• Energy Research

Resumen El calentamiento del océano está aumentando la incidencia, la escala y la gravedad del blanqueamiento y la mortalidad de los corales a escala mundial, que culminó en el tercer evento mundial de blanqueamiento de corales que ocurrió durante las olas de calor marinas récord de 2014-2017. Si bien los efectos locales de estos eventos han sido ampliamente reportados, las implicaciones globales siguen siendo desconocidas. El análisis de 15.066 estudios de arrecifes durante 2014-2017 reveló que el 80% de los arrecifes estudiados experimentaron un blanqueamiento significativo de los corales y el 35% experimentó una mortalidad significativa de los corales. El alcance global del blanqueamiento y la mortalidad significativos de los corales se evaluó extrapolando los resultados de los estudios de arrecifes utilizando datos completos de teledetección del estrés por calor regional. Este modelo predijo que el 51% de los arrecifes de coral del mundo sufrieron un blanqueamiento significativo y una mortalidad significativa del 15%, superando el daño de cualquier evento de blanqueamiento global anterior. Estas observaciones demuestran que el daño generalizado del calentamiento global a los arrecifes de coral se está acelerando y subraya la amenaza que el cambio climático antropogénico representa para la transformación irreversible de estos ecosistemas esenciales. Résumé Le réchauffement des océans augmente l'incidence, l'ampleur et la gravité du blanchiment et de la mortalité des coraux à l'échelle mondiale, culminant avec le troisième événement mondial de blanchiment des coraux survenu lors de vagues de chaleur marines record de 2014-2017. Bien que les effets locaux de ces événements aient été largement rapportés, les implications mondiales restent inconnues. L'analyse de 15 066 enquêtes sur les récifs au cours de la période 2014-2017 a révélé que 80 % des récifs étudiés ont connu un blanchissement important des coraux et 35 % ont connu une mortalité importante des coraux. L'étendue mondiale du blanchiment et de la mortalité importants des coraux a été évaluée en extrapolant les résultats des enquêtes sur les récifs à l'aide de données complètes de télédétection du stress thermique régional. Ce modèle prévoyait que 51 % des récifs coralliens du monde souffraient d'un blanchissement important et 15 % d'une mortalité importante, dépassant les dommages causés par tout événement de blanchissement mondial antérieur. Ces observations démontrent que les dommages généralisés causés par le réchauffement climatique aux récifs coralliens s'accélèrent et soulignent la menace que le changement climatique anthropique fait peser sur la transformation irréversible de ces écosystèmes essentiels. Abstract Ocean warming is increasing the incidence, scale, and severity of global-scale coral bleaching and mortality, culminating in the third global coral bleaching event that occurred during record marine heatwaves of 2014-2017. While local effects of these events have been widely reported, the global implications remain unknown. Analysis of 15,066 reef surveys during 2014-2017 revealed that 80% of surveyed reefs experienced significant coral bleaching and 35% experienced significant coral mortality. The global extent of significant coral bleaching and mortality was assessed by extrapolating results from reef surveys using comprehensive remote-sensing data of regional heat stress. This model predicted that 51% of the world's coral reefs suffered significant bleaching and 15% significant mortality, surpassing damage from any prior global bleaching event. These observations demonstrate that global warming's widespread damage to coral reefs is accelerating and underscores the threat anthropogenic climate change poses for the irreversible transformation of these essential ecosystems. يؤدي ارتفاع درجة حرارة المحيطات إلى زيادة حدوث وحجم وشدة تبييض الشعاب المرجانية ونفوقها على نطاق عالمي، وبلغت ذروتها في الحدث العالمي الثالث لتبييض الشعاب المرجانية الذي حدث خلال موجات الحر البحرية القياسية في الفترة 2014-2017. في حين تم الإبلاغ عن الآثار المحلية لهذه الأحداث على نطاق واسع، إلا أن الآثار العالمية لا تزال غير معروفة. كشف تحليل 15,066 مسحًا للشعاب المرجانية خلال الفترة 2014-2017 أن 80 ٪ من الشعاب المرجانية التي تم مسحها عانت من ابيضاض مرجاني كبير و 35 ٪ عانت من وفيات مرجانية كبيرة. تم تقييم المدى العالمي للتبييض والوفيات المرجانية الكبيرة من خلال استقراء النتائج من المسوحات المرجانية باستخدام بيانات شاملة للاستشعار عن بعد للإجهاد الحراري الإقليمي. وتوقع هذا النموذج أن 51 ٪ من الشعاب المرجانية في العالم عانت من تبييض كبير و 15 ٪ من الوفيات الكبيرة، متجاوزة الأضرار الناجمة عن أي حدث تبييض عالمي سابق. تُظهر هذه الملاحظات أن الأضرار الواسعة النطاق للاحترار العالمي التي لحقت بالشعاب المرجانية تتسارع وتؤكد التهديد الذي يشكله تغير المناخ البشري المنشأ على التحول الذي لا رجعة فيه لهذه النظم الإيكولوجية الأساسية.

Resumen El calentamiento del océano está aumentando la incidencia, la escala y la gravedad del blanqueamiento y la mortalidad de los corales a escala mundial, que culminó en el tercer evento mundial de blanqueamiento de corales que ocurrió durante las olas de calor marinas récord de 2014-2017. Si bien los efectos locales de estos eventos han sido ampliamente reportados, las implicaciones globales siguen siendo desconocidas. El análisis de 15.066 estudios de arrecifes durante 2014-2017 reveló que el 80% de los arrecifes estudiados experimentaron un blanqueamiento significativo de los corales y el 35% experimentó una mortalidad significativa de los corales. El alcance global del blanqueamiento y la mortalidad significativos de los corales se evaluó extrapolando los resultados de los estudios de arrecifes utilizando datos completos de teledetección del estrés por calor regional. Este modelo predijo que el 51% de los arrecifes de coral del mundo sufrieron un blanqueamiento significativo y una mortalidad significativa del 15%, superando el daño de cualquier evento de blanqueamiento global anterior. Estas observaciones demuestran que el daño generalizado del calentamiento global a los arrecifes de coral se está acelerando y subraya la amenaza que el cambio climático antropogénico representa para la transformación irreversible de estos ecosistemas esenciales. Résumé Le réchauffement des océans augmente l'incidence, l'ampleur et la gravité du blanchiment et de la mortalité des coraux à l'échelle mondiale, culminant avec le troisième événement mondial de blanchiment des coraux survenu lors de vagues de chaleur marines record de 2014-2017. Bien que les effets locaux de ces événements aient été largement rapportés, les implications mondiales restent inconnues. L'analyse de 15 066 enquêtes sur les récifs au cours de la période 2014-2017 a révélé que 80 % des récifs étudiés ont connu un blanchissement important des coraux et 35 % ont connu une mortalité importante des coraux. L'étendue mondiale du blanchiment et de la mortalité importants des coraux a été évaluée en extrapolant les résultats des enquêtes sur les récifs à l'aide de données complètes de télédétection du stress thermique régional. Ce modèle prévoyait que 51 % des récifs coralliens du monde souffraient d'un blanchissement important et 15 % d'une mortalité importante, dépassant les dommages causés par tout événement de blanchissement mondial antérieur. Ces observations démontrent que les dommages généralisés causés par le réchauffement climatique aux récifs coralliens s'accélèrent et soulignent la menace que le changement climatique anthropique fait peser sur la transformation irréversible de ces écosystèmes essentiels. Abstract Ocean warming is increasing the incidence, scale, and severity of global-scale coral bleaching and mortality, culminating in the third global coral bleaching event that occurred during record marine heatwaves of 2014-2017. While local effects of these events have been widely reported, the global implications remain unknown. Analysis of 15,066 reef surveys during 2014-2017 revealed that 80% of surveyed reefs experienced significant coral bleaching and 35% experienced significant coral mortality. The global extent of significant coral bleaching and mortality was assessed by extrapolating results from reef surveys using comprehensive remote-sensing data of regional heat stress. This model predicted that 51% of the world's coral reefs suffered significant bleaching and 15% significant mortality, surpassing damage from any prior global bleaching event. These observations demonstrate that global warming's widespread damage to coral reefs is accelerating and underscores the threat anthropogenic climate change poses for the irreversible transformation of these essential ecosystems. يؤدي ارتفاع درجة حرارة المحيطات إلى زيادة حدوث وحجم وشدة تبييض الشعاب المرجانية ونفوقها على نطاق عالمي، وبلغت ذروتها في الحدث العالمي الثالث لتبييض الشعاب المرجانية الذي حدث خلال موجات الحر البحرية القياسية في الفترة 2014-2017. في حين تم الإبلاغ عن الآثار المحلية لهذه الأحداث على نطاق واسع، إلا أن الآثار العالمية لا تزال غير معروفة. كشف تحليل 15,066 مسحًا للشعاب المرجانية خلال الفترة 2014-2017 أن 80 ٪ من الشعاب المرجانية التي تم مسحها عانت من ابيضاض مرجاني كبير و 35 ٪ عانت من وفيات مرجانية كبيرة. تم تقييم المدى العالمي للتبييض والوفيات المرجانية الكبيرة من خلال استقراء النتائج من المسوحات المرجانية باستخدام بيانات شاملة للاستشعار عن بعد للإجهاد الحراري الإقليمي. وتوقع هذا النموذج أن 51 ٪ من الشعاب المرجانية في العالم عانت من تبييض كبير و 15 ٪ من الوفيات الكبيرة، متجاوزة الأضرار الناجمة عن أي حدث تبييض عالمي سابق. تُظهر هذه الملاحظات أن الأضرار الواسعة النطاق للاحترار العالمي التي لحقت بالشعاب المرجانية تتسارع وتؤكد التهديد الذي يشكله تغير المناخ البشري المنشأ على التحول الذي لا رجعة فيه لهذه النظم الإيكولوجية الأساسية.

Over the last four decades the Mexican Caribbean has experienced intensive coastal development, and change on the reef system condition has already been observed. This paper describes the reef system characteristics, at local and seascape scales, and discusses the current status and trends, considering the main research efforts from academia and Non-Governmental Organizations. To date, the coral cover of most reefs in the region is between 15 and 20%, following a slight recovery on mean coral cover over the last decade. During this same period, fleshy macroalgae and herbivorous fish biomass appear to have increased. At seascape scales, an increase of macroalgae and the loss of seagrass habitat have been observed. Considering that anthropogenic and environmental disturbances will most likely increase, the establishment of newly protected areas in the Mexican Caribbean is appropriate, but sufficient accompanying funding is required.

Over the last four decades the Mexican Caribbean has experienced intensive coastal development, and change on the reef system condition has already been observed. This paper describes the reef system characteristics, at local and seascape scales, and discusses the current status and trends, considering the main research efforts from academia and Non-Governmental Organizations. To date, the coral cover of most reefs in the region is between 15 and 20%, following a slight recovery on mean coral cover over the last decade. During this same period, fleshy macroalgae and herbivorous fish biomass appear to have increased. At seascape scales, an increase of macroalgae and the loss of seagrass habitat have been observed. Considering that anthropogenic and environmental disturbances will most likely increase, the establishment of newly protected areas in the Mexican Caribbean is appropriate, but sufficient accompanying funding is required.

Ecological processes on coral reefs commonly have limited spatial and temporal scales and may not be recorded in their long-term geological history. The widespread degradation of Caribbean coral reefs over the last 40 years therefore provides an opportunity to assess the impact of more significant ecological changes on the geological and geomorphic structure of reefs. Here, we document the changing ecology of communities in a coral reef seascape within the context of its geomorphic zonation. By comparing basic ecological indices between historical and modern data we show that in 35 years the reef-front zone was transformed from a complex coral assemblage with a three-dimensional structure, to a size-homogenized and flattened one that is quasi indistinguishable from the adjacent non-accretional coral-ground zone. Today coral assemblages at Punta Maroma are characterized by the dominance of opportunistic species which are either tolerant to adverse environmental conditions, including sedimentation, or are known to be the first scleractinian species to recruit on disturbed reefs, implying they reflect a post-hurricane stage of adjustment. Despite an increase in similarity in ecological indices, the reef-front and coral-ground geomorphic zones still retain significant differences in coral assemblages and benthic habitat and are not homogeneous. The partial convergence of coral assemblages certainly has important consequences for the ecology and geological viability of the reef and its role in coastal protection, but environmental physical drivers continue to exert a fundamental role in the character and zonation of benthic communities of this reef seascape.

Ecological processes on coral reefs commonly have limited spatial and temporal scales and may not be recorded in their long-term geological history. The widespread degradation of Caribbean coral reefs over the last 40 years therefore provides an opportunity to assess the impact of more significant ecological changes on the geological and geomorphic structure of reefs. Here, we document the changing ecology of communities in a coral reef seascape within the context of its geomorphic zonation. By comparing basic ecological indices between historical and modern data we show that in 35 years the reef-front zone was transformed from a complex coral assemblage with a three-dimensional structure, to a size-homogenized and flattened one that is quasi indistinguishable from the adjacent non-accretional coral-ground zone. Today coral assemblages at Punta Maroma are characterized by the dominance of opportunistic species which are either tolerant to adverse environmental conditions, including sedimentation, or are known to be the first scleractinian species to recruit on disturbed reefs, implying they reflect a post-hurricane stage of adjustment. Despite an increase in similarity in ecological indices, the reef-front and coral-ground geomorphic zones still retain significant differences in coral assemblages and benthic habitat and are not homogeneous. The partial convergence of coral assemblages certainly has important consequences for the ecology and geological viability of the reef and its role in coastal protection, but environmental physical drivers continue to exert a fundamental role in the character and zonation of benthic communities of this reef seascape.

Sea-level rise (SLR) is predicted to elevate water depths above coral reefs and to increase coastal wave exposure as ecological degradation limits vertical reef growth, but projections lack data on interactions between local rates of reef growth and sea level rise. Here we calculate the vertical growth potential of more than 200 tropical western Atlantic and Indian Ocean reefs, and compare these against recent and projected rates of SLR under different Representative Concentration Pathway (RCP) scenarios. Although many reefs retain accretion rates close to recent SLR trends, few will have the capacity to track SLR projections under RCP4.5 scenarios without sustained ecological recovery, and under RCP8.5 scenarios most reefs are predicted to experience mean water depth increases of more than 0.5 m by 2100. Coral cover strongly predicts reef capacity to track SLR, but threshold cover levels that will be necessary to prevent submergence are well above those observed on most reefs. Urgent action is thus needed to mitigate climate, sea-level and future ecological changes in order to limit the magnitude of future reef submergence.