Creepy crawlies on Svalbard; unseen and often forgotten

Creepy crawlies on Svalbard; unseen and often forgotten

Top image: Moth photographed in Adventdalen. Photo: James Speed.

When thinking of animals in Svalbard perhaps the first to spring to mind are the ‘cuddly’ ones, the polar bear, reindeer, fox or perhaps the highly visible (and often noisy) sea birds. But, whereas there are three species of terrestrial mammal on Svalbard and only 28 species of birds breed regularly on the archipelago, there are over 1,100 species of terrestrial or freshwater invertebrate! And this is only a start.

1 August 2010
Text: Steve Coulson, UNIS Associate professor in terrestrial ecology

The true number may be far greater since we only know the fauna from the regions around Isfjorden and Ny-Ålesund.

But what is an ‘invertebrate’? Invertebrate is a general term for all animals without backbones, and includes those with hard bodies, for example insects, and those with soft bodies, such as worms. On Svalbard these animals draw little attention often being small, hidden away and not readily visible. Nonetheless, they perform many important ecosystem functions, for example involved in organic soil formation processes, nutrient cycling and pollination not to mention their own complex food webs.

There are approximately 350 species of insect, mite and spider on Svalbard. The most obvious are perhaps the small flying chironomid common throughout the summer. These spend most of their lives as small larvae in the soil or freshwater before emerging for a brief period as the adult fly. Also common in Longyearbyen during the summer are the big black blue-bottle fly, Protophormia terraenovae. This is the same species that can be a considerable nuisance to klippfisk (salted and dried cod) and with the larvae occasionally infesting the drying fish.

In certain localities in Svalbard mosquitoes are found in large numbers. There is only one species (Aedes nigripes) here and the same species is also found on the mainland and on Greenland. The mosquito was observed here in the mid-19th century so the story it arrived with phosphate miners is, while appealing, unfortunately unlikely to be true.

Although butterflies are usually a common sight during a mainland summer, on Svalbard there are only two species to be found, both drab coloured (see top image).

One is widespread but only found in low numbers. The other is restricted to one short length of coastline in Kongsfjorden, probably because of comparatively mild local microclimate here.

Lice and wasps
Perhaps surprisingly we have two species of aphid (plant lice) on Svalbard. Both species are Svalbard endemics; that is, they are only known from Svalbard. The most common species can be found feeding on Mountain Avens (Dryas octopetala) flowers in July. Many animals can also be found in the freshwaters, for example caddisfly, Trichoptera. Along with the chironomid these for an important food item for the arctic char.

Wasps on Svalbard are represented by small black parasitoids wasps. These insects lay their eggs in the bodies of other insects, often the larvae of butterflies. The eggs hatch into larvae which grow within the host’s body. Once fully grown they emerge from the host and pupate.

Spiders and mites

Predatory mite

Predatory mite eating a compatriate. Photo: Steve Coulson/UNIS.

Spiders and soil mites are closely related. Spiders are represented by 18 species, all small and often black in colour, to be found under rocks and stones and predating the flies and springtails (Collembola).

There are some 80 species of mites. The majority live in the soil feeding on dead plant material or fungae. However, some are active predators, for example a red mite is often to be seen on warm rocks in the summer, especially along the beach, moving quickly over the surface in search of prey (see picture).

There are no true earthworms on Svalbard but instead there are large numbers of a relative, the pot worms. These are small off-white worms up to 15 mm in length. Collembola, or springtails, are small insect-like animals to be found in the soil (see picture).

These are all less than 2 mm long and can often be found in huge numbers; up to 500,000 per square metre. Their name springtail comes from the long tail-like organ that is used to “spring” the animal into the air to escape danger.

Springtail, Svalbard

Springtail. This animal is approximately 3mm in length. The springing organ can be seen stretched out behind. Photo: A. Fjellberg.

It is generally considered unlikely that invertebrates were present in Svalbard during the last glacial maxima. This means that the fauna (and flora) we see today has colonised since the retreat of the ice. How do these animals, often less than 1 mm in length and with no wings, manage to cross the Barents Sea or Fram Straight to colonise Svalbard?

Many probably arrive drifting on the ocean surface or with driftwood. Others may arrive hitch-hiking on migrating birds. Human introduction, either planned or accidental, is a significant problem in the Antarctic islands but there is less evidence for this route in Svalbard.

Blowin’ in the wind
However, wind is probably a major avenue. Small animals may be swept up into the air column and carried large distances. Indeed, many spiders as juveniles produce a specific silk thread which the use like a kite to catch the wind and so enable take-off. Even Charles Darwin in “On the Origin of Species” published in 1859 speculated on these routes observing as he did insects alighting on his ship whilst it was many kilometres out to sea.

However, the meteorological conditions enabling take-off of the invertebrates is less well understood. The new structure looking like an isolated tall fence close to the old aurora observatory in Adventdalen is trapping flightless animals that have been swept into the air by the wind.

Trap catches will be related to meteorological data gathered by the adjacent Adventdalen weather station to determine which species become airborne, when they can achieve flight and the optimal take-off conditions.

Invertebrates must be tough to survive on Svalbard. Once here the animals must tolerate short cool summers and long, cold winters. Most Svalbard invertebrates overwinter in the soil and so must be able to tolerate up to 10 months frozen in a block of ice. In fact we know that many can survive at least four years in this state.

Water bears (Tardigrades) are especially resilient. There are some 80 species of these known from Svalbard and two of these have been shown recently by a Swedish research group to survive two weeks in the vacuum of space while attached to the outside of the space shuttle (rather disappointingly for me, UNIS does not, yet, have the funding to begin similar work).

The invertebrate fauna of Svalbard is hence surprisingly rich and diverse.

More information concerning the invertebrates from Svalbard can be found on the SPIDER webpage (funded by the Svalbard Environmental Fund).

 

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