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From the afternoon of April 1st to the morning of April 9th 2015, CAGE at the Department of Geology Uit, the Arctic University of Norway, arranged a scientific cruise aimed at investigating the western Barents Sea slope, western and northern Svalbard margin, methane seep sites at Vestnesa and Storfjorden Trough and the Barents Sea on R/V “Helmer Hanssen”. Investigated areas were (in order of visiting sites on the cruise): Malangen Trough, Bjørnøya Trough Mouth Fan south and mid, Storfjorden Fan, Vestnesa Ridge, the northwest Svalbard slope to north of Schmeerenburgfjorden. On the track towards Tromsø we sampled in Storfjorden Trough. The scientific sampling was done within the framework of several ongoing projects at the Department of Geology, University of Tromsø: “CAGE -Centre for Arctic Gas hydrate, Environment and Climate”, in which the sub-projects “Paleo-CIRCUS”, “OA-Ocean Acidification” is included. A total of 2 gravity cores, 8 plankton net casts and 22 CTD (conductivity-temperature-depth) casts were performed along the route to Northern Svalbard at the western Barents Sea slope. Data were also collected in Storfjorden Trough and the mouth of Storfjorden. In addition, CTD’s and a small chirp and multibeam survey was performed off Schmeerenburgfjorden, north of fjorden and in its northernmost part. Chirp profiles and multibeam lines were acquired during transits and during the survey of outer Schmeerenburgfjorden. The recording started from c. 71 N on the western Barents Sea slope and ended at 70.00 N. The cruise may be known as: CAGE15_1_CO2

From the late afternoon of July 23rd to the morning of August 3rd, 2015, the Department of Geology Uit, the Arctic University of Norway, arranged a AMGG-Research School scientific teaching cruise aimed atinvestigating the western and northern Svalbard margin and the Barents Sea, the Fram Strait to east Greenland, methane seep sites at Vestnesa, Prins Karls Forland and Storfjorden Trough and on R/V “Helmer Hanssen”. Investigated areas were (in order of visiting sites on the cruise): west of Prins Karls Forland, Vestnesa Ridge, Molloy Deep, Fram Strait, East Greenland margin, Smeerenburgfjorden, Hinlopen, Storfjorden, Storfjorden Trough, and Leirdjupet south of Spitsbergenbanken. The scientific sampling was done within the framework of several ongoing projects at the Department of Geology, University of Tromsø: “CAGE – Centre for Arctic Gashydrate, Environment and Climate”, in which the sub-projects “Paleo-CIRCUS”, “OA-Ocean Acidification” is included. The responsible for this year’s course in GEO8144/GEO3144 is Prof. T.L. Rasmussen. A total of 26 gravity cores, 5 piston cores, 12 plankton net casts and 27 CTD (conductivity-temperature-depth) casts were performed at the planned stations. A total of 86.3 km (46 nm) of airgun surveys were run. 108.97 m mud was obtained in total. Chirp profiles and multibeam lines were acquired during transits and during surveys in Storfjorden, Storfjorden Trough and Leirdjupet. In addition, CTD’s and a small chirp and multibeam survey was performed Storfjorden and in Leirdjupet and airgun lines were run in Storfjorden Trough. The recording of echo-sounding started from c. 78 °N on the shelf outside Isfjorden and ended at c. 72 °N, with pauses when passing through protected areas of Svalbard (Smeerenburgfjorden and Hinlopen and respecting the 12 nm zone in Storfjorden). The cruise may be known as: CAGE15_7_AMGG

From the afternoon of February 8th to the late morning of February 15th 2016, CAGE at the Department of Geology Uit, the Arctic University of Norway, arranged a scientific cruise aimed at investigating water masses and planktonic faunas at the western Svalbard margin and western Barents Sea slope, also visiting methane seep sites off Vestnesa Ridge, Prins Karls Forland (PKF) and in Storfjorden Trough on R/V “Helmer Hanssen”. Investigated areas were (in order of visiting sites on the cruise): PKF, Storfjorden Fan, Storfjorden Trough, Bjørnøya Trough Mouth Fan, north, mid and south and the slope off Troms (off Malangen). Seep sites at Vestnesa Ridge were abandoned because of bad weather conditions. The scientific sampling was done within the framework of several ongoing projects at the Department of Geology, University of Tromsø: “CAGE – Centre for Arctic Gashydrate, Environment and Climate”. A total of 1 boxcore, 8 plankton net (4 multinet and 4 plankton net) casts and 14 CTD (conductivity-temperature-depth) casts were performed along the route from western Svalbard to Norway along the western Barents Sea slope. Data were also collected in Storfjorden Trough and Storfjorden – no sea ice yet. Chirp profiles and multibeam lines were acquired during transits and in Storfjorden. The cruise may be known as: CAGE16_1

From the afternoon of July 21st to the morning of July 29th 2014, CAGE at the Department of Geology Uit, the Arctic University of Norway, arranged a scientific cruise with teaching (GEO3144/8144- Arctic Marine Geology and Geophysics Cruise) aimed at investigating and teaching students about the western Svalbard margin, methane seep sites at Vestnesa and Storfjorden Trough and the Barents Sea on R/V “Helmer Hanssen”. Investigated areas were (in order of visiting sites on the cruise): Vestnesa Ridge, the west Svalbard slope, Storfjorden Trough, Storfjorden and western Barents Sea. The scientific sampling was done within the framework of several ongoing projects at the Department of Geology, University of Tromsø: “CAGE – Centre for Arctic Gas hydrate Environment and Climate”, in which the sub-projects “Paleo-CIRCUS”, “OA-Ocean Acidification” is included. A total of 11 gravity cores, 7 box-cores (with a total of 18 sub-samples retrieved), 9 plankton net casts and 16 CTD (conductivity-temperature-depth) casts were performed at Vestnesa Ridge, Storfjorden Fan, Storfjorden Trough, Storfjorden and the western Barents Sea, respectively. All gravity cores were logged onboard by magnetic susceptibility loop sensor for stratigraphical purposes and educational purposes. Chirp profiles and multibeam echo sounder lines were acquired during transits and during surveys of Storfjorden and several pockmarks at the Vestnesa Ridge. A total of 129 lines were collected during transits and during surveys. A total of six seismic lines were performed with the airgun. The cruise may be known as: CAGE14_4_CO2_GEO

The flow of the Atlantic Water (AW) via the Return Atlantic Current (RAC) regulates the oceanographical conditions in the Northwestern (NW) Greenland Sea in the Fram Strait. As the intensity of the RAC might significantly influence both deep-water formation in the area and the stability of the Northeast Greenland Ice Sheet (NE GIS), knowledge of its variability in the past is important. Here we present a reconstruction of the paleoceanographic forcing of the AW on climatic conditions and associated environmental changes in the NW Greenland Sea by means of foraminiferal assemblages, stable (oxygen and carbon) isotopes, and various sedimentological parameters from sediment core GR02-GC retrieved from NE Greenland continental slope (1170 m water depth). Our data indicate an almost continuous presence of AW in the NW Greenland Sea during the last 35 kyr BP. Two peaks of low planktic δ18O values at ~34.5 and 33 kyr BP are interpreted as meltwater signals associated with warm AW-induced melting of the adjacent NE GIS. The NE GIS advanced between 32 and 29 kyr BP, resulting in reduced meltwater influx to the NW Greenland Sea. Increased iceberg calving and melting after 29 kyr BP, were probably linked to surface warming and glacier advance to the shelf-break lasting until 23.5 kyr BP. During the Last Glacial Maximum, the extensive sea ice cover was associated with the presence of subsurface AW at the study site. During the Bølling–Allerød (B/A, ~14.6–12.7 kyr BP) strong melting of glaciers and sea ice was probably caused by the combined effect of the B/A warming and the flow of warm AW. The RAC was weakened during the Younger Dryas (~12.8–11.7 kyr BP), which reduced the advection of warm AW to the NW Greenland Sea. After 11.7 kyr BP, the RAC reached its modern strength, whereas, during the Holocene Thermal Maximum, it reached its maximum strength for the study period. In addition, short-term weakening of AW inflow to the core site was observed, especially at 10.5, 8.5, and 5.8 kyr BP.

One of four marine cores of glacial sediments collected from a water depth of about 1200 m at Vestnesa Ridge (west of Svalbard) contained small fragments of coal, charcoal and moss. This material was restricted to a single level, and 14C dating of bivalves both above and below indicates an age of c. 18.0–15.5 kyr BP. Chemical analyses of the coal indicate that the provenance area was from the northern part of Andøya, North Norway. The moss fragment was identified as Aulacomnium turgidum, which is a well-known species from the northern part of Andøya, which was an ice-free refugium with tundra vegetation during the Weichselian maximum. One small piece of charcoal with reasonably well-preserved cell structures is derived from burnt Salix sp. These findings are important, because they demonstrate the presence of drift ice carrying organic material from the northern part of Andøya towards the west coast of Svalbard during Heinrich event H1, an event of extensive ice-rafting in the Nordic seas. This also implies that some components of the vascular plant communities growing on Svalbard today, might originally have been imported as seeds floating on sea ice, before stranding along the coast of Svalbard. The plant colonization of Svalbard can thus have started already during Heinrich event H1. The finding of charcoal can only be explained by a fire due to lightning and not by campfire, because the first human population arrived in northern Norway at a much later time (probably during Preboreal). The charcoal is thus from the oldest known wild fire in Norway.

Four cores from Vestnesa Ridge on the western Svalbard margin from water depth of 1200 m have been studied. The Vestnesa Ridge is known for the presence of numerous pockmarks and active methane gas seepage is often observed in the form of acoustic gas flares. Three of the cores were collected from a pockmark with active seepage of methane and one core was taken just outside the seepage area for comparison. The cores show a range of influence from methane from no seepage (control core), moderate seepage, strong seepage to very strong seepage. All cores have been analyzed for the distribution of macrofossils, trace fossils, planktic foraminifera, stable isotopes, geochemistry and sedimentology. The main purpose of the study is to improve knowledge about the fossil macrofauna and past methane emissions in the area. The results show a major difference between the fauna recovered from cores taken inside a pockmark with chemosymbiotic bivalves and in some cases with a rich macrofauna and from the core recovered outside the pockmark that contained no macrofauna. The faunal relationships with the sedimentary environments confirm a close connection between the macrofauna and the presence/absence of cold-seepage, particularly seen in the occurrence of chemosymbiotic bivalves Archivesica arctica, Isorropodon nyeggaensis, potentially chemosymbiotic Rhacothyas kolgae and polychaetes. A barren zone in the core that was taken from the deepest part of the pockmark may indicate that a blow-out took place in the late glacial and the deglaciation into the early Holocene at c. 21,000–9000 years.

Despite their high abundance and diversity, microfossil taxa adapted to a particular chemosynthetic environment have rarely been studied and are therefore poorly known. Here we report on an ostracod species, Rosaliella svalbardensis gen. et sp. nov., from a cold methane seep site at the western Svalbard margin, Fram Strait. The new species shows a distinct morphology, different from other eucytherurine ostracod genera. It has a marked similarity to Xylocythere, an ostracod genus known from chemosynthetic environments of wood falls and hydrothermal vents. Rosaliella svalbardensis is probably an endemic species or genus linked to methane seeps. We speculate that the surface ornamentation of pore clusters, secondary reticulation, and pit clusters may be related to ectosymbiosis with chemoautotrophic bacteria. This new discovery of specialized microfossil taxa is important because they can be used as an indicator species for past and present seep environments (http://zoobank.org/urn:lsid:zoobank.org:pub:6075FF30-29D5-4DAB-9141-AE722CD3A69B).

Two cores from 1200 m water depth from Vestnesa Ridge on the western Svalbard margin have been investigated for the distribution of benthic and planktic foraminiferal assemblages, oxygen and carbon isotopes, geochemical and sedimentological parameters including magnetic susceptibility, total organic carbon (TOC) and CaCO 3 content of the sediment. Vestnesa Ridge is known for the presence of numerous pockmarks, where methane gas is bubbling out from the seafloor. One core was taken from a pockmark with active seepage of methane, while the second core was taken just outside the seepage area for comparison. The purpose of the study is to reconstruct the palaeoceanography and compare to published palaeoceanographic records from the area and evaluate if seepage of methane have had any impact on the distribution patterns of benthic foraminiferal species and the sedimentary environments through time. The results indicate almost continuous presence of Atlantic water throughout the last 43,000 years. During the Heinrich H1 interval ca. 18,000–15,300 years Atlantic water flowed subsurface along the bottom and the period stands out with the highest bottom-water temperatures of the last 43,000 years. Settlement of a community of chemo-synthesizing bivalves indicates increase in the release of methane beginning during H1. However, in both records of seep versus non-seep environments, the distribution patterns of benthic foraminiferal species, diversity, and productivity of the specimens were the same, indicating that seepage of methane had no influence on the foraminiferal faunas. Our results show that the palaeoceanographic development at Vestnesa Ridge was similar to the development over the western Svalbard margin and the Fram Strait confirming previously published results. We conclude that the benthic foraminifera at the methane seep site were mainly controlled by palaeoceanographic changes and associated changes in the sedimentary environment and palaeoproductivity overprinting any eventual influence of seepage of methane.

The effect of seeping of methane on marine sediment records has been studied in four gravity cores from Vestnesa Ridge, Svalbard margin. The area shows acoustic signs in the form of flares indicating active methane gas seepage. For a better understanding of the timing and variability of the flux of methane in the past and the effects on potential proxies, a detailed study of the diagenetic processes that may affect the composition and structure of both sediments and foraminiferal shells is needed. Here we discuss deep-sea records from methane-influenced environments in three cores from an active and very heterogeneous seep-area (pockmark) and one core from outside the pockmark for background. The results include the distribution and stable isotopes of authigenic carbonates and of benthic and planktonic foraminifera, magnetic susceptibility, AMS-14C dates, sedimentary data and biostratigraphy. Extremely low δ13C values recorded in both benthic and planktonic foraminifera during the Bolling-Allerod interstadials indicate possible increased methane flux beginning at late Heinrich event H1. The recorded low values are mainly a result of diagenetic overprint by methane-derived authigenic carbonates. The δ18O signals of authigenic carbonates are close to those of foraminiferal calcite and thus the δ18O records remain a valid stratigraphical tool in methane seep sites, except in the case of severely encrusted samples. In addition, the records from the active pockmark show nearly constant values of low magnetic susceptibility in contrast to higher and more variable magnetic susceptibility values from the control station and other published records from normal sediments west of Svalbard. This phenomenon is probably caused by dissolution of magnetic minerals in the reducing environmental conditions of methane seep sediments, associated with anaerobic oxidation of methane and formation of paramagnetic minerals (pyrite). This process enables magnetic susceptibility to be used as a common diagnostic tool for identifying methane-related palaeo-reductive environments.

We present results from a sediment core collected from a pockmark field on the Vestnesa Ridge (~ 80° N) in the eastern Fram Strait. This is the only deep-water gateway to the Arctic, and one of the northernmost marine gas hydrate provinces in the world. Eight 14C AMS dates reveal a detailed chronology for the last 14 ka BP. The δ 13C record measured on the benthonic foraminiferal species Cassidulina neoteretis shows two distinct intervals with negative values termed carbon isotope excursion (CIE I and CIE II, respectively). The values were as low as −4.37‰ in CIE I, correlating with the Bølling–Allerød interstadials, and as low as −3.41‰ in CIE II, correlating with the early Holocene. In the Bølling–Allerød interstadials, the planktonic foraminifera also show negative values, probably indicating secondary methane-derived authigenic precipitation affecting the foraminiferal shells. After a cleaning procedure designed to remove authigenic carbonate coatings on benthonic foraminiferal tests from this event, the 13C values are still negative (as low as −2.75‰). The CIE I and CIE II occurred during periods of ocean warming, sea-level rise and increased concentrations of methane (CH4) in the atmosphere. CIEs with similar timing have been reported from other areas in the North Atlantic, suggesting a regional event. The trigger mechanisms for such regional events remain to be determined. We speculate that sea-level rise and seabed loading due to high sediment supply in combination with increased seismic activity as a result of rapid deglaciation may have triggered the escape of significant amounts of methane to the seafloor and the water column above.

The sandhopper Talitrus saltator is common on sandy beaches at different latitudes. Therefore, behavioural variations allowing them to cope with a wide range of environmental variation are expected. To test the hypothesis that behavioural adaptations to natural environments are characterised by different salinities, we compared two behaviours (substrate choice and escape from immersion) of two T. saltator populations from a Mediterranean (high salinity) and a Baltic Sea (low salinity) sandy beach. T. saltator preferred to burrow in the high salinity substrate, irrespective of its beach of origin. Regarding orientation to escape from immersion, Baltic sandhoppers always oriented landwards, whereas Mediterranean sandhoppers showed a significant orientation landwards only when immersed in high salinity sea water. These behavioural traits matched the different environments, and this adaptation capability can be used as a model to analyse the response of a keystone species to environmental changes.