200 Years of Antarctic Exploration
From discovering a continent to exploring for microbes
The 27thJanuary 2020 will mark the 200thanniversary of the discovery of the Antarctic ice shelf by a Russian expedition circumnavigating the Earth. The leader was Fabian Gottlieb von Bellingshausen in his ship, the Vostok, and his deputy Mikhail Lazarev in the Mirny.
They did not land, the first human to touch Antarctica was probably the American seal hunter, John Davis, who actually walked on the ice of the continent a year later around 1821. So, the existence of this huge continent, larger than Australia, was proved. This underlines how difficult exploration was in those days and we can understand why there were no further expeditions until James Clark Ross in the ships, Erebus and Terror (now the names of Antarctic volcanic mountains), attempted to reach the magnetic South Pole; they landed in January 1841 but did not succeed. Their ships were reinforced with steel plates and, as well as sails, had steam engines. The Erebus returned to the Antarctic as well as travelling to the Arctic under Captain John Franklin, where it was abandoned in 1845, all 135 crewmen died, mainly, due to disease microbes and possible food poisoning. The wreck was discovered by a Canadian team in 2015.
James Clark Ross said that there were no scientific discoveries, or ‘problems’ to investigate to merit further exploration in the far south. This put others off exploring further and the actual South Pole was not reached until Roald Amundsen’s team on the 14thDecember 1910 five weeks before Robert Scott’s fateful expedition when all five died on the return journey.
We have now managed to overcome the physical challenges of travelling to Antarctica and even living there. There are even tourist trips to the continent, my favourite dream is one that starts from Patagonia and ends up in New Zealand! There are also scientists and technicians who live there all year round investigating a huge variety of topics from neutrinos to glaciers, climate change and microbes.
The big news about Antarctic exploration always used to come from the ‘old style´ heroic explorers such as dramatic crossings, like those led by Ranulph Fiennes who, with Dr Mike Stroud, crossed the continent completely unsupported as well as circumnavigating the Earth from pole to Pole. In recent years we hear more about science such as about ice cores drilled in the glaciers which have given us extraordinary insights into the past climate of the Earth from about 800,000 years ago. But there is more. What fascinates me are the explorations into life in Antarctica. Not the spectacular Emperor penguins, Leopard seals and icefish of the coastal parts of the continent but the true inhabitants, such as the tiny rotifers, nematodes and tardigrades and microscopic algae and microbes.
The dry valleys of McMurdo are named because they are not covered by ice and snow and, like the rest of Antarctica, as dry a desert as you will find anywhere on Earth. The snow precipitation in the Taylor Valley is between 3 – 6mm per year and even when it does snow it usually evaporates in a very short time, so the rocky soil does not get wet. This is similar to the Atacama Desert! There are ice-covered lakes in the valley as well. Yet here, with temperatures averaging -17ºC and air temperatures down to -46ºC it is the drought that limits microbe growth not the cold. Even at -18ºC there is a microscopic layer of liquid water in the surface of the ice crystals and many microbes (and planta and animals) have complex ways of preventing themselves freezing solid, including producing internal antifreeze chemicals. Nevertheless, there are 27 species of lichen in Antarctica, and one, Buellia frigida actuallylives on the surface of the rocks, it has been recorded as growing at a rate of 0.0036mm per year (3.6mm per millennium!), and one was found to be 5,367 years old. It is inside the rocks, in endolithic communities, that microbes thrive. If you split a rock here you will find coloured layers, black fungi (containing melanin, like in our skin, to protect against ultraviolet radiation, remember the hole in the ozone layer over Antarctica exacerbates the danger), white lichens, green algae and blue-green cyanobacteria. There are also many other species of bacteria living here, such as those feeding off the products of photosynthesis from the cyanobacteria, this is a stable and long-lived ecosystem. Researchers have found that these rock communities and those in the soil despite containing low numbers of organisms, are surprisingly rich in different species, each valley differs quite considerably from its neighbours. There is a worry that human interference could damage these communities, but there are very few tourists! At least, there is an active awareness of the possible effects.
The most southerly multicellular animals also live here. Like Scottnema lindsayae, a little nematode worm, its lifecycle, from egg to adult, is 218 days at 10ºC but here it probably takes decades. They are able to remove 99% of their body water, curl up and wait out the bad times indefinitely. There are also small Bdelloid rotifers which are well known for avoiding sex, they have no choice as they are all females, all the offspring arise by parthenogenesis, virgin birth. They are able to dry out and freeze too, and even blow away in the dust. The rotifers and strange creatures called tardigrades (both of which can be found living in mosses elsewhere) were probably dispersed around the whole continent some 300 million years age, after Antarctica split off the super-continent Gondwanaland. The Antarctic species are found all over the continent but nowhere else on Earth.
But the best for last, the hundreds of Antarctic Subglacial Lakes. 800m below the ice there is a large lake, over 60m2, called Lake Whillans. It is a sloping lake, 2 meters deep but trapped in the ice. In 2013 Amanda Achberger and her team drilled, very, very carefully, down through the glacier using a non-contaminating hot-water drill. This project cost $10 million, it is not cheap drilling in Antarctica. So, what did they find? They were looking for microbes and found microbes. They found primary producers (the role plants play in most terrestrial ecosystems) like Thiobacillus that can oxidise sulphur andSideroxydanswhich can oxidise iron for energy, instead of light which plants use. They can be the basis of whole food webs. They also found Methylobacter,which metabolises methane and deeper down organisms which produce methane from carbon dioxide and hydrogen. It has been estimated that there could be 1029microbial cells in Antarctic ecosystems, more than estimates of total microbe numbers in all the oceans of the world. In fact, more that the number of stars in the observable universe. Quite a lot really!
Then there is the mysterious Lake Vostok. It is bigger than Lake Titicaca at 250km long and 50km wide and between 500 and 800m deep. It is also happens to be 4km below the glacier surface. It is warm for Antarctica, at 3ºC, warmed by geothermal heating from the Earth’s crust and is thought to have been cut off by the ice for 15million years! A Russian, French and American team tried drilling down to it in 1998, the primary aim was looking into the past climate and so the drill bit was not sterilised and there were many contaminating microbes in the drill fluid. They did not drill into the lake but stopped short yet managed, in 2012, to sample the ice which came from the lake water, forced up into the drill hole by the water pressure from below. In 2013 a paper was published by Yury M. Shtarkmann and team in which they claimed to have found RNA from 1,623 organisms: extremophile bacteria, archaea, rotifers, tardigrades, algae, fungi, crustaceans, sea anemones, molluscs, fish … on and on. This seemed too good to be true, a complex ecosystem 4km deep under the ice! As it happens no one seems to believe it and generally think these all came from contamination in the drill and its fluids. You must remember that the methods of identifying organisms from their RNA or DNA are incredibly sensitive. So the mystery remains.
Antarctic exploration under the ice continues today with the international beyond EPICA project which will be funded by the EU. Over the next 4 years they plan to drill down 2.75 km to ice over 1 million years in the past. I hope that they will be thinking about microbe sampling at the same time.
Antarctic exploration is not dead, in fact it is thriving, I wonder what the next 200 years will bring. Will many of the Antarctic glaciers have melted into the oceans?
Why Antarctica is so important:
Scientific paper about Lake Vostok: