Single non-normalized data of electron probe analyses of all glass shard samples from the Seward Peninsula and the Lipari obsidian reference standard

Permafrost degradation influences the morphology, biogeochemical cycling and hydrology of Arctic landscapes over a range of time scales. To reconstruct temporal patterns of early to late Holocene permafrost and thermokarst dynamics, site-specific palaeo-records are needed. Here we present a multi-proxy study of a 350-cm-long permafrost core from a drained lake basin on the northern Seward Peninsula, Alaska, revealing Lateglacial to Holocene thermokarst lake dynamics in a central location of Beringia. Use of radiocarbon dating, micropalaeontology (ostracods and testaceans), sedimentology (grain-size analyses, magnetic susceptibility, tephra analyses), geochemistry (total nitrogen and carbon, total organic carbon, d13Corg) and stable water isotopes (d18O, dD, d excess) of ground ice allowed the reconstruction of several distinct thermokarst lake phases. These include a pre-lacustrine environment at the base of the core characterized by the Devil Mountain Maar tephra (22 800±280 cal. a BP, Unit A), which has vertically subsided in places due to subsequent development of a deep thermokarst lake that initiated around 11 800 cal. a BP (Unit B). At about 9000 cal. a BP this lake transitioned from a stable depositional environment to a very dynamic lake system (Unit C) characterized by fluctuating lake levels, potentially intermediate wetland development, and expansion and erosion of shore deposits. Complete drainage of this lake occurred at 1060 cal. a BP, including post-drainage sediment freezing from the top down to 154 cm and gradual accumulation of terrestrial peat (Unit D), as well as uniform upward talik refreezing. This core-based reconstruction of multiple thermokarst lake generations since 11 800 cal. a BP improves our understanding of the temporal scales of thermokarst lake development from initiation to drainage, demonstrates complex landscape evolution in the ice-rich permafrost regions of Central Beringia during the Lateglacial and Holocene, and enhances our understanding of biogeochemical cycles in thermokarst-affected regions of the Arctic.

Macroparasites of allis shad (Alosa alosa) and twaite shad (Alosa fallax) of the Western Iberian Peninsula Rivers : ecological, phylogenetic and zoonotic insights

Acknowledgments The authors sincerely thank M.N. Cueto, J.M. Antonio and M.E. Garci of the ECOBIOMAR group at IIM-CSIC for molecular analysis, technical support and quality images of some parasites. M. Bao is supported by a PhD grant from the University of Aberdeen and also by financial support of the contract from the EU Project PARASITE (grant number 312068). A. Roura is supported by BFundación Barrié de la Maza^ postdoctoral fellowship and a Securing Food, Water and the Environment Research Focus Area grant (La Trobe University). This study was partially supported by a PhD grant from the Portuguese Foundation for Science and Technology (FCT) (SFRH/BD/4892/2008) and partially supported by the European Regional Development Fund (ERDF) through the COMPETE—Operational Competitiveness Programme and national funds through FCT—Foundation for Science and Technology, under the project BPEst-C/MAR/LA0015/2013. The authors thank the staff of the Station of Hydrobiology of the USC BEncoro do Con^ due their participation in the surveys, with special mention to J. Sánchez for separating digenean fauna existing in the stomachs of A. fallax. This work has been partially supported by the project 10PXIB2111059PR of the Xunta de Galicia and the project MIGRANET of the Interreg IV B SUDOE (South-West Europe) Territorial Cooperation Programme (SOE2/P2/E288). D.J. Nachón is supported by a PhD grant from the Xunta de Galicia (PRE/2011/198)

Pollen record and age determination of profile CS98-10 at Cape Shpindler, Yugorski Peninsula, northwest Russia

New pollen and radiocarbon data from an 8.6-m coastal section, Cape Shpindler (69°43' N; 62°48' E), Yugorski Peninsula, document the latest Pleistocene and Holocene environmental history of this low Arctic region. Twelve AMS 14C dates indicate that the deposits accumulated since about 13,000 until 2000 radiocarbon years BP. A thermokarst lake formed ca. 13,000-12,800 years BP, when scarce arctic tundra vegetation dominated the area. By 12,500 years BP, a shallow lake existed at the site, and Arctic tundra with Poaceae, Cyperaceae, Salix, Saxifraga, and Artemisia dominated nearby vegetation. Climate was colder than today. Betula nana became dominant during the Early Preboreal period about 9500 years BP, responding to a warm event, which was one of the warmest during the Holocene. Decline in B. nana and Salix after 9500 years BP reflects a brief event of Preboreal cooling. A subsequent increase in Betula and Alnus fruticosa pollen percentages reflects amelioration of environmental conditions at the end of Preboreal period (ca. 9300 years BP). A decline in arboreal taxa later, with a dramatic increase in herb taxa, reflects a short cold event at about 9200 years BP. The pollen data reflect a northward movement of tree birch, peaking at the middle Boreal period, around 8500 years BP. Open Betula forest existed on the Kara Sea coast of the Yugorski Peninsula during the Atlantic period (8000-4500 years BP), indicating that climate was significantly warmer than today. Deteriorating climate around the Atlantic-Subboreal boundary (ca. 4500 years BP) is recorded by a decline in Betula percentages. Sedimentation slowed at the site, and processes of denudation and/or soil formation started at the beginning of the Subatlantic period, when vegetation cover on Yugorski Peninsula shifted to near-modern assemblages.

Macro-epibenthic communities, bathymetry and enviromental information at the tip of the Antarctic Peninsula

The Southern Ocean ecosystem at the Antarctic Peninsula has steep natural environmental gradients, e.g. in terms of water masses and ice cover, and experiences regional above global average climate change. An ecological macroepibenthic survey was conducted in three ecoregions in the north-western Weddell Sea, on the continental shelf of the Antarctic Peninsula in the Bransfield Strait and on the shelf of the South Shetland Islands in the Drake Passage, defined by their environmental envelop. The aim was to improve the so far poor knowledge of the structure of this component of the Southern Ocean ecosystem and its ecological driving forces. It can also provide a baseline to assess the impact of ongoing climate change to the benthic diversity, functioning and ecosystem services. Different intermediate-scaled topographic features such as canyon systems including the corresponding topographically defined habitats 'bank', 'upper slope', 'slope' and 'canyon/deep' were sampled. In addition, the physical and biological environmental factors such as sea-ice cover, chlorophyll-a concentration, small-scale bottom topography and water masses were analysed. Catches by Agassiz trawl showed high among-station variability in biomass of 96 higher systematic groups including ecological key taxa. Large-scale patterns separating the three ecoregions from each other could be correlated with the two environmental factors, sea-ice and depth. Attribution to habitats only poorly explained benthic composition, and small-scale bottom topography did not explain such patterns at all. The large-scale factors, sea-ice and depth, might have caused large-scale differences in pelagic benthic coupling, whilst small-scale variability, also affecting larger scales, seemed to be predominantly driven by unknown physical drivers or biological interactions.

Diatoms and biomarkers in sediments from the Antarctic Peninsula

The Antarctic Peninsula (AP) has been identified as one of the most rapidly warming region on Earth. Satellite monitoring currently allows for a detailed understanding of the relationship between sea ice extent and duration and atmospheric and oceanic circulations in this region. However, our knowledge on ocean-ice-atmosphere interactions is still relatively poor for the period extending beyond the last 30 years. Here, we describe environmental conditions in Northwestern and Northeastern Antarctic Peninsula areas over the last century using diatom census counts and diatom specific biomarkers (HBIs) in two marine sediment multicores (MTC-38C and -18A, respectively). Diatom census counts and HBIs show abrupt changes between 1935 and 1950, marked by ocean warming and sea ice retreat in both sides of the AP. Since 1950, inferred environmental conditions do not provide evidence for any trend related to the recent warming but demonstrate a pronounced variability on pluri-annual to decadal time scale. We propose that multi-decadal sea ice variations over the last century are forced by the recent warming, while the annual-to-decadal variability is mainly governed by synoptic and regional wind fields in relation with the position and intensity of the atmospheric low-pressure trough around the AP. However, the positive shift of the SAM since the last two decades cannot explain the regional trend observed in this study, probably due to the effect of local processes on the response of our biological proxies.

Firn line elevation of the Dickson Land peninsula

The Dickson Land peninsula is located in central West-Spitsbergen between the NNE branches of Isfjorden. The climatic firn line lying at 500 m causes plateau glaciers with outlet tongues which are characteristic of S-Dickson Land. The distribution of valley glaciers and the variations of the orographic firn line depend on wind direction. In comparing the firn lines established by the methods of LICHTENECKER (1938) and VISSER (1938), to the values calculated by the method of v. HÖFER (1879), differences of up to l07 m are found. These differences may depend on the inclination and distance relationships of the glaciers above and below the real firn lines. During the latest glacial advance, Dickson Land was located on the peripheries of two local glaciation centers. At that time an inland glaciation of West-Spitsbergen did not exist . The formation of a subglacial channel system dates back to the maximum extent of the late glacial phase before 17500 B.P, (+2000/-1375 years). A correlation of postglacial stadia and 14C dated marine terraces (FEYLING-HANSSEN & OLSSON, 1960; FEYLING-HANSSEN, 1965) is possible. Considering isostatic movement and the difference between calculated and real firn lines, a postglacial stadium at about 10400 B. P. can be reconstructed with a firn line lying 265 m above former sea level. On average, the absolute depression below the recent firn line amounted to 246 m. Stagnation at 9650 B.P. coincided with a firn line at 315 m above former sea level and a depression of 173 m. Around 1890 A.D., glacial fluctuations corresponded to a firn line at 415 m (depression: 64 m). To some extent the morphology of the main valleys appears to depend on structure and petrography. Therefore their value as indicators of former glaciations is questionable. The periglacial forms are shown on a large-scale map. At the time of the "Holocene warm interval", between 7000 and 2000 B.P. (FEYLING-HANSSEN, 1955a, 1965), an increase of periglacial activity seems likely. This can be explained by a simultaneous increase in the depth of the active layer in both soil and bedrock.

Clay-mineral composition and biogenic opal content of Late Neogene to Quaternary sediments of the Antarctic Peninsula region

Clay-mineral composition and biogenic opal content in upper Miocene to Quaternary drift sediments recovered at two Ocean Drilling Program (ODP) sites from the continental rise in the Bellingshausen Sea had been analyzed in order to reconstruct the climatic and glacial history of the Antarctic Peninsula. The clay mineral composition at both sites is dominated by smectite, illite, and chlorite, and alternates between a smectite-enriched and a chlorite-enriched assemblage throughout the last 9.3 my. The spatial distribution of clay minerals in Holocene sediments west of the Antarctic Peninsula facilitates the identification of particular source areas, and thus the reconstruction of transport pathways. The similarity to clay mineral variations reported from upper Quaternary sequences suggests that the short-term clay-mineralogical fluctuations in the ODP cores reflect glacial-interglacial cyclicity. Thus, repeated ice advances and retreats in response to a varying size of the Antarctic Peninsula ice cap are likely to have occurred throughout the late Neogene and Quaternary. The clay minerals in the drift sediments exhibit only slight long-term variations, which are caused by local changes in glacial erosion and in supply of source rocks, rather than by major climatic changes. The opal records at the ODP sites are dominated by long-term variations since the late Miocene. We infer that the opal content in the drift sediments, although it is influenced by dissolution in the water column and the sediment column and by the burial with lithogenic detritus, provides a signal of paleoproductivity. Because the annual sea-ice coverage is regarded as the main factor controlling biological productivity, the opal signal helps to reconstruct paleoceanographic changes in the Bellingshausen Sea. Slightly enhanced opal deposition during the late Miocene indicates slightly warmer climatic conditions in the Antarctic Peninsula area than at present. During the early Pliocene, enhanced opal deposition in the Pacific sector of the Southern Ocean and coinciding high opal concentrations in sedimentary sequences from the Atlantic and Indian sectors document a strong reduction of sea-ice cover and relatively warm climatic conditions. Thereby, the early onset of the Pliocene warmth in the Bellingshausen Sea points to a positive feedback of regional Antarctic climate on the global thermohaline circulation. A decrease of opal deposition between 3.1 and 2.6 Ma likely reflects sea-ice expansion in response to reduced supply of northern-sourced deep-waters to the Southern Ocean, caused by the onset of Northern Hemisphere glaciation. Throughout the Quaternary, a relatively constant level of opal deposition on the Antarctic continental margin indicates relatively stable climatic conditions.

The Composition of Holocene Aeolianites; Western Eyre Peninsula, Great Australian Bight, South Australia

The Australian southern continental margin is the world’s largest site of cool-water carbonate deposition, and the Great Australian Bight is its largest sector. The Eyre Peninsula is fringed by coastal beaches with aeolianites and marks the eastern edge of the Great Australian Bight. Five shoreline transects of varying lengths spanned a 150km longitudinal distance and at each the intertidal, beach, dune and secondary dune environments were sampled, for a total of 18 samples. Sediments are a mixture of modern, relict, and Cenozoic carbonates, and quartz grains. Carbonate aeolianites on the western Eyre Peninsula are mostly composed of modern carbonate grains: predominantly molluscs (23-33%) and benthic foraminifera (10-26%), locally abundant coralline algae (3-28%), echinoids (2-22%), and bryozoans (2-14%). Cenozoic grain abundance ranges from 1-6% whereas relict grain abundance ranges from 0-17%. A southward increase in bryozoan particles correlates with a nutrient element abundance and decrease in temperature due to a large seasonal coastal upwelling system that drives 2-3 major upwelling events per year, bringing cold, nutrient rich, Sub-Antarctic Surface Water (<12°C) onto the shelf. In southern, mostly wind protected locations, the beach and dune sediment compositions are similar, indicating that wind energy has successfully carried all sediment components of the beach into the adjacent dunes. In northern, exposed locations, the composition is not the same everywhere, and trends indicate that relative wind energy has the ability to impact grain composition through preferential wind transport. Aeolianite composition is therefore a function of both upwelling and the degree of coastal exposure.

The Influence of Geological Process on Interpreting Ediacaran Fossils in the Catalina Formation, Bonavista Peninsula, Newfoundland

Understanding the nature of the earliest complex fossils has presented many challenges over the past century since Billings first described Ediacaran fossils from Newfoundland in 1872. Previous studies have documented abundant Ediacaran fossils in the Bonavista Peninsula of Newfoundland. This thesis focuses on the H14 surface north of Catalina, which contains a nearly monospecific assemblage that includes hundreds of specimens of the rangeomorph, Fractofusus andersoni. Three factors need to be considered when trying to interpret these organisms. The first of these three factors is structural deformation. The area has undergone deformation during the formation of the Appalachian orogenic belt. This has distorted both fossil shape and orientation, requiring retrodeformation to restore the shapes and relationships of fossils to their original form. Two additional taphonomic factors influencing fossil visibility are: partly or completely ash covered fossils and the removal of fossil impressions from the bedding plane by modern weathering. These processes hinder acceptance of some previously published interpretations.

Terrain Controls and Landscape-Scale Susceptibility Modelling of Active-Layer Detachments, Sabine Peninsula, Melville Island, Nunavut

Modelling the susceptibility of permafrost slopes to disturbance can identify areas at risk to future disturbance and result in safer infrastructure and resource development in the Arctic. In this study, we use terrain attributes derived from a digital elevation model, an inventory of permafrost slope disturbances known as active-layer detachments (ALDs) and generalised additive modelling to produce a map of permafrost slope disturbance susceptibility for an area on northern Melville Island, in the Canadian High Arctic. By examining terrain variables and their relative importance, we identified factors important for initiating slope disturbance. The model was calibrated and validated using 70 and 30 per cent of a data-set of 760 mapped ALDs, including disturbed and randomised undisturbed samples. The generalised additive model calibrated and validated very well, with areas under the receiver operating characteristic curve of 0.89 and 0.81, respectively, demonstrating its effectiveness at predicting disturbed and undisturbed samples. ALDs were most likely to occur below the marine limit on slope angles between 3 and 10° and in areas with low values of potential incoming solar radiation (north-facing slopes).

Tidal and wind influences on circulation in the southern mouth of the Ría de Vigo (NW Iberian Peninsula)

Tidal and wind influences on the velocity field in the Ría de Vigo were assessed using atmospheric data from two meteorological stations located at Bouzas port and on an oceanic buoy off Silleiro Cape along with oceanic data from an ADCP moored in the Ría for a 72-day period. A two-layer circulation pattern was observed. Near-surface and near-bottom currents are primarily influenced by wind (especially remote winds), separated by an intermediate layer dominated by tidal variability. At subtidal frequencies, residual currents are well correlated with wind variability. Remote wind forcing exhibited a markedly high correlation with surface layer currents, indicating the major role played by wind in the long-term upwelling-modulated circulation of the Ría.

Tidal and wind influences on circulation in the southern mouth of the Ría de Vigo (NW Iberian Peninsula)

Tidal and wind influences on the velocity field in the Ría de Vigo were assessed using atmospheric data from two meteorological stations located at Bouzas port and on an oceanic buoy off Silleiro Cape along with oceanic data from an ADCP moored in the Ría for a 72-day period. A two-layer circulation pattern was observed. Near-surface and near-bottom currents are primarily influenced by wind (especially remote winds), separated by an intermediate layer dominated by tidal variability. At subtidal frequencies, residual currents are well correlated with wind variability. Remote wind forcing exhibited a markedly high correlation with surface layer currents, indicating the major role played by wind in the long-term upwelling-modulated circulation of the Ría.

Winter distribution and size structure of Antarctic krill Euphausia superba populations in-shore along the West Antarctic Peninsula

Antarctic krill Euphausia superba are a key component of food webs in the maritime West Antarctic Peninsula, and their life history is tied to the seasonal cycles of sea ice and primary production in the region. Previous work has shown a general in-shore migration of krill in winter in this region; however, the very near-shore has not often been sampled as part of these surveys. We investigated distribution, abundance, and size structure of krill in 3 fjordic bays along the peninsula, and in the adjacent Gerlache Strait area using vertically stratified MOCNESS net tows and ADCP acoustic biomass estimates. Krill abundance was high within bays, with net estimated densities exceeding 60 krill m-3, while acoustic estimates were an order of magnitude higher. Krill within bays were larger than krill in the Gerlache Strait. Within bays, krill aggregations were observed near the seafloor during the day with aggregations extending to the sediment interface, and exhibited diel vertical migration higher into the water column at night. We suggest these high winter krill abundances within fjords are indicative of an active seasonal migration by krill in the peninsula region. Potential drivers for such a migration include reduced advective losses and costs, and availability of sediment food resources within fjords. Seasonally near-shore krill may also affect stock and recruitment assessments and may have implications for managing the krill fishery in this area.