain forests, coral reefs). In all cases, the interaction between historical human impacts and episodic high intensity natural disturbance (e.g., hurricanes, fires) has triggered a reduction in species diversity and induced significant changes in habitat distribution or species dominance. The lack of monitoring programs assessing before/after effects of major disturbances in Mexico is one of the major limitations to quantifying the commonalities and differences of disturbance effects on ecosystem properties.     

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.     

Global human footprint on the linkage between biodiversity and ecosystem functioning in reef fishes

Difficulties in scaling up theoretical and experimental results have raised controversy over the consequences of biodiversity loss for the functioning of natural ecosystems. Using a global survey of reef fish assemblages, we show that in contrast to previous theoretical and experimental studies, ecosystem functioning (as measured by standing biomass) scales in a non-saturating manner with biodiversity (as measured by species and functional richness) in this ecosystem. Our field study also shows a significant and negative interaction between human population density and biodiversity on ecosystem functioning (i.e., for the same human density there were larger reductions in standing biomass at more diverse reefs). Human effects were found to be related to fishing, coastal development, and land use stressors, and currently affect over 75% of the world's coral reefs. Our results indicate that the consequences of biodiversity loss in coral reefs have been considerably underestimated based on existing knowledge and that reef fish assemblages, particularly the most diverse, are greatly vulnerable to the expansion and intensity of anthropogenic stressors in coastal areas.     

Cycles of coral reef ‘turn‐on’, rapid growth and ‘turn‐off’ over the past 8500 years: a context for understanding modern ecological states and trajectories

Human activities threaten reef ecosystems globally, forcing ecological change at rates and scales regarded as unprecedented in the Holocene. These changes are so profound that a cessation of reef accretion (reef ‘turn‐off’) and net erosion of reef structures is argued by many as the ultimate and imminent trajectory. Here, we use a regional scale reef growth dataset, based on 76 core records (constrained by 211 radiometric dates) from 22 reefs along and across the inner‐shelf of the Great Barrier Reef, Australia, to examine the timing of different phases of reef initiation (‘turn‐on’), growth and ‘turn‐off’ during the Holocene. This dataset delineates two temporally discrete episodes of reef‐building over the last 8500 years: the first associated with the Holocene transgression‐early highstand period [～8.5–5.5 k calibrated years bp (cal ybp )]; the second since ～2.3 k cal ybp . During both periods, reefs accreted rapidly to sea level before entering late evolutionary states – states naturally characterized by reduced coral cover and low accretion potential – and a clear hiatus occurs between these reef‐building episodes for which no records of reef initiation exist. These transitions mimic those projected under current environmental disturbance regimes, but have been driven entirely by natural forcing factors. Our results demonstrate that, even through the late Holocene, reef health and growth has fluctuated through cycles independent of anthropogenic forcing. Consequently, degraded reef states cannot de facto be considered to automatically reflect increased anthropogenic stress. Indeed, in many cases degraded or nonaccreting reef communities may reflect past reef growth histories (as dictated by reef growth–sea level interactions) as much as contemporary environmental change. Recognizing when changes in reef condition reflect these natural ‘turn‐on’– growth –‘turn‐off’ cycles and how they interact with on‐going human disturbance is critical for effective coral reef management and for understanding future reef ecological trajectories.     

Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems

Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change.     

Millennial-scale change in the structure of a Caribbean reef ecosystem and the role of human and natural disturbance

Caribbean coral reefs have transformed into algal-dominated habitats over the past half-century, but the role of specific anthropogenic drivers is unresolved due to the lack of ecosystem-level data predating human disturbance. To better understand the extent and causes of long-term Caribbean reef declines, we produced a continuous 3000-yr record of the ecosystem state of three reefs in Bocas del Toro, Caribbean Panama. From fossils and sediments obtained from reef matrix cores, we tracked changes in reef accretion rates and the taxonomic and functional group composition of fish, coral, urchin, bivalve and benthic foraminifera. This dataset provided a comprehensive picture of reef community and environmental change. At all sites, reefs shifted from systems with greater relative abundance of herbivorous fish, epifaunal suspension feeding bivalves and Diadema urchins to systems with greater relative abundance of micropredator fish, infaunal bivalves and Echinometra urchins. These transitions were initiated a millennium ago at two less-degraded reefs fringing offshore islands and ~250 yr ago at a degraded patch reef near the continental coast. Ecosystem shifts were accompanied by a decline in reef accretion rates, and at the patch reef, a decline in water quality since the 18th century. Within all cores, synchronous increases in infaunal bivalves and declines in herbivorous fish regardless of water quality suggest a loss of hard substrate and increasingly hypoxic sediment conditions related to herbivore loss. While the early timing of ecosystem transitions at the fringing reefs implicates large-scale hydrological change, the more recent timing of change and loss of water quality at the patch reef implicates terrigenous runoff from land-clearing. Our whole-ecosystem reconstruction reveals that reef ecosystem deterioration appears to follow a predictable trajectory whether driven by natural or anthropogenic disturbances and that historical local human activities have quickly unraveled reefs at a scale similar to longer-term natural environmental change.     

How much time can herbivore protection buy for coral reefs under realistic regimes of hurricanes and coral bleaching?

Coral reefs have been more severely impacted by recent climate instability than any other ecosystem on Earth. Corals tolerate a narrow range of physical environmental stress, and increases in sea temperature of just 1 °C over several weeks can result in mass coral mortality, often exceeding 95% of individuals over hundreds of square kilometres. Even conservative climate models predict that mass coral bleaching events could occur annually by 2050. Unfortunately, managers of coral‐reef resources have few options available to meet this challenge. Here, we investigate the role that fisheries conservation tools, including the designation of marine reserves, can play in altering future trajectories of Caribbean coral reefs. We use an individual‐based model of the ecological dynamics to test the influence of spatially realistic regimes of disturbance on coral populations. Two major sources of disturbance, hurricanes and coral bleaching, are simulated in contrasting regions of the Caribbean: Belize, Bonaire, and the Bahamas. Simulations are extended to 2099 using the HadGEM1 climate model. We find that coral populations can maintain themselves under all levels of hurricane disturbance providing that grazing levels are high. Regional differences in hurricane frequency are found to cause strikingly different spatial patterns of reef health with greater patchiness occurring in Belize, which has less frequent disturbance, than the Bahamas. The addition of coral bleaching led to a much more homogenous reef state over the seascape. Moreover, in the presence of bleaching, all reefs exhibited a decline in health over time, though with substantial variation among regions. Although the protection of herbivores does not prevent reef degradation it does delay rates of coral loss even under the most severe thermal and hurricane regimes. Thus, we can estimate the degree to which local conservation can help buy time for reefs with values ranging between 18 years in the Bahamas and over 50 years in Bonaire, compared with heavily fished systems. Ultimately, we demonstrate that local conservation measures can benefit reef ecosystem services but that their impact will vary spatially and temporally. Recognizing where such management interventions will either help or fail is an important step towards both achieving sustainable use of coral‐reef resources and maximizing resource management investments.     

Human activity selectively impacts the ecosystem roles of parrotfishes on coral reefs

Around the globe, coral reefs and other marine ecosystems are increasingly overfished. Conventionally, studies of fishing impacts have focused on the population size and dynamics of targeted stocks rather than the broader ecosystem-wide effects of harvesting. Using parrotfishes as an example, we show how coral reef fish populations respond to escalating fishing pressure across the Indian and Pacific Oceans. Based on these fish abundance data, we infer the potential impact on four key functional roles performed by parrotfishes. Rates of bioerosion and coral predation are highly sensitive to human activity, whereas grazing and sediment removal are resilient to fishing. Our results offer new insights into the vulnerability and resilience of coral reefs to the ever-growing human footprint. The depletion of fishes causes differential decline of key ecosystem functions, radically changing the dynamics of coral reefs and setting the stage for future ecological surprises.     

The Changing Health of Coral Reefs

Throughout their entire global range coral reefs are in decline. Coral bleaching, macroalgal overgrowth and coral diseases — responses signaling the declining health of coral reefs — have occurred with increasing frequency and intensity in recent decades. Decreased calcification may also be affecting coral reefs over longer time scales. Declines in coral reef health have been attributed to various natural and anthropogenic processes, but assignment of causality has proved problematic. Coral bleaching has been observed during extreme climate events such as El Niño; furthermore, there are indications that exposure to UV radiation, air, infectious microbes, and elevated temperature plays a role in the dramatic increase of coral bleaching since the mid-1970s. Macroalgal overgrowth is usually ascribed to eutrophi-cation and coral diseases to weakening of the coral host resistance by anthropogenic pollution. An issue precluding a strict anthropogenic cause of coral reef decline is that both overgrowth and coral diseases are known to occur, although less frequently, on reefs remote from human development. While its causes are still being unraveled, the overall decline in coral reef health sends an unambiguous signal that the coral reef system is losing its ability to withstand sudden or persistent environmental changes.     

Will increased storm disturbance affect the biodiversity of intertidal,nonscleractinian sessile fauna on coral reefs?

Relatively little is known about how the future effects of climatic change, including increases in sea level, temperature and storm severity and frequency, will impact on patterns of biodiversity on coral reefs, with the notable exception of recent work on corals and fish in tropical reef ecosystems. Sessile invertebrates such as ascidians, sponges and bryozoans occupying intertidal rubble habitats on coral reefs contribute significantly to the overall biodiversity and ecosystem function, but there is little or no information available on the likely impacts on these species from climate change. The existing strong physical gradients in these intertidal habitats will be exacerbated under predicted climatic change. By examining the distribution and abundance of nonscleractinian, sessile invertebrate assemblages exposed to different levels of wave action and at different heights on the shore around a coral reef, we show that coral reef intertidal biodiversity is particularly sensitive to physical disturbance. As physical disturbance regimes increase due to more intense storms and wave action associated with global warming, we can expect to see a corresponding decrease in the diversity of these cryptic sessile assemblages. This could impact negatively on the future health and productivity of coral reef ecosystems, given the ecosystem services these organisms provide.     

Ecosystem‐based management of coral reefs under climate change

Coral reefs provide food and livelihoods for hundreds of millions of people as well as harbour some of the highest regions of biodiversity in the ocean. However, overexploitation, land‐use change and other local anthropogenic threats to coral reefs have left many degraded. Additionally, coral reefs are faced with the dual emerging threats of ocean warming and acidification due to rising CO₂ emissions, with dire predictions that they will not survive the century. This review evaluates the impacts of climate change on coral reef organisms, communities and ecosystems, focusing on the interactions between climate change factors and local anthropogenic stressors. It then explores the shortcomings of existing management and the move towards ecosystem‐based management and resilience thinking, before highlighting the need for climate change‐ready marine protected areas (MPAs), reduction in local anthropogenic stressors, novel approaches such as human‐assisted evolution and the importance of sustainable socialecological systems. It concludes that designation of climate change‐ready MPAs, integrated with other management strategies involving stakeholders and participation at multiple scales such as marine spatial planning, will be required to maximise coral reef resilience under climate change. However, efforts to reduce carbon emissions are critical if the long‐term efficacy of local management actions is to be maintained and coral reefs are to survive.     

Limited functional redundancy in high diversity systems: resilience and ecosystem function on coral reefs

Abstract Biodiversity is frequently associated with functional redundancy. Indo‐Pacific coral reefs incorporate some of the most diverse ecosystems on the globe with over 3000 species of fishes recorded from the region. Despite this diversity, we document changes in ecosystem function on coral reefs at regional biogeographical scales as a result of overfishing of just one species, the giant humphead parrotfish (Bolbometopon muricatum). Each parrotfish ingests over 5 tonnes of structural reef carbonates per year, almost half being living corals. On relatively unexploited oceanic reefs, total ingestion rates per m² balance estimated rates of reef growth. However, human activity and ecosystem disruption are strongly correlated, regardless of local fish biodiversity. The results emphasize the need to consider the functional role of species when formulating management strategies and the potential weakness of the link between biodiversity and ecosystem resilience.     

Reef coral diversity and global change

Regional anthropogenic processes such as pollution, dredging, and overfishing on coral reefs currently threaten the biodiversity of stony corals and other reef-associated organisms. Global climate change may interact with anthropogenic processes to create additional impacts on coral diversity in the near future. In order to predict these changes, it is necessary to understand the magnitude and causes of variation in scleractinian coral diversity throughout their 240 million year history. The fossil record documents long periods of speciation in corals, interrupted repeatedly by events of mass extinction. Some of these events relate clearly to changes in global climate. Diversity in reef corals has increased since their last period of extinction at the end of the Cretaceous (65 My bp ), and is still rising. During the last 8 million years, the fragmentation of the once pantropical Tethys Sea separated corals into two major biogeographical provinces. Periods of glaciation also have caused major changes in sea level and temperature. Accumulated evidence supports the theory that relative habitat area and changing patterns of oceanic circulation are mainly responsible for the two observed centres of recent coral diversity at the western tropical margins of the Atlantic and Pacific oceans. At predicted rates of climate change in the near future, coral reefs are likely to survive as an ecosystem. Increases in sea level may actually benefit corals and lead to regional increases in diversity if new habitat area on back reefs is opened to increased water circulation and thus coral dispersal. Rising temperature may cause higher rates of coral mortality and even local extinction in isolated, small populations such as those on oceanic islands. The effects of increases in ultraviolet radiation (UV) are largely unknown, but likely to be negative. UV may damage planktonic coral propagules in oceanic surface waters and thus decrease rates of gene flow between coral populations. This may result in increased local extinctions, again with the strongest impact on widely separated reefs with small coral populations. The largest threats to coral diversity are regional anthropogenic impacts, which may interact with global climate change to exacerbate rates of local species extinctions. Centres of high reef coral diversity coincide with human population centres in south-east Asia and the Caribbean, and thus the greatest potential for species loss lies in these geographical areas.     

Spatial Resilience of Coral Reefs

There have been several earlier studies that addressed the influence of natural disturbance regimes on coral reefs. Humans alter natural disturbance regimes, introduce new stressors, and modify background conditions of reefs. We focus on how coral reef ecosystems relate to disturbance in an increasingly human-dominated environment. The concept of ecosystem resilience—that is, the capacity of complex systems with multiple stable states to absorb disturbance, reorganize, and adapt to change—is central in this context. Instead of focusing on the recovery of certain species and populations within disturbed sites of individual reefs, we address spatial resilience—that is, the dynamic capacity of a reef matrix to reorganize and maintain ecosystem function following disturbance. The interplay between disturbance and ecosystem resilience is highlighted. We begin the identification of spatial sources of resilience in dynamic seascapes and exemplify and discuss the relation between “ecological memory” (biological legacies, mobile link species, and support areas) and functional diversity for seascape resilience. Managing for resilience in dynamic seascapes not only enhances the likelihood of conserving coral reefs, it also provides insurance to society by sustaining essential ecosystem services. Received 25 February 2000; accepted 31 January 2001.     

New directions in coral reef microbial ecology

Microbial processes largely control the health and resilience of coral reef ecosystems, and new technologies have led to an exciting wave of discovery regarding the mechanisms by which microbial communities support the functioning of these incredibly diverse and valuable systems. There are three questions at the forefront of discovery: What mechanisms underlie coral reef health and resilience? How do environmental and anthropogenic pressures affect ecosystem function? What is the ecology of microbial diseases of corals? The goal is to understand the functioning of coral reefs as integrated systems from microbes and molecules to regional and ocean‐basin scale ecosystems to enable accurate predictions of resilience and responses to perturbations such as climate change and eutrophication. This review outlines recent discoveries regarding the microbial ecology of different microenvironments within coral ecosystems, and highlights research directions that take advantage of new technologies to build a quantitative and mechanistic understanding of how coral health is connected through microbial processes to its surrounding environment. The time is ripe for natural resource managers and microbial ecologists to work together to create an integrated understanding of coral reef functioning. In the context of long‐term survival and conservation of reefs, the need for this work is immediate.     

Global change and coral reefs: impacts on reefs, economies and human cultures

Coral reefs have reconstituted themselves after previous large sea-level variations, and climate changes. For the past 6000 years of unusually stable sea-level, reefs have grown without serious interruptions. During recent decades, however, new stresses threaten localized devastation of many reefs. A new period of global climate change is occurring, stimulated by anthropogenic increases in greenhouse gases. Coral reefs will cope well with predicted sea-level rises of 4.5 cm per decade, but reef islands will not. Higher sea levels will provide corals with greater room for growth across reef flats, but there are no foreseeable mechanisms for reef island growth to keep pace with sea-level rise, therefore many low islands may ultimately become uninhabitable. Climate change will introduce localized variations in weather patterns, but changes to individual reefs cannot be predicted. Reefs on average should cope well with regional climate change, as they have coped with similar previous fluctuations. Air temperature increases of 0.2–0.3 °C/decade will induce slower increases in sea-surface temperatures, which may cause localized, or regional increases in coral bleaching. Changes in rainfall will impact on reefs near land masses. Likewise, increased storms and variations in El Nino Southern Oscillation (ENSO) may stress some reefs, but not others. The greatest impact of climate change will be a synergistic enhancement of direct anthropogenic stresses (excessive sediment and pollution from the land; over-fishing, especially via destructive methods; mining of coral rock and sand; and engineering modifications), which currently cause most damage to coral reefs. Many of the world's reefs have been degraded and more will be damaged as anthropogenic impacts increase under the ‘demophoric’ increases in population (demos) and economic (phoric) activity. This biotic and habitat loss will result in severe economic and social losses. Reefs, however, have considerable recovery powers and losses can be minimized by effective management of direct human impacts and reducing indirect threats of global climate change.     

海洋酸化对珊瑚礁生态系统的影响研究进展

目前,大气CO2浓度的升高已导致海水pH值比工业革命前下降了约0.1,海水碳酸盐平衡体系随之变化,进而影响珊瑚礁生态系统的健康。近年来的研究表明海洋酸化导致造礁石珊瑚幼体补充和群落恢复更加困难,造礁石珊瑚和其它造礁生物(Reef-building organisms)钙化率降低甚至溶解,乃至影响珊瑚礁鱼类的生命活动。虽然海洋酸化对造礁石珊瑚光合作用的影响不显著,但珊瑚-虫黄藻共生体系会受到一定影响。建议选择典型海区进行长期系统监测,结合室内与原位模拟试验,从个体、种群、群落到系统不同层面,运用生理学和分子生物学技术,结合生态学研究手段,综合研究珊瑚的相应响应,以期深入认识海洋酸化对珊瑚礁生态系统健康(例如珊瑚白化)的影响及其效应。     

Migration of hawksbill turtles Eretmochelys imbricata from Tortuguero, Costa Rica

The hawksbill turtle Eretmochelys imbricata is a widely distributed and critically endangered species that feeds on sponges and fills an important ecological role in the coral reef ecosystem. At Tortuguero, Costa Rica, trend analyses indicate considerable decline in nesting estimated at 77.2–94.5% between 1956 and 2003, as a result of excessive turtle fishing. We analyzed flipper tag returns, satellite telemetry and genetic samples to determine movements and habitat use of adult female Tortuguero hawksbills. Tag returns and satellite telemetry show hawksbills migrate to foraging grounds in Nicaragua and Honduras. Genetic analysis indicates the hawksbills may also migrate to Cuban, Puerto Rican, and possibly Mexican waters. We conclude hawksbills represent an internationally shared resource. There is a close correlation between tag recapture sites, hawksbill foraging grounds and coral reef distribution. Caribbean coral reef decline may reduce food availability and negatively impact hawksbill turtles. Conversely, hawksbill decline may shift the balance on coral reefs by reducing predation pressure on sponges and hence make coral reefs less resilient to natural and anthropogenic threats. Strategies aiming to conserve hawksbills and coral reefs must consider both the extensive hawksbill migrations and the close relationship between the species and the coral reef ecosystem.