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.

Description: Presence-absence data on hourly acoustic presence of bowhead whales (Balaena mysticetus) 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 SV1088 (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. Hourly acoustic presence of bowhead whales was assessed based on automated detections 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 an SNR ('signal-to-noise ratio') threshold of 8 dB and a Mahalanobis distance threshold of 1.5. All automated detections of bowhead whale vocalizations were visually reviewed by a trained analyst on an hourly basis in spectrograms using Raven Pro 1.5 (Bioacoustics Research Program, Cornell Lab of Ornithology, Ithaca, USA; window size: 2.5 min; frequency range: 0-1,300 Hz; spectrogram settings: FFT 1,024, overlap 90 %, Hann window). This table contains information on acoustic presence (indicated by “1”, with at least one verified bowhead whale call present in a given hour) or acoustic absence (indicated by “0”) of bowhead whale vocalizations on an hourly basis for the recording period from July 2016 to July 2017.

Description: Presence-absence data on hourly acoustic presence of bowhead whales (Balaena mysticetus) were obtained from passive acoustic monitoring (PAM) data collected by passive acoustic recorder SV1091 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 78° 50.01' N, 000° 00.09' E, mooring ARKR02-01, 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 SV1091 (deployment period from July 2016 to July 2018). The recorder was moored at 806 m depth and scheduled to record continuously at a sample rate of 48,000 Hz. Hourly acoustic presence of bowhead whales was assessed based on automated detections 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 an SNR ('signal-to-noise ratio') threshold of 8 dB and a Mahalanobis distance threshold of 1.5. All automated detections of bowhead whale vocalizations were visually reviewed by a trained analyst on an hourly basis in spectrograms using Raven Pro 1.5 (Bioacoustics Research Program, Cornell Lab of Ornithology, Ithaca, USA; window size: 2.5 min; frequency range: 0-1,300 Hz; spectrogram settings: FFT 1,024, overlap 90 %, Hann window). This table contains information on acoustic presence (indicated by “1”, with at least one verified bowhead whale call present in a given hour) or acoustic absence (indicated by “0”) of bowhead whale vocalizations on an hourly basis for the recording period from July 2016 to July 2017.

Description: Acoustic presence data on Antarctic blue whales (Balaenoptera musculus intermedia) were obtained from passive acoustic monitoring (PAM) data collected at five different positions in the Weddell Sea and along the Greenwich meridian between March 2008 and November 2013. Passive acoustic recorders used were of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) or type AURAL (Autonomous Underwater Recorder for Acoustic Listening (AURAL; Model 2, Multi-Électronique). The acoustic recorders were attached to oceanographic deep-sea moorings of the Hybrid Antarctic Float Observation System (HAFOS) and a total of 10 acoustic recorders was deployed during three consecutive periods of recorder deployment: March 2008-December 2010; December 2010-December 2012; and December 2012-December 2014. Recorders were moored at depths between ca. 200 m and 1000 m. Sono.Vault recorders were scheduled to record continuously at sample rates of 5,333 Hz. AURAL recorders were scheduled to record on duty cycles of 4.5 min per 3 hours or 5 min per 4 hours at sample rates of 32.768 Hz. After recovery, the passive acoustic data were prepared for further analysis following the Standard Operating Procedures (SOP) for PAM data collected by the Ocean Acoustics Group of AWI according to Thomisch et al. (2023a, regarding definitions and terminology) and Thomisch et al. (2023b, with regard to data preparation procedures). Daily acoustic presence of Antarctic blue whales was assessed based on automated detections of Z-call vocalizations by spectrogram cross-correlation using a pre-defined spectrogram template in a frequency band from 17.5 to 29 Hz. Received levels were obtained for each detected Z-call, as sound pressure level SPLrms [dB re: 1μPa] within the 25–29 Hz band of each detected Z-call event, for details on automated detection please refer to Thomisch et al. (2016). To avoid a spatial mismatch between the actual position of calling animals and the recorders, ABW detections were filtered to only keep detections that originated from within a ~10 km radius from the recorders. Assuming a source level of 189 dB re: 1μPa over 25–29 Hz and a spherical transmission loss TL[dB] = 20log₁₀(r), approximate distances between vocalizing Antarctic blue whales and the respective recording site locations were estimated for each detected Z-call. Daily acoustic presences were estimated as days with at least one detection event within a ~10 km radius of the respective recording sites; i.e., Z-calls with calculated received levels of ≥109 dB, considering a nominal TL of 80 dB. Data presented in this current publication series were used together in presence-only species distribution models (SDMs) to predict the year-round habitat suitability of Antarctic blue whales in the Weddell Sea (El-Gabbas et al. 2023). Data contain information on the detection time and the estimated received level SPLrms [dB re: 1μPa] for each Antarctic blue whale vocalization within a ~10 km radius from the respective recorders.

Description: Passive acoustic monitoring (PAM) data were collected by the Perennial Acoustic Observatory in the Antarctic Ocean (PALAOA) near Neumayer Station III at 70.5028° S, 8.2057° W, on the Ekström ice shelf, Antarctica. This long-term observatory was set up in 2005 (Kindermann et al. 2007, hdl:10013/epic.30936.d001). After modifications of the hardware setup in December 2014, PALAOA collected passive acoustic data using a Sono.Vault recorder (manufactured by develogic GmbH, Hamburg, Germany). From 01 January 2022 to 27 February 2022, PALAOA recorded continuously at a sample rate of 96 kHz, at 155 m depth. Recording ended due to the breakoff of part of the ice shelf in February 2022, which damaged the recording hardware (see also Report on Expedition PS129, https://doi.org/10.57738/BzPM_0776_2023). 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 Operating 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). We thankfully acknowledge the support of the Neumayer Station overwintering teams, and in particular of the radio operators, in maintaining and operating PALAOA.

Description: Presence-absence data on hourly acoustic presence of bowhead whales (Balaena mysticetus) were obtained from passive acoustic monitoring (PAM) data collected by passive acoustic recorder SV1097 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 78° 10.21' N, 000° 00.04' E, mooring ARKR01-01, in Fram Strait. Passive acoustic data were collected as part of the Frontiers in Arctic Marine Monitoring (FRAM) observatory in Fram Strait from August 2016 to August 2017 (recording period) by SV1097 (deployment period from August 2016 to July 2018). The recorder was moored at 799 m depth and scheduled to record continuously at a sample rate of 48,000 Hz. Hourly acoustic presence of bowhead whales was assessed based on automated detections 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 an SNR ('signal-to-noise ratio') threshold of 8 dB and a Mahalanobis distance threshold of 1.5. All automated detections of bowhead whale vocalizations were visually reviewed by a trained analyst on an hourly basis in spectrograms using Raven Pro 1.5 (Bioacoustics Research Program, Cornell Lab of Ornithology, Ithaca, USA; window size: 2.5 min; frequency range: 0-1,300 Hz; spectrogram settings: FFT 1,024, overlap 90 %, Hann window). This table contains information on acoustic presence (indicated by “1”, with at least one verified bowhead whale call present in a given hour) or acoustic absence (indicated by “0”) of bowhead whale vocalizations on an hourly basis for the recording period from August 2016 to August 2017.

Description: Presence-absence data on hourly acoustic presence of bowhead whales (Balaena mysticetus) were obtained from passive acoustic monitoring (PAM) data collected by five recorders of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at different positions in Fram Strait between June 2012 and August 2017. Passive acoustic data were collected as part of the Frontiers in Arctic Marine Monitoring (FRAM) observatory in Fram Strait, with two recorders deployed in 2012 (recorders SV1021 and SV1026) and three recorders deployed in 2016 (recorders SV1091, SV1097 and SV1088). Recorders were moored at depths around 800 m and scheduled to record continuously at sample rates of 5,333 Hz (SV1021 and SV1026) and 48,000 Hz (SV1091, SV1097 and SV1088). Bowhead whale vocalizations were automatically detected and classified based on a user-developed call library in the LFDCS ('Low-Frequency Detection and Classification System') software (Baumgartner and Mussoline, 2011), using an SNR ('signal-to-noise ratio') threshold of 8 dB and a Mahalanobis distance threshold of 1.5. To obtain hourly acoustic presence data, all automated detections of bowhead whale vocalizations were visually reviewed by a trained analyst on an hourly basis in spectrograms using Raven Pro 1.5 (Bioacoustics Research Program, Cornell Lab of Ornithology, Ithaca, USA; window size: 2.5 min; frequency range: 0-1,300 Hz; spectrogram settings: FFT 1,024, overlap 90 %, Hann window). Tables contain information on acoustic presence (indicated by “1”, with at least one verified bowhead whale call present in a given hour) or acoustic absence (indicated by “0”) of bowhead whale vocalizations on an hourly basis for the respective recording period of each recorder.

Description: Passive acoustic monitoring (PAM) data were collected by the Perennial Acoustic Observatory in the Antarctic Ocean (PALAOA) near Neumayer Station III at 70.4261° S, 8.2161° W, on the Ekström ice shelf, Antarctica. This long-term observatory was set up in 2005 (Kindermann et al. 2007, hdl:10013/epic.30936.d001). After modifications of the hardware setup in December 2014, PALAOA collected passive acoustic data using a Sono.Vault recorder (manufactured by develogic GmbH, Hamburg, Germany). From 01 January 2021 to 31 December 2021, PALAOA recorded continuously at a sample rate of 96 kHz, at 155 m depth. 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 Operating 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). We thankfully acknowledge the support of the Neumayer Station overwintering teams, and in particular of the radio operators, in maintaining and operating PALAOA.

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.