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The Multi-disciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC), was conducted from October 2019 to September 2020. The Research Vessel Polarstern was frozen into the ice in the Central Arctic Ocean north of Norway and drifted with the prevailing currents from north to south, traversing multiple Arctic basins and regimes and serving as a floating laboratory for an international, multidisciplinary program focusing on multiple facets of ice, ocean, atmosphere, biogeochemistry, and ecosystem responses to ongoing changing environmental conditions. Zooplankton ecology was investigated as part of the ecosystem team program. Abundance data from the area has been limited, particularly for the winter season. Weekly net tows were scheduled with multiple nets (mesh sizes 53, 150 and 1000 microns (µm)) to add to that data. This data set contains zooplankton abundance data (individuals per cubic meter) for the 53 µm ring net samples, sampling location and net depth information. Abundant zooplankton were identified to species and stage, including nauplii. Less abundant specimens were identified to subgroup, genus, group or family. 

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition was conducted from October 2019-September 2020. During this ~1 year period, the Research Vessel (R/V) Polarstern was frozen into the ice in the Central Arctic Ocean north of Norway and drifted with the prevailing currents from north to south, traversing multiple Arctic basins and regimes, and was re-located in late July to near the North Pole after drifting through Fram Strait. The ship served as a floating laboratory for an international, multidisciplinary program focusing on multiple facets of ice, ocean, atmosphere, biogeochemistry, and ecosystem responses to ongoing changing environmental conditions. Zooplankton ecology was investigated as part of the ecosystem team program. Here we present data on key zooplankton morphological and compositional parameters collected over the period of the drift. This data set contains the carbon and nitrogen content (micrograms [µg]) and lengths for individuals or groups of calanoid copepods and other taxa (e.g., amphipods, chaetognaths), width (micrometers [µm]) for copepods, and body area (micrometers squared [µm2]) and lipid sac area (µm2) for Calanus spp. copepods collected in different water depth intervals at approximately weekly intervals during the period of the drift. 

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition was conducted from October 2019-September 2020. During this ~1 year period, the Research Vessel (R/V) Polarstern was frozen into the ice in the Central Arctic Ocean north of Norway and drifted with the prevailing currents from north to south, traversing multiple Arctic basins and regimes, and was re-located in late July to near the North Pole after drifting through Fram Strait. The ship served as a floating laboratory for an international, multidisciplinary program focusing on multiple facets of ice, ocean, atmosphere, biogeochemistry, and ecosystem responses to ongoing changing environmental conditions. Zooplankton ecology was investigated as part of the ecosystem team program. Here we present data on key zooplankton rate processes collected over the period of the drift including: respiration, feeding, and reproduction. 

Abundance (ind. m-3) of zooplankton taxa was calculated from samples of Polarstern cruise PS122 (MOSAiC). Samples were taken with a Ring net with an opening area of 0.79 m2 and a mesh size of 1000 µm. Samples were analysed via image-based ZooScan analysis. The classified images are available at the web application EcoTaxa: https://ecotaxa.obs-vlfr.fr/prj/9966. 

These files contain metadata describing the samples used in 18S ribosomal DNA sequencing of gut contents from zooplankton collected during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. Raw sequence data along with these files are deposited in the Sequence Read Archive (SRA), and will be accessible through National Center for Biotechnology Information (NCBI), BioProject Identification (ID) PRJNA789896 upon manuscript publication (expected December 2022). The study looks at the Eukaryotic organisms in the guts of Arctic zooplankton collected through the year-long drift survey. The majority of the samples used were female copepods (Calanus glacialis, Calanus hyperboreus, and Metridia longa), with a few other organisms and life stages included. 

Abstract Microalgae are the main source of the omega‐3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), essential for the healthy development of most marine and terrestrial fauna including humans. Inverse correlations of algal EPA and DHA proportions (% of total fatty acids) with temperature have led to suggestions of a warming‐induced decline in the global production of these biomolecules and an enhanced importance of high latitude organisms for their provision. The cold Arctic Ocean is a potential hotspot of EPA and DHA production, but consequences of global warming are unknown. Here, we combine a full‐seasonal EPA and DHA dataset from the Central Arctic Ocean (CAO), with results from 13 previous field studies and 32 cultured algal strains to examine five potential climate change effects; ice algae loss, community shifts, increase in light, nutrients, and temperature. The algal EPA and DHA proportions were lower in the ice‐covered CAO than in warmer peripheral shelf seas, which indicates that the paradigm of an inverse correlation of EPA and DHA proportions with temperature may not hold in the Arctic. We found no systematic differences in the summed EPA and DHA proportions of sea ice versus pelagic algae, and in diatoms versus non‐diatoms. Overall, the algal EPA and DHA proportions varied up to four‐fold seasonally and 10‐fold regionally, pointing to strong light and nutrient limitations in the CAO. Where these limitations ease in a warming Arctic, EPA and DHA proportions are likely to increase alongside increasing primary production, with nutritional benefits for a non‐ice‐associated food web. 

Potassium ion (K + ) plays a critical role as an essential electrolyte in all biological systems. Genetically-encoded fluorescent K + biosensors are promising tools to further improve our understanding of K + -dependent processes under normal and pathological conditions. Here, we report the crystal structure of a previously reported genetically-encoded fluorescent K + biosensor, GINKO1, in the K + -bound state. Using structure-guided optimization and directed evolution, we have engineered an improved K + biosensor, designated GINKO2, with higher sensitivity and specificity. We have demonstrated the utility of GINKO2 for in vivo detection and imaging of K + dynamics in multiple model organisms, including bacteria, plants, and mice.