• Energy Research

El mar Mediterráneo es un punto caliente de biodiversidad marina. Aquí combinamos un extenso análisis de la literatura con opiniones de expertos para actualizar las estimaciones disponibles públicamente de los principales taxones en este ecosistema marino y para revisar y actualizar varias listas de especies. También evaluamos los patrones espaciales y temporales generales de la diversidad de especies e identificamos los principales cambios y amenazas. Nuestros resultados enumeraron aproximadamente 17.000 especies marinas que se encuentran en el mar Mediterráneo. Sin embargo, nuestras estimaciones de la diversidad marina aún están incompletas, ya que en el futuro se añadirán especies aún no descritas. La diversidad de microbios está sustancialmente subestimada, y las áreas de aguas profundas y partes de la región sur y este aún son poco conocidas. Además, la invasión de especies exóticas es un factor crucial que seguirá cambiando la biodiversidad del Mediterráneo, principalmente en su cuenca oriental que puede extenderse rápidamente hacia el norte y hacia el oeste debido al calentamiento del mar Mediterráneo. Los patrones espaciales mostraron una disminución general de la biodiversidad de las regiones noroeste a sureste después de un gradiente de producción, con algunas excepciones y cautela debido a las lagunas en nuestro conocimiento de la biota a lo largo de los bordes sur y este. La biodiversidad también fue generalmente mayor en las zonas costeras y las plataformas continentales, y disminuye con la profundidad. Las tendencias temporales indicaron que la sobreexplotación y la pérdida de hábitat han sido los principales impulsores humanos de los cambios históricos en la biodiversidad. En la actualidad, la pérdida y degradación del hábitat, seguida de los impactos de la pesca, la contaminación, el cambio climático, la eutrofización y el establecimiento de especies exóticas son las amenazas más importantes y afectan al mayor número de grupos taxonómicos. Se espera que todos estos impactos crezcan en importancia en el futuro, especialmente el cambio climático y la degradación del hábitat. La identificación espacial de los puntos calientes destacó la importancia ecológica de la mayoría de las plataformas del Mediterráneo occidental (y en particular, el Estrecho de Gibraltar y el Mar de Alborán adyacente), la costa de África occidental, el Adriático y el Mar Egeo, que muestran altas concentraciones de especies en peligro de extinción, amenazadas o vulnerables. La cuenca levantina, gravemente afectada por la invasión de especies, también está en peligro de extinción. Este resumen ha sido traducido a otros idiomas (Archivo S1). La mer Méditerranée est un point chaud de la biodiversité marine. Ici, nous avons combiné une analyse documentaire approfondie avec des avis d'experts pour mettre à jour les estimations accessibles au public des principaux taxons de cet écosystème marin et pour réviser et mettre à jour plusieurs listes d'espèces. Nous avons également évalué les schémas spatiaux et temporels globaux de la diversité des espèces et identifié les principaux changements et menaces. Nos résultats ont répertorié environ 17 000 espèces marines présentes dans la mer Méditerranée. Cependant, nos estimations de la diversité marine sont encore incomplètes car des espèces encore non décrites seront ajoutées à l'avenir. La diversité pour les microbes est considérablement sous-estimée, et les zones d'eau profonde et les parties de la région sud et est sont encore mal connues. En outre, l'invasion d'espèces exotiques est un facteur crucial qui continuera à modifier la biodiversité de la Méditerranée, principalement dans son bassin oriental qui peut se propager rapidement vers le nord et l'ouest en raison du réchauffement de la mer Méditerranée. Les modèles spatiaux ont montré une diminution générale de la biodiversité des régions du nord-ouest au sud-est suivant un gradient de production, à quelques exceptions près et avec prudence en raison de lacunes dans nos connaissances du biote le long des rives sud et est. La biodiversité était également généralement plus élevée dans les zones côtières et les plateaux continentaux, et diminuait avec la profondeur. Les tendances temporelles ont indiqué que la surexploitation et la perte d'habitat ont été les principaux moteurs humains des changements historiques de la biodiversité. À l'heure actuelle, la perte et la dégradation de l'habitat, suivies des impacts de la pêche, de la pollution, du changement climatique, de l'eutrophisation et de l'établissement d'espèces exotiques sont les menaces les plus importantes et affectent le plus grand nombre de groupes taxonomiques. Tous ces impacts devraient prendre de l'importance à l'avenir, en particulier le changement climatique et la dégradation de l'habitat. L'identification spatiale des points chauds a mis en évidence l'importance écologique de la plupart des plateaux de la Méditerranée occidentale (et en particulier du détroit de Gibraltar et de la mer d'Alboran adjacente), de la côte ouest africaine, de l'Adriatique et de la mer Égée, qui présentent de fortes concentrations d'espèces menacées, menacées ou vulnérables. Le bassin levantin, gravement touché par l'invasion des espèces, est également menacé. Ce résumé a été traduit dans d'autres langues (Fichier S1). The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet-undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well. This abstract has been translated to other languages (File S1). البحر الأبيض المتوسط هو نقطة ساخنة للتنوع البيولوجي البحري. هنا قمنا بدمج تحليل شامل للأدبيات مع آراء الخبراء لتحديث التقديرات المتاحة للجمهور للأنواع الرئيسية في هذا النظام البيئي البحري ومراجعة وتحديث العديد من قوائم الأنواع. كما قمنا بتقييم الأنماط المكانية والزمنية العامة لتنوع الأنواع وحددنا التغييرات والتهديدات الرئيسية. أدرجت نتائجنا ما يقرب من 17000 نوع بحري موجود في البحر الأبيض المتوسط. ومع ذلك، لا تزال تقديراتنا للتنوع البحري غير مكتملة حيث ستتم إضافة الأنواع التي لم يتم وصفها بعد في المستقبل. يتم التقليل بشكل كبير من تنوع الميكروبات، ولا تزال مناطق البحار العميقة وأجزاء من المنطقة الجنوبية والشرقية غير معروفة بشكل جيد. بالإضافة إلى ذلك، فإن غزو الأنواع الغريبة هو عامل حاسم سيستمر في تغيير التنوع البيولوجي للبحر الأبيض المتوسط، ولا سيما في حوضه الشرقي الذي يمكن أن ينتشر بسرعة نحو الشمال والغرب بسبب ارتفاع درجة حرارة البحر الأبيض المتوسط. أظهرت الأنماط المكانية انخفاضًا عامًا في التنوع البيولوجي من المناطق الشمالية الغربية إلى الجنوبية الشرقية بعد تدرج الإنتاج، مع بعض الاستثناءات والحذر بسبب الفجوات في معرفتنا بالحيوانات على طول الحافات الجنوبية والشرقية. كما كان التنوع البيولوجي أعلى بشكل عام في المناطق الساحلية والجروف القارية، ويتناقص مع العمق. أشارت الاتجاهات الزمنية إلى أن الاستغلال المفرط وفقدان الموائل كانا المحركين الرئيسيين للتغيرات التاريخية في التنوع البيولوجي. في الوقت الحاضر، يعد فقدان الموائل وتدهورها، متبوعًا بتأثيرات الصيد والتلوث وتغير المناخ وتغذيتها بالمغذيات وإنشاء أنواع غريبة، من أهم التهديدات ويؤثر على أكبر عدد من المجموعات التصنيفية. ومن المتوقع أن تزداد أهمية كل هذه الآثار في المستقبل، لا سيما تغير المناخ وتدهور الموائل. سلط التحديد المكاني للنقاط الساخنة الضوء على الأهمية البيئية لمعظم أرفف غرب البحر الأبيض المتوسط (ولا سيما مضيق جبل طارق وبحر البوران المجاور) وساحل غرب إفريقيا والبحر الأدرياتيكي وبحر إيجة، والتي تظهر تركيزات عالية من الأنواع المهددة بالانقراض أو المهددة أو المعرضة للخطر. كما أن حوض بلاد الشام، الذي تأثر بشدة بغزو الأنواع، معرض للخطر أيضًا. تمت ترجمة هذا الملخص إلى لغات أخرى (الملف S1).

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to reproductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young.

In marine ecosystems climatic fluctuation and other physical variables greatly influence population dynamics, but differential effects of physical variables on the demographic parameters of the two sexes and different age classes are largely unexplored. We analyzed the effects of climate on the survival and recruitment of both sexes and several age classes of a long‐lived tropical seabird, the Blue‐footed Booby (Sula nebouxii), using long‐term observations on marked individuals. Results demonstrated a complex interaction between yearly fluctuations in climate (both local and global indexes, during both winter and breeding season) and the sex and age of individuals. Youngest birds' survival and recruitment were commonly affected by local climate, whereas oldest birds' parameters tended to be constant and less influenced by environmental variables. These results confirm the theoretical prediction that sex‐ and age‐related variation in life‐history demographic traits is greater under poor environmental conditions, and they highlight the importance of including variability in fitness components in demographic and evolutionary models. Males and females showed similar variation in survival but different recruitment patterns, in relation to both age and the spatial scale of climatic influence (local or global). Results indicate different life‐history tactics for each sex and different ages, with birds likely trying to maximize their fitness by responding to the environmental contingencies of each year.

AbstractAgents of global change commonly have a higher impact on island ecosystem dynamics. In the Mediterranean region, those dynamics have historically been influenced by anthropogenic impacts, for example, the introduction of invasive species and overharvesting of resources. Here, we analysed the spatio‐temporal dynamics of vegetation in sa Dragonera island, which experienced a large environmental change ca. 4000 years ago by the arrival of humans. Anthropogenic impacts, such as herbivory by goats and over‐logging, ended in the 1970s, while in 2011 the site became the largest Mediterranean island where rats were eradicated. Invasive rats and goats played the ecological role of two endemic species, the cave goat and the giant dormouse, which inhabited the island for more than 5 million years and were rapidly extinct by humans. We used Landsat imagery to explore NDVI as a proxy of vegetation productivity over the years 1984–2021, orthophotos to assess changes in land and vegetation covers and historical plant inventories to study the dynamics in plant diversity. Results showed that those indicators steadily increased both in spring and in summer, while the noise around the trends was partially explained by climate variability. The regime shifts in the temporal dynamics of vegetation productivity suggested a transient from a perturbed to a non‐perturbed stable state. Trends in successional dynamics, spatial self‐organization and plant diversity also showed the same type of transient dynamics. Historical perturbations related to harvesting (mainly the synergies between goat browsing, burning and forest over‐logging) were more important than rat eradication or the influence of climate to explain the vegetation dynamics. Our study shows the transient nature of this small island ecosystem after 4000 years of perturbations and its current path towards vegetation dynamics more controlled by ecological interactions lacking large herbivores and omnivores, drought dynamics and the carrying capacity of the island.

Sex of offspring in most turtles is determined by temperature-dependent sex determination (TSD). In sea turtles, higher incubation temperatures produce female hatchlings and primary sex ratios are often highly female-biased. Because of the current rate of climate warming, highly female-biased sex ratios have raised concern among scientists and managers because populations might become too female biased for genetic viability.We tested the effects of higher incubation temperatures on embryo and hatchling mortality and on sex ratios in a population of leatherback turtles (Dermochelys coriacea) in the eastern Pacific. The long-term study provided a large sample size in a location influenced by El Niño Southern Oscillation that resulted in highly variable climatic conditions between seasons. High temperatures reduced emergence success. Output of female hatchlings increased with incubation temperature as it reached the upper end of the transitional range (range of temperatures that produce both sexes) (30. °C) and decreased afterwards because high temperatures increased mortality of 'female clutches'. Effect of temperature on female hatchling output lessened female-biased sex ratios from 85% female primary sex ratios to 79% secondary sex ratios (sex ratios of total number of hatchlings emerged). If male turtles reproduce more often than females, operational sex ratios will be closer to 1:1. Female-biased primary sex ratios should not raise concerns by default, but climate change may still threaten populations by reducing hatchling output and increasing frequency of seasons with 100% female production. Clutch relocation to cooler conditions may alter sex ratios and should be used cautiously unless temperatures are so high that no hatchlings survive. In addition, it is unknown what differential survival of male versus female hatchlings may have on the eventual adult sex ratio after they enter the ocean and disperse. © 2014 Elsevier Ltd. Funding was provided by the Earthwatch Institute, The Betz Chair Endowment of Drexel University, The Leatherback Trust, The Goldring Family Foundation, The Schrey Distinguished Professorship of Indiana University-Purdue University Fort Wayne, the Balearic Government (FEDER funds) and by a Marie Curie International Incoming Fellowship within the 7th European Community Framework Programme Peer Reviewed