Alfred Wegener Institute for Polar and Marine Research
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Erfassung der Migrationsmuster und Brutverhaltensanalyse von Steinwälzern (Arenaria interpres) mithilfe von Lichtloggern und maschinellem Lernen
Get PDFDurch den Einsatz von Light Level Geolocators (Helldunkelgeolokatoren) bieten sich viele Möglichkeiten, detaillierte Einblicke in den Zug und das Verhalten von Vögeln zu gewinnen. Neben der Rekonstruktion von Zugwegen kann mithilfe von Licht-, Temperatur- und Leitfähigkeitsdaten das Brutverhalten von Steinwälzern (Arenaria interpres) durch den Einsatz von Machine-Learning-Algorithmen analysiert werden. Hierfür wurde ein selbst klassifizierter Trainingsdatensatz erstellt, durch den mehrere Modelle trainiert wurden, die unterschiedliche Methoden des maschinellen Lernens nutzen. Das Auftreten von einer der drei klassifizierten Verhaltensweisen (“random”, “incubation” und “brooding”) wurde durch Wahrscheinlichkeiten für den Brutzeitraum in der hohen Arktis angegeben. Die Machine-Learning-Algorithmen ermöglichen es, diese Verhaltensmuster zu identifizieren und die zeitliche Verteilung der verschiedenen Aktivitäten während der Brutzeit zu untersuchen. Dies erlaubt u.a. eine genaue Analyse der Länge der Brut und ihres Erfolgs.
Die Kombination von Light Level Geolocators und neuartigen Machine-Learning-Algorithmen erwies sich als sehr schnelle und effektive Methode zur Untersuchung der Migration und des Brutverhaltens von Steinwälzern. Vor allem für große Datensätze erlaubt diese Methode eine objektive Einschätzung der Brutphänologie und kann darüber hinaus ein großer Zeitgewinn sein, da nur wenige Datensätze (Trainingsdaten) selbst klassifiziert werden müssen. Diese Herangehensweise bietet wertvolle Einblicke in die Ökologie dieser Vögel und kann als Grundlage für weitere Forschungen dienen. Hierdurch könnten z.B. in Zukunft auch Änderungen in der Brutphänologie von Individuen untersucht werden
Low‐frequency noise affects development and movement patterns of a calanoid copepod
Get PDFAnthropogenic stressors are omnipresent in marine environments and interfere with organisms of all sizes, from large whales to small organisms. We investigated potential interactive multistressor effects of increased temperature with chronic low-frequency sound on the development and movement patterns of the calanoid copepod Acartia tonsa, a model species for small marine zooplankton. Copepods were reared while exposed to chronic low-frequency sound around 15 and 22 dB re 1 μPa2 Hz−1 above control sound pressure levels at frequencies between 110 and 120 Hz, at 21°C (increased temperature) and 18°C (control temperature). For each sound and temperature scenario, we assessed after-incubation development rate, stage distribution, and movement patterns. We found that fewer copepods reached the developmental stages copepodites IV to VI in low-frequency sound conditions, even though warmer conditions increased developmental rate. By using high-speed videography in both control and low-frequency sound conditions, we observed that copepods showed more escape behaviors (drops) and fewer feeding-associated behaviors (helical swimming) when exposed to low-frequency sound (~ 42 dB higher than normal at 142 Hz). Copepods reared with added low-frequency sound showed fewer feeding-associated behaviors and did not reverse these trends despite the absence of added sound in their feeding environment. These significant behavioral changes suggest detrimental negative, life-long, consequences for copepods exposed to low-frequency sound
Warming effects on the life cycles of two parasitic copepods with different invasion histories
Get PDFAbstractClimate change may exacerbate the impact of invasive parasites from warmer climates through pre‐existing temperature adaptations. We investigated temperature impacts on two closely related marine parasitic copepod species that share the blue mussel (Mytilus edulis) as host: Mytilicola orientalis has invaded the system from a warmer climate <20 years ago, whereas its established congener Mytilicola intestinalis has had >90 years to adapt. In laboratory experiments with temperatures 10–26°C, covering current and future temperatures as well as heat waves, the development of both life cycle stages of both species accelerated with increasing temperature. In the parasitic stages, the growth of the established invader increased evenly from 10°C to 22°C, whereas the recent invader barely grew at all at 10°C and grew faster already at 18°C. In contrast, temperature had little effect on the transition success between life cycle stages. However, the highest temperature (26°C) limited the egg development success of the established invader and the host entry success of both species, whereas the infection success of the established invader increased at 18°C and 22°C. In general, our experiments indicate that the main effect of temperature on both species is through development speed and not life cycle stage transition success. Based on regional long‐term temperature data and predictions, the numbers of completed life cycles per year will increase for both parasites. The established invader seems better adapted for low current temperatures (around 10°C), whereas the more recent invader barely develops at these temperatures but can cope in high temperatures (around 26°C). Hence, pre‐existing temperature adaptations of the recent invader may allow the species to better cope with heat waves.</jats:p
Continued warming of deep waters in the Fram Strait
Get PDFThe Fram Strait is the only deep gateway between the Arctic and the rest of the World Ocean, and it is thus a key region to understand how the deep Arctic will evolve. However, studies and data regarding the deep ocean are scarce, making it difficult to understand its role in the climate system. Here, we analyse oceanographic data obtained close to the Fram Strait sill depth of 2500m by two long-term mooring locations (F11 and HG-FEVI) in the Fram Strait between 2010-2023 to investigate long-term changes in the hydrographic properties. For additional context, we compile hydrographic profile data from the 1980s for the adjacent basins: the Greenland Sea and the Eurasian Basin. At mooring F11 in the western Fram Strait, we find a clear seasonality, with increased Greenland Sea Deep Water (GSDW) presence during summer and increased Eurasian Basin Deep Water (EBDW) presence during winter. Evaluating long-term changes, we find a modest temperature increase of ∼1/40.1°C for EBDW from the 1980s. For GSDW, south of the Fram Strait, we find a strong temperature increase of ∼1/40.4-0.5°C for the same period. The different warming rates have led to GSDW becoming warmer than EBDW since ∼1/42017-2018. This means that the Greenland Sea is no longer a heat sink for the Arctic Ocean at depth but is rather a heat source. It is therefore possible that EBDW temperatures will increase faster in the future
In-ice light measurements during the MOSAiC expedition
Get PDFWe present light measurements in Arctic sea ice obtained during the year-long MOSAiC drift through the central Arctic Ocean in 2019–2020. Such measurements are important as sea ice plays a fundamental role in the Arctic climate and ecosystem. The partitioning of solar irradiance determines the availability of radiation energy for thermodynamic processes and primary productivity. However, observations of light partitioning along the vertical path through the ice are rare. The data we present were collected by two measurement systems, the lightharp and the lightchain, both measuring autonomously multi-spectral light intensity in different depths within the ice. We present the dataset, retrieval methods for derived optical properties, and the conversion into the final, freely available data product, following standardized conventions. We particularly focus on the specifications of the newly developed lightharp system. Combined with the interdisciplinary and multi-instrument setup of MOSAiC, we expect great potential of the dataset to foster our understanding of light transmission and reflection in the sea-ice cover and interactions with physical sea-ice properties and the polar ecosystem
A position and wave spectra dataset of Marginal Ice Zone dynamics collected around Svalbard in 2022 and 2023
Get PDFSea ice is a key element of the global Earth system, with a major impact on global climate and regional weather. Unfortunately, accurate sea ice modeling is challenging due to the diversity and complexity of underlying physics happening there, and a relative lack of ground truth observations. This is especially true for the Marginal Ice Zone (MIZ), which is the area where sea ice is affected by incoming ocean waves. Waves contribute to making the area dynamic, and due to the low survival time of the buoys deployed there, the MIZ is challenging to monitor. In 2022-2023, we released 79 OpenMetBuoys (OMBs) around Svalbard, both in the MIZ and the ocean immediately outside of it. OMBs are affordable enough to be deployed in large number, and gather information about drift (GNSS position) and waves (1-dimensional elevation spectrum). This provides data focusing on the area around Svalbard with unprecedented spatial and temporal resolution. We expect that this will allow to perform validation and calibration of ice models and remote sensing algorithms
Active layer thickness database for the Lena Delta region (NE Siberia) and its analysis in relation with landscape parameters
Get PDFResolving the term “offshore aquaculture” by decoupling “exposed” and “distance from the coast”
Get PDFThe terms “offshore” and “open ocean” have been used to describe aquaculture sites that are further from the coast or in higher energy environments. Neither term has been clearly defined in the scientific literature nor in a legal context, and the terms are often used interchangeably. These and other related terms (for example “exposed”, “high-energy”) variously refer to aspects of a site such as the geographic distance from shore or infrastructure, the level of exposure to large waves and strong currents, the geographic fetch, the water depth, or some combination of these parameters. The ICES Working Group (ICES, 2024) on Open Ocean Aquaculture (WGOOA) therefore identified a need to define the terminology to reduce ambiguity for these types of aquaculture sites or more precisely, to: (1) promote a common understanding and avoid misuse for different classifications; (2) enable regulators to identify the characteristics of a marine site; (3) allow farmers to be able to assess or quantitatively compare sites for development; (4) equip developers and producers to identify operational parameters in which the equipment and vessels will need to operate; (5) provide insurers and investors with the terminology to consistently assess risk and premiums; and (6) circumvent the emergence of narratives that root in different cognitive interpretations of the terminology in public discourse. This paper describes the evolution of the use of the term “offshore aquaculture” and define the most relevant parameters to shift to a more definitive and robust term “exposed aquaculture” that can inherently relay clearer information. Adoption of this more definitive definition of “exposed” will allow the user to define a site with more than just distance from shore. Key differences and the importance of these terms are discussed that affect various interest groups. Follow-up articles in this compilation from scientific members of the WGOOA as well as other scientists outside ICES are incorporated that develop a set of definitions and a rigorous exposure index.</jats:p
Passive Sampler Derived Profiles and Mass Flows of Perfluorinated Alkyl Substances (PFASs) across the Fram Strait in the North Atlantic
Get PDFPer- and polyfluorinated alkyl substances (PFAS) are a family of pollutants of high concern due to their ubiquity and negative human health impacts. The long-range marine transport of PFAS was observed during year-long deployments of passive tube samplers in the Fram Strait across three depth transects. Time weighted average concentrations ranged from 2.4-360 pg L-1, and 10 different PFAS were regularly observed. PFAS profiles and concentrations were generally similar to those previously characterized for polycyclic aromatic hydrocarbons (PAHs) at these sites. The detection of several anionic PFAS in “old” water demonstrated that they are not perfect water mass tracers, but are also transported to depth via settling particles. Mass flows of PFAS through the Fram Strait in and out of the Arctic Ocean were basically similar (97 ±29 Mg year-1 northward flow, 107 ±39 Mg year-1 southward flow). For FOSA, export from the Arctic Ocean via the Fram Strait exceeded import by Atlantic Water, likely due to preferential transport and deposition in the Arctic Ocean. These observations suggest that PFAS in the Arctic are governed by the same feedback loop previously described for PAHs in the region – with additional atmospheric transport delivering volatile PFASs to the Arctic, which then get exported via water masses
Cloud micro- and macrophysical properties from ground-based remote sensing during the MOSAiC drift experiment
Get PDFIn the framework of the Multidisciplinary drifting Observatory for the Study of Arctic Climate Polarstern expedition, the Leibniz Institute for Tropospheric Research, Leipzig, Germany, operated the shipborne OCEANET-Atmosphere facility for cloud and aerosol observations throughout the whole year. OCEANET-Atmosphere comprises, amongst others, a multiwavelength Raman lidar, a microwave radiometer, and an optical disdrometer. A cloud radar was operated aboard Polarstern by the US Atmospheric Radiation Measurement program. These measurements were processed by applying the so-called Cloudnet methodology to derive cloud properties. To gain a comprehensive view of the clouds, lidar and cloud radar capabilities for low- and high-altitude observations were combined. Cloudnet offers a variety of products with a spatiotemporal resolution of 30 s and 30 m, such as the target classification, and liquid and ice microphysical properties. Additionally, a lidar-based low-level stratus retrieval was applied for cloud detection below the lowest range gate of the cloud radar. Based on the presented dataset, e.g., studies on cloud formation processes and their radiative impact, and model evaluation studies can be conducted