Periodic Reporting for period 1 - ArCeph (Tracking impacts of climate change in the Arctic marine ecosystems through cephalopod diversity and life histories)
Reporting period: 2022-05-15 to 2024-05-14
Climate change and particularly warming of the ocean is impacting global ecosystems but nowhere changes are occurring as rapid as in the polar areas. These changes affect the Arctic marine ecosystems from the surface to the deep seafloor, and from microorganisms, to commercially exploited fishes to charismatic megafauna. Countering climate change effects is stated as one of the key goals of both global development, in the 2030 Agenda for Sustainable Development, and of regional development, e.g. EU strategy of managing the Arctic. To accomplish this, the study of structure and functioning of Arctic marine ecosystems are among the priorities of current Arctic science. In the Arctic, one of the dominant but severely understudied invertebrate taxa are the cephalopods. Cephalopoda (Phylum Mollusca) are opportunistic marine molluscs with a single reproductive cycle and typically a short lifespan. They occur from shallow waters to the deep seas, are pivotal components in marine food webs and have life history and physiological characteristics that make them potential winners of climate change. Their opportunistic nature is underpinned by expansions beyond their centre of distribution. This altogether makes cephalopods mirrors of ecosystem change due to climate change. In the Arctic regions, however, they are severely understudied. By implementing traditional and novel methodologies, the EU-funded ArCeph Action investigates the biodiversity, the historical background and the ecological role of cephalopods in the Arctic and their ontogenetic and temporary changes in the climate change context. The Action addresses this matter via 3 scientific work packages that focus on the following research hypotheses: Hypothesis 1) diversity and distribution of current Arctic cephalopod populations shifts due to climate changes; Hypothesis 2) environmental conditions experienced during the life of individual cephalopods can be documented and used to assess the climate change impact on life histories, where comparing historical with new specimens will highlight climate change impact; and Hypothesis 3) the role of cephalopods in the Arctic food web is even more pivotal then we currently understand, and this would be tested with innovative food web modelling methods.
During 2022–2024, extensive work on the assessment of the role of cephalopods in the Arctic ecosystems and foodweb shifts due to climate change was undertaken. Changes in cephalopod diversity, distribution and abundance in the Barents Sea were assessed using 18 years of annual bottom trawl data (2005–2022) (Golikov et al. 2024a). Taxonomic work was performed to clarify the situation of a dominant cephalopod that occurs widely within the Arctic basin (Golikov et al. 2023a). Using underwater video-imagery, a new behaviour of Arctic deep-sea bentho-pelagic cephalopods was discovered which may have consequences for trophic coupling between the seafloor and the water column (Golikov et al. 2023b). The Action validated a new methodology on how to apply trophic markers (= stable isotopes of carbon and nitrogen, δ13C and δ15N) to chitinous cephalopod beaks to obtain individual level stable isotope data and trajectories (Golikov et al. 2022, Xavier et al. 2022). This new methodology was successfully applied on historical and contemporary samples of the most abundant Arctic species of cephalopods from 1882 to 2019 (Golikov et al. 2024b). Finally, the recommendations were suggested about ecological monitoring of cephalopods using taxonomy, diversity, distribution and abundance-related parts of the work (Golikov et al. 2024a). Currently, ongoing activities include: 1. Environmental DNA data are being used to prepare the peer-reviewed scientific paper (lead by one of my collaborators); 2. Individual-level long-term trends in stable isotope signatures are being compared between cephalopods from the Arctic and Antarctic (Golikov et al. in preparation); and 3. The Action enabled the compilation of a database from literature and new data for a food web model of the Barents Sea (Golikov et al. in preparation).
Peer-reviewed scientific papers:
Golikov et al. 2022, doi: 10.3390/ani12243548
Golikov et al. 2023a, doi: 10.1186/s40851-023-00220-x
Golikov et al. 2023b, doi: 10.1098/rspb.2023.0640
Golikov et al. 2024a, doi: 10.3389/fmars.2024.1392585
Golikov et al. 2024b, in review
Xavier et al. 2022, doi: 10.3389/fphys.2022.1038064
Peer-reviewed scientific papers:
Golikov et al. 2022, doi: 10.3390/ani12243548
Golikov et al. 2023a, doi: 10.1186/s40851-023-00220-x
Golikov et al. 2023b, doi: 10.1098/rspb.2023.0640
Golikov et al. 2024a, doi: 10.3389/fmars.2024.1392585
Golikov et al. 2024b, in review
Xavier et al. 2022, doi: 10.3389/fphys.2022.1038064
Main result of the Action arises from the combination of hypotheses 1 and 2. It is shown that both cephalopods’ community composition and abundance in the Barents Sea (= the most climate change-impacted area of the Arctic), and trophic ecology of the most abundant Arctic cephalopod species, change in the late 1990s/early 2000s. This timing coincides with the known onset of increased environmental impact of the climate change in the Arctic. On community level, boreal-subtropical species of cephalopods appear in the Arctic, and local Arctic species of squid moves eastward to the previously too cold areas. At the same time, abundance of cephalopods as a whole, and of most of the individual taxa significantly increases. On species level, trophic ecology shifts reflects climate-driven ecosystem shifts: increased generalization of food webs coincides with increased diet generalism and niche width of the squid, while increased abundance of boreal piscivorous fishes is responsible for the squid’s increased trophic level.
Another important finding is that new trophic pathway through deep-sea bentho-pelagic cephalopods is found in the Arctic. Deep-sea cirrate octopods are reported to feed on the seafloor but live in the water column, 500–2600 m above the seafloor. This newly discovered trophic pathways directly connects small-sized benthos (= in general, basal food web elements) with large pelagic top predators (= apex food web elements). This migration behaviour is unique in cephalopods, but also present in Echinodermata and Osteichthyes.
Other important results are: 1. Cephalopods are demonstrated to be good model organisms to study marine ecosystem changes via retrospective stable isotope analysis. This new method can now be used by other researchers working on cephalopods; and 2. Two new species of cephalopods are found in the Arctic.
The results arising from this Action has received a lot of public attention: the Fellow held several interviews; and one of the scientific papers (Golikov et al. 2023b) reached top 5% Altmetric score.
Another important finding is that new trophic pathway through deep-sea bentho-pelagic cephalopods is found in the Arctic. Deep-sea cirrate octopods are reported to feed on the seafloor but live in the water column, 500–2600 m above the seafloor. This newly discovered trophic pathways directly connects small-sized benthos (= in general, basal food web elements) with large pelagic top predators (= apex food web elements). This migration behaviour is unique in cephalopods, but also present in Echinodermata and Osteichthyes.
Other important results are: 1. Cephalopods are demonstrated to be good model organisms to study marine ecosystem changes via retrospective stable isotope analysis. This new method can now be used by other researchers working on cephalopods; and 2. Two new species of cephalopods are found in the Arctic.
The results arising from this Action has received a lot of public attention: the Fellow held several interviews; and one of the scientific papers (Golikov et al. 2023b) reached top 5% Altmetric score.