ALBERT

Description: The recent identification of the bio-duck call as Antarctic minke whale (AMW) vocalization allows the use of passive acoustic monitoring to retrospectively investigate year-round spatial-temporal patterns in minke whale occurrence in ice-covered areas. Here, we present an analysis of AMW occurrence patterns based on a 9-year passive acoustic dataset (2008–2016) from 21 locations throughout the Atlantic sector of the Southern Ocean (Weddell Sea). AMWs were detected acoustically at all mooring locations from May to December, with the highest presence between August and November (bio-duck calls present at more than 80% of days). At the southernmost recording locations, the bio-duck call was present up to 10 months of the year. Substantial inter-annual variation in the seasonality of vocal activity correlated to variation in local ice concentration. Our analysis indicates that part of the AMW population stays in the Weddell Sea during austral winter. The period with the highest acoustic presence in the Weddell Sea (September–October) coincides with the timing of the breeding season of AMW in lower latitudes. The bio-duck call could therefore play a role in mating, although other behavioural functions of the call cannot be excluded to date.

Description: Southern Hemisphere humpback whales ( Megaptera novaeangliae ) inhabit a wide variety of ecosystems including both low- and high-latitude areas. Understanding the habitat selection of humpback whale populations is key for humpback whale stock management and general ecosystem management. In the Atlantic sector of the Southern Ocean ( ASSO ), the investigation of baleen whale distribution by sighting surveys is temporally restricted to the austral summer. The implementation of autonomous passive acoustic monitoring, in turn, allows the study of vocal baleen whales year-round. This study describes the results of analysing passive acoustic data spanning 12 recording positions throughout the ASSO applying a combination of automatic and manual analysis methods to register humpback whale acoustic activity. Humpback whales were present at nine recording positions with higher acoustic activities towards lower latitudes and the eastern and western edges of the ASSO . During all months, except December (the month with the fewest recordings), humpback whale acoustic activity was registered in the ASSO . The acoustic presence of humpback whales at various locations in the ASSO confirms previous observations that part of the population remains in high-latitude waters beyond austral summer, presumably to feed. The spatial and temporal extent of humpback whale presence in the ASSO suggests that this area may be used by multiple humpback whale breeding populations as a feeding ground.

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: Humpback whale males are known to sing on their low-latitude breeding grounds, but it is well established that songs are also commonly produced ‘off-season’ on the feeding grounds or during migration. This opens exciting opportunities to investigate migratory aggregations, study humpback whale behavioral plasticity and potentially even assign individual singers to specific breeding grounds. In this study, we analyzed passive acoustic data from 13 recording positions and multiple years (2011–2018) within the Atlantic sector of the Southern Ocean (ASSO). Humpback whale song was detected at nine recording positions in five years. Most songs were recorded in May, austral fall, coinciding with the rapid increase in sea ice concentration at most recording positions. The spatio-temporal pattern in humpback whale singing activity on Southern Ocean feeding grounds is most likely shaped by local prey availability and humpback whale migratory strategies. Furthermore, the comparative analyses of song structures clearly show a differentiation of two song groups, of which one was solely recorded at the western edge of the ASSO and the other song group was recorded throughout the ASSO. This new finding suggests a common feeding ground occupation by multiple humpback whale populations in the ASSO, allowing for cultural and potentially even genetic exchange among populations.

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.