Stephen J. Coulson

Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic

One predicted consequence of global warming is an increased frequency of extreme weather events, such as heat waves, droughts, or heavy rainfalls. In parts of the Arctic, extreme warm spells and heavy rain-on-snow (ROS) events in winter are already more frequent. How these weather events impact snow-pack and permafrost characteristics is rarely documented empirically, and the implications for wildlife and society are hence far from understood. Here we characterize and document the effects of an extreme warm spell and ROS event that occurred in High Arctic Svalbard in January–February 2012, during the polar night. In this normally cold semi-desert environment, we recorded above-zero temperatures (up to 7 °C) across the entire archipelago and record-breaking precipitation, with up to 98 mm rainfall in one day (return period of >500 years prior to this event) and 272 mm over the two-week long warm spell. These precipitation amounts are equivalent to 25 and 70% respectively of the mean annual total precipitation. The extreme event caused significant increase in permafrost temperatures down to at least 5 m depth, induced slush avalanches with resultant damage to infrastructure, and left a significant ground-ice cover (∼5–20 cm thick basal ice). The ground-ice not only affected inhabitants by closing roads and airports as well as reducing mobility and thereby tourism income, but it also led to high starvation-induced mortality in all monitored populations of the wild reindeer by blocking access to the winter food source. Based on empirical-statistical downscaling of global climate models run under the moderate RCP4.5 emission scenario, we predict strong future warming with average mid-winter temperatures even approaching 0 °C, suggesting increased frequency of ROS. This will have far-reaching implications for Arctic ecosystems and societies through the changes in snow-pack and permafrost properties.

A Holarctic Biogeographical Analysis of the Collembola (Arthropoda, Hexapoda) Unravels Recent Post-Glacial Colonization Patterns

We aimed to describe the main Arctic biogeographical patterns of the Collembola, and analyze historical factors and current climatic regimes determining Arctic collembolan species distribution. Furthermore, we aimed to identify possible dispersal routes, colonization sources and glacial refugia for Arctic collembola. We implemented a Gaussian Mixture Clustering method on species distribution ranges and applied a distance- based parametric bootstrap test on presence-absence collembolan species distribution data. Additionally, multivariate analysis was performed considering species distributions, biodiversity, cluster distribution and environmental factors (temperature and precipitation). No clear relation was found between current climatic regimes and species distribution in the Arctic. Gaussian Mixture Clustering found common elements within Siberian areas, Atlantic areas, the Canadian Arctic, a mid-Siberian cluster and specific Beringian elements, following the same pattern previously described, using a variety of molecular methods, for Arctic plants. Species distribution hence indicate the influence of recent glacial history, as LGM glacial refugia (mid-Siberia, and Beringia) and major dispersal routes to high Arctic island groups can be identified. Endemic species are found in the high Arctic, but no specific biogeographical pattern can be clearly identified as a sign of high Arctic glacial refugia. Ocean currents patterns are suggested as being an important factor shaping the distribution of Arctic Collembola, which is consistent with Antarctic studies in collembolan biogeography. The clear relations between cluster distribution and geographical areas considering their recent glacial history, lack of relationship of species distribution with current climatic regimes, and consistency with previously described Arctic patterns in a series of organisms inferred using a variety of methods, suggest that historical phenomena shaping contemporary collembolan distribution can be inferred through biogeographical analysis.

Current knowledge of the Tardigrada of Svalbard with the first records of water bears from Nordaustlandet (High Arctic)

The first investigations of the tardigrades of Svalbard took place in the early 20th century and 30 papers on the subject have been published to date. In this article, we summarize available information on the distribution of tardigrades in this Arctic archipelago with remarks on the dubious species and records. Additionally, we examined 28 new moss, lichen and soil samples collected from the islands of Nordaustlandet, Edgeøya and Prins Karls Forland. These samples yielded 324 specimens, 15 exuvia and 132 free-laid eggs belonging to 16 limnoterrestrial species (Heterotardigrada and Eutardigrada). These include five first records of water bears from Nordaustlandet, eight new records for Edgeøya and four for Prince Karls Forland. The most dense population of tardigrades was found in a sample with 253 specimens/10 g of dry material and the least dense population in a sample with three specimens/10 g of dry material. The most frequently recorded species in samples collected in this study were Testechiniscus spitsbergensis Scourfield, 1897, Macrobiotus harmsworthi harmsworthi Murray, 1907, and M. islandicus islandicus Richters, 1904. This article also provides the first ever scanning electron microscope photomicrographs of Tenuibiotus voronkovi Tumanov, 2007.

Overwintering of terrestrial Arctic arthropods: the fauna of Svalbard now and in the future

There are over 500 species of arthropods recorded from Svalbard. These animals overwinter either within the soil or on the ground surface, and have to tolerate an environment where the ground is frozen for over 9 months each year. Three cold-tolerance strategies have been described from Svalbard invertebrates: freeze avoidance, freeze tolerance and desiccation. Once in a coldtolerant state the animals can be extremely cold tolerant in terms of both minimum exposure temperature and period of exposure. How the overwintering capabilities of these animals will be affected by climate changes during the next 100 years, as predicted by climate models, is not yet known. Four principle factors with an impact on overwintering of the terrestrial arthropod fauna are outlined here: (1) warmer winter temperatures, with an increased frequency of extreme events such as freeze–thaw cycles and surface icing; (2) changes in snow fall and snow lie; (3) pollutant load; and (4) dispersal of invertebrates to Svalbard. Finally, areas where further research is required are highlighted: including the development of controlled multi-season field experiments; effect of freeze–thaw cycles; changes in thickness and distribution of snow lie, with the subsequent effects on duration of the summer period; chill susceptibility of soil arthropods; assessing potential colonizing species and the likelihood of these species becoming established; assessing the effect of gene flow from surrounding populations; interactions between pollution and cold tolerance; anoxia stress; and the genetics of cold tolerance.

First record of Thinoseius spinosus (Acari: Eviphididae) from the high Arctic island of Spitsbergen (Svalbard) including a key to deutonymphs of genus Thinoseius

ABSTRACT Thinoseius spinosus is reported from the high Arctic island of Spitsbergen, Svalbard, for the first time. The deutonymphs were phoretic on the calliphorid dipteran Protophormia terraenovae. Mites were observed on 20.4% of adult flies. The number of mites per fly varied between 0 up to a maximum of 17 (median number of mites per fly with mites = 1). Although mites were found attached all over the body it seems likely that during dispersal the mites are usually found intercalated between the abdominal plates. An overview of the currently known species of Thinoseius, their occurrence and a key to the deutonymphs are presented.

The invertebrate fauna of anthropogenic soils in the High-Arctic settlement of Barentsburg, Svalbard

The terrestrial environment of the High Arctic consists of a mosaic of habitat types. In addition to the natural habitat diversity, various human-influenced types may occur. For the resident invertebrate fauna, these anthropogenic habitats may be either unusually favourable or detrimental. In the town of Barentsburg, Svalbard, soils were imported for the greenhouses from southern Russia. These soils were subsequently discarded outside the greenhouses and have become augmented with manure from the cowsheds. Both the greenhouse and the cowsheds are now derelict. This site represents an unusually nutrient-rich location with considerable development of organic soils, in stark contrast to the naturally forming organic soils in Svalbard, which are typically thin and nutrient poor. Few previous studies have examined the soil invertebrate communities of human-disturbed or -created habitats in the Arctic. In an often nutrient-poor terrestrial environment, it is unclear how the invertebrate fauna will react to such nutrient enhancement. In these soils, 46 species of invertebrates were determined. Eleven species have not been recorded from other habitats in Svalbard and are hence likely to have been introduced. The native species assemblage in the anthropogenic soils was not atypical for many natural sites in Svalbard. Despite the enriched organic soils and highly ameliorated winter temperature conditions, the soil invertebrate fauna biodiversity does not appear to be enhanced beyond the presence of certain probably introduced species.

Community Structure of Oribatid and Gamasid Mites (Acari) in Moss-Grass Tundra in Svalbard (Spitsbergen, Norway)

Abstract The mite fauna of patches of High Arctic moss-grass tundra of Svalbard in Petuniabukta, Billefjord (moss, grasses, Salix polaris, bare soil), and adjacent to Vestpynten, Adventfjord (moss, moss mixed with grasses, Cassiope tetragona, S. polaris), were investigated. Our aim was to describe the mite fauna of this tundra with particular focus on the stage structure that is rarely investigated. We observed that the oribatid mites were distinctly more abundant and richer in species (22) than the gamasid mites (7) and their density and diversity varied between vegetation and location. Species diversity of Oribatida and Gamasida and the Shannon H′ index of mite communities were low, and Liochthonius sellnicki or Tectocepheus velatus dominated the Oribatida and Oppiella translamellata and Diapterobates notatus were relatively abundant, while the Gamasida were dominated by Arctoseius multidentatus, with Zercon forsslundi and Z. solenites relatively abundant. The juvenile densities of the Oribatida were usually greater than adults. Eniochthonius minutissimus and Metabelba sp. are new records for Svalbard.

The parasitic tick Ixodes uriae (Acari: Ixodidae) on seabirds from Spitsbergen, Svalbard

The parasitic tick Ixodes uriae was recorded from Brünnich’s guillemots (Uria lomvia) at two colonies on Spitsbergen, the principal island in the Arctic archipelago of Svalbard. Six Brünnich’s guillemots from 30 studied at the Ossian Sars seabird colony were found to be parasitized. A tick was also collected from below the larger Fuglehuken colony. However, ticks were not seen on Brünnich’s guillemots examined at the smaller Krossfjorden colony, and neither were they observed in two black-legged kittiwake (Rissa tridactyla) colonies (Blomstrandhalvøya and Krykkjefjellet). It is suggested that either the tick has only recently been established in Svalbard or the population has increased from a low level, and has consequently become visible to small-scale sampling studies. Implications for the seabird population of the northern Barents Sea are discussed.

Disease transmission in an extreme environment: Nematode parasites infect reindeer during the Arctic winter

Parasitic nematodes are found in almost all wild vertebrate populations but few studies have investigated these host-parasite relationships in the wild. For parasites with free-living stages, the external environment has a major influence on life-history traits, and development and survival is generally low at sub-zero temperatures. For reindeer that inhabit the high Arctic archipelago of Svalbard, parasite transmission is expected to occur in the summer, due to the extreme environmental conditions and the reduced food intake by the host in winter. Here we show experimentally that, contrary to most parasitic nematodes, Marshallagia marshalli of Svalbard reindeer is transmitted during the Arctic winter. Winter transmission was demonstrated by removing parasites in the autumn, using a novel delayed-release anthelmintic bolus, and estimating re-infection rates in reindeer sampled in October, February and April. Larval stages of nematodes were identified using molecular tools, whereas adult stages were identified using microscopy. The abundance of M. marshalli adult worms and L4s increased significantly from October to April, indicating that reindeer were being infected with L3s from the pasture throughout the winter. To our knowledge, this study is the first to experimentally demonstrate over-winter transmission of a gastro-intestinal nematode parasite in a wild animal. Potential mechanisms associated with this unusual transmission strategy are discussed in light of our knowledge of the life-history traits of this parasite.

High-Arctic gamasid mites (Acari, Mesostigmata): community composition on Spitsbergen, Svalbard

This study investigates assemblages of mesostigmatid mites on Spitsbergen, in the Arctic archipelago of Svalbard, Norway. Soil samples were collected from three areas with differing vegetational communities in Adventdalen. The greatest gamasid mite density and species diversity was observed at the location with the richest vegetation cover, Dryas octopetala heath, where 10 species were collected and there was a mean total gamasid mite density of 1000 individuals per m2. The vegetation-poor saline meadow site revealed five species and had a mean total gamasid mite density of 130 individuals per m2. The floristically more diverse Luzula tundra site yielded four species and had a density of 270 individuals per m2. The most frequently found species were Zercon forsslundi, Arctoseius haarlovi and A. weberi. Results indicate that even in High-Arctic regions, where species diversity is less than at lower latitudes, there is specialization amongst the gamasid mite community depending on local environmental conditions. Apart from isolated checklists, only sporadic information concerning the ecology of High-Arctic gamasid mites is available. Many of the gamasid mites reported from Svalbard are relatively rare.