Alfred Wegener Institute for Polar and Marine Research
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Comparing simulated marine reservoir ages of the non-polar surface ocean between different models under consideration of abrupt changes in the Atlantic Meridional Overturning Circulation during last 55 kyr
Get PDFTaxonomic uncertainty in North Atlantic and Mediterranean zooplankton limits species-level monitoring accuracy
No full textAbstract
Taxonomic discussions often permeate the broader scientific community slowly, yet they may hold more relevance than typically assumed. In many zooplankton groups, identification issues arise from cryptic species complexes, increasingly revealed by molecular approaches, and from groups with high morphological similarity. These challenges can lead to substantial uncertainties in species-level identification, questioning whether the expected species are truly covered and whether those sharing names across ecosystems are indeed distinct entities. This review provides a condensed overview on identification challenges of key species in the ICES zooplankton time series from the North Atlantic and adjacent seas. Examples are given across all relevant groups, including copepods, gelatinous plankton, and meroplanktonic larvae. The high prevalence of challenging species complexes underscores the need to further explore the implications of an accurate species assignment for understanding what defines a species’ role in an ecosystem. This review highlights the dynamic nature of taxonomy, with species being split and cryptic species eventually becoming morphologically distinguishable. It provides examples showing that relying solely on molecular methods without deep taxonomic expertise poses significant risks. It also aims to serve as a starting point for delving deeper into the taxonomy of the ICES zooplankton time series.</jats:p
Organic matter decomposition and greenhouse gas production in thermokarst lake taliks on the Baldwin Peninsula, Alaska
Get PDFIn the continuous permafrost zone, thermokarst processes are altering and accelerating as the climate changes. Surface subsidence is accelerating and thermokarst lakes are draining, while gullies are expanding and thaw slumps are widening. On the Baldwin Peninsula in West Alaska, such processes are evident and have direct consequences for the local environment as well as the city of Kotzebue. Furthermore, these landscape dynamics have far-reaching effects on biogeochemical cycles, as microbial activity in thawed sediments of thermokarst landforms decomposes organic matter and releases greenhouse gases, further contributing to global warming.
To investigate these processes, sediment cores were collected in March 2024 along two transects that extend from upland areas through thermokarst disturbances into the near-shore zone of the Kotzebue Sound. Taliks were identified and sampled in two thermokarst lakes, a semi-drained lake, and a drained lake basin. These unfrozen sediments are of particular interest concerning organic matter decomposition and greenhouse gas production. A one-year long incubation experiment coupled with pre- and post-incubation n-alkane biomarker analyses on the sediments, aims to decipher organic matter patterns and potentials. First findings from this laboratory work will be presented at the 15th DACH Permafrost Conference
Eukaryote biodiversity in supratidal microbialite pools: A foundational environmental DNA assessment
Get PDFCoastlines are a mosaic of habitats, including rocky shores, sandy beaches, estuaries, and artificial substrata. Although modern microbialite pool formations were only recently discovered as an additional coastal habitat along the southern African coastline, they are now known to be surprisingly common to this region. These ecosystems function similarly to estuaries, where seawater and freshwater mix, but with groundwater as the freshwater source instead of river flow. Traditional community assessments from morphological identifications have revealed some similarities between the organisms inhabiting microbialite pools to those of nearby estuaries, but no systematic comparison has so far been undertaken. Here, we used molecular methods based on environmental DNA (eDNA) metabarcoding to characterise the eukaryote assemblages within and between three coastal southern African microbialite pools. We hypothesised that the three sites are taxonomically analogous to one another, which would support the existence of similar core ecological communities. Three genetic markers, one for metazoans (COI) and two for algae (rbcL and the V2+V3 regions of 18S rRNA) were targeted for metabarcoding. Our results show that the biodiversity of the pools was dominated by diatoms (particularly of the genera Navicula and Nitzschia) and, among the metazoans, by malacostracans, rotifers and nematodes. Although the three microbialite pools had similar broadscale community compositions at higher taxonomic levels (class and family), distinct community structure at lower taxonomic levels was observed, which may be a result of numerous opportunistic species being present in addition to the core organisms. The macroinvertebrate fauna of microbialite pools (e.g. peracarid crustaceans, polychaetes and insects) is well documented, although most are still missing from the DNA barcoding reference library. In contrast, the meiofauna (e.g. rotifers, nematodes and ostracods) is understudied. It remains unclear whether the two dominant diatom genera are the primary contributors to microbialite formation, or if other yet-undescribed species also contribute to the process. This study serves as an initial step in uncovering the hidden level of biodiversity within the unique microbialite ecosystems along the southern African coastline
All Aboard! Providing Shipboard Technical Skills While Building Capacity in Ocean Observations
Get PDFShipboard training equips early career ocean professionals (ECOPs) with the skills, knowledge, and confidence to tackle the challenges of marine research. Such training helps develop a workforce essential for implementing a truly global ocean observation system and advancing understanding of the ocean and its sustainable use. Working with other organizations and individuals, the Partnership for Observation of the Global Ocean (POGO) offers opportunities to ECOPs, mainly from developing countries, to join research cruises and acquire hands-on experience with real-world oceanographic work. These learning experiences can be organized either as one-on-one training on research cruises with spare berths or collective training on dedicated expeditions designed for larger groups of international students. This article introduces POGO’s shipboard training program by presenting examples from each of the modalities, and it explores the program’s long-term impacts and future directions
Biodiversity Information of benthic Species at ARtificial structures – BISAR
Get PDFUnderstanding the effects of artificial structures in marine landscapes is required for ecosystem-based management. Global demand for oil and gas and accelerated commitments to renewable energy development has led to the proliferation of marine artificial structures. Investigating the cumulative effects of these structures on marine ecosystems requires data on the benthic community over large geographical and long-time scales. It is imperative to share the data collected by many stakeholders in an integrated information system to benefit science, industry and policy. BISAR is the first data product containing harmonised and quality-checked international data on benthos from artificial structures in the North Sea. BISAR was compiled from environmental impact assessment studies and scientific projects (3864 samples, 890 taxa). Data derive from 34 artificial structures and surrounding soft sediments (years: 2003 to 2019). Structures include offshore wind turbines, oil and gas platforms and a research platform. Data from a geogenic reef, allow comparison of natural and artificial reef communities. We aim to host future BISAR data dynamically in the CRITTERBASE web portal
Potential planetary health impacts of the airborne plastisphere
Get PDFMicroplastics are a ubiquitous yet long-overlooked component of airborne particulate matter. The surface of these plastic particles provides a unique niche for microorganisms, collectively known as the plastisphere. The plastisphere in aquatic and terrestrial ecosystems harbors microbial communities with distinct compositions, structures, and functional profiles, posing potential planetary health risks. The characteristics, fate, and impacts of the microbiome associated with airborne microplastics, however, remain largely unknown. In this review, we fill the knowledge gaps by exploring how airborne microplastics serve as key habitats for microorganisms and the potential planetary health implications. We show that microplastics are expected to carry and sustain microorganisms over long distances and timescales in air, potentially dispersing pathogens, antibiotic-resistance genes, and other bioactive agents across ecosystems. These interactions may perturb ecological processes and biological health on a planetary scale. Interdisciplinary research and innovative methodologies are urgently required to better understand and mitigate the airborne plastisphere risks
Can Parameterizations Reproduce the Gravity Wave Momentum Fluxes and Drag Simulated by a Global High‐Resolution Model?
Get PDFAbstract We compare the gravity wave (GW) parameterizations used in the IPSLCM6 climate model with the GWs resolved in the ICON global model with 5 km horizontal resolution. The parameterizations are run offline using ICON fields coarse‐grained to a 100 km grid and compared to the GWs with smaller scales that are resolved in ICON. Overall, the drags are comparable, the momentum fluxes align well, and each GW parameterization (fronts, convection, and mountains) plays a role at geographical locations consistent with ICON. Among the differences, we find that in ICON, GWs are substantially attenuated above the subtropical jets; this is underestimated by the parameterizations. It also seems that, in this comparison, ICON underestimates frontal waves in the mid‐latitudes, that the parameterizations underestimate the convective waves in the tropics, and that the mountain waves are more alike.
Plain Language Summary To simulate the middle atmosphere, climate models use parameterizations of small‐scale gravity waves that are generated in the troposphere and break in the middle atmosphere. The direct in situ observations of these waves are sparse and non‐global, while remotely sensed satellite observations are more global but have quite coarse resolutions. To compensate for these deficiencies, the recent high‐resolution global simulations of the atmosphere are promising because they explicitly solve a good fraction of the gravity wave spectra and their dissipation. Here we show that these simulations can help to validate relationships of parameterized gravity waves to their sources and to adjust their characteristic phase speed. Such comparisons can also establish whether high‐resolution simulations resolve enough GW momentum flux to simulate the observed middle atmosphere climate.
Key Points In the stratosphere, parameterizations simulate well the regions where gravity wave fluxes are large, compared to a high‐resolution model An attenuation of the resolved gravity waves above the subtropical jets is described by the parameterization but is underestimated The parameterizations give good estimates of the mountain waves but underestimate the convective waves and overestimate the frontal wave
Neither private nor new: unpacking narratives of ‘ocean privatisation’
Get PDFJoining others who call attention to the ways in which the ocean, its spaces, and its resources are being commodified, enclosed, and extracted in ways that benefit some at the expense of others, this paper offers a synthesis and review, echoing and extending the cautions being posited around ocean privatisation discourses and their tendencies toward simplistic conceptualisations and presentist thinking that all too often limit critical analysis. Therefore, this paper synthesises and analyses existing literature on the institutions and processes through which the ‘privatisation’ of the ocean has been, and is being, implemented, leading to two important points. First, it is showed how privatisation processes are often more complex than the word suggests. Privatisation is anything but ‘private’. The enclosure, appropriation, and rationalisation of space, resources, knowledge, and governance in the marine domain are occurring in institutional matrices where private actors operate in an array of relationships with the state (in its many, multiple guises), as well as non-governmental, and inter-governmental actors. Secondly, when viewing privatisation with a sensitivity to the array of institutions and actors involved, it is vital to recognise that what passes for a more recent capitalist tendency in the ocean realm rather continues long-standing, historical trajectories of violent extraction (which are equally complex in configuration). Expanding on these critiques, this paper turns to longstanding traditions that offer ways of thinking beyond privatisation and that engage the ocean not as a space of enclosure and extraction but as a space of relationality and livelihoods