Numer and type of seeds introduced by footwear of travelers to Svalbard and germination success in 2008

Expanding visitation to Polar regions combined with climate warming increases the potential for alien species introduction and establishment. We quantified vascular plant propagule pressure associated with different groups of travelers to the high-Arctic archipelago of Svalbard, and evaluated the potential of introduced seeds to germinate under the most favorable average Svalbard soil temperature (10°C). We sampled the footwear of 259 travelers arriving by air to Svalbard during the summer of 2008, recording 1,019 seeds: a mean of 3.9 (±0.8) seeds per traveler. Assuming the seed influx is representative for the whole year, we estimate a yearly seed load of around 270,000 by this vector alone. Seeds of 53 species were identified from 17 families, with Poaceae having both highest diversity and number of seeds. Eight of the families identified are among those most invasive worldwide, while the majority of the species identified were non-native to Svalbard. The number of seeds was highest on footwear that had been used in forested and alpine areas in the 3 months prior to traveling to Svalbard, and increased with the amount of soil affixed to footwear. In total, 26% of the collected seeds germinated under simulated Svalbard conditions. Our results demonstrate high propagule transport through aviation to highly visited cold-climate regions and isolated islands is occurring. Alien species establishment is expected to increase with climate change, particularly in high latitude regions, making the need for regional management considerations a priority.

Points and dates of tagging and recapture of mature cod in the southern Barents Sea in 1937-1955

Barents cod spawn in the Motovsky Bay during the periods of warming in the Arctic when proportion of mature fish in the population is high enough. Cod spawning is most likely to occur in the Motovsky Bay when large cod forage in southeastern waters, and prespawning fish migrate close by the Murmansk coast. Under such conditions cod spawn in the Motovsky Bay, but low water temperature and slow egg drift toward Murmansk coastal waters delay development of cod eggs. As a result the eggs remain at the first stage for a long time; this causes high egg mortality before hatching. Larvae that survive and become pelagic and then bottom juveniles nevertheless have little chance to survive in winter because they are not biologically ready for overwintering. Thus, delay in egg development at the first stage delays subsequent stages of fish ontogeny, and strongly impairs survival of cod juveniles from the Motovsky Bay.

(Tables 1,2) Viability of Poa trivialis seeds transported to Antarctica from different locations

Antarctic ecosystems are at risk from the introduction of invasive species. The first step in the process of invasion is the transportation of alien species to Antarctic in a viable state. However, the effect of long-distance human-mediated dispersal, over different time-scales, on propagule viability is not well known. We assessed the viability of Poa trivialis seeds transported to Antarctica from the UK, South Africa and Australia by ship or by ship and aircraft. Following transportation to the Antarctic Treaty area, no reduction in seed viability was found, despite journey times lasting up to 284 days and seeds experiencing temperatures as low as -1.5°C. This work confirms that human-mediated transport may overcome the dispersal barrier for some propagules, and highlights the need for effective pre-departure biosecurity measures.