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Biome degradation characterizes the Anthropocene Epoch, and modern ecology is deeply involved with describing the changes underway. Most research has focused on the role of acute disturbances in causing conspicuous changes in ecosystem structure, which leads to an underappreciation of the chronic effects causing large changes through the cumulative effects of small perturbations over decades. Coral reefs epitomize this trend, because the changes in community structure are profound, yet the data to quantify these effects are usually insufficient to evaluate the relative roles of different disturbance types. Here, four decades of surveys from two coral reefs (9 and 14 m depth) off St. John, US Virgin Islands, are used to quantify the associations of acute and chronic events with the changes in benthic community structure. These reefs profoundly changed over 36 years, with coral death altering species assemblages to depress abundances of the ecologically important coral Orbicella spp. and elevating the coverage of macroalgae and crustose coralline algae/turf/bare space (CTB). Linear mixed models revealed the prominent role of chronic variation in temperature in accounting for changes in coverage of corals, macroalgae, and CTB, with rising temperature associated with increases in coral cover on the deep reef, and declines on the shallow reef. Hurricanes were also associated with declines in coral cover on the shallow reef, and increases on the deep reef. Multivariate analyses revealed strong associations between community structure and temperature, but weaker associations with hurricanes, bleaching, and diseases. These results highlight the overwhelming importance of chronically increasing temperature in altering the benthic community structure of Caribbean reefs. [ABSTRACT FROM AUTHOR]

Tropical reefs often undergo acute disturbances that result in landscape-scale loss of coral. Due to increasing threats to coral reefs from climate change and anthropogenic perturbations, it is critical to understand mechanisms that drive recovery of these ecosystems. We explored this issue on the fore reef of Moorea, French Polynesia, following a crown-of-thorns seastar outbreak and cyclone that dramatically reduced cover of coral. During the five-years following the disturbances, the rate of re-establishment of coral cover differed systematically around the triangular-shaped island; coral cover returned most rapidly at sites where the least amount of live coral remained after the disturbances. Although sites differed greatly in the rate of return of coral, all showed at least some evidence of re-assembly to their pre-disturbance community structure in terms of relative abundance of coral taxa and other benthic space holders. The primary driver of spatial variation in recovery was recruitment of sexually-produced corals; subsequent growth and survivorship were less important in shaping the spatial pattern. Our findings suggest that, although the coral community has been resilient, some areas are unlikely to attain the coral cover and taxonomic structure they had prior to the most recent disturbances before the advent of another landscape-scale perturbation.

Global climate change and other anthropogenic stressors have heightened the need to rapidly characterize ecological changes in marine benthic communities across large scales. Digital photography enables rapid collection of survey images to meet this need, but the subsequent image annotation is typically a time consuming, manual task. We investigated the feasibility of using automated point-annotation to expedite cover estimation of the 17 dominant benthic categories from survey-images captured at four Pacific coral reefs. Inter- and intra- annotator variability among six human experts was quantified and compared to semi- and fully- automated annotation methods, which are made available at coralnet.ucsd.edu. Our results indicate high expert agreement for identification of coral genera, but lower agreement for algal functional groups, in particular between turf algae and crustose coralline algae. This indicates the need for unequivocal definitions of algal groups, careful training of multiple annotators, and enhanced imaging technology. Semi-automated annotation, where 50% of the annotation decisions were performed automatically, yielded cover estimate errors comparable to those of the human experts. Furthermore, fully-automated annotation yielded rapid, unbiased cover estimates but with increased variance. These results show that automated annotation can increase spatial coverage and decrease time and financial outlay for image-based reef surveys.

Identifying relatively intact areas within ecosystems and determining the conditions favoring their existence is necessary for effective management in the context of widespread environmental degradation. In this study, we used 3766 surveys of randomly selected sites in the United States and U.S. Territories to identify the correlates of sites categorized as "oases" (defined as sites with relatively high total coral cover). We used occupancy models to evaluate the influence of 10 environmental predictors on the probability that an area (21.2‐km2 cell) would harbor coral oases defined at four spatial extents: cross‐basin, basin, region, and subregion. Across all four spatial extents, oases were more likely to occur in habitats with high light attenuation. The influence of the other environmental predictors on the probability of oasis occurrence were less consistent and varied with the scale of observation. Oases were most likely in areas of low human population density, but this effect was evident only at the cross‐basin and subregional extents. At the regional and subregional extents oases were more likely where sea‐surface temperature was more variable, whereas at the larger spatial extents the opposite was true. By identifying the correlates of oasis occurrence, the model can inform the prioritization of reef areas for management. Areas with biophysical conditions that confer corals with physiological resilience, as well as limited human impacts, likely support coral reef oases across spatial extents. Our approach is widely applicable to the development of conservation strategies to protect biodiversity and ecosystems in an era of magnified human disturbance. [ABSTRACT FROM AUTHOR]

The biological world is rapidly changing following decades of anthropogenic disturbances. Under these conditions, species with stable or increasing abundances have been described as winners with the potential for future success, but this assertion is unreliable without knowledge of the selective basis of winning. The incentive to find winners is acute for reef corals, for which large declines in abundance have motivated restoration efforts targeting winning corals. On Caribbean reefs, Porites astreoides has emerged as a potential winner, but the demographic basis of this categorization is poorly known. Here we test for demographic benchmarks of winning in this species by quantifying abundances and sizes of colonies over 28 yr on the south coast of St. John, US Virgin Islands. From 1992 to 2001, the density of colonies of P. astreoides showed little variation while colonies increased in size by 58%, but from 2002 to 2019, population density increased 2.7‐fold, and colony size declined by 41%; accompanying these trends, the mean absolute cover of Porites spp. declined by 46% from 2010 to 2019. Low recruitment and rising abundances of colonies ≤4 cm diameter suggest that partial mortality and fission depressed colony sizes. The reversal over three decades of a positive demographic trend for a ubiquitous coral underscores the challenges of identifying winners from short‐term population performance. Without a mechanistic understanding of fitness, the search for winners based on demographic trends may be futile. [ABSTRACT FROM AUTHOR]

With coral cover declining on most tropical reefs, efforts are intensifying to understand the mechanisms by which environmental stressors are driving populations into demographic deficit. Here, the population dynamics of sexual cohorts of small corals (≤ 4 cm diameter) in St. John, US Virgin Islands were used to test the hypothesis that the association of vital rates with environmental conditions has changed over 22 yr. The annual fate of 3999 corals at six sites and 7--9 m depth were used to populate Leslie Matrices and calculate assemblage growth rates (λ, without recruitment), mortality of the smallest corals, and graduation from the largest size class. Vital rates were tested for associations with temperature, the number of days with seawater warmer than 29.4°C (i.e., hot days), and rainfall. Transition probabilities varied among years, and usually more corals remained in their original size class than moved among size classes. Corals in the smallest size class had the highest mortality rate (42% yr-1), λ had a grand mean of 0.688, and there were trends for λ to vary with the number of hot days and rainfall through quadratic relationships. The linear dependence of λ on rainfall over consecutive 3-yr periods declined over two decades, suggesting that this colony size-defined coral assemblage has undergone phenotypic change in their responsiveness to varying environmental conditions. [ABSTRACT FROM AUTHOR]

In this study, fore reef coral communities were exposed to high pCO2 for a year to explore the relationship between net accretion (G net) and community structure (planar area growth). Coral reef communities simulating the fore reef at 17-m depth on Mo'orea, French Polynesia, were assembled in three outdoor flumes (each 500 l) that were maintained at ambient (396 µatm), 782 µatm, and 1434 µatm pCO2, supplied with seawater at 300 l h−1, and exposed to light simulating 17-m depth. The communities were constructed using corals from the fore reef, and the responses of massive Porites spp., Acropora spp., and Pocillopora verrucosa were assessed through monthly measurements of G net and planar area. High pCO2 depressed G net but did not affect colony area by taxon, although the areas of Acropora spp. and P. verrucosa summed to cause multivariate community structure to differ among treatments. These results suggest that skeletal plasticity modulates the effects of reduced G net at high pCO2 on planar growth, at least over a year. The low sensitivity of the planar growth of fore reef corals to the effects of ocean acidification (OA) on net calcification supports the counterintuitive conclusion that coral community structure may not be strongly affected by OA. [ABSTRACT FROM AUTHOR]

Invertebrate ectosymbionts within the coralla of scleractinians enhance host fitness through protection from corallivores and nutrient addition. Here, we explore the ectosymbiotic relationship between the coral Pocillopora verrucosa and the crab Trapezia serenei and the shrimp Alpheus spp., to test for effects on coral calcification under contrasts of seawater temperature (27.7 °C and 29.9 °C) and pH (ambient, 8.0 and reduced, 7.7). Regardless of temperature, ectosymbionts depressed calcification by 55% (vs without ectosymbionts) at ambient pH; however, ectosymbionts only depressed calcification under ambient pH but not at reduced pH. These results suggest that P. verrucosa grows fastest at ambient pH without ectosymbionts, but when ectosymbionts are present, colonies are protected from further declines in calcification at reduced pH. This implies that there may be a change from a currently parasitic ectosymbiont-coral relationship to a commensal relationship that could increase fitness advantages for corals hosting crustacean ectosymbionts under ocean acidification conditions. [ABSTRACT FROM AUTHOR]

Human activities have led to widespread ecological decline; however, the severity of degradation is spatially heterogeneous due to some locations resisting, escaping, or rebounding from disturbances.We developed a framework for identifying oases within coral reef regions using long‐term monitoring data. We calculated standardised estimates of coral cover (z‐scores) to distinguish sites that deviated positively from regional means. We also used the coefficient of variation (CV) of coral cover to quantify how oases varied temporally, and to distinguish among types of oases. We estimated "coral calcification capacity" (CCC), a measure of the coral community's ability to produce calcium carbonate structures and tested for an association between this metric and z‐scores of coral cover.We illustrated our z‐score approach within a modelling framework by extracting z‐scores and CVs from simulated data based on four generalized trajectories of coral cover. We then applied the approach to time‐series data from long‐term reef monitoring programmes in four focal regions in the Pacific (the main Hawaiian Islands and Mo'orea, French Polynesia) and western Atlantic (the Florida Keys and St. John, US Virgin Islands). Among the 123 sites analysed, 38 had positive z‐scores for median coral cover and were categorised as oases.Synthesis and applications. Our framework provides ecosystem managers with a valuable tool for conservation by identifying "oases" within degraded areas. By evaluating trajectories of change in state (e.g., coral cover) among oases, our approach may help in identifying the mechanisms responsible for spatial variability in ecosystem condition. Increased mechanistic understanding can guide whether management of a particular location should emphasise protection, mitigation or restoration. Analysis of the empirical data suggest that the majority of our coral reef oases originated by either escaping or resisting disturbances, although some sites showed a high capacity for recovery, while others were candidates for restoration. Finally, our measure of reef condition (i.e., median z‐scores of coral cover) correlated positively with coral calcification capacity suggesting that our approach identified oases that are also exceptional for one critical component of ecological function. Our framework provides ecosystem managers with a valuable tool for conservation by identifying "oases" within degraded areas. By evaluating trajectories of change in state (e.g., coral cover) among oases, our approach may help in identifying the mechanisms responsible for spatial variability in ecosystem condition. Increased mechanistic understanding can guide whether management of a particular location should emphasise protection, mitigation or restoration. Analysis of the empirical data suggest that the majority of our coral reef oases originated by either escaping or resisting disturbances, although some sites showed a high capacity for recovery, while others were candidates for restoration. Finally, our measure of reef condition (i.e., median z‐scores of coral cover) correlated positively with coral calcification capacity suggesting that our approach identified oases that are also exceptional for one critical component of ecological function. [ABSTRACT FROM AUTHOR]

An important goal of coral reef science is to understand the roles played by environmental conditions in determining benthic community structure. Pursuit of this goal typically involves testing for associations between community structure and environmental conditions, and in recent years, attention has focused on temperature and seawater pH. Such analyses are helpful in projecting coral reef community structure into the future, but their efficacy depends on the extent to which changes in community structure are correctly associated with causative processes, and whether future conditions are a subset of those experienced in the past. Here, we describe variation from 2014 to 2017 in one environmental factor, photosynthetically active radiation (PAR), at 19-m depth on the reefs of St. John, US Virgin Islands, and evaluate the extent to which this factor could cause changes in benthic community structure. The transmission of downwelling surface PAR to 19-m depth (TPAR-19) varied from 2.0 to 40.0% among days, and from 4.8 to 15.8% among months within a year, and was lower and more variable in the autumn versus other seasons. Monthly TPAR-19 was inversely associated with monthly rainfall, suggesting that runoff affected seawater clarity. The monthly diffuse attenuation coefficient (Kd-PAR) varied 1.7-fold from 0.097 to 0.164 m−1 and was within the range expected for coral reefs. Given the high temporal variation in underwater light intensity, and its importance to foundational reef taxa, understanding of the response of coral reefs to temperature and pH (and other factors) will remain incomplete without closer attention to this physical environmental condition. [ABSTRACT FROM AUTHOR]

This study tested the hypothesis that intraspecific morphological plasticity within a scleractinian coral elicits differential responses to elevated P CO2 and temperature. In Mo'orea, French Polynesia, two short-term laboratory experiments (21 and 14 days) were conducted to test the effects of P CO2 (400 vs. 700 μatm), and P CO2 (400 vs 1000 μatm) combined with temperature (27.0 vs. 29.8 °C), on branches and plates of Porites rus . Experiments employed two irradiances (~ 1000 vs 200 μmol photons m − 2 s − 1 ), which characterized the microenvironments on the shallow fringing reefs where branching and plating morphologies are common, respectively. Calcification of both morphologies was insensitive to P CO2 , as well as the combined effects of elevated P CO2 and temperature. Mean calcification rates were faster in high light than in low light for both morphologies, and biomass was greater in plates than branches in all treatments. Together, our results suggest P. rus is robust to increased P CO2 and high temperature within the constraints of the treatments applied. Morphological plasticity in this species does not mediate physiological resistance to low pH and high temperature. [ABSTRACT FROM AUTHOR]

Scleractinian corals on tropical reefs are exposed to many natural and anthropogenic disturbances, and while much is known about their responses to such conditions, it is unclear whether the responses will remain the same in a future affected by climate change and ocean acidification. To evaluate how one aspect of these effects — wound repair — might be influenced by ocean acidification, small colonies of massive Porites spp. from the back reef of Moorea, French Polynesia, were damaged to simulate the effects of single bites by corallivorous fishes, and healing was measured under contrasting P CO2 regimes. Using experiments lasting 19–20 d and employing superficial (2013) or deep (2014) lesions, the effects of damage were evaluated at ~ 400 μatm (ambient) and ~ 1000 μatm P CO2 (both at ~ 28.5 °C) using calcification and healing as dependent variables. Damage reduced calcification of massive Porites spp. in 2013, but not in 2014, and P CO2 had no effect on area-normalized calcification or healing in both years, although biomass-normalized calcification was reduced by high P CO2 in 2014. Overall these results reveal the physiological resilience of this functional group of corals to the extent of ocean acidification expected by the end of this century, and suggest that over this period small colonies will remain capable of recovery from minor damage arising from fish corallivory. [ABSTRACT FROM AUTHOR]

Body size has large effects on organism physiology, but these effects remain poorly understood in modular animals with complex morphologies. Using two trials of a ~24 day experiment conducted in 2014 and 2015, we tested the hypothesis that colony size of the coral Pocillopora verrucosa affects the response of calcification, aerobic respiration and gross photosynthesis to temperature (~26.5 and ~29.7°C) and PCO2 (~40 and ~1000 μatm). Large corals calcified more than small corals, but at a slower size-specific rate; areanormalized calcification declined with size. Whole-colony and areanormalized calcification were unaffected by temperature, PCO2, or the interaction between the two. Whole-colony respiration increased with colony size, but the slopes of these relationships differed between treatments. Area-normalized gross photosynthesis declined with colony size, but whole-colony photosynthesis was unaffected by PCO2, and showed a weak response to temperature. When scaled up to predict the response of large corals, area-normalized metrics of physiological performance measured using small corals provide inaccurate estimates of the physiological performance of large colonies. Together, these results demonstrate the importance of colony size in modulating the response of branching corals to elevated temperature and high PCO2. [ABSTRACT FROM AUTHOR]

Body size has large effects on organism physiology, but these effects remain poorly understood in modular animals with complex morphologies. Using two trials of a ~24 day experiment conducted in 2014 and 2015, we tested the hypothesis that colony size of the coral Pocillopora verrucosa affects the response of calcification, aerobic respiration and gross photosynthesis to temperature (~26.5 and ~29.7°C) and PCO2 (~40 and ~1000 μatm). Large corals calcified more than small corals, but at a slower size-specific rate; areanormalized calcification declined with size. Whole-colony and areanormalized calcification were unaffected by temperature, PCO2, or the interaction between the two. Whole-colony respiration increased with colony size, but the slopes of these relationships differed between treatments. Area-normalized gross photosynthesis declined with colony size, but whole-colony photosynthesis was unaffected by PCO2, and showed a weak response to temperature. When scaled up to predict the response of large corals, area-normalized metrics of physiological performance measured using small corals provide inaccurate estimates of the physiological performance of large colonies. Together, these results demonstrate the importance of colony size in modulating the response of branching corals to elevated temperature and high PCO2. [ABSTRACT FROM AUTHOR]

K-12 science programs in the United States are implementing inquiry-based lessons to expose students to the scientific process, and in some states these changes are mandated by regulations. At the same time, university faculty in science, technology, engineering, and math (STEM) disciplines are being encouraged by agencies funding their research to develop outreach activities that typically involve schools. Outreach programs promoting interactions between schools and universities are one means to address this need, and here we describe such a program between a Los Angeles independent school and California State University, Northridge. Our program exploits experiential learning focused on marine biology to engage students in ecological research with application to contemporary environmental issues such as climate change. Moreover, it addresses multiple aspects of the Next Generation Science Standards within a flexible framework that can be adapted to multiple curricular needs. Coral reefs are used as a model system in this program, but the concepts can easily be extended to other coastal marine environments. The program has evolved through three phases: (1) fostering interactions among educational partners, and developing curricula through research that exploits problem-solving skills; (2) completion of scientific activities in the classroom and field; and (3) engaging students in the scientific process through professional conferences and publication. These efforts have led to a self-sustaining program of interactions among schoolchildren, undergraduates, graduate students, K-12 educators, and university faculty that is promoting STEM careers and generating peer-reviewed publications. [ABSTRACT FROM AUTHOR]

Tropical coral reefs exemplify ecosystems imperiled by environmental change. Anticipating the future of reef ecosystems requires understanding how scleractinian corals respond to the multiple environmental disturbances that threaten their survival. We analyzed the stability of coral reefs at three habitats at different depths along the south shore of St. John, U.S. Virgin Islands, using multivariate autoregression (MAR) models and two decades of monitoring data. We quantified several measures of ecosystem stability, including the magnitude of typical stochastic fluctuations, the rate of recovery following disturbance, and the sensitivity of coral cover to hurricanes and elevated sea temperature. Our results show that, even within a ~4 km shore, coral communities in different habitats display different stability properties, and that the stability of each habitat corresponds with the habitat's known synecology. Two Orbicella-dominated habitats are less prone to annual stochastic fluctuations than coral communities in shallower water, but they recover slowly from disturbance, and one habitat has suffered recent losses in scleractinian cover that will not be quickly reversed. In contrast, a shallower, low-coral-cover habitat is subject to greater stochastic fluctuations, but rebounds more quickly from disturbance and is more robust to hurricanes and seawater warming. In some sense, the shallower community is more stable, although the stability arguably arises from having little coral cover left. Our results sharpen understanding of recent changes in coral communities at these habitats, provide a more detailed understanding of how these habitats may change in future environments, and illustrate how MAR models can be used to assess stability of communities founded upon long-lived species. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We tested the effect of light and Pco2 on the calcification and survival of Pocillopora damicornis recruits settled from larvae released in southern Taiwan. In March 2011, recruits were incubated at 31, 41, 70,122 and 226μmol photons m-2s-1 under ambient (493patm) and high Pco2 (878μatm). After 5days, calcification was measured gravimetrically and survivorship estimated as the number of living recruits. Calcification was affected by the interaction of Pco2 with light, and at 493patm Pco2 the response to light intensity resembled a positive parabola. At 878μatm Pco2- the effect of light on calcification differed from that observed at 493 μatm Pco2, with the result that there were large differences in calcification between 493 patm and 878 patm Pco2 at intermediate light intensities (ca. 70 μmol photons m-2 s-1), but similar rates of calcification at the highest and lowest light intensities. Survivorship was affected by light and Pco2, and was highest at 122(μmol photons m-2S-1 in both PcO2 treatments, but was unrelated to calcification. In June 2012 the experiment was repeated, and again the results suggested that exposure to high Pco2 decreased calcification of P. damicornis recruits at intermediate light intensities, but not at lower or higher intensities. Together, our findings demonstrate that the effect of PCo2 on coral recruits can be light dependent, with inhibitory effects of high Pco2 on calcification at intermediate light intensities that disappear at both higher and lower light intensities. [ABSTRACT FROM AUTHOR]

The article presents a study on the effect of rising temperature to juvenile Caribbean corals' respiration. It notes that the rising temperature has its vital role to determine the effect of climatic changes to the coral population. Moreover, temperature elevation measures the oxygen diffusion boundary layer (DBL) in darkness at a constant flow speed. Accordingly, the result shows insignificant effect of temperature to DBL thickness, however, interactive effects of temperatures and the taxon on oxygen concentration which is adjacent to respiration rates and tissue are observed. Furthermore, kinetic model of the effects of temperature on aerobic respiration is inconsistent with the trends and its behavioral effects reflects on the metabolic activity changes of the coenosarc.

Abstract. To better understand the consequences of climate change for scleractinian corals, Stylophora pistillata was used to test the effects of temperature on the settlement and physiology of coral larvae. Freshly released larvae were exposed to temperatures of 23 °C, 25 °C (ambient), and 29 °C at light intensities of ≈150 μmol photons m[sup-2] s[sup-1]. The effects were assessed after 12 h as settlement to various substrata (including a choice between crustose coralline algae [CCA] and limestone) and as maximum quantum yield of PSII (F[subv]/F[subm]) in the larvae versus in their parents. Regardless of temperature, 50%-73% of the larvae metamorphosed onto the plastic of the incubation trays or in a few cases were drifting in the water, and 14% settled on limestone. However, elevated temperature (29 °C) reduced the percentage of larvae swimming by 81%, and increased the percentage choosing CCA nearly 7-fold, both relative to the outcomes at 23 °C. Because temperature did not affect settlement on limestone or plastic, increased settlement on CCA reflected temperature-mediated choices by larvae that otherwise would have remained swimming. Interestingly, F[subv]/F[subm] was unaffected by temperature, but it was 4% lower in the larvae than in the parents. These results are important because they show that temperature can affect the settlement of coral larvae and because they reveal photophysiological differences between life stages that might provide insights into the events associated with larval development. [ABSTRACT FROM AUTHOR]

To date, coral death has been the most conspicuous outcome of warming tropical seas, but as temperatures stabilize at higher values, the consequences for the corals remaining will be mediated by their demographic responses to the sub-lethal effects of temperature. To gain insight into the nature of these responses, here I develop a model to test the effect of increased temperature on populations of three pocilloporid corals at One Tree Island, near the southern extreme of the Great Barrier Reef (GBR). Using Seriatopora hystrix, S. caliendrum and Pocillopora damicornis as study species, the effects of temperature on growth were determined empirically, and the dynamics of their populations determined under natural temperatures over a 6-month period between 1999 and 2000 [defined as the study year (SY)]. The two data sets were combined in a demographic test of the possibility that the thermal regime projected for the southern GBR in the next 55–83 years—warmer by 3°C than the study year (the SY+3 regime), which is equivalent to 1.4°C warmer than the recent warm year of 1998—would alter coral population trajectories through the effects on coral growth alone; the analyses first were completed by species, then by family after pooling among species. Laboratory experiments showed that growth rates (i.e., calcification) varied significantly among species and temperatures, and displayed curvilinear thermal responses with growth maxima at ∼27.1°C. Based on these temperature-growth responses, the SY+3 regime is projected to: (1) increase annualized growth rates of all taxa by 24–39%, and defer the timing of peak growth from the summer to the autumn and spring, (2) alter the intrinsic rate of population growth (λ) for S. hystrix (λ decreases 26%) and S. caliendrum (λ increases 5%), but not for P. damicornis, and (3) have a minor effect on λ (a 0.3% increase) for the Pocilloporidae, largely because λ varies more among species than it does between temperatures. Ten-year population projections suggest that the effects of a sub-lethal increase in temperature (i.e., the SY+3 regime) are relatively small compared to the interspecific differences in population dynamics, but nevertheless will alter the population size and increase the relative abundance of large colonies at the expense of smaller colonies for all three species, as well as the Pocilloporidae. These effects may play an important role in determining the nuances of coral population structure as seawater warms, and their significance may intensity if the coral species pool is depleted of thermally sensitive species by bleaching. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA), a consequence of anthropogenic carbon dioxide emissions, poses a serious threat to marine organisms in polar, open ocean, deep sea, coastal, and coral reef ecosystems. The many diverse taxonomic groups that precipitate calcium carbonate from seawater are at particularly high risk. Here we review the rapidly expanding literature concerning the biological and ecological impacts of OA on calcification and other physiological processes, using a cross-scale, process-oriented approach. We conclude that ( a) variation exists across all scales of organization, from sub-cellular to global, thus limiting generalizations; ( b) OA will combine with multiple interactive climate change stressors to produce unanticipated stabilizing and destabilizing feedbacks, influencing ecosystem- and global-level impacts; and ( c) ecosystem function and services will be affected to an unknown extent. Critical uncertainties remain, especially concerning the relative potential for phenotypic plasticity and genetic adaptation in response to OA by key groups of marine calcifying metazoans and micro-organisms. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics Volume 41 is November 2, 2010. Please see for revised estimates. [ABSTRACT FROM AUTHOR]