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: Data on song type repertoire of bowhead whales (Balaena mysticetus) and temporal trends in the occurrence of these song types were obtained from passive acoustic monitoring (PAM) data collected by passive acoustic recorder SV1088 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 79° 00.02' N, 005° 40.12' E, mooring ARKF05-17, in Fram Strait. Passive acoustic data were collected as part of the Frontiers in Arctic Marine Monitoring (FRAM) observatory in Fram Strait from July 2016 to July 2017 (recording period) by SN1088 (deployment period from July 2016 to September 2018). The recorder was moored at 808 m depth and scheduled to record continuously at a sample rate of 48,000 Hz. For the assessment of the song repertoire of bowhead whales within a one-year period, spectrograms were visually checked for the presence of bowhead whale songs, based on hourly presence information obtained from automated detection of bowhead whale vocalizations using the LFDCS ('Low-Frequency Detection and Classification System') software (Baumgartner and Mussoline, 2011, https://doi.org/10.1121/1.3562166), using a user-developed call library, an SNR ('signal-to-noise- ratio') threshold of 8 dB and a Mahalanobis distance threshold of 1.5. The term 'song' comprised both call sequences and true songs, thereby following the differentiation of Stafford et al. (2012; https://doi.org/10.3354/esr00444). Other bowhead whales signals recorded, such as constant calls, moans or down- and upsweeps that did not show any repetitive pattern, were not included in the song repertoire analysis. Only true songs and call sequences that were clearly distinguishable against the background noise and repeated at least three times within a day were considered for song repertoire analysis. Classification of songs was based on descriptive song characteristics, such as spectral structure of units, the arrangement of units and their frequency range. Song types were numbered in their order of first occurrence, and variants of the song types are assigned a sub-number. Table contains information on presence (indicated by “1, indicating the presence of a particular song type or song-type variant which was clearly distinguishable against the background noise and repeated at least three times within a day) or absence (indicated by “0”) of different bowhead whale song types on a daily basis for the recording period from July 2016 to July 2017.