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

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

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

Environmental niche overlap in sibling planktonic species Calanus finmarchicus and C. glacialis in Arctic fjords

Knowledge of environmental preferences of the key planktonic species, such as Calanus copepods in the Arctic, is crucial to understand ecosystem function and its future under climate change. Here, we assessed the environmental conditions influencing the development stages of Atlantic Calanus finmarchicus and Arctic Calanus glacialis, and we quantified the extent to which their niches overlap by incorporating multiple environmental data. We based our analysis on a 3-year seasonal collection of zooplankton by sediment traps, located on moorings in two contrasting Svalbard fjords: the Arctic Rijpfjorden and the Atlantic-influenced Kongsfjorden. Despite large differences in water temperature between the fjords, local realized ecological niches of the sibling Calanus species overlapped almost perfectly. The exception was the earliest copepodites of C. glacialis in Rijpfjorden, which probably utilized the local ice algal bloom in spring. However, during periods with no sea ice, like in Kongsfjorden, the siblings of both Calanus species showed high synchronization in the population structure. Interestingly, differences in temperature preferences of C. finmarchicus and C. glacialis were much higher between the studied fjords than between the species. Our analysis confirmed the high plasticity of Calanus copepods and their abilities to adapt to highly variable environmental settings, not only on an interannual basis but also in a climate warming context, indicating some resilience in the Calanus community

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

The effect of temperature on egg development rate and hatching success in Calanus glacialis and C. finmarchicus

The pelagic copepods Calanus glacialis and C. finmarchicus are important components of Arctic marine ecosystems. Projected climate warming may influence the roles they play in the ecosystem. Arctic C. glacialis and boreal C. finmarchicus eggs were incubated at temperatures of 0, 2.5, 5, 7.5 and 10°C to investigate the effects of increasing temperature on egg development rate and hatching success. The effect of increasing temperature on median development time, described by B[ebreve]lehrádek's temperature function, was examined using a Bayesian approach. For the studied temperature range, we observed the increase of egg development rates with the increasing temperature, although there was no change in hatching success. Calanus finmarchicus eggs hatched significantly faster than C. glacialis above approximately 2°C; the difference was progressively larger at higher temperatures. This may indicate that the boreal species have physiological advantages in areas where ambient temperatures increase, which may lead to C. finmarchicus outcompeting the Arctic species in situations where timing is important, for example, in relation to spring bloom dynamics. Development time to hatching (DH) was evaluated using B[ebreve]lehrádek's model and a set of different assumptions. The models that best fitted our data were those with species-specific parameters: DH (h)=5940 (T+9.7)−1.63 for C. finmarchicus and DH (h)=14168 (T+14)−1.75 for C. glacialis