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Surface seawater carbonate chemistry, nutrients and phytoplankton community composition on a transect between North Sea and Arctic Ocean, 2008

This data was collected during the 'ICE CHASER' cruise from the southern North Sea to the Arctic (Svalbard) in July-Aug 2008. This data consists of coccolithophore abundance, calcification and primary production rates, carbonate chemistry parameters and ancillary data of macronutrients, chlorophyll-a, average mixed layer irradiance, daily irradiance above the sea surface, euphotic and mixed layer depth, temperature and salinity.

High-resolution measurements of essential climate variables in the North Sea from the autonomous surface vehicle HALOBATES during RV Heincke cruise HE650

During the RV Heincke cruise HE650 in the German Bight, the autonomous surface vehicle HALOBATES was deployed to obtain high-resolution measurements of key climate variables, including sea surface temperature (SST) and salinity (SSS). The platform sampled the upper ocean across five depths, extending from the near-surface layer (NSL; approximately 30–100 cm depth) to the sea-surface microlayer (SML), which occupies the uppermost millimetres of the ocean. Temperature and conductivity, from which salinity was derived, were measured using conductivity–temperature–depth (CTD) sensors integrated into HALOBATES' flow-through system. Additional temperature sensors mounted beneath the catamaran provided in situ observations at six NSL depths. Discrete water samples were used to calibrate the salinity measurements and account for potential sensor offsets. Meteorological conditions were simultaneously monitored using two data loggers equipped with meteorological stations installed on the catamaran. HALOBATES operated continuously during the deployment on 6th November 2024.

Ecosystem functions of rare arable plants - field study: Araneae data

Partly taken from the materials and methods of https://doi.org/10.1016/j.baae.2022.12.003: To compare the activity densities of ground-dwelling predators between treatments with and without RAPs, spiders were sampled using pitfall traps, which were set up after each round of aphid counting (one per plot, twice per year; Brown & Matthews, 2016). The traps (with a volume of 400 ml and a width of 90 mm) were filled with a mixture of water and ethylene glycol (1:1; 120 ml) and dug at ground level into the middle of each plot. The traps were covered with a plastic roof and a metal grid (15 × 15 mm grid size) to avoid overflowing during rain and accidental rodent catches (Császár et al., 2018). The traps were activated for 7 days. Subsequently, all arthropods were transferred into 70% ethanol. Spiders were identified to species according to Nentwig et al. (2019). Spider hunting strategy (active hunter or web-builder) was used as the feeding trait according to Cardoso et al. (2011).

Ecosystem functions of rare arable plants - field study: Aphidoidea data

Taken from materials and methods of https://doi.org/10.1016/j.baae.2022.12.003: Aphids were counted on 50 randomly selected shoots in two crop rows (100 shoots in total) per plot and sampling round. To reduce edge effects, rows with less than 20 cm to the edge were excluded. Counting took place twice a year, that is, once during crop flowering (BBCH 61; beginning of aphid population growth) and once during crop milk ripening stage (BBCH 75).

Ecosystem functions of rare arable plants - field study: Soil data

Taken from the methods of https://doi.org/10.1016/j.agee.2020.107237: The effect of rare arable plants on soil nutrient concentration was measured by taking soil samples in the 1st and 2nd study year (March 2018 and August 2019). One soil sample per plot was taken to a 20 cm depth and analyzed by the AGROLAB Group (Landshut, Germany) for soil organic matter [%] and nitrogen concentration [%] (DIN EN 15936; 2012 and DIN EN 16168; 2012-11).

Ecosystem functions of rare arable plants - field study: Carabidae data

Partly taken from the materials and methods of https://doi.org/10.1016/j.baae.2022.12.003: To compare the activity densities of ground-dwelling predators between treatments with and without RAPs, carabids were sampled using pitfall traps, which were set up after each round of aphid counting (one per plot, twice per year; Brown & Matthews, 2016). The traps (with a volume of 400 ml and a width of 90 mm) were filled with a mixture of water and ethylene glycol (1:1; 120 ml) and dug at ground level into the middle of each plot. The traps were covered with a plastic roof and a metal grid (15 × 15 mm grid size) to avoid overflowing during rain and accidental rodent catches (Császár et al., 2018). The traps were activated for 7 days. Subsequently, all arthropods were transferred into 70% ethanol. Carabids were identified to species according to Hůrka (1996). Carabid feeding behavior was classified according to Homburg et al. (2014). To simplify the dataset, carabid feeding behavior was classified as predominantly granivorous (species mainly feed on seeds and fruits) or as carnivorous/omnivorous, because carnivorous and omnivorous species are potentially feeding on aphids and other non-plant material.

Ecosystem functions of rare arable plants - field study: Plants biomass data

Taken from the methods of https://doi.org/10.1016/j.agee.2020.107237: Vegetation surveys were performed once in July for both study years. Plant species were classified and each species' percent cover for both the arable plant community and the crop were visually estimated per plot. Species were divided into rare arable plants, other spontaneously occurring arable plants, the sown crop species, and volunteer crops that re-emerged after cultivation in previous years. To measure the productivity of our plots, both the crop biomass and arable plant biomass (rare arable plants + volunteer crops + spontaneous arable plants) were collected in July and August in both study years. For the arable plant biomass, three 0.5 m × 0.5 m sampling quadrats were randomly placed in the plot, harvested, and dried at 65 °C for 48 h. Crop biomass was measured after cutting, drying, and weighing three randomly selected crop rows per plot. To minimize edge effects, the outmost crop rows were excluded from the sampling. Arable plants and crop biomasses were projected as g m ⁻².

ICEFLUX allometric measurements of polar zooplankton and fish

This dataset summarizes allometric measurements on zooplankton and nekton species performed in the framework of the Dutch and German ICEFLUX projects. Measurements were performed on 639 individuals of 15 species from the Southern Ocean and 2374 individuals of 14 species from the Arctic Ocean, including euphausiids, fish, pelagic and ice-associated amphipods, cnidarians, salps, siphonophores, chaetognaths and a copepod. Animals were collected during three expeditions in the Southern Ocean (winter and summer) and three expeditions in the Arctic Ocean (spring and summer). In addition to measurements on length and mass, the sizes of body parts were measured, such as carapaces, eyes, heads, telsons, tails and otoliths.

High-resolution measurements of essential climate variables in the North Sea from the autonomous surface vehicle HALOBATES during RV Heincke cruise HE626/2

During the RV Heincke cruise HE626/2 in the German Bight, the autonomous surface vehicle HALOBATES was deployed to obtain high-resolution measurements of key climate variables, including sea surface temperature (SST) and salinity (SSS). The platform sampled the upper ocean across seven depths, with approximately 10 cm vertical spacing, extending from the near-surface layer (NSL; approximately 30–100 cm depth) to the sea-surface microlayer (SML), which occupies the uppermost millimetres of the ocean. Temperature and conductivity, from which salinity was derived, were measured using conductivity–temperature–depth (CTD) sensors integrated into HALOBATES' flow-through system. Additional temperature sensors mounted beneath the catamaran provided in situ observations at six NSL depths. Discrete water samples were used to calibrate the salinity measurements and account for potential sensor offsets. Meteorological conditions were simultaneously monitored using two data loggers equipped with meteorological stations installed on the catamaran. HALOBATES operated continuously during the deployment period from 27 October to 2 November 2023.

Response of benthic foraminifera to ocean acidification in their natural sediment environment: a long-term culturing experiment

Calcifying foraminifera are expected to be endangered by ocean acidification; however, the response of a complete community kept in natural sediment and over multiple generations under controlled laboratory conditions has not been constrained to date. During 6 months of incubation, foraminiferal assemblages were kept and treated in natural sediment with pCO2-enriched seawater of 430, 907, 1865 and 3247 µatm pCO2. The fauna was dominated by Ammonia aomoriensis and Elphidium species, whereas agglutinated species were rare. After 6 months of incubation, pore water alkalinity was much higher in comparison to the overlying seawater. Consequently, the saturation state of Omega calc was much higher in the sediment than in the water column in nearly all pCO2 treatments and remained close to saturation. As a result, the life cycle (population density, growth and reproduction) of living assemblages varied markedly during the experimental period, but was largely unaffected by the pCO2 treatments applied. According to the size-frequency distribution, we conclude that foraminifera start reproduction at a diameter of 250 µm. Mortality of living Ammonia aomoriensis was unaffected, whereas size of large and dead tests decreased with elevated pCO2 from 285 µm (pCO2 from 430 to 1865 µatm) to 258 µm (pCO2 3247 µatm). The total organic content of living Ammonia aomoriensis has been determined to be 4.3% of CaCO3 weight. Living individuals had a calcium carbonate production rate of 0.47 g/m**2/a, whereas dead empty tests accumulated a rate of 0.27 g /m**2/a. Although Omega calc was close to 1, approximately 30% of the empty tests of Ammonia aomoriensis showed dissolution features at high pCO2 of 3247 µatm during the last 2 months of incubation. In contrast, tests of the subdominant species, Elphidium incertum, stayed intact. Our results emphasize that the sensitivity to ocean acidification of the endobenthic foraminifera Ammonia aomoriensis in their natural sediment habitat is much lower compared to the experimental response of specimens isolated from the sediment.

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