• Energy Research

AbstractAimPredictions for the future of coral reefs are largely based on thermal exposure and poorly account for potential geographic variation in biological sensitivity to thermal stress. Without accounting for complex sensitivity responses, simple climate exposure models and associated predictions may lead to poor estimates of future coral survival and lead to policies that fail to identify and implement the most appropriate interventions. To begin filling this gap, we evaluated a number of attributes of coral taxa and communities that are predicted to influence coral resistance to thermal stress over a large geographic range.LocationWestern Indo‐Pacific and Central Indo‐Pacific Ocean Realms.Major taxa studiedZooxanthellate Scleractinia – hard corals.MethodsWe evaluated the geographic variability of coral resistance to thermal stress as the ratio of thermal exposure and sensitivity in 12 countries during the 2016 global‐bleaching event. Thermal exposure was estimated by two metrics: (a) historical excess summer heat (cumulative thermal anomaly, CTA), and (b) a multivariate index of sea‐surface temperature (SST), light, and water flow (climate exposure, CE). Sensitivity was estimated for 226 sites using coordinated bleaching observations and underwater surveys of coral communities. We then evaluated coral resistance to thermal stress using 48 generalized linear mixed models (GLMMs) to compare the potential influences of geography, historical SST variation, coral cover and coral richness.ResultsGeographic faunal provinces and ecoregions were the strongest predictors of coral resistance to thermal stress, with sites in the Australian, Indonesian and Fiji‐Caroline Islands coral provinces having higher resistance to thermal stress than Africa‐India and Japan‐Vietnam provinces. Ecoregions also showed strong gradients in resistance with highest resistance to thermal stress in the western Pacific and Coral Triangle and lower resistance in the surrounding ecoregions. A more detailed evaluation of Coral Triangle and non‐Coral Triangle sites found higher resistance to thermal stress within the Coral Triangle, associated with c. 2.5 times more recent historical thermal anomalies and more centralized, warmer, and cool‐water skew SST distributions, than in non‐Coral Triangle sites. Our findings identify the importance of environmental history and geographic context in future predictions of bleaching, and identify some potential drivers of coral resistance to thermal stress.Main conclusionsSimple threshold models of heat stress and coral acclimation are commonly used to predict the future of coral reefs. Here and elsewhere we show that large‐scale responses of coral communities to heat stress are geographically variable and associated with differential environmental stresses and histories.

La gestion des récifs coralliens pour la résilience au changement climatique est un concept populaire, mais il a été difficile à mettre en œuvre car les preuves scientifiques empiriques n'ont pas été évaluées ou ne sont parfois pas favorables à la théorie, ce qui conduit à l'incertitude lors de l'examen des méthodes et de l'identification des récifs prioritaires. Nous avons demandé à des experts et examiné la littérature scientifique pour obtenir des conseils sur les multiples facteurs physiques et biologiques qui affectent la capacité des récifs coralliens à résister et à se remettre des perturbations climatiques. Onze facteurs clés pour éclairer les décisions basées sur la mise à l'échelle des preuves scientifiques et la faisabilité de la quantification des facteurs ont été identifiés. Les facteurs importants pour la résistance et la récupération, qui sont des composantes importantes de la résilience, n'étaient pas fortement liés et devraient être évalués de manière indépendante. L'abondance d'espèces coralliennes résistantes (tolérantes à la chaleur) et la variabilité des températures passées ont été perçues comme offrant la plus grande résistance au changement climatique, tandis que les taux de recrutement des coraux et l'abondance des macroalgues ont été les plus influents dans le processus de rétablissement. Sur la base des 11 facteurs clés, nous avons testé un cadre fondé sur des données probantes pour la résilience au changement climatique dans une aire marine protégée indonésienne. Les résultats suggèrent que notre cadre pondéré par les preuves a amélioré les méthodes non pondérées existantes en termes de caractérisation de la résilience et de distinction des sites prioritaires. L'évaluation soutient le concept selon lequel, malgré une grande complexité écologique, relativement peu de variables fortes peuvent être importantes pour influencer la dynamique des écosystèmes. Il s'agit de la première évaluation rigoureuse des facteurs favorisant la résilience des récifs coralliens en fonction de leur importance perçue, des preuves empiriques et de la faisabilité de la mesure. Il y avait peu de différences entre les perceptions des scientifiques de l'importance des facteurs et les preuves scientifiques trouvées dans les publications de revues, mais d'autres études d'impact avant et après seront nécessaires pour tester pleinement la validité de tous les facteurs. Les méthodes ici augmenteront la faisabilité et la défensibilité d'inclure des mesures clés de résilience dans les évaluations des récifs coralliens, ainsi que de réduire les coûts. Adaptation, aires marines protégées, établissement des priorités, résistance, récupération. La gestión de los arrecifes de coral para la resiliencia al cambio climático es un concepto popular, pero ha sido difícil de implementar porque la evidencia científica empírica no se ha evaluado o, a veces, no respalda la teoría, lo que genera incertidumbre al considerar los métodos e identificar los arrecifes prioritarios. Pedimos a expertos y revisamos la literatura científica para obtener orientación sobre los múltiples factores físicos y biológicos que afectan la capacidad de los arrecifes de coral para resistir y recuperarse de las perturbaciones climáticas. Se identificaron once factores clave para informar las decisiones basadas en la evidencia científica a escala y la viabilidad de cuantificar los factores. Los factores importantes para la resistencia y la recuperación, que son componentes importantes de la resiliencia, no estaban fuertemente relacionados y deben evaluarse de forma independiente. Se percibió que la abundancia de especies de coral resistentes (tolerantes al calor) y la variabilidad de la temperatura pasada proporcionaban la mayor resistencia al cambio climático, mientras que las tasas de reclutamiento de coral y la abundancia de macroalgas fueron las más influyentes en el proceso de recuperación. Con base en los 11 factores clave, probamos un marco basado en evidencia para la resiliencia al cambio climático en un área marina protegida de Indonesia. Los resultados sugieren que nuestro marco ponderado por la evidencia mejoró los métodos no ponderados existentes en términos de caracterizar la resiliencia y distinguir los sitios prioritarios. La evaluación respalda el concepto de que, a pesar de la alta complejidad ecológica, relativamente pocas variables fuertes pueden ser importantes para influir en la dinámica de los ecosistemas. Esta es la primera evaluación rigurosa de los factores que promueven la resiliencia de los arrecifes de coral en función de su importancia percibida, la evidencia empírica y la viabilidad de la medición. Hubo pocas diferencias entre las percepciones de los científicos sobre la importancia de los factores y la evidencia científica que se encuentra en las publicaciones de revistas, pero se requerirán más estudios antes y después del impacto para probar completamente la validez de todos los factores. Los métodos aquí mencionados aumentarán la viabilidad y la defendibilidad de incluir métricas clave de resiliencia en las evaluaciones de los arrecifes de coral, así como reducirán los costos. Adaptación, áreas marinas protegidas, priorización, resistencia, recuperación. Managing coral reefs for resilience to climate change is a popular concept but has been difficult to implement because the empirical scientific evidence has either not been evaluated or is sometimes unsupportive of theory, which leads to uncertainty when considering methods and identifying priority reefs. We asked experts and reviewed the scientific literature for guidance on the multiple physical and biological factors that affect the ability of coral reefs to resist and recover from climate disturbance. Eleven key factors to inform decisions based on scaling scientific evidence and the achievability of quantifying the factors were identified. Factors important to resistance and recovery, which are important components of resilience, were not strongly related, and should be assessed independently. The abundance of resistant (heat-tolerant) coral species and past temperature variability were perceived to provide the greatest resistance to climate change, while coral recruitment rates, and macroalgae abundance were most influential in the recovery process. Based on the 11 key factors, we tested an evidence-based framework for climate change resilience in an Indonesian marine protected area. The results suggest our evidence-weighted framework improved upon existing un-weighted methods in terms of characterizing resilience and distinguishing priority sites. The evaluation supports the concept that, despite high ecological complexity, relatively few strong variables can be important in influencing ecosystem dynamics. This is the first rigorous assessment of factors promoting coral reef resilience based on their perceived importance, empirical evidence, and feasibility of measurement. There were few differences between scientists' perceptions of factor importance and the scientific evidence found in journal publications but more before and after impact studies will be required to fully test the validity of all the factors. The methods here will increase the feasibility and defensibility of including key resilience metrics in evaluations of coral reefs, as well as reduce costs. Adaptation, marine protected areas, priority setting, resistance, recovery. تعد إدارة الشعاب المرجانية من أجل المرونة في مواجهة تغير المناخ مفهومًا شائعًا ولكن كان من الصعب تنفيذه لأن الأدلة العلمية التجريبية إما لم يتم تقييمها أو أنها في بعض الأحيان غير داعمة للنظرية، مما يؤدي إلى عدم اليقين عند النظر في الأساليب وتحديد الشعاب المرجانية ذات الأولوية. طلبنا من الخبراء وراجعنا الأدبيات العلمية للحصول على إرشادات حول العوامل الفيزيائية والبيولوجية المتعددة التي تؤثر على قدرة الشعاب المرجانية على المقاومة والتعافي من اضطرابات المناخ. تم تحديد أحد عشر عاملاً رئيسياً لتوجيه القرارات بناءً على قياس الأدلة العلمية وإمكانية تحقيق القياس الكمي للعوامل. لم تكن العوامل المهمة للمقاومة والتعافي، والتي تعد مكونات مهمة للمرونة، مرتبطة ارتباطًا وثيقًا، ويجب تقييمها بشكل مستقل. كان يُنظر إلى وفرة الأنواع المرجانية المقاومة (المقاومة للحرارة) وتقلب درجات الحرارة في الماضي على أنها توفر أكبر مقاومة لتغير المناخ، في حين كانت معدلات تجنيد المرجان ووفرة الطحالب الكلية أكثر تأثيرًا في عملية التعافي. استنادًا إلى العوامل الرئيسية الأحد عشر، اختبرنا إطارًا قائمًا على الأدلة لمرونة تغير المناخ في منطقة محمية بحرية إندونيسية. تشير النتائج إلى أن إطارنا المرجح بالأدلة قد تحسن على الأساليب غير المرجحة الحالية من حيث توصيف المرونة وتمييز المواقع ذات الأولوية. يدعم التقييم المفهوم القائل بأنه على الرغم من التعقيد البيئي الكبير، إلا أن عددًا قليلاً نسبيًا من المتغيرات القوية يمكن أن يكون مهمًا في التأثير على ديناميكيات النظام الإيكولوجي. هذا هو أول تقييم دقيق للعوامل التي تعزز مرونة الشعاب المرجانية بناءً على أهميتها المتصورة والأدلة التجريبية وجدوى القياس. كانت هناك اختلافات قليلة بين تصورات العلماء لأهمية العوامل والأدلة العلمية الموجودة في منشورات المجلات ولكن ستكون هناك حاجة إلى المزيد قبل دراسات التأثير وبعدها لاختبار صحة جميع العوامل بشكل كامل. ستزيد الطرق هنا من الجدوى وإمكانية الدفاع عن تضمين مقاييس المرونة الرئيسية في تقييمات الشعاب المرجانية، بالإضافة إلى تقليل التكاليف. التكيف، والمناطق البحرية المحمية، وتحديد الأولويات، والمقاومة، والتعافي.

A major gap exists in integrating climate projections and social–ecological vulnerability analyses at scales that matter, which has affected local-scale adaptation planning and actions to date. We address this gap by providing a novel methodology that integrates information on: (i) the expected future climate, including climate-related extreme events, at the village level; (ii) an ecological assessment of the impacts of these climate forecasts on coral reefs; and (iii) the social adaptive capacity of the artisanal fishers, to create an integrated vulnerability assessment on coastal communities in five villages in Papua New Guinea. We show that, despite relatively proximate geographies, there are substantial differences in both the predicted extreme rainfall and temperature events and the social adaptive capacity among the five fishing-dependent communities, meaning that they have likely different vulnerabilities to future climate change. Our methodology shows that it is possible to capture social information and integrate this with climate and ecological modeling in ways that are best suited to address the impacts of climate-mediated environmental changes currently underway across different scales.

In Bangladesh, rapid population growth and associated land-use changes are escalating water scarcity issues, which will be further exacerbated under ongoing climate change. As such, predicting the consequences of climate and land-use change on freshwater supplies is critical for the sustainable management of water resources. In this study, a Soil and Water Assessment Tool (SWAT) associated with a Land Cover Model (LCM) were used to simulate long-term stream flows in the Halda Basin, Bangladesh, under baseline and future climate and land-use change scenarios. In addition, the separate and combined impacts of both types of change on long-term streamflow projections were assessed. Results indicate that by the 2060s, the maximum temperature of the Halda Basin may rise by 1.6 °C in comparison to the baseline 1986–2005 period, while minimum temperature will also increase, albeit at a lower rate than maximum temperature. Precipitation during the dry season is expected to increase, although it may decline in the monsoon period. Simulations show that these changes in climate are likely to increase future streamflow in the Halda catchment, with monthly streamflow influenced mainly by the variability in precipitation. The LCM projected decreases in grassland along with cultivated land at the expense of artificial areas. Combined, future climate and land-use changes are projected to increase annual streamflow, with climate change likely to be a greater driver of altered streamflow than land-use changes. Our results should guide environmental management authorities in more sustainable and strategic water resource planning under global climate change.

Among the many causes of habitat loss, urbanization coupled with climate change has produced some of the greatest local extinction rates and has led to the loss of many native species. Managing native vegetation in a rapidly expanding urban setting requires land management strategies that are cognizant of these impacts and how species and communities may adapt to a future climate. Here, we demonstrate how identifying climate refugia for threatened vegetation communities in an urban matrix can be used to support management decisions by local government authorities under the dual pressures of urban expansion and climate change. This research was focused on a local government area in New South Wales, Australia, that is undergoing significant residential, commercial and agricultural expansion resulting in the transition of native forest to other more intensive land-uses. Our results indicate that the key drivers of change from native vegetation to urban and agriculture classes were population density and the proximity to urban areas. We found two of the most cleared vegetation community types are physically restricted to land owned or managed by council, suggesting their long-term ecological viability is uncertain under a warming climate. We propose that land use planning decisions must recognize the compounding spatial and temporal pressures of urban development, land clearing and climate change, and how current policy responses, such as biodiversity offsetting, can respond positively to habitat shifts in order to secure the longevity of important ecological communities.

Without drastic efforts to reduce carbon emissions and mitigate globalized stressors, tropical coral reefs are in jeopardy. Strategic conservation and management requires identification of the environmental and socioeconomic factors driving the persistence of scleractinian coral assemblages—the foundation species of coral reef ecosystems. Here, we compiled coral abundance data from 2,584 Indo-Pacific reefs to evaluate the influence of 21 climate, social and environmental drivers on the ecology of reef coral assemblages. Higher abundances of framework-building corals were typically associated with: weaker thermal disturbances and longer intervals for potential recovery; slower human population growth; reduced access by human settlements and markets; and less nearby agriculture. We therefore propose a framework of three management strategies (protect, recover or transform) by considering: (1) if reefs were above or below a proposed threshold of >10% cover of the coral taxa important for structural complexity and carbonate production; and (2) reef exposure to severe thermal stress during the 2014–2017 global coral bleaching event. Our findings can guide urgent management efforts for coral reefs, by identifying key threats across multiple scales and strategic policy priorities that might sustain a network of functioning reefs in the Indo-Pacific to avoid ecosystem collapse.