Alfred Wegener Institute for Polar and Marine Research
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Destabilization of mutualistic interactions shapes the early heat stress response of the coral holobiont
Get PDFBackgroundThe stability of the symbiotic relationship between coral and their dinoflagellate algae (Symbiodiniaceae) is disrupted by ocean warming. Although the coral thermal response depends on the complex interactions between host, Symbiodiniaceae and prokaryotes, the mechanisms underlying the initial destabilization of these symbioses are poorly understood.ResultsIn a 2-month manipulative experiment, we exposed the coral Porites lutea to gradually increasing temperatures corresponding to 0–8 degree heating weeks (DHW) and assessed the response of the coral holobiont using coral and Symbiodiniaceae transcriptomics, microbial 16S rRNA gene sequencing and physiological measurements. From early stages of heat stress (< 1 DHW), the increase in metabolic turnover shifted the holobiont to a net heterotrophic state in which algal-derived nutrients were insufficient to meet host energy demands, resulting in reduced holobiont performance at 1 DHW. We postulate the altered nutrient cycling also affected the coral-associated microbial community, with the relative abundance of Endozoicomonas bacteria declining under increasing heat stress. Integration of holobiont stress responses correlated this decline to an increase in expression of a host ADP-ribosylation factor, suggesting that Symbiodiniaceae and Endozoicomonas may underlie similar endosymbiotic regulatory processes.ConclusionsThe thermotolerance of coral holobionts therefore is influenced by the nutritional status of its members and their interactions, and this identified metabolic interdependency highlights the importance of applying an integrative approach to guide coral reef conservation efforts.1eX9fiMXdD4vUDcCw31JRUVideo Abstrac
Selective breeding enhances coral heat tolerance even over small spatial scales
Get PDFCoral reefs globally are experiencing escalating mass bleaching and mortality. Reefs along the Western Indian Ocean have been relatively unimpacted. We established heat tolerance baselines and selective breeding efforts for two widespread reef-building Acropora species within the Ningaloo World Heritage Area. To accomplish these goals, we included corals from two thermally distinct southern and northern reefs (mean monthly maximum 27.9°C and 26.6°C, respectively), which reflect both present-day and stress histories. Fitness responses were measured in control and heat stress temperatures (adults = 31.0°C; larvae = 35.5°C), including survival, tissue necrosis, bleaching and photosynthesis. Larvae with one parent from the warmer population exhibited >2.2-fold higher survival under heat stress, while those with both parents from the warmer population survived 1.6-fold better (compared with control larvae with two parents from the cooler population). Photosynthesis was maintained in both species and both populations, suggesting heat responses were host-driven. Adults from both populations of one species (Acropora tenuis) exhibited similar responses to heat, while the other (Acropora millepora) was more variable. These findings are the first to demonstrate that selective breeding can provide heat tolerance enhancement for corals in the Indian Ocean and will be critical to preparing for future marine heatwaves
Justicia en territorios pesqueros. Violaciones de los derechos humanos de comunidades pesqueras artesanales en el Caribe colombiano
No full textEsta obra analiza la efectividad del sistema jurídico colombiano en la búsqueda de la justicia y la reclamación de derechos humanos en espacios marinos y costeros por medio de las experiencias de tres comunidades pesqueras en Colombia. Una comunidad que no tiene ningún tipo de reconocimiento étnico (Don Jaca), una comunidad indígena wayúu (Manaure) y una comunidad negra (La Boquilla), quienes han reclamado sus derechos sobre sus territorios pesqueros ancestrales por medio del uso de herramientas jurídicas frente a proyectos de infraestructura y desarrollo costero para puertos carboníferos (Sentencia T-229/1993), exploraciones de hidrocarburos off-shore (T-011/2018) y turismo (T-376/2012 y T-226/2016), respectivamente. A través de la revisión de información secundaria y el uso de instrumentos metodológicos participativos, el equipo de investigadoras recopiló el sentir de cada una de las comunidades y logró reconstruir históricamente los cambios y transformaciones sociales y ambientales en el territorio pesquero. Los resultados obtenidos para cada caso de estudio se presentan a partir de la comprensión de los modos de vida y relación de las comunidades con los territorios pesqueros, el conflicto pesquero judicializado (problemáticas y afectaciones), la noción de la justicia en el mar (desde un enfoque de derechos humanos) y las estrategias de defensa y lucha de las comunidades
Agroclimatic landscapes of pergamon: Modeling agricultural suitability of an ancient city and its environs
Get PDFThe relationship between humans and the natural environment is shaped by the perception, utilization, and management of natural resources. In the Mediterranean region, the cultivation of resources has played a crucial role in shaping landscapes over time. Assessing the potential of landscapes for using various natural resources provides insights into the functioning of socio-ecological systems and highlights areas susceptible to environmental fluctuations and human exploitation. The environs of Pergamon - the ancient capital of the Pergamene Kingdom and later a major Roman city in Asia Minor - serve as an exemplary case of human-environment interaction in Western Anatolia. This work reconstructs the climatic potential for cultivating annual crops commonly used in Mediterranean rainfed agricultural systems, focusing on the Pergamon micro-region. Paleoclimate simulations from MPI-ESM 1.2 with high spatial resolution T63 (~1.875° x 1.875° on a gaussian grid) were integrated into the EcoCrop niche model to explore spatio-temporal changes in agricultural suitability from 400 BCE to 400 CE. The results highlight the consistent agricultural potential of the western Bakırçay plain due to its favorable climatic conditions. In contrast, the eastern plain and surrounding foothills exhibit greater variability, necessitating adaptive land management strategies. Comparisons with a pollen-based reconstruction confirmed the general alignment in climatic trends, supporting the plausibility of the modeled scenarios. Favorable conditions may have sustained agricultural productivity but also highlight dependencies on regional trade networks, decoupling Pergamon's economy from local subsistence agriculture and introducing vulnerabilities to trade disruptions. This study challenges the notion of a uniform "Roman" Climate Optimum, highlighting the importance of understanding local agroclimatic conditions and adaptive land management strategies in ancient societies
Arctic‐Boreal Bryophyte Dynamics Since the Last Glacial Inferred From Ancient DNA Metabarcoding
No full textABSTRACT Aim This study investigates the main changes in bryophyte diversity and composition during the last 30,000 years in arctic and boreal ecosystems. Turnover in biological and ecological trait compositions of recorded bryophytes is assessed to explore changes in dominant life‐strategies and habitats. Location The study area covers Siberia and Alaska (55°–90° N, 50°–150° E and 40°–90° N, 150° E‐140° W). Taxon Bryophytes. Methods We leveraged a dataset of plant DNA metabarcoding (chloroplast, trn L) of sedimentary ancient DNA from 26 lake sediment cores. Our statistical analyses only target DNA reads assigned to bryophytes. Results A total of 120 amplicon sequence variants were obtained, which could be assigned 100% to bryophyte taxa. Our results indicate that the dominant families in the palaeo‐record reflect well the dominant families observed in Siberia and Alaska, and compositional changes reflect mainly the modern latitudinal gradient. For example, Sphagnum shows a clear post‐glacial expansion pattern. Richness was high in times of high habitat diversity. Our data reveal a turnover from biological traits characteristic of an r‐strategy (colonists/short‐lived, small size, monoicous, long sporophyte season, small spores) during the glacial towards a K‐strategy (long‐lived, large size, dioicous, short sporophyte season, large spores) during the Holocene. The ecological traits indicate a shift towards taxa with a preference for high summer temperature, forested habitats, soil acidity and wetlands. Main Conclusions Our results indicated substantial changes in the diversity and taxonomic composition, and dominant biological and ecological traits of bryophyte communities along with past warming and related habitat changes at the transition from glacial period to Holocene. This may to some extent represent an analogue for ongoing ecological change in northern high latitudes. Leveraging bryophyte records in sedimentary ancient DNA reveals promising results which could be enhanced once bryophyte representation in biodiversity and genetic databases has increased and bryophyte‐specific ancient DNA methods become established
A Python interface to the Fortran-based Parallel Data Assimilation Framework: pyPDAF v1.0.2
Get PDFAbstract. Data assimilation (DA) is an essential component of numerical weather and climate prediction. Efficient implementation of DA algorithms benefits both research and operational prediction. Currently, a variety of DA software programs are available. One of the notable DA libraries is the Parallel Data Assimilation Framework (PDAF) designed for ensemble data assimilation. The DA framework is widely used with complex high-dimensional climate models, and is applied for research on atmosphere, ocean, sea ice and marine ecosystem modelling, as well as operational ocean forecasting. Meanwhile, there are increasing demands for flexible and efficient DA implementations using Python due to the increasing amount of intermediate complexity models as well as machine learning based models coded in Python. To accommodate for such demands, we introduce a Python interface to PDAF, pyPDAF. pyPDAF allows for flexible DA system development while retaining the efficient implementation of the core DA algorithms in the Fortran-based PDAF. The ideal use-case of pyPDAF is a DA system where the model integration is independent from the DA program, which reads the model forecast ensemble, produces an analysis, and updates the restart files of the model, or a DA system where the model can be used in Python. With implementations of both PDAF and pyPDAF, this study demonstrates the use of pyPDAF and PDAF in a coupled data assimilation (CDA) setup in a coupled atmosphere-ocean model, the Modular Arbitrary-Order Ocean-Atmosphere Model (MAOOAM). This study demonstrates that pyPDAF allows for PDAF functionalities from Python where users can utilise Python functions to handle case-specific information from observations and numerical model. The study also shows that pyPDAF can be used with high-dimensional systems with little slow-down per analysis step of only up to 13 % for the localized ensemble Kalman filter LETKF in the example used in this study. The study also shows that, compared to PDAF, the overhead of pyPDAF is comparatively smaller when computationally intensive components dominate the DA system. This can be the case for systems with high-dimensional state vectors
Iceberg influence on snow distribution and slush formation on Antarctic landfast sea ice from airborne multi-sensor observations
Get PDFAbstract. Landfast sea ice fringes much of the coast of Antarctica and plays an important role for coastal ice–ocean–atmosphere interaction and ice shelf stability, as well as for the sea ice associated ecosystem. It is often characterized by embedded icebergs, which influence wind-driven snow distribution and properties. Using high-resolution data from an airborne multi-sensor survey over landfast sea ice in Atka Bay, Dronning Maud Land, in December 2022, we investigate the characteristics of extensive snow drifts around icebergs and their impact on flooding. An airborne quad-polarized, ultra-wideband microwave (UWBM) snow radar and laser scanner reveal persistent snow accumulation patterns around icebergs, with thick snow drifts on the windward side of icebergs, elongated lateral snow drifts parallel to the prevailing wind direction along their sides, and virtually snow-free regions with rough ice surfaces in their lee. The mass of the thick wind-facing and lateral snow drifts pushes the sea ice locally below sea level leading to flooding and slush formation at the base of the snow drifts. These heterogeneous snow–water–sea-ice interfaces cause increased cross-polarized backscatter due to depolarization in the UWBM radar returns, providing a means for slush detection by airborne radar surveys. Presence of slush is confirmed by ground-based electromagnetic induction sounding data as well as with in situ measurements. Our study documents the significant influence of icebergs on snow thickness variability and redistribution over landfast sea ice and for slush formation. Moreover, it demonstrates that the snow in the lee of icebergs is thin, resulting in high radar backscatter in SAR imagery. These insights improve our understanding of wind-driven snow distribution and its impact on flooding on iceberg-laden landfast sea ice, contributing to better assessments of snow transport, sea ice mass balance, and climate modeling around Antarctica
Distribution of rare earth elements and their signatures from the Mackenzie River delta to the Abyssal Arctic Ocean
Get PDFNarrators of submersive affective atmospheres: Analysing oceanic representations through narratives of sound
Get PDFArt-science installations with a focus on marine research are a critical way that the ocean is experienced by various publics beyond the physical boundaries of the sea. Like ocean themed cinema, documentaries, music, photo exhibitions, aquariums, museums and so on they contribute to how oceans are imagined and experienced without the need to get wet. Although they can never quite replicate the ocean, they offer touching points for embodied engagement with alternative imaginaries of the sea. Mirrors is a sound installation that follows the acoustic journey of the Minke Whale as it travels from Antarctica to the coast of Namibia, which debuted in 2023 as part of an international marine biodiversity symposium. Drawing from the development and delivery of Mirrors, this paper contends that sound installations are one way that audiences can know the ocean as they uniquely capture underwater worlds and anthropogenic impacts on marine life. This paper argues that key to the success of this is being able to create narratives that can inspire oceanic imaginations through what is introduced for the first time in this paper as ‘submersive affective atmospheres’