Influence of allochtonous nutrients delivered by colonial seabirds on soil collembolan communities on Spitsbergen

Despite a widespread recognition of the role of seabird colonies in the fertilization of nutrient-poor polar terrestrial ecosystems, qualitative and quantitative data documenting any consequential influence on soil invertebrate communities are still lacking. Therefore, we studied community structure and abundance of springtails (Collembola) in ornithogenic tundra near two large seabird colonies in Hornsund, south-west Spitsbergen. We found considerably (5–20×) higher densities and biomass of Collembola in the vicinities of both colonies (the effect extending up to ca. 50 m from the colony edge) than in comparable control areas of tundra not influenced by allochtonous nutrient input. The most common springtails observed in the seabird-influenced areas were Folsomia quadrioculata, Hypogastrura viatica and Megaphorura arctica. The latter species appeared the most resistant to ornithogenic nutrient input and was found commonly closest to the bird colonies. Collembolan abundance decreased with increasing distance from the seabird colonies. However, relationships between collembolan density and specific physicochemical soil parameters and vegetation characteristics were weak. The most important factors were the cover of the nitrophilous green alga Prasiola crispa, total plant biomass and soil solution conductivity, all of which were correlated with distance from the colony and estimated amount by guano deposition. Community composition and abundance of springtails showed no evidence of being influenced of seabird diet, with no differences apparent between communities found in ornithogenic tundra developing in the vicinity of planktivorous and piscivorous seabird colonies. The study provides confirmation of the influence of marine nutrient input by seabirds on soil microfaunal communities

Polar Bear Predatory Behaviour toward Molting Barnacle Geese and Nesting Glaucous Gulls on Spitsbergen

A polar bear (Ursus maritimus) was observed stalking and chasing a flock of adult flightless barnacle geese (Branta leucopsis) in a coastal bay in Hornsund, southwest Spitsbergen. Before chasing the geese, the polar bear appeared to make use of the cover provided by a rocky pier in order to swim close to them. Immediately after that unsuccessful attempt, the bear plundered a glaucous gull (Larus hyperboreus) nest situated on coastal rock and captured three nestlings. These observations are the first documented instances of a polar bear hunting for barnacle goose and glaucous gull and provide additional evidence of the use of terrestrial prey by polar bears during the season of minimal ice extent.Un ours polaire (Ursus maritimus) a été observé en train de traquer et de pourchasser une bande de bernaches nonnettes (Branta leucopsis) coureuses adultes dans une baie côtière de Hornsund, dans le sud-ouest de Spitsbergen. Avant d’avoir chassé les bernaches, l’ours polaire semblait s’être servi d’un quai rocailleux pour se cacher et nager près des bernaches. Immédiatement après cette tentative échouée, l’ours a pillé un nid de goélands bourgmestres (Larus hyperboreus) situé sur un rocher côtier et a capturé trois oisillons. Ces observations, les premiers exemples de bernaches nonnettes et de goélands bourgmestres pourchassés par un ours polaire, fournissent d’autres preuves selon lesquelles les ours polaires ont des proies terrestres pendant la saison de l’étendue minimale de glace

Glaucous Gulls Kleptoparasiting Arctic Foxes in Magdalenefjorden, NW Spitsbergen

Observations were made of glaucous gulls (Larus hyperboreus) stealing little auks (Alle alle) stored in a den by arctic foxes (Vulpes lagopus) in Magdalenefjorden, northwest Spitsbergen. Before stealing the spoil, the gulls observed and followed foxes transporting little auks hunted in a nearby colony. Skill in detecting and successfully taking over the food cached by arctic foxes may help glaucous gulls to survive critical periods of lowered prey availability and enhanced energy demands, such as the little auk incubation period, when the auks are well hidden in the nests and inaccessible for gulls feeding their own large nestlings. These observations are the first documented instances of the glaucous gulls kleptoparasiting arctic foxes and provide additional evidence of the complex nature of interactions occurring between these two opportunistic Arctic predators.On a observé des goélands bourgmestres (Larus hyperboreus) en train de voler des mergules nains (Alle alle) qui avaient été placés dans une tanière par des renards arctiques (Vulpes lagopus) à Magdalenefjorden, dans le nord-ouest de Spitsbergen. Avant de voler les mergules, les goélands observaient les renards et les suivaient en train de transporter les mergules nains chassés dans une colonie située tout près. L’aptitude à détecter la nourriture cachée par les renards arctiques et à s’en accaparer pourrait aider les goélands bourgmestres à survivre pendant les périodes critiques où il y a peu de proies et où le besoin en énergie est plus grand, telle que la période d’incubation des mergules nains, soit lorsque les mergules sont bien cachés dans les nids et qu’ils ne sont pas accessibles aux goélands qui nourrissent leurs propres nichées d’envergure. Ces observations constituent les premiers cas documentés de goélands bourgmestres en train de faire du cleptoparasitisme chez le renard arctique, en plus de présenter des preuves supplémentaires de la nature complexe des interactions entre ces deux prédateurs opportunistes de l’Arctique

Is ornithogenic fertilisation important for collembolan communities in Arctic terrestrial ecosystems?

In the Arctic, areas close to seabird colonies are often characterized by exceptionally rich vegetation communities linked with the high nutrient subsidies transported by seabirds from the marine environment to the land. These areas also support soil invertebrate communities of which springtails (Collembola) often represent the most abundant and diverse group. Our study focused on springtail community composition in the vicinity of seabird (little auk, great skua and glaucous gull) nesting areas in different parts of Svalbard (Magdalenefjorden, Isfjorden and Bjørnøya), and on their comparison with adjacent areas not impacted by seabirds. Out of a total of 35 springtail species recorded, seven were found only within the ornithogenically influenced sites. Although geographical location was the strongest factor differentiating these springtail communities, ornithogenic influence was also significant regardless of the location. When each location was considered separately, seabirds were responsible for a relatively small but strongly significant proportion (8.6, 5.2 and 3.9%, respectively, for each site) of total springtail community variability. Species whose occurrence was positively correlated with seabird presence were Folsomia coeruleogrisea, Friesea quinquespinosa, Lepidocyrtus lignorum and Oligaphorura groenlandica near Magdalenefjorden, Arrhopalites principalis, Folsomia bisetosella and Protaphorura macfadyeni in Isfjorden, and Folsomia quadrioculata on Bjørnøya

Seabird colony effects on soil properties and vegetation zonation patterns on King George Island, Maritime Antarctic

Seabirds are among the most important vectors transferring biogenic compounds from the sea onto land in the polar regions and, consequently, influencing the properties of soil and vegetation. We studied the influence of bird colonies (Adélie penguin Pygoscelis adeliae, gentoo penguin P. papua and giant petrels Macronectes giganteus) on soil properties and plant communities on King George Island, Maritime Antarctic. We designated seven transects, each starting from the colony edge and running to a natural boundary feature, which were divided into contiguous sample plots where we identified specific plant taxa (Prasiola crispa, Deschampsia antarctica, Colobanthus quitensis, Usnea sp.), as well as hydrophilous and xerophilous ecological groups of mosses. Based on percentage contributions of each of these taxa, we distinguished six distinct vegetation zones along the transects, in which we measured physical (moisture, conductivity and pH) and chemical (NO3 −, NO2 −, NH4 +, K+ and PO4 3− content) soil parameters. Our study confirmed that, with increasing distance from bird colonies, the concentration of nutrients and soil conductivity decreased, while pH increased. The vegetation zones were clearly related to this gradient of seabird colony influence and occurred in the same sequence for all three bird species examined, although the largest colony of Adélie penguins had the strongest effect on vegetation. Similarly, the physical and chemical soil properties did not differ significantly between the colonie

Impact of planktivorous little auks (Alle alle) on soil organic matter in Spitsbergen, High Arctic

Seabirds constitute an important link between marine and terrestrial ecosystems, one of its manifestations being the transport of organic matter from the sea to breeding grounds. The main aim of our study was to determine the impact of gregarious and planktivorous little auks on the quantity and chemistry of soil organic matter along the western coast of Spitsbergen, Svalbard archipelago. Samples from the vicinity of four breeding colonies and respective controls were investigated using the elemental analyzers as well as the Fourier transform infrared spectrometer with attenuated total reflection module. The results clearly indicate that soils affected by little auks are characterized by significantly higher content of soil organic carbon, total nitrogen, water-extractable organic carbon, and water-extractable total nitrogen in comparison with those unaffected by the birds. The size of the local population of little auks appears to be the crucial factor here. The chemistry of soil organic matter in soils affected by little auks is significantly different from that in soils unaffected by the birds. This is associated with fertilization of soils via guano deposition as well as differences in the quantity and quality of vegetation cover related to aforementioned process

Cyanobacterial and green algal assemblages in various tundra habitats in the high Arctic (West Spitsbergen, Norway)

The diversity of cyanobacteria and algae from various microhabitats in Spitsbergen is comparatively well known. However, the relationships between environmental factors and the structure of microflora communities remain largely unclear. This study was conducted in Hornsund Bay, which exhibits large variability in the physicochemical characteristics of habitats, particularly with regard to the availability of nitrogen and phosphorus. This variability, to a large degree, is caused by seabird colonies, which fertilize nutrient-poor terrestrial ecosystems near their nesting areas. The large variations in ecological conditions and vegetation types in the study area aid assessment of habitats representing different combinations of factors potentially influencing the formation of cyanobacterial and algal assemblages. The aim of this study was to examine the influence of physicochemical parameters on the taxonomic composition and diversity of green algae and cyanobacteria (particularly the coccoid, oscillatorialean, and heterocystous taxa). The study encompassed two groups of habitats – soil surface habitats and water-saturated habitats, both characterized by diverse influences of seabird colonies, vegetation cover, and moisture. Our results showed that taxonomic diversity and composition of cyanobacteria and algae were mainly influenced by P–PO43−, N–NH4+ and Ca2+ (soil surface habitats), and NO3−, as well as moisture (index of wetness) and pH (water-saturated habitats). The variability of these physicochemical properties was largely due to the variability of the seabird colony influence. Taken together, our findings aid in understanding the processes of formation of phycoflora assemblages in Arctic tundra