ALBERT

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.

Description: Climate change proceeding at unprecedented pace is currently redistributing life on Earth. In the Arctic region, climate change is acting more rapidly than elsewhere on this planet, and has dramatically altered sea ice thickness and extent. However, for many Arctic taxa, the distribution ranges and population connectivity have remained undocumented. This is particularly so for Arctic gelatinous zooplankton, of which the diversity, abundances and role in the food web are understudied. The hydromedusa Aglantha digitale is highly abundant in the Arctic Ocean, and characterized by a widespread distribution, ranging from temperate waters to the central Arctic. Its distribution in the water column has been linked to the presence of Atlantic water masses, which renders it a likely candidate to benefit from the ongoing “Atlantification” of the Arctic. Despite its ubiquity and abundance, its genetic diversity remains unknown, and it is unclear whether this species is composed of different geographic lineages throughout its distribution range. To compare the genetic diversity and assess the phylogeography of A. digitale, we collected samples from several recent international cruises. Geographic populations from temperate waters, sub-Arctic Greenland, Svalbard and the central Arctic are compared based on sequences of the mitochondrial cytochrome c oxidase subunit I (COI). A better understanding of the distribution and connectivity will help to predict potential range shifts of A. digitale in an “Atlantified” Arctic.

Description: Global warming in the Arctic region causes alterations in the composition and structure of marine communities. Such changes are particularly pronounced in the transitional zones such as Fram Strait where the increased inflow of warm Atlantic waters accelerates this process. In other ecoregions of the world’s oceans, warming has caused an increase in the biomass of gelatinous zooplankton (or jellies). Jellies are versatile predators in diverse marine ecosystems. Despite the potential impact of jelly communities on the Arctic food webs, their ecological roles have been poorly studied. We hypothesise that the Arctic pelagic community consists of a significant component of gelatinous fauna, some of which are expanding from the North Atlantic. To test this hypothesis, we obtained baseline data on vertical distribution and diversity of Arctic jellies using towed camera video transects during expeditions to the HAUSGARTEN LTER in Fram Strait in 2019, 2020 and 2021. The data include the abundance of 17 groups of gelatinous zooplankton, among which the most abundant were the hydrozoan family of Rhopalonematidae, mainly consisting of Aglantha and Rhopalonema, and the siphonophore suborders Physonectae and Calycophorae. Based on the obtained abundance data, we fitted bayesian joint species distribution models (JSDMs) to understand current patterns of species distributions at different depth layers and to provide predictive insights into community assembly processes. Variance partitioning over the explanatory variables showed that depth and temperature explained a substantial amount of variation for most of the taxa. The trained models were later coupled with climate change scenarios, which allowed us to forecast spatial niche range shifts in ecosystems.

Description: Jellyfish (ctenophores and cnidarians) are known to be major drivers of ecosystem changes. Increases in biomass, referred to as “jellification”, have been observed in several marine ecosystems, causing, amongst others, the collapse of major fisheries. For the Arctic, comprehensive datasets on jellyfish are currently missing, impeding our ability to detect changes of a similar magnitude. The Helmholtz Young Investigator Group “ARJEL” aims to combine the most recent technologies in optics and environmental DNA analyses, to better understand the role of jellies in the Arctic seas. We apply species and community distribution models to a broad set of archived and newly obtained data to understand distribution patterns and to predict range and community shifts under future climate-change scenarios. The role of jellies in the Arctic food web, their seasonal and regional variation in feeding habits and their importance as prey for planktonic predators and fish is assessed with DNA metabarcoding and biomarker studies. We investigate the role of “jelly-falls” in sustaining the benthic food web. Experimental studies will determine jellyfish’ thermal windows and resilience. The outcomes of the models, trophic data, and insights into the connectivity and adaptability of jellyfish species, will allow us to improve food web and ecosystem models, currently neglecting jellyfish. An understanding of jellyfish-fish interactions, and how these will be impacted by climate-change driven range shifts, will shed light on the fate of commercially exploited Arctic fish stocks. We will present the project aims and first results, as well as our planned research activities during our stay at AWIPEV, Kongsfjorden, in January 2022. Our ongoing foci include: i) the comparison of jellyfish’ communities in Arctic vs. Atlantic-influenced Svalbard fjords to forecast the impact of the ongoing Atlantification; ii) the comparison between various methods for assessing jellyfish diversity; iii) the ecology of overwintering jellyfish in Kongsfjorden.

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 aims to combine the most recent technologies in optics, acoustics, and environmental DNA (eDNA) analyses. Based on data collected during recent international campaigns, we attempt to link distributional patterns of jellies to oceanographic features and sea ice. 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 and their importance as prey for planktonic predators and fish is assessed with molecular diet studies, which will improve food web models currently neglecting jellies as major predators and prey. We also explore the genetic connectivity of dominant jelly species across the Arctic Ocean and its adjacent seas. An overview of the project’s goals, methods and first results will be given. Our ongoing research foci include: 1. the comparison of species composition and abundances of ctenophores and cnidarians in Arctic vs. Atlantic-influenced Svalbard fjords to better understand the impact of the ongoing Atlantification of the Arctic; and 2. the comparison between optical methods, net catches and eDNA for assessing jelly diversity and abundances.

Description: Gelatinous zooplankton are known to play an important role in World Ocean ecosystems. As climate change continues to cause profound environmental shifts in Fram Strait, a key transitional zone between the North-Atlantic and the Arctic Ocean, the lack of understanding of how gelatinous zooplankton are affected by these environmental changes creates a significant gap in knowledge about the future state of Arctic ecosystems. In this study, we used in situ observations obtained by the towed underwater camera system PELAGIOS (Pelagic In situ Observation System) to establish one of the first regional baselines of large gelatinous zooplankton diversity and abundance in mesopelagic and bathypelagic zones. Our data included 16 taxa of gelatinous zooplankton, with the most abundant being from the family Rhopalonematidae (Aglantha digitale and Sminthea arctica) and the suborders Physonectae and Calycophorae. We used a joint species distribution modelling approach to better understand their three-dimensional distribution patterns and assess the environmental drivers of gelatinous community structures. The most significant drivers were temperature and depth. Spatial distribution modelling based on in situ measurements revealed that the highest abundance and diversity of jellyfish are expected at the edges of the West Spitsbergen and East Greenland current systems. The near-future projections indicate that with continued temperature increase, the gelatinous zooplankton community in the Fram Strait will become less diverse but more abundant. Among taxa of the Rhopalonematidae family, we expect the abundance of Aglantha digitale to increase by 2% throughout the water column, while Sminthea arctica will experience a loss of up to 60% by 2050.

Description: The primary aim of this expedition was to investigate the spatial and temporal distribution, the ecology and physiology, as well as competition of co-occurring gadoid species (Atlantic cod, Polar cod, haddock) in the communities of Arctic and Atlantic influence around Svalbard. We sampled the benthic and pelagic communities (including plankton) on the shallow shelf regions of Svalbard to estimate the effects of climate change on Arctic ecosystems to obtain a picture of the entire system structure and function for a long-term monitoring program of the ‘Atlantification’ of the Svalbard region. We assessed the potential impact of changes in trophic interaction (predator-prey relations) of Atlantic cod (Gadus morhua), Polar cod (Boreogadus saida), haddock (Melanogrammus aeglefinus) and decapod crabs on the productivity and stability of benthic and pelagic communities in Arctic ecosystems, into which their distribution ranges now extend due to ocean warming. In addition to a stock assessment and distribution analysis of gadoid fish and decapod crabs, we aimed to obtain specimens of these species in the Atlantic and polar waters around Svalbard, which were transported alive back to Germany. Laboratory experiments under scenarios of climate change at the Alfred Wegener Institute then provided (and still provide) further insight into capacities for adaptation, performance and interaction of selected species of the Arctic ecosystem around Svalbard. The results will on the one hand be used in an international Norwegian-German project and the pan-Arctic data management system (Piepenburg et al. 2011), on the other hand they will flow into fisheries modelling at the University of Hamburg, the Thuenen Institute and socio-economic modelling approaches that build on the German ocean acidification project BIOACID (www.bioacid.de).