ALBERT

Description: The toxin-producing dinoflagellate Alexandrium pseudogonyaulax has become increasingly abundant in northern European waters, replacing other Alexandrium species. A. pseudogonyaulax produces goniodomins and lytic substances, which can be cytotoxic toward other organisms, including fish, but we still know little about the environmental conditions influencing its growth and toxicity. Here, we investigated the impacts of different nitrogen sources and light intensities, common bottom-up drivers of bloom formation, on the growth and toxin content of three A. pseudogonyaulax strains isolated from the Danish Limfjord. While the growth rates were significantly influenced by nitrogen source and light intensity, the intracellular toxin contents only showed strong differences between the exponential and stationary growth phases. Moreover, the photophysiological response of A. pseudogonyaulax showed little variation across varying light intensities, while light-harvesting pigments were significantly more abundant under low light conditions. This study additionally highlights considerable physiological variability between strains, emphasizing the importance of conducting laboratory experiments with several algal strains. A high physiological plasticity toward changing abiotic parameters points to a long-term establishment of A. pseudogonyaulax in northern European waters.

Description: Model reconstruction of past ice dynamic changes are essential for our understanding of future ice sheet responses to climate change. However, paleo ice sheet model studies are poorly constrained as spatiotemporal coverage of proxy reconstructions are sparse. Previously, we showed, that it is possible to identify or exclude past ice sheet instabilities by using the isotopic record and age structure of a deep ice core in vicinity to dynamic outlet sectors as a constraint for flow parameterizations in an ice sheet model. Here, we highlight key Antarctic ice sheet domains in which deep ice cores in concert with radar observations of the ice sheet’s stratigraphy hold great potential to provide an even more rigid observational tuning target for ice flow models. In some of these regions dated deep ice cores are already available, often including coverage of internal reflection horizons potentially connecting the ice core age structure with faster flowing outlet sectors. In other regions either an ice core providing age constraints or radar observations are not yet available. We discuss the potential of ice core/stratigraphically calibrated ice flow modelling of dynamic Antarctic drainage systems. Furthermore, we present first model estimates of the age structure in these regions and identify promising sites for future ice coring expeditions or ice penetrating radar missions.

Description: 〈jats:p〉Abstract. Stable water isotopes stored in snow, firn and ice are used to reconstruct climatic parameters. The imprint of these parameters at the snow surface and their preservation in the upper snowpack are determined by a number of processes influencing the recording of the environmental signal. Here, we present a dataset of approximately 3800 snow samples analysed for their stable water isotope composition, which were obtained during the summer season next to the deep drilling site of the East Greenland Ice Core Project in northeast Greenland (75.635411° N, 36.000250° W). Sampling was carried out every third day between 14 May and 3 August 2018 along a 39 m long transect. Three depth intervals in the top 10 cm were sampled at 30 positions with a higher resolution closer to the surface (0–1 and 1–4 cm depth vs. 4–10 cm). The sample analysis was carried out at two renowned stable water isotope laboratories that produced isotope data with the overall highest uncertainty of 0.09 ‰ for δ18O and 0.8 ‰ for δD. This unique dataset shows the strongest δ18O variability closest to the surface, damped and delayed variations in the lowest layer, and a trend towards increasing homogeneity towards the end of the season, especially in the deepest layer. Additional information on the snow height and its temporal changes suggests a non-uniform spatial imprint of the seasonal climatic information in this area, potentially following the stratigraphic noise of the surface. The data can be used to study the relation between snow height (changes) and the imprint and preservation of the isotopic composition at a site with 10–14 cm w.e. yr−1 accumulation. The high-temporal-resolution sampling allows additional analyses on (post-)depositional processes, such as vapour–snow exchange. The data can be accessed at https://doi.org/10.1594/PANGAEA.956626 (Zuhr et al., 2023a). 〈/jats:p〉

Description: The toxin-producing dinoflagellate Alexandrium pseudogonyaulax has become increasingly abundant in northern European waters, replacing other Alexandrium species. A. pseudogonyaulax produces goniodomins and lytic substances, which can be cytotoxic toward other organisms, including fish, but we still know little about the environmental conditions influencing its growth and toxicity. Here, we investigated the impacts of different nitrogen sources and light intensities, common bottom-up drivers of bloom formation, on the growth and toxin content of three A. pseudogonyaulax strains isolated from the Danish Limfjord. While the growth rates were significantly influenced by nitrogen source and light intensity, the intracellular toxin contents only showed strong differences between the exponential and stationary growth phases. Moreover, the photophysiological response of A. pseudogonyaulax showed little variation across varying light intensities, while light-harvesting pigments were significantly more abundant under low light conditions. This study additionally highlights considerable physiological variability between strains, emphasizing the importance of conducting laboratory experiments with several algal strains. A high physiological plasticity toward changing abiotic parameters points to a long-term establishment of A. pseudogonyaulax in northern European waters.

Description: The subglacial landscape of Antarctica records and influences the behaviour of its overlying ice sheet. However, in many places, the evolution of the landscape and its control on ice sheet behaviour have not been investigated in detail. Using recently released radio-echo sounding data, we investigate the subglacial landscape of the Evans–Rutford region of West Antarctica. Following quantitative analysis of the landscape morphology under ice-loaded and ice-unloaded conditions, we identify 10 flat surfaces distributed across the region. Across these 10 surfaces, we identify two distinct populations based on clustering of elevations, which potentially represent remnants of regionally coherent pre-glacial surfaces underlying the West Antarctic Ice Sheet (WAIS). The surfaces are bounded by deeply incised glacial troughs, some of which have potential tectonic controls. We assess two hypotheses for the evolution of the regional landscape: (1) passive-margin evolution associated with the break-up of the Gondwana supercontinent or (2) an extensive planation surface that may have been uplifted in association with either the West Antarctic Rift System or cessation of subduction at the base of the Antarctic Peninsula. We suggest that passive-margin evolution is the most likely of these two mechanisms, with the erosion of glacial troughs adjacent to, and incising, the flat surfaces likely having coincided with the growth of the WAIS. These flat surfaces also demonstrate similarities to other identified surfaces, indicating that a similar formational process may have been acting more widely around the Weddell Sea embayment. The subsequent fluctuations of ice flow, basal thermal regime, and erosion patterns of the WAIS are therefore controlled by the regional tectonic structures.

Description: The strategic ambition is to develop an operational, comprehensive, and resourced system that delivers priority observations and information to guide mitigation and adaptation responses to climate change, sustains ocean health within a sustainable blue economy, and facilitates informed decision-making for science, business and society. Such a system is envisioned to be co-designed, fit-for-purpose, multidisciplinary, geographically expanded, responsive, and sustainable in time, delivering ocean observations to all nations and users, prioritising societal needs. Transforming ocean observations into accessible information will require integration across disciplines, across national observing systems, along the value chain, and across stakeholders. Innovative technology approaches and a diversified set of actors and approaches will be required for success. The Global Ocean Observing System (GOOS) of IOC UNESCO can provide the implementation framework for Challenge 7 and the UN Ocean Decade provides the opportunity and vehicle for transformation. Five recommendations have been identified to fulfil the strategic ambition of Ocean Decade Challenge 7. Act now on known observational needs. Upgrade and expand ocean observing capacity in poorly-observed areas such as polar regions, island nations and territories, coastal areas of developing nations, coastal systems that are rapidly changing, and the under-observed deep ocean. Thematic priorities for ocean observing by 2030 should focus on key climate risk and adaptation needs, extreme events, coastal services for ocean management, ocean carbon, marine pollution, biogeochemistry, and biodiversity. Adopt new economic thinking. Establish new and sustained financing mechanisms for global ocean observing, including resourcing for Small Island Developing States (SIDS) and Least Developed Countries (LDCs). Use economic models for ocean investment to diversify and accelerate investment in ocean observing and infrastructure from new actors. Partnerships are key. Increase national, regional and global coordination, focusing on co-design and partnerships. Improved coordination that uses the GOOS framework to ensure standards, best practices for a sustainably expanded GOOS. Diversify partnerships across sectors (economic, public, private, and philanthropic) and embrace the abilities and needs of the different stakeholders to co-design, co-develop, and co-deliver observations that translate into the information required by these sectors. Technology and innovation will be a pillar. Integrate and harmonise observations across observing platforms (in situ, satellite, emerging networks). Develop innovative in situ, autonomous and cost-effective technologies to maximise reach, ensuring standardisation and best practices. Technology barriers still need to be lowered to ensure everyone has equitable access to observing technology and has the ability to use these assets. Artificial Intelligence (AI) and Machine Learning (ML) tools will provide user-ready information from integrated observations to democratise information for users. Expanded, capable, and diversified workforce. Expand and diversify the workforce of skilled and trained ocean professionals. Training and capacity development will be critical across the observing ‘ecosystem’ outlined in the Framework for Ocean Observing (FOO), from data collection to data analysis and modelling, and for data use and application.

Description: Published

Description: Refereed

Description: By 2030, the success of Ocean Decade Challenge No.1 ‘Understand and Beat Marine Pollution’ will be demonstrated by the generation of scientifically sound data enabling a holistic understanding of the extent and impact of pollution across the land-ocean continuum, thereby supporting the achievement of a cleaner and healthier ocean where all ecosystems and their inhabitants thrive free from the impacts of marine pollution, allowing for their full functioning and service provision. This success will be based on completion of a comprehensive review of all available evidence about marine pollution, including an analysis of data gaps and the development and implementation of strategies for filling those gaps, as well as a comprehensive analysis of solutions for addressing and preventing the negative effects of marine pollution. Achieving this success will require knitting together existing and new data sets using AI and other technologies, identifying priority pollutants and areas for action, and providing globally consistent monitoring, data collection, storage and sharing protocols. Success will further be demonstrated through the establishment of new connections and partnerships among users across the public - private spectrum that lead to the funding, development and implementation of new technologies and projects aimed at monitoring, controlling, reducing, and/or mitigating marine pollution from any source, including the creation and sustainability of a global network of strategically positioned sentinel stations and regional laboratory hubs for sustained, long-term monitoring of marine pollution. Success will include fulfilment of the following critical knowledge gaps: • a comprehensive and holistic understanding of the impacts of priority pollutants (e.g., pollutants found or expected to emerge in high concentrations, or with high toxicity, or with significant adverse effects on biota or human health) across the land to ocean continuum; • a better understanding of the sources, sinks, fate and impacts of all pollutants, including the pollutants of emerging concern; • improved knowledge on the distribution and impacts of marine pollution, particularly in the Global South and deep ocean waters, which currently represent the largest geographical gaps. and the following priority datasets gaps: • long-term time series of marine pollutants; • baseline and toxicity data of pollutants across the land-ocean continuum; • data on the impacts of the co-occurrence of multiple pollutants; • data on the effects of climate change on the toxicity, bioavailability and impacts of multiple co-existent pollutants. • It will include development of: • a global network of strategically positioned sentinel stations for continuous, long-term monitoring; • cost-effective, real-time monitoring systems and technologies for tracking pollutant sources, distribution, and transfers across the land-ocean continuum; • a global network of regional laboratory hubs focused on generating high-quality data, promoting capacity building and facilitating technology transfer; • training programs on harmonized protocols for the acquisition, reporting and recording of quality-controlled data on marine pollution; • environmentally robust new technologies and processes for the control and mitigation of marine pollution.

Description: Published

Description: Refereed