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: The pelagic ecosystem of the Arctic Ocean is threatened by severe changes such as the reduction in sea‐ice coverage and increased inflow of warmer Atlantic water. The latter is already altering the zooplankton community, highlighting the need for monitoring studies. It is therefore essential to accelerate the taxonomic identification to speed up sample analysis, and to expand the analysis to biomass and size assessments, providing data for modeling efforts. Our case study in Fram Strait illustrates that image‐based analyses with the ZooScan provide abundance data and taxonomic resolutions that are comparable to microscopic analyses and are suitable for zooplankton monitoring purposes in the Arctic. We also show that image analysis allows to differentiate developmental stages of the key species Calanus spp. and Metridia longa and, thus, to study their population dynamics. Our results emphasize that older preserved samples can be successfully reanalyzed with ZooScan. To explore the applicability of image parameters for calculating total mesozooplankton and Calanus spp. biomasses, we used (1) conversion factors (CFs) translating wet mass to dry mass (DM), and (2) length–mass (LM) relationships. For Calanus spp., the calculated biomass values yielded similar results as direct DM measurements. Total mesozooplankton biomass ranged between 1.6 and 15 (LM) or 2.4 and 21 (CF) g DM m², respectively, which corresponds to previous studies in Fram Strait. Ultimately, a normalized biomass size spectra analysis provides 1st insights into the mesozooplankton size structure at different depths, revealing steep slopes in the linear fit in communities influenced by Atlantic water inflow.

Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

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: 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 SV1026 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 78° 50.01' N, 006° 59.99' E, mooring ARKF04-15, in Fram Strait. Passive acoustic data were collected as part of the Frontiers in Arctic Marine Monitoring (FRAM) observatory in Fram Strait from June to November 2012 (recording period) by SV1026 (deployment period from June 2012 to June 2015). The recorder was moored at 743 m depth and scheduled to record continuously at a sample rate of 5,333 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, doi: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 June to November 2012.

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 SV1021 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 78° 49.76' N, 000° 25.77' E, mooring ARKF016-09, in Fram Strait. Passive acoustic data were collected as part of the Frontiers in Arctic Marine Monitoring (FRAM) observatory in Fram Strait from June to November 2012 (recording period) by SV1021 (deployment period from June 2012 to September 2014). The recorder was moored at 800 m depth and scheduled to record continuously at a sample rate of 5,333 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 June to November 2012.

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 66°01.13' S and 00°04.77' E, mooring AWI230-06, recorder AU0085, between March 2008 and December 2010. The passive acoustic recorder was of type AURAL (Autonomous Underwater Recorder for Acoustic Listening (AURAL; Model 2, Multi-Électronique) and attached to oceanographic deep-sea mooring AWI230-06 of the Hybrid Antarctic Float Observation System (HAFOS). It was deployed from March 2008 and December 2010, moored at a depth of 189 m and scheduled to record on a duty cycle of 5 min per 4 hours at a sample rate 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 of the respective recording sites. 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 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., under review). 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 of recorder AU0085, mooring site AWI230-06.

Description: Acoustic presence data on Antarctic blue whales (Balaenoptera musculus intermedia) were obtained from passive acoustic monitoring (PAM) data collected at 68°59.86' S and 00°06.51' W, mooring AWI232-11, recorder SV1011, between December 2012 and November 2013. The passive acoustic recorder was of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) and attached to oceanographic deep-sea mooring AWI232-11 of the Hybrid Antarctic Float Observation System (HAFOS). It was deployed from December 2012 to December 2014, moored at a depth of 958 m and recorded continuously at a sample rate of 5,333 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 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., under review). 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 of recorder SV1011, mooring site AWI232-11.