An unusual form of life was recently discovered on a glacier located on a remote island in the Southern Ocean. Signy Island is part of the sub-Antarctic South Orkney Islands, about 600 kilometers northeast of the Antarctic Peninsula and 900 km southeast of Tierra del Fuego. The site of a former whaling station and the current home of a British research facility, Signy Island is largely covered with ice, the surface of which is pockmarked with holes in many sections. The life-form was found in one of these surface holes.
Material called cryoconite –windblown dust made of rock, soot and microscopic organisms– has settled on the surface of ice on Signy Island, as it has on many other glaciers and icesheets. Generally dark in color, cryoconite absorbs solar energy and melts the ice surface. The melting creates depressions in which cryoconite settles, further intensifying the melt. This process can create deep and sometimes narrow tubular holes which contain significant amounts of sediment.
Researcher Dr. Ronald Lewis-Smith from the Centre for Antarctic Plant Ecology and Diversity in Dumfriesshire, Scotland, collected sediment from the bottom of these ice tubes in November 1999. He carefully cultured the materials at the research station on Signy Island, and over the following months some plants began to grow. The first ones to appear, consisting of mosses and a kind of non-flowering plant called liverworts, were all native to the island. A more unusual one appeared after a few more months. Initially identified as a liverwort, it was sent to a laboratory in England, where it was cultivated on a base of sterilized moss from Signy Island.
As this plant grew, it became evident that it was a fern, and therefore not a native to the island. It took several years for it to grow large enough to be identified. Photographs of the plant and two fronds were sent to the Natural History Museum in London, where specialist identified it as Elaphoglossum hybridum. This species is found across a wide area of southern Africa, and also on islands in the southern Indian Ocean, as well as Tristan da Cunha and Gough Island in the South Atlantic Ocean.
These sites all lie to the north and the east of Signy Island. Some locations are as close as 1500 km to the island. However, the prevailing winds are from the west,. As the author states, “The most probable explanation for the spore, from which the present plant developed, reaching Signy Island was by encircling the Southern Hemisphere on an east–west trajectory at high altitude.” The survival of this viable spore is thus a testimony both to its ruggerd vitality and to the ability of the glacier to preserve it.
This fern could not grow in Signy Island’s current climate, but Lewis-Smith’s research does show that diaspores–plant seeds or spores –could be preserved in glacier ice and be viable for growth if the climate becomes more hospitable for them in the future. It is striking to think of the future of Signy Island when current warming trends progress further. Glaciers might contribute to the appearance of new species in two ways. Firstly, as they retreat, there will be an expansion of the ice-free areas in which plants can grow. And secondly, they may release biological material such as this spore, from which new species, not known on the island, may grow. Perhaps, thanks to climate change, Signy Island could one day resemble Fern Gully. The new ferns could be a testimony to the glaciers, which will be much diminished by that time.