ALBERT

Description: During the KOP183 project Arctic jellyfish in the Polar Night at the AWIPEV station in January-February 2022, we assessed the Polar Night gelatinous zooplankton community and their overwintering strategies. By means of net catches from WP2 and WP3 plankton nets deployed from MS Teisten, and hand nets deployed from the pontoon in Ny-Alesund, we characterized the species diversity of gelatinous zooplankton, including hydrozoan and scyphozoan medusae, as well as ctenophores. At least 15 different species of gelatinous zooplankton (6 Hydrozoa of which 2 Siphonophora, 2 Scyphozoa, 8 Ctenophora), were observed, based on morphological examination. Several of these species were so far not known to overwinter. DNA barcoding of these specimens is currently ongoing and will likely reveal an even higher species diversity, knowing that a number of unidentified species were sampled.

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: Rapid warming in the Arctic is drastically impacting marine ecosystems; affecting species composition, distribution and food web structure. Themisto amphipods are a key link between secondary producers and marine vertebrates at higher trophic levels. Two co-existing species dominate in the region: Themisto libellula, considered an Arctic species and Themisto abyssorum, a sub-Arctic, boreal species. T. libellula is larger, feeds on herbivorous copepods and is crucial prey for seabirds, key fish species and marine mammals. Whereas T. abyssorum is smaller, feeds on carnivorous zooplankton and is considered an indicator of warmer water masses. Both species have already exhibited changes in abundance and range shifts, likely due to the Atlantification of the Arctic. Many aspects of the ecology and genetic structure of these two species are not well studied, despite their importance in the food web and biogeochemical cycles. Further understanding of phylogeography and distributional patterns is crucial to understanding how they will be affected by climate change and how this will impact the ecosystem. This study focuses on the genetic structure and connectivity of both Themisto species as well as their association with Arctic and Atlantic water masses. We do this by analysing and comparing mitochondrial cytochrome oxidase I gene sequences according to the geographic populations, from Svalbard fjord systems, the Fram Strait and Southern Greenland. Distributional data are statistically analysed in relation to hydrographic data. These data reveal a contrasting genetic structure, predicting T. libellula will be less able to cope with environmental changes than T. abyssorum.

Description: The Arctic is experiencing climate change-related warming at a faster rate than any other region. This is inducing unprecedented reductions in sea ice cover, increasing freshwater inflow and rising ocean temperatures. These environmental changes are already having drastic impacts on the marine ecosystem; affecting species composition, distribution and food web structure in the Arctic Ocean. Pelagic Themisto amphipods are an important link between secondary producers and marine vertebrates at higher trophic levels. Two co-existing species dominate the Arctic region: Themisto libellula, considered a genuine Arctic species and Themisto abyssorum, considered a sub-Arctic, boreal species. Both prey on mesoplankton but are thought to occupy different niches. T. libellula is larger, feeds on herbivorous copepods and is a key prey item for seabirds, key Arctic fish species and certain marine mammals. Whereas T. abyssorum is smaller, feeds on omnivorous and carnivorous zooplankton and is considered an indicator species of warmer water masses. Both species have exhibited recent changes in abundance and range shifts, likely as a result of the Atlantification of the Arctic. Many aspects of the ecology and genetic structure of these two species are not well studied, despite their importance in the food web and biogeochemical cycles. Further understanding of the phylogeography and distributional patterns of these key zooplankton species is crucial to understanding how they will be affected by climate change and how this will impact the ecosystem. This study focuses on the genetic structure and connectivity of both Themisto species as well as their association with Arctic and Atlantic water masses. We do this by analysing and comparing mitochondrial cytochrome oxidase I gene sequences according to the geographic populations. These data reveal a contrasting genetic structure, predicting T. libellula will be less able to cope with environmental changes than T. abyssorum. Distributional data of both species and their abundances are statistically analysed in relation to hydrographic data. Individuals were collected between 2016 and 2020 on a number of international campaigns, from a broad geographic distribution including Svalbard fjord systems, the Fram Strait and Southern Greenland.

Description: The Arctic is warming two times faster than the global mean, and a phenomenon known as the ‘Atlantification of the Arctic’ via the Fram Strait is having growing influences on both biological and physical processes in the region. Changes to community composition and function are already underway and these environmental changes will continue to rapidly alter Arctic ecosystems. Greater understanding of how this impacting local marine biodiversity is crucial for formulating accurate predictions of future Arctic marine ecosystems and management decisions. Gelatinous zooplankton (GZP) is a highly diverse group of taxa, including cnidarians, ctenophores and tunicates. Very little is currently known about GZP ecology, particularly in the Arctic Ocean, and even less about how they are being impacted by climate-related changes. Not only are they often actively left out of zooplankton surveys, but GZP are notoriously difficult to catch in good condition because their fragile bodies are easily destroyed by traditional sampling methods. These challenges contribute to GZP taxa regularly being underestimated in biodiversity, distribution and abundance, which has led to a lack of reliable and comprehensive baseline data available, especially in the Arctic. The aim of this study is to apply non-invasive environmental DNA (eDNA) metabarcoding methods to investigate GZP biodiversity and distribution across the Fram Strait. COI mitochondrial and 18s rRNA amplicons from water and sediment samples will be sequenced with Next Generation Sequencing (NGS) and validated with depth-stratified net-catch data. Net-caught specimens will be barcoded where possible, to complement existing reference databases. Oceanographic data will then be incorporated in order to form a holistic baseline dataset of GZP biodiversity across the region. Such data would be a valuable contribution to future research into the deviations in Arctic GZP biodiversity, community composition and distribution over time, as a result of on-going environmental changes.

Description: Environmental DNA (eDNA) studies have burgeoned over the last two decades and the application of eDNA has increased exponentially since 2010, albeit at a slower pace in the marine system. We provide a literature overview on marine metazoan eDNA studies and assess recent achievements in answering questions related to species distributions, biodiversity and biomass. We investigate which are the better studied taxonomic groups, geographic regions and the genetic markers used. We evaluate the use of eDNA for addressing ecological and environmental issues through food web, ecotoxicological, surveillance and management studies. Based on this state of the art, we highlight exciting prospects of eDNA for marine time series, population genetic studies, the use of natural sampler DNA, and eDNA data for building trophic networks and ecosystem models. We discuss the current limitations, in terms of marker choice and incompleteness of reference databases. We also present recent advances using experiments and modeling to better understand persistence, decay and dispersal of eDNA in coastal and oceanic systems. Finally, we explore promising avenues for marine eDNA research, including autonomous or passive eDNA sampling, as well as the combined applications of eDNA with different surveillance methods and further molecular advances.

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: 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.