Description: Between Greenland and Spitsbergen, Fram Strait is a region where cold ice-covered Polar Water exits the Arctic Ocean with the East Greenland Current (EGC) and warm Atlantic Water enters the Arctic Ocean with the West Spitsbergen Current (WSC). In this compilation, we present two different data sets from plankton ecological observations in Fram Strait: (1) long-term measurements of satellite-derived (1998-2012) and in situ chlorophyll a (chl a) measurements (mainly summer cruises, 1991-2012) plus protist compositions (a station in WSC, eight summer cruises, 1998-2011); and (2) short-term measurements of a multidisciplinary approach that includes traditional plankton investigations, remote sensing, zooplankton, microbiological and molecular studies, and biogeochemical analyses carried out during two expeditions in June/July in the years 2010 and 2011. Both summer satellite-derived and in situ chl a concentrations showed slight trends towards higher values in the WSC since 1998 and 1991, respectively. In contrast, no trends were visible in the EGC. The protist composition in the WSC showed differences for the summer months: a dominance of diatoms was replaced by a dominance of Phaeocystis pouchetii and other small pico- and nanoplankton species. The observed differences in eastern Fram Strait were partially due to a warm anomaly in the WSC. Although changes associated with warmer water temperatures were observed, further long-term investigations are needed to distinguish between natural variability and climate change in Fram Strait. Results of two summer studies in 2010 and 2011 revealed the variability in plankton ecology in Fram Strait.

Description: Mesozooplankton samples were collected with the Multinet midi (Hydrobios, Kiel) and Bongo nets during the POLARSTERN cruise PS78 (ARK-XXVI/1) on a transect across Fram Strait. The samples were analyzed with imaged-based ZooScan analysis (Gorsky et al. 2010) and microscopic counts to compare the taxonomic resolution and abundance of both methods as described in Cornils et al. (2022). The data collection includes abundance, biovolume, biomass and length measurements derived from the image-based analysis with ZooScan as well as abundances based on microscopic counts. To compare biomass estimates from image parameters direct measurements of prosome length and individual dry mass of Calanus spp. are also provided. The data analysis is described in Cornils et al. (2022).The R scripts deposited at GitHub (Cornils 2022) allow the transformation of the EcoTaxa image dataset https://ecotaxa.obs-vlfr.fr/prj/2771 to abundance, biovolume and dry mass of the zooplankton organisms.

Description: Passive acoustic monitoring (PAM) data were collected by recorder SV1021 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 78.8293° N, 0.4295° E, mooring F16-9, in Fram Strait. During a deployment period from June 2012 to September 2014, passive acoustic data were collected from June 2012 to November 2012 (recording period) by SV1021 as part of the Frontiers in Arctic Marine Monitoring (FRAM) observatory in Fram Strait. The recorder was moored at 800 m depth and scheduled to record continuously at a sample rate of 5,333 Hz. Further details about the data acquisition and processing of this data set can be found in the accompanying metadata file (see Additional metadata) as well as the data processing report (see Data Processing Report). Passive acoustic data archived here represent data processing Level 1+, according to the standards defined in the associated Standard Operation Procedure (SOP) Glossary (Thomisch et al. 2023a). Further information on data processing with regard to data preparation and standardization can be found in the associated SOP Part 1: Data preparation and standardization (Thomisch et al. 2023b).