Small, but far from insignificant

Small, but far from insignificant

Top image: Invertebrate springtail Megaphorura arctica. Photo: © Pål Hermansen.

They are no bigger than 2mm and yet their total biomass in Svalbard is probably bigger than the biomass of all Svalbard polar bears together! New research can tell us more about how, when and from where the springtails arrived in Svalbard.

13 July 2011
Press release from UNIS

Springtails (No.: Spretthaler) are little invertebrates living in Arctic soils. They do have different colours and shapes, but most of them are quite small and pale, with long bodies, little antennas, three pairs of legs, no wings, but they do have a jumping organ called furcula, that allows them to jump fairly far and high when their habitat get disturbed.

Essential to the ecosystem
The most of the 63 species of springtails found in Svalbard are not bigger than 2mm, and yet their total biomass in Svalbard is probably bigger than the biomass of all Svalbard polar bears together!

They are essential for Arctic terrestrial ecosystems, with an impact in ecosystem functions such as nitrogen fixation or nutrients recycling. Despite the importance of these small but essential Arctic bugs, we don’t know much about their recent history like where and when they came from or if they survived in the Arctic during the glacial periods.

The High Arctic and Svalbard in particular, has been covered by ice in large extensions several times in the past. During the Last Glacial Maximum, which ended in Svalbard approximately 10.000 years ago, the environment was presumably so harsh that close to none of the species now living in Svalbard could have survived. The same applies for most of the High Arctic areas.

New Svalbard species
In the recently published article by Malu Ávila-Jiménez and Steve Coulson in the journal Insects, the history of this group has been studied based on their geographical distribution throughout the entire Arctic region.

The study revealed the presence of developed springtail communities in well-known glacial refugia, in Beringia and Mid-Siberia, during the Last Glacial Maximum. No indications of glacial survival of this group in Svalbard were found, but clear dispersal patterns can be drawn from the study, as there was found a strong connection between Svalbard, Greenland and mainland Norway, and a second link between Svalbard and Mid-Siberia.

These results have been further analysed in Malu Ávila-Jiménez PhD thesis High Arctic Invertebrate Biogeography: Patterns and Colonization Processes since the Last Glacial Maximum, recently submitted. These analyses have been combined with additional biodiversity data, particularly from the less surveyed areas in eastern Svalbard, including Nordaustlandet and Edgeøya, and molecular data from a springtail species.

Seven species, never described before in Svalbard, were found only in the Edgeøya samples, and they have been never found in the western Svalbard, indicating the existence of specific eastern communities. These species are thought to survive perfectly in western Svalbard, and yet they are not found there.

Can survive 14 days in sea water
However, most of these new species are linked to Siberian regions. This pattern, showing two separate links, one with north Atlantic areas and a second one with eastern Palaearctic (Siberia), is repeated across geographical scales, and across species, giving for the first time a solid insight into from where, when, and how these animals made it to Svalbard.

The eastern coast of Svalbard is s thus the first stop for invertebrates colonizing from eastern Palaearctic (Siberia) regions, whereas the west coast of Svalbard is mostly first hit by animals colonizing from mainland Norway. Springtails follow in most cases the ocean current patterns, which is no feat as these animals in many cases can survive over 14 days in sea water suspension!

These studies are of high relevance for further monitoring of natural (non-human mediated) biological invasions, which are known to cause important (and in many cases very fast) changes in existing communities and ecosystems in an environmental change scenario.

Ávila-Jiménez and Coulson will keep studying the dispersal and biogeography of Arctic invertebrates, hoping to obtain in the near future more biodiversity data from eastern Svalbard, as the surveys carried out in the east revealed not only how little we know about dispersal dynamics in Arctic invertebrates, but the urgent need to continue the surveys in eastern Svalbard until the biodiversity checklists are completed.

Reference
Ávila-Jiménez, María Luisa; Coulson, Stephen James. 2011. “A Holarctic Biogeographical Analysis of the Collembola (Arthropoda, Hexapoda) Unravels Recent Post-Glacial Colonization Patterns.” Insects 2, no. 3: 273-296.

 

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