ALBERT

Description: Global warming causes profound environmental shifts in the Arctic Ocean, altering the composition and structure of communities. In the Fram Strait, a transitional zone between the North-Atlantic and Arctic Ocean, climate change effects are particularly pronounced and accelerated due to an increased inflow of warm Atlantic water. Gelatinous zooplankton are known as key predators, consuming a great variety of prey and playing an important role in marine ecosystems. Insufficient knowledge of how gelatinous zooplankton are affected by environmental change has resulted in a notable gap in the understanding of the future state of Arctic ecosystems. We analyzed the diversity and abundance of gelatinous zooplankton down to 2600 m depth and established the first regional baseline dataset using optical observations obtained by the towed underwater camera system PELAGIOS (Pelagic In situ Observation System). Our data estimate the abundance of 20 taxa of gelatinous zooplankton. The most abundant taxa belong to the family of Rhopalonematidae, mainly consisting of Aglantha digitale and Sminthea arctica, and the suborder Physonectae. Using the observational data, we employed a joint species distribution modelling approach to better understand their distributional patterns. Variance partitioning over the explanatory variables showed that depth and temperature explained a substantial amount of variation for most of the taxa, suggesting that these parameters drive diversity and distribution. Spatial distribution modelling revealed that the highest abundance and diversity of jellyfish are expected in the marginal sea-ice zones. By coupling the model with climate scenarios of environmental changes, we were able to project potential changes in the spatial distribution and composition of gelatinous communities from 2020 to 2050 (during the summer season). The near-future projections confirmed that with further temperature increases, gelatinous zooplankton communities in the Fram Strait would become less diverse but more abundant. Among taxa of the Rhopalonematidae family, the abundance of Aglantha digitale in the entire water column would increase by 2%, while a loss of up to 60% is to be expected for Sminthea arctica by 2050. The combination of in situ observations and species distribution modelling shows promise as a tool for predicting gelatinous zooplankton community shifts in a changing ocean.

Description: Narcomedusae play a key role as top-down regulators in the midwater, the largest and most understudied biome on Earth. Here, we used ecological niche modeling in three-dimensions (3D), ecomorphology, and phylogeny, to answer evolutionary and ecological questions about the widespread narcomedusan genus Solmissus. Our phylogenetic analyses confirmed that Solmissus incisa represents a complex of several cryptic species. Both the different genetic clades and tentacle morphotypes were widespread and often overlapped geographically- the main difference in their distribution and ecological niche being depth. This demonstrated the importance of including the third dimension when modeling the distribution of pelagic species. Contrary to our hypothesis, we found the modeled distribution of the Solmissus genus (n = 1444) and both tentacle morphotypes to be mostly driven by low dissolved oxygen values and a salinity of 34, and slightly by depth and temperature. Solmissus spp. were reproducing all year round, with specimens reproducing in slightly warmer waters (up to 1.25 & DEG;C warmer). Our results suggest that Solmissus spp. will likely come out as climate change winners by expanding their distribution when facing ocean deoxygenation and by increasing their reproduction due to global warming. However, because most available midwater data comes from the northern Pacific, this sampling bias was undoubtedly reflected in the output of our ecological niche models, which should be assessed carefully. Our study illustrated the value of online databases including imagery and videography records, for studying midwater organisms and treating midwater biogeographic regions as 3D spaces.

Description: We collected optical datasets during horizontal video transects with the Pelagic In Situ Observation System (PELAGIOS), a towed camera system, deployed at different localities in the Fram Strait during the R/V Polarstern expedition PS121 in August/September 2019. This system allowed to collect video footage of the larger-sized pelagic fauna (macro- and megazooplankton) in the water column at 4 stations, at depths ranging from 20 m to 2000m. Gelatinous zooplankton taxa, including ctenophores, cnidarian medusae and siphonophores, were annotated and identified to the lowest taxonomic level possible (species, genus). In this dataset, we present the annotations of these video transects with the associated metadata, and for each annotation, a 4-second videoclip. The name of each video file contains the following information: Observation ID, Expedition, Station, Taxa, Depth (example 1_PS121_HG4_Aglantha_digitale_400.mp4). This dataset was used to assess diversity, distributions and abundance data on gelatinous zooplankton in the rapidly changing Atlantic-Arctic gateway, Fram Strait.

Description: We collected optical datasets during horizontal video transects with the Pelagic In Situ Observation System (PELAGIOS), a towed camera system, deployed at different localities in the Fram Strait during the R/V Polarstern expedition PS126 from May to June 2021. This system allowed to collect video footage of the larger-sized pelagic fauna (macro- and megazooplankton) in the water column at 3 stations, at depths ranging from 20 m to 2000m. Gelatinous zooplankton taxa, including ctenophores, cnidarian medusae and siphonophores, were annotated and identified to the lowest taxonomic level possible (species, genus). In this dataset, we present the annotations of these video transects with the associated metadata, and for each annotation, a 4-second videoclip. The name of each video file contains the following information: Observation ID, Expedition, Station, Taxa, Depth (example 1_PS126_HG4_Aglantha_digitale_400.mp4). This dataset was used to assess diversity, distributions and abundance data on gelatinous zooplankton in the rapidly changing Atlantic-Arctic gateway, Fram Strait.

Description: Gelatinous zooplankton or “jellies” (ctenophores, cnidarians, tunicates) are known to be major drivers of ecosystem changes. Increases in jelly biomass, referred to as “jellification”, have been observed in several marine ecosystems, causing, amongst others, the collapse of major fisheries. For the Arctic region, abundance data on jellies are virtually non-existent, impeding our ability to detect changes of a similar magnitude. To better understand the role of jellies in the Arctic seas, the Helmholtz Young Investigator Group ARJEL (2019-2026), aims to combine the most recent technologies in optics, acoustics, and environmental DNA analyses. Based on data collected during recent international campaigns, we attempt to link distributional patterns of jellies to sea-ice and oceanographic features. Furthermore, we apply species distribution models to a broad set of archived data to understand observed species and community patterns and to predict changes under future climate-change scenarios. The role of jellies in the Arctic food web, their importance for planktonic predators and fish and their link to the sea-ice trophic pathway is assessed with molecular diet studies. Physiological and transcriptomic studies serve to predict range expansions, and the consequences of expansion will be predicted based on food web models. An overview of the project’s goals, methods and first results will be given. One of our first research highlights include the comparison of species composition and abundances of ctenophores and cnidarians in Arctic vs. Atlantic-influenced Svalbard fjords. We also demonstrate a seasonality in species composition of the gelatinous component of the zooplankton observed during the year-long expedition MOSAiC in the central-Arctic.

Description: Gelatinous zooplankton or “jellies” (ctenophores, cnidarians, tunicates) are known to be major drivers of ecosystem changes. Increases in jelly biomass, referred to as “jellification”, have been observed in several marine ecosystems, causing, amongst others, the collapse of major fisheries. For the Arctic region, abundance data on jellies are virtually non-existent, impeding our ability to detect changes of a similar magnitude. To better understand the role of jellies in the Arctic seas, the Helmholtz Young Investigator Group ARJEL (2019-2026), aims to combine the most recent technologies in optics, acoustics, and environmental DNA analyses. Based on data collected during recent international campaigns, we attempt to link distributional patterns of jellies to sea-ice and oceanographic features. Furthermore, we apply species distribution models to a broad set of archived data to understand observed species and community patterns and to predict changes under future climate-change scenarios. The role of jellies in the Arctic food web, their importance for planktonic predators and fish and their link to the sea-ice trophic pathway is assessed with molecular diet and biomarker studies. Physiological and transcriptomic studies serve to predict range expansions, and the consequences of expansion will be predicted based on food web models. An overview of the project’s goals, methods and first results will be given, with scope for collaborations.

Description: Gelatinous zooplankton are known to be major drivers of ecosystem changes. Increases in jelly biomass, referred to as “jellification”, have been observed in several marine ecosystems, causing, amongst others, the collapse of major fisheries. For the Arctic region, abundance data on jellies are virtually non-existent, impeding our ability to detect changes of a similar magnitude. To better understand the role of jellies in the Arctic seas, the Helmholtz Young Investigator project ARJEL (2019-2025), will combine the most recent technologies in optics, acoustics, and environmental DNA analyses. Integrative field surveys will allow us to link distributional patterns of jellies to sea-ice and oceanographic features. Furthermore, we will apply species distribution models to a broader set of archived data to understand observed species patterns and to predict changes under future scenarios. The role of jellies in the Arctic food web, their importance for higher trophic levels and their link to the sea-ice trophic pathway will be elucidated with metabarcoding and biomarker studies. Physiological and transcriptomic studies serve to predict range expansions, and consequences of expansion will be predicted based on food web models. An overview of the goals and methods planned will be given with scope for collaborations.