To investigate the potential impact of marine heatwaves on the intertidal fauna of the German Wadden Sea, a mesocosm experiment was conducted on the island of Sylt, Germany, from June to August 2022. Organisms of the two common bivalve species Cerastoderma edule and Macoma balthica were collected from the upper intertidal of the local Wadden Sea in May 2022. Organisms were then placed into open boxes filled half with sieved sediment (1000 µm) from the sampling area, as single-species communities mimicking in-situ observed densities of 119 individuals m-2 (C. edule) and 357 m-2 (M. balthica) and with initial community wet weights corresponding to approximately 35.7 g m-2 (both species) to ensure comparability. The communities were introduced into outdoor land-based mesocosm tanks equipped with tidal simulation, seawater flow through and temperature control on June 1st, 2022. After an adjustment phase of three weeks, four replicate tanks (and communities) were exposed to a single, mild 15-day heatwave with water temperatures of maximum 2.8°C above ambient, entailing nine days at peak temperature and three days onset/ offset each. Another four replicates were exposed to a strong heatwave of the same design but with maximum 4.4°C above ambient, and four more replicates were kept under ambient conditions for control. Before and during heatwave exposure, community filtration rates were measured keeping the communities intact, using their host boxes as incubation chambers within the mesocosms. To initialize measurements, chlorophyll spikes were provoked by adding Rhodomonas salina mono culture to the boxes' water columns, after which water samples were taken with a 10-minute interval and immediately analyzed for the relative change in chlorophyll-a concentration using a bbe© AlgaeLabAnalyser (370 – 610 nm). To obtain absolute chlorophyll-a values, additional water samples were taken after 1, 20, and 60 minutes and filtered through glass microfiber filters. Subsequently, 90% acetone solution was yielded from the filters and measured for light absorbance rates at 750, 663, 645, and 630 nm wave lengths using an UVIKON© XS UV/Vis spectrophotometer. Chlorophyll-a concentrations were then calculated from absorbance rates following Jeffrey and Humphrey (1975). In a next step, 10-minute interval values were interpolated by fitting the results to the relative concentration changes previously determined via the AlgaeLabAnalyser. Community filtration rates in µg chlorophyll-a per hour were calculated for each 10-min interval from the respective concentration changes, normalized to per hour and the incubated water volume. Filtration rates differed significantly between species, with higher community filtration rates for C. edule than M. balthica, the latter resembling the bare sand controls. For C. edule, the mild heatwave induced elevated community filtration rates at high chlorophyll-a concentration compared to communities exposed to no heatwave, the same was not observed for the strong heatwave. Due to the methodology applied, the exact number of alive and actively filtering individuals at the times of measurement is unknown, thus results represent community-level responses.
15N nitrate uptake assays were conducted using tracer additions of highly enriched (98%) 15N-labeled nitrate for four Arctic-adapted strains of Thalassiosira gravida and three temperate-adapted strains of Thalassiosira rotula. The experiments were carried out to understand the nitrate uptake kinetics of these strains under controlled laboratory conditions. The conduction of the assays comprised in this dataset took place between 2022-03-09 and 2022-07-15 at the Alfred Wegener Institute, Bremerhaven, Germany. Prior to the experiment, the Arctic strains were maintained at 4°C and the temperate strains at 15°C in climate chambers, with a light intensity of 30 µmol photons m-2s-1 and a photoperiod of 16:8h light:dark. The cultures were kept in exponential growth by semi-continuous dilution with K-medium, enriched with silicon and devoid of ammonium. For precultivation, 2L batch cultures of each strain were grown in ESAW medium at a light intensity of 25 µmol photons m-2 s-1 and a light:dark cycle of 16:8h. Arctic strains were cultivated at 9°C, while temperate strains were grown at 16°C, representing their respective lowest optimum temperatures. The initial nitrate concentration in the medium was set to approximately 100 µM L-1 (equivalent to 1/5 K-medium) to ensure sufficient biomass for subsequent 15N isotope analysis. Upon reaching mid-exponential growth phase, a nitrogen depletion procedure was implemented. This involved decanting 90% of the supernatant from the batch culture flasks and resuspending the sedimented cells in nitrate- and ammonia-free modified ESAW medium. This process was repeated twice more over the course of 48 hours, allowing cells to sediment between each dilution step. This dilution series resulted in a calculated final nitrate concentration of 0.1 µM NaNO3 L-1 at maximum, not accounting for ongoing nitrogen uptake by the diatoms, which likely further depleted the dissolved nitrate concentrations. This approach was deemed the best compromise between maintaining a sufficiently dense culture and achieving nitrogen depletion. 24 hours after the final dilution with nitrogen-free medium, the uptake assay was prepared. Aliquots of 40 ml culture from the batch cultures were transferred into 50 ml culture flasks for the nitrate addition treatments. The experimental design included seven nitrate levels (each with four replicates) and a nitrate-depleted control treatment. The seven nitrate concentrations tested were 0.1, 0.4, 0.8, 2, 10, 50, and 100 µmol NaNO3 L-1. For concentrations of 2 µmol NaNO3 L-1 and below, a 1:1 ratio of 14N:15N was used, while a 9:1 ratio was employed for concentrations above 2 µmol NaNO3 L-1. The experimental units were incubated for 40 minutes under the same conditions as the batch cultures. Following incubation, the samples were filtered onto pre-combusted glass microfiber filters (Whatman GF/F, Maidstone, UK). To reduce dissolved 15N contamination on the filter, an additional 100 ml of nitrate-free medium was filtered through each sample. The filters were then dried at 60°C for 48 hours before being folded into tin capsules and stored in the dark until further analysis. Particulate organic carbon (POC), particulate organic nitrogen (PON), and the particulate 15N:14N ratio were measured using an elemental analyzer (Flash 2000, Thermo Scientific, Karlsruhe, Germany) coupled to an isotope ratio mass spectrometer (IRMS, Thermo Scientific, Karlsruhe, Germany), following the methodology described by Morrien et al. (2017).
To determine the effect of the rate of temperature increase (acute vs. gradual) and magnitude as well as the timing of nutrient addition on a natural marine phytoplankton community, a bottle incubation experiment has been conducted at the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven, Germany. The community was collected at the Helgoland Roads long-term time series site in the German part of the North Sea (https://deims.org/1e96ef9b-0915-4661-849f-b3a72f5aa9b1) on the 6ᵗʰ of March 2022. The surface water containing the phytoplankton community was collected from the RV HEINCKE with a pipe covered with a 200 µm net attached to a diaphragm pump. In the first experimental run, the community was exposed to either gradual or acute temperature increase (from 6 to either 12 or 18°C) with 25 different N:P supply ratios added as a batch at the beginning of the bottle incubation. Simultaneously, the same community was gradually acclimated to their experimental temperatures under ambient nutrients and was used in a second experimental run in which it received the same 25 different N:P supply ratios after temperature acclimation. The light conditions were set to 175 µmol s-1 m-2 and a day-night cycle of 12h:12h which corresponds to the natural conditions at that time of the year. With this, it was possible to test the effect of a gradual vs. acute temperature increase and the timing of nutrient addition i.e., before or after the temperature change. This experimental set-up summed up to 400 units (8 temperature treatments x 5 nitrogen levels x 5 phosphorus levels x 2 replicates). Each experimental run was ended after 12 days. Fluorescence (395/680 Exc./Em.) was measured every second day using a SYNERGY H1 microplate reader (BioTek®) to determine phototrophic growth over time. At the end of each experiment, one replicate was filtered onto pre-combusted acid-washed glass microfiber filters (WHATMAN® GF/C) for intracellular carbon (POC), nitrogen (PON), and phosphorus (POP) content. The POP filters were pre-combusted and then analysed by molybdate reaction after digestion with a potassium peroxydisulfate solution (Wetzel and Likens 2003). The POC and PON filters were dried at 60°C before they were measured in an elemental analyser (Flash EA 1112, Thermo Scientific, Walthman, MA, USA).
Plastik wurde in einer Vielzahl von Umweltkompartimenten nachgewiesen, überwiegend als Mikroplastik, d.h. Kunststoffteile kleiner als 5 mm. Erste Untersuchungen wurden in marinen und aquatischen Systemen durchgeführt; Böden sind hingegen erst kürzlich in Bezug auf Mikroplastik in den Fokus gerückt, wobei Daten zeigen, dass es sich um eine verbreitete Kontamination der Böden handelt, mit potenziellen Folgen für bodenphysikalische, -chemische und -biologische Parameter. Angesichts der Vielzahl von Eintragspfaden, zu denen Plastikmüll, Kompost, Ablagerung aus der Luft und Straßen gehören, ist davon auszugehen, dass Mikroplastik in Böden der Biodiversitäts-Exploratorien vorhanden ist. Unsere Forschung hat zwei Ziele: Erstens wollen wir wissen, ob Mikroplastik (Vorhandensein und/oder Typ) die Intensität der Landnutzung widerspiegeln kann. Dafür werden wir Böden aus allen 150 EPs im Grünland beproben und mit Extraktions- und Identifikationsmethoden (Fourier-Transform-Infrarot-Spektroskopie-Mikroskopie) auf Mikroplastikgehalt, -art und -zusammensetzung untersuchen. Wir können diese Daten dann mit Komponenten der Landnutzungsintensität (LUI) sowie mit Bodeneigenschaften verknüpfen. Zweitens wollen wir die Auswirkungen einer experimentellen Mikroplastik-Zugabe im Feld entlang des Landnutzungsgradienten testen. Wir werden dies mit dem Einsatz und der Wiederentnahme (nach einem Jahr) von kleinen Mesh-Beuteln mit Mikroplastik-kontaminiertem Boden angehen, die in allen VPs im Grünland vergraben werden (mit dem Boden der jeweiligen VPs). Wir verwende hierfür Polyesterfasern, von denen wir bereits wissen, dass sie klare und konsistente Auswirkungen auf bodenphysikalische Eigenschaften und Bodenprozesse haben. Unsere Messvariablen umfassen pilzbezogene Bodenprozesse (Zersetzung, Bodenaggregation) und Pilz-Lebensgemeinschaften, die mittels Illumina MiSeq Hochdurchsatzsequenzierung erfasst werden. Mit unserem Feldversuch wollen wir testen, wie sich Mikroplastik-Effekte zwischen Bodenart und Umweltkontext sowie der Intensität der Landnutzung unterscheiden. Alle experimentellen Objekte werden anschließend aus dem Feld entfernt, um sicherzustellen, dass es keine dauerhafte Kontamination der Exploratorien-Böden gibt. Da wir in diesem Bereich nur einen Mikroplastik-Typ verwenden werden und die Mikroplastik-Verschmutzung aber ein vielschichtiges Thema ist, werden wir auch ein komplementäres Laborexperiment durchführen, bei dem wir nur einen Bodentyp pro Exploratorium verwenden, aber zusätzlich zu den Mikrofasern eine Reihe von verschiedenen Mikroplastik-Typen testen. Insgesamt wird dieses Projekt Einblicke in die Verbreitung und Wirkung von Mikroplastik in Böden liefern, indem sie die einzigartige Fülle der für die Exploratorien verfügbaren Informationen nutzt und gleichzeitig eine neue Variable bietet, die für andere Forscher (z.B. in Syntheseprojekten), aber auch für Stakeholder von Interesse sein kann.
Die Stromzuführung in Rundteiltischen und Rotier-Indexierspindeln für Erodieranlagen geschieht traditionell über Schleifkohlen aus Kupferlegierungen. Die Übertragungsfläche muss zu Beginn erst einlaufen, später verschmutzen die Schleifkohlen durch den Abtrag des Werkstücks beim Erodieren, was die Stromübertragung und den Erodierprozess stört und den Ausschuss erhöhen kann. Umgekehrt gelangt der Abrieb aus der Rotation in das Dielektrikum. Zudem müssen die Schleifkohlen regelmäßig erneuert werden. Die Hirschmann GmbH aus Fluorn-Winzeln bei Rottweil entwickelte eine Stromzuführung ohne Schleifkohlen, direkt im Gehäuse der Rundteiltische integriert, bei der hunderttausende leitfähige Mikrofasern den Strom direkt auf die Welle bringen. Nach Firmenangaben ist damit eine Verschleißfreiheit für die 200.000 Stunden Standzeit des Motors auf der Achse gewährleistet, bei Entfall aller Reinigungs- oder Wartungstätigkeiten. Daher ist auch das Einlaufen der Übertragungsfläche hinfällig. Die Prozessstabilität des Drahterodierens mit integriertem Rundteiltisch verbessert sich dementsprechend.
<p>Litter observed was micro, Multiple, Plastic > Fiber. Standardised value: 500-7200 items/m3 (unit=items/m3, method=RANGE) Source: "Sampling microfibres at the sea surface: The effects of mesh size, sample volume and water depth" (https://doi.org/10.1016/j.envpol.2019.113413).</p> <p>Remarks from litterbase to the data harmonization process: Litter quantities were taken from publications The most commonly used units [items / km²; items / km; items / m³] can be used to filter data. If possible, other dimensions were standardised to these units to allow comparison. The remaining units were not converted and are combined in “Other Unit / No Value” and displayed by symbols of uniform size not providing quantitative information If no litter quantity was given for a location (presence data), it was included in “Other Unit / No Value” If quantities were presented in several dimensions (e.g. weight and counts), items / km² was used A 9th-root transformation was applied to reduce the absolute difference between extremely large and small values enabling a comparative presentation in a single map If several quantities were reported for one site, the mean is shown in the map Spatially extensive data sets were aggregated to means for sub-areas Litter was grouped into size categories, thus macro: ≥ 5mm; micro: < 5 mm; nano: < 100 nm If no precise position was given, broader geographic information (e.g. beach name) was used to extract positions from Google Maps Slide bars can be used to select studies from certain time periods (year of publication) Further details are displayed by clicking on the symbols</p>
<p>Litter observed was micro, Plastic. Standardised value: 2.40e+04 items/m3 (unit=items/m3, method=MEAN) Source: "The Widespread Environmental Footprint of Indigo Denim Microfibers from Blue Jeans" (www.doi.org/10.1021/acs.estlett.0c00498).</p> <p>Remarks from litterbase to the data harmonization process: Litter quantities were taken from publications The most commonly used units [items / km²; items / km; items / m³] can be used to filter data. If possible, other dimensions were standardised to these units to allow comparison. The remaining units were not converted and are combined in “Other Unit / No Value” and displayed by symbols of uniform size not providing quantitative information If no litter quantity was given for a location (presence data), it was included in “Other Unit / No Value” If quantities were presented in several dimensions (e.g. weight and counts), items / km² was used A 9th-root transformation was applied to reduce the absolute difference between extremely large and small values enabling a comparative presentation in a single map If several quantities were reported for one site, the mean is shown in the map Spatially extensive data sets were aggregated to means for sub-areas Litter was grouped into size categories, thus macro: ≥ 5mm; micro: < 5 mm; nano: < 100 nm If no precise position was given, broader geographic information (e.g. beach name) was used to extract positions from Google Maps Slide bars can be used to select studies from certain time periods (year of publication) Further details are displayed by clicking on the symbols</p>
<p>Litter observed was micro, Plastic. Standardised value: 2.83e+00 items/g (unit=OTHER, method=MEAN) Source: "The Widespread Environmental Footprint of Indigo Denim Microfibers from Blue Jeans" (www.doi.org/10.1021/acs.estlett.0c00498).</p> <p>Remarks from litterbase to the data harmonization process: Litter quantities were taken from publications The most commonly used units [items / km²; items / km; items / m³] can be used to filter data. If possible, other dimensions were standardised to these units to allow comparison. The remaining units were not converted and are combined in “Other Unit / No Value” and displayed by symbols of uniform size not providing quantitative information If no litter quantity was given for a location (presence data), it was included in “Other Unit / No Value” If quantities were presented in several dimensions (e.g. weight and counts), items / km² was used A 9th-root transformation was applied to reduce the absolute difference between extremely large and small values enabling a comparative presentation in a single map If several quantities were reported for one site, the mean is shown in the map Spatially extensive data sets were aggregated to means for sub-areas Litter was grouped into size categories, thus macro: ≥ 5mm; micro: < 5 mm; nano: < 100 nm If no precise position was given, broader geographic information (e.g. beach name) was used to extract positions from Google Maps Slide bars can be used to select studies from certain time periods (year of publication) Further details are displayed by clicking on the symbols</p>
<p>Litter observed was micro, Plastic. Standardised value: 2.28e+00 items/g (unit=OTHER, method=MEAN) Source: "The Widespread Environmental Footprint of Indigo Denim Microfibers from Blue Jeans" (www.doi.org/10.1021/acs.estlett.0c00498).</p> <p>Remarks from litterbase to the data harmonization process: Litter quantities were taken from publications The most commonly used units [items / km²; items / km; items / m³] can be used to filter data. If possible, other dimensions were standardised to these units to allow comparison. The remaining units were not converted and are combined in “Other Unit / No Value” and displayed by symbols of uniform size not providing quantitative information If no litter quantity was given for a location (presence data), it was included in “Other Unit / No Value” If quantities were presented in several dimensions (e.g. weight and counts), items / km² was used A 9th-root transformation was applied to reduce the absolute difference between extremely large and small values enabling a comparative presentation in a single map If several quantities were reported for one site, the mean is shown in the map Spatially extensive data sets were aggregated to means for sub-areas Litter was grouped into size categories, thus macro: ≥ 5mm; micro: < 5 mm; nano: < 100 nm If no precise position was given, broader geographic information (e.g. beach name) was used to extract positions from Google Maps Slide bars can be used to select studies from certain time periods (year of publication) Further details are displayed by clicking on the symbols</p>
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