Introduction: Processes and Palaeo-Environmental Changes in the Arctic from Past to Present (PalaeoArc) special issue

PalaeoArc (Processes and Palaeo-Environmental Changes in the Arctic: From Past to Present) is an international network research programme, the aim of which is to understand and explain the climatically induced environmental changes in the Arctic that have taken place throughout the Quaternary and continue in the present-day (see http://www.palaeoarc.no/). This network builds on and extends the impressive legacy of previous palaeo-Arctic network programs and projects extending back to the 1980s. This began with the “Polar North Atlantic Margins—Late Cenozoic Evolution” project (PONAM: 1990–1994; Hjort and Persson 1994; Landvik and Salvigsen 1995; Elverhøi et al. 1998), which was followed by the “Quaternary Environment of the Eurasian North” project (QUEEN: 1996–2002; e.g., Larsen, Funder, and Thiede 1999; Thiede et al. 2001, 2004; Kjær et al. 2006). These were then followed by the “Arctic Palaeoclimate and Its Extremes” project (APEX: 2004–2012; Jakobsson et al. 2008, 2010, 2014) and the “Palaeo-Arctic Spatial and Temporal Gateways” project (PAST Gateways: 2012–2018; Ó Cofaigh et al. 2016, 2018). The latest incarnation of the network—PalaeoArc—was conceived at the final meeting of the PAST Gateways project in Durham, UK, in April 2019, when a new international steering committee was appointed to organize a series of activities and annual conferences for the following six years (2019–2024). The new international network held its first meeting in Poznań (20–24 May 2019), hosted by the Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Poznań (see Lyså et al. 2019), comprising the usual mix of talks, posters, discussions, workshops, and a field excursion. The network planned to organize a conference hosted by the Department of Earth Sciences at the University of Pisa in May 2020, but this had to be postponed due to the COVID-19 pandemic and was eventually held online in May 2021, endorsed by the International Arctic Science Council, Italian Geological Society, and Italian Association for the Study of the Quaternary. The meeting proved incredibly popular and was “attended” by over 250 Arctic scientists from twenty-six different countries over a four-day period, allowing glacial and marine geologists, palaeoceanographers, palaeoecologists, and specialists in permafrost and numerical modeling to discuss records of Arctic environmental change over decadal to millennial timescales. The collection of articles in this special issue stems from this second PalaeoArc International Conference and encompasses the diverse range of topics presented at the meeting, each of which addresses the overarching aims of PalaeoArc (detailed below). The third international PalaeoArc conference took place (in person) in Rovaniemi in August 2022. The network has been extended for a year, with further meetings planned in Akureyri (2023), Stockholm (2024), and Tromsø (2025)

Environmental changes in Krossfjorden, Svalbard, since 1950 : Benthic foraminiferal and stable isotope evidence

Environmental changes for the past ca. 50 years were studied in a short sediment core from inner Krossfjorden, Svalbard, investigating benthic foraminifera and stable isotopes (delta O-18, delta C-13). A depth-age model based on anthropogenic Cs-137 time markers indicates that record covers the period from 1955 to 2007 and has sediment accumulation rates of ca. 0.3 to 1 cm/year. The benthic foraminifera are arctic and/or common in glaciomarine environments. Six fauna assemblages were identified using stratigraphically constrained cluster analysis. Benthic foraminiferal fauna assemblages are mainly dominated by Cassidulina reniforme. Elphidium clavatum is dominant from 1973 to 1986 and 2002 to 2007, likely due to greater turbidity in the water column. We interpret the increased percentages of Spiroplectammina biformis over the same intervals to reflect a slightly lower salinity probably caused by meltwater. During a short time period, 1970 to 1973, Stainforthia concava dominates the benthic foraminiferal fauna interpreted to reflect increased productivity within a marginal ice zone. Other species as Islandiella norcrossi, Nonionellina labradorica, Islandiella helenae, and Melonis barleanus also indicate more nutrient-rich waters are present but not very abundant throughout the record probably due to the glacier proximal position of the study site. The stable isotope record (delta O-18) shows lighter values from 2001 to 2007, which seem to correlate well with oceanographic monitoring data showing increasing core temperatures of West Spitsbergen Current.Peer reviewe

Introduction: Processes and Palaeo-Environmental Changes in the Arctic from Past to Present (PalaeoArc) special issue

PalaeoArc (Processes and Palaeo-Environmental Changes in the Arctic: From Past to Present) is an international network research programme, the aim of which is to understand and explain the climatically induced environmental changes in the Arctic that have taken place throughout the Quaternary and continue in the present-day (see http://www.palaeoarc.no/). This network builds on and extends the impressive legacy of previous palaeo-Arctic network programs and projects extending back to the 1980s. This began with the “Polar North Atlantic Margins—Late Cenozoic Evolution” project (PONAM: 1990–1994; Hjort and Persson 1994; Landvik and Salvigsen 1995; Elverhøi et al. 1998), which was followed by the “Quaternary Environment of the Eurasian North” project (QUEEN: 1996–2002; e.g., Larsen, Funder, and Thiede 1999; Thiede et al. 2001, 2004; Kjær et al. 2006). These were then followed by the “Arctic Palaeoclimate and Its Extremes” project (APEX: 2004–2012; Jakobsson et al. 2008, 2010, 2014) and the “Palaeo-Arctic Spatial and Temporal Gateways” project (PAST Gateways: 2012–2018; Ó Cofaigh et al. 2016, 2018). The latest incarnation of the network—PalaeoArc—was conceived at the final meeting of the PAST Gateways project in Durham, UK, in April 2019, when a new international steering committee was appointed to organize a series of activities and annual conferences for the following six years (2019–2024). The new international network held its first meeting in Poznań (20–24 May 2019), hosted by the Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Poznań (see Lyså et al. 2019), comprising the usual mix of talks, posters, discussions, workshops, and a field excursion. The network planned to organize a conference hosted by the Department of Earth Sciences at the University of Pisa in May 2020, but this had to be postponed due to the COVID-19 pandemic and was eventually held online in May 2021, endorsed by the International Arctic Science Council, Italian Geological Society, and Italian Association for the Study of the Quaternary. The meeting proved incredibly popular and was “attended” by over 250 Arctic scientists from twenty-six different countries over a four-day period, allowing glacial and marine geologists, palaeoceanographers, palaeoecologists, and specialists in permafrost and numerical modeling to discuss records of Arctic environmental change over decadal to millennial timescales. The collection of articles in this special issue stems from this second PalaeoArc International Conference and encompasses the diverse range of topics presented at the meeting, each of which addresses the overarching aims of PalaeoArc (detailed below). The third international PalaeoArc conference took place (in person) in Rovaniemi in August 2022. The network has been extended for a year, with further meetings planned in Akureyri (2023), Stockholm (2024), and Tromsø (2025)

Contribution of Soft-shelled Monothalamous Taxa to Foraminiferal Assemblages in the Adriatic Sea

Monothalamous foraminifera with organic and agglutinated test walls (‘‘allogromiids’’ sensu lato) deserve attention because of their importance in deep-sea and shallow-water soft-bottom communities and their crucial phylogenetic position at the base of the foraminiferal evolutionary tree. However, our knowledge of the biodiversity and ecology of monothalamous foraminifera is very incomplete and geographically patchy. Here, we present a short review based on the available data on monothalamous, soft-walled foraminiferal taxa from the Adriatic Sea in response to several environmental parameters (i.e., organic matter, oxygen, grain size, depth). The main results of the studies provide evidence of the importance of these foraminiferal taxa in this shallow, temperate latitude area;they represent a start for the identification of soft-shelled monothalamous morphotypes that could be potential bioindicators of environments influenced by inputs of fresh waters, increasing eutrophication and consequent fluctuations in bottom-water oxygenation. The contribution of this soft-shelled component to living benthic foraminiferal assemblages appears not negligible and excluding it from foraminiferal studies can potentially lead to a loss of ecological information. The study, therefore, provide an atlas of the Adriatic soft-shelled foraminiferal taxa in order to 1) encourage the species-level description, if possible, or alternatively a basic morphotype characterization, 2) facilitate future comparisons of taxa from similar settings, 3) promote their potential use in future biomonitoring investigations together with the hard-shelled foraminifera

Variability in intermediate water circulation of the western Tyrrhenian margin (NE Corsica) over the past 56 kyr

The Marion Dufrene core MD01-2472 made of hemipelagic fine-grained sediments (silt and clays) was collected at 501 m depth on the East Corsica continental slope in 2001 and studied in detail in its 12 uppermost meters. The correlation between sedimentological parameters (Sortable Silt), isotopic data and 14C dating allowed to establish the chronology of main climate events (Younger Dryas/YD, Bölling-Alleröd/B-A, Heinrich events/HS) on this record and to evaluate the impact of major climate oscillations on bottom water condition variability. The sea temperature changes are identified thanks to the planktonic foraminifera assemblages. HS are marked by planktonic foraminifers with peaks of the polar species N. pachyderma (left-coiling), whilst interstadials are marked by warm planktonics that become very abundant during the B-A and Holocene. The occurrence of reworked ostracod species (originating from the continental shelf) and the presence of shallow water Elphidium/Ammonia benthic foraminifera are used to estimate the degree of along-slope transport at the core site. This has revealed two intervals of along-slope transport also associated with coarse-grained contourites, deposited during the YD and HS2 episodes. Intervals with Krithe spp. (ostracod), C. wuellerstorfi (benthic foraminifera) indicate bottom water oxygenation during stadials, whereas interstadials are typified by A. acuminata and Paracypris sp (ostracods) indicating low oxygenated environments. The Last Glacial Maximum is dominated by the planktonic foraminifer T. quinqueloba suggesting high surface primary productivity associated with the establishment of mestrophic bottom conditions. During the Holocene, benthic assemblages indicate oligo-mesotrophic conditions and weak hydrodynamic bottom regime. We hypothesize that there is relationship between the Levantine Intermediate Water (LIW) intensification during cold rapid climate events and benthic fauna assemblages due to changes in: 1) bottom water ventilation, corresponding to a significant reinforcement of the LIW velocity, and 2) the export of nutrients (generating changes in trophic conditions) and/or sediment particles by bottom currents (contributing to the formation of contourites)

Mid-Holocene relative sea-level changes along Atlantic Patagonia: new data from Camarones, Chubut, Argentina

This paper concerns the relative sea-level changes associated with the Atlantic Patagonian coast derived from sea-level index points whose elevation was determined by a differential global position system (DGPS). Bio encrustations from outcrops located near Camarones, Chubut, Argentina, consist of autochthonous deposits characterized by Austromegabalanus psittacus (Molina, 1782), encrusting acer vulinid foraminifera, coralline red algae and bryozoans. The association of the different organisms is interpreted as being associated with an intertidal environment, and they have been used as index points to establish the relative sea-level position. The main conclusion is that the relative sea-level between c. 7000 and 5300 cal. yr BP was in the range ofc. 2?4 m a.s.l., with a mean value of c. 3.5 m a.s.l. Our data seem to support the existence of different rates of relative sea-level fall in different sectors of Atlantic Patagonia during the Holocene and highlight the importance of a more precise and accurate relative sea-level estimation by producing new data and revisiting the indicative meaning of most of the indicators so far used in the area.Facultad de Ciencias Naturales y Muse