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Knowledge Co-Creation - Profiles of researchers

Unlocking the Unknown Ecology and Physiology of Plants Living on the Lakebeds of Antarctica

Yukiko Tanabe
Assistant Professor, Waseda Institute for Advanced Study

Environments Isolated for 20,000 Years

My field of specialization is research into the ecology and physiology of plants living in the Arctic and Antarctica. I have been fascinated by the polar regions ever since seeing them on television as a child. After taking time out from university to live in an Eskimo village and travel in Alaska, I had vague notions of researching arctic plants. A great deal of research has already been carried out into Arctic plants, but research on Antarctica has been barely touched. When I entered graduate school, my Ph. D. supervisor recommended that I research the plants found in Antarctic lakes as nobody had tackled this theme previously, so this was what I decided to do.

The best way to carry out this research was to visit Antarctica itself, but the Japanese Antarctic Research expedition was made up of only around thirty researchers. At best only a few of the younger students would be able to join the team. I had decided it was unlikely I would be given the opportunity to visit Antarctica during my time as a graduate student, and prepared to carry out research using collected samples and data. However, I could hardly believe my luck when a space on the biology research team became available and I was allowed to take part in the 2007-08 expedition. Carrying out observations and experiments with a physical sense of the natural polar environment gave me a far richer source of ideas that staying in the laboratory would have.

The Antarctica has numerous lakes and most of the lake water is extremely clear and almost entirely lacking in sources of nutrition. Despite this, for some reason the lakebeds are covered in plant life. Normally, plants are unable to grow unless they absorb nitrogen compounds such as phosphorus or ammonia dissolved in the water. So where and how do these plants find the nutrients to absorb and use for growth? One way they do this is from the numerous cyanobacteria found at the Antarctica. Cyanobacteria are incredible organisms that absorb nitrogen from the air and use this as a source of nutrition. Cyanobacteria are thought to have fixed this rich nitrogen source, and then flourished on the lakebeds and fertilized the sediment.

Plants are thought to have spread gradually over approximately 20,000 years since the last glacial maximum period to create the current ecosystem, which is composed of approximately 100 varieties of cyanobacteria, mosses and algae. A 20,000 year record of life has been preserved here, isolated from the outside world for a huge stretch of time, undisturbed by human and even other organisms. This is an invaluable place from the perspective of pursuing theoretical models of biology and ecosystems.

The Antarctic continent is scattered with lakes. In winter, these freeze up to 2 meters depth, but under the ice the water temperature is 2 to 3°C, far warmer than the world above.

Traveling for approximately one month from the Port of Fremantle in Australia to Syowa Station in Antarctica onboard the observation vessel Shirase (left); after arriving, the biology research team stayed at a hut away from Syowa Station near to the lakes (right).

The Amazing World of Antarctic Lakes

There are more than 100 lakes in the vicinity of Syowa Station alone, and for about 11 months of the year they are covered in ice. In the remaining month, the ice-cover melts during the short Antarctic summer. During this period, we launch rubber dinghies onto the lakes to collect samples and carry out observations and experiments. Most lakes are between 3 and 10 meters deep and the deepest is around 50 meters. The clarity of the water is extremely high and you can see the lakebed very well from the dinghies. We use a tool that is similar to a claw crane arcade game to collect plants and lakebed sediment. The lake itself is our laboratory, and we try to manipulate the environment and carry out cultivation.

Sometimes we change into diving suits and swim to the bottom of the lakes. Even in summer the water temperature is around 2°C. That is cold enough to give you a headache when you are in the water and freeze your hair instantly when you return to land! However, physically entering the water allows you to see a fascinating world that you would never be able to discover above the water. So far, I have surveyed between 30 and 40 lakes by dinghy and dived in three. Each and every lake is a closed system made up of a different ecosystem. Essentially, the lakes are composed of mosses, algae and cyanobacteria. However, differences can be seen in the dominant species and in the size of plant communities. There is huge variety; some lakes have forest-like growth, whereas others spread tightly to the surface like a carpet.

Making observations and sampling from dinghies and diving during the short period of summer. The lakes are extremely transparent, allowing you to see clearly down to the lakebeds.

Lakebeds contain vast worlds that could not be imagined from the harsh land environment of Antarctica.

I have visited Antarctica three times for field surveys. On each trip I have had a different research theme and gradually developed my research: on my first trip I examined photosynthetic systems; on my second trip I examined the nutrition cycle; and on my third trip I examined the development and evolution of ecosystems. This is a field where no previous research has been carried out so whatever I publish is new. Despite this, some of the research results have been revolutionary.

Firstly, lakebed nutrition was far in excess of what we imagined. The land surface and lake water are not especially rich in nutrients. However, the lakebeds themselves, which are something like a bottomless swamp, contain a huge volume of nutrition. Incredibly, we have discovered that some Antarctic lakes have higher concentrations of nutrients in the lakebeds than the content of the lakebed of Lake Shinji in Japan, which is a nutrient-rich lake (lakes with high nutrient concentrations, such as nitrogen compounds). There is a possibility of a unique life cycle contained solely within the Antarctic lakebeds whereby all nutrition is provided by the lakebeds and photosynthetic production and biodegradation are repeated. One of my goal is clarify how this system works.

Moreover, during research into photosynthetic systems we discovered an incredible symbiotic system among plant communities. Powerful ultra-violet light shines into the highly transparent lakes at a high enough level to damage plant growth. It is amazing that plants are able to grow despite these conditions. Making a horizontal cut to the plant communities by a few millimeters revealed that (only on the surface) the plants produce large quantities of a substance that offers protection against this ultra-violet light and strong visible light. In other words, we discovered that the extremely active level of photosynthesis is occurring as a result of plants at the top of their communities cutting out strong ultra-violet light and light, rather like a pair of sunglasses, and allowing the right amount of light to pass through to the rest of the plant community below (Diagram 1). It would appear that these plants are altruistically sacrificing themselves to save their companions!

Diagram 1. Color patterns of plant communities collected from the lakebeds. The surface is a bright orange color. This coloring offers protection from the UV and light, creating a gentler environment at colors lower down where photosynthesis can occur.

My personal mantra is to use this research not only to observe and report on the plant ecosystems we discover but also to produce research results that take us a step deeper into the plants’ physiological systems and then to go one step further by trying to build theoretical models around the fundamental question of what living things really are.

Switching from Engineering to Science during the Second Year of my Ph.D.

I arrived at my current field of research in a rather roundabout way. Originally, I studied engineering at university and after graduating I entered engineering graduate school. Right up to the second year of my Ph.D. I continued to study engineering. I worked on the research and development of artificial photosynthetic systems. It was a sought-after field which boasted excellent job prospects, but as I approached the end of my studies I began to ask myself if I was really suited to engineering. Until that time I had believed science to provide a foundation and engineering to be the application, but the truth is that these two field approach the same science from completely different perspectives. The aim of engineering is to “create something of practical value,” and the results are more important than the process. The aim of science is to “throw light on the hidden secrets of nature” and priority is given to the process of discovering phenomena and interpreting the implications. As I began to understand this difference I began to realize that I wanted to do science and that I had to make a decision before it was too late. I looked for a supervisor and changed graduate schools.

I’m sure there aren’t many people who get so far into their research before deciding to change their specialization! I felt unsure and anxious, but if I was going to work in a field of research for my whole life I decided it was better to make a bold change of course towards a field that really suited me. I was lucky that approval was given for my credits to be switched and I was able to switch directly over to the second year of a Ph.D. course.

I had a slower start than my peers but I am lucky enough to lead the research life of my dreams, carrying out research into plant ecology in both polar regions as I commute between the Antarctic and the Arctic. In 2013, I published a collection of photographs and essays - The end of the wonderful earth [Suteki na Chikyu no Hate]. In 2014, my research results were recognized and I received the Young Scientists’ Prize, which is awarded by the Minister of Education, Culture, Sports, Science and Technology. I love the great outdoors and exploration and for as long as I can move I want to continue showing people what I can do, carrying out research and providing society with new information.

The end of the wonderful earth (Poplar Publishing, August 2013). The book contains numerous photographs of nature and essays.

Yukiko Tanabe
Assistant Professor, Waseda Institute for Advanced Study

Assistant Professor Tanabe was born in Aomori City, 1978. She is a plant physiology and ecology researcher and has a Ph.D. in science. After dropping out of a Ph.D. course at Kyoto University Graduate School in 2006, she completed her Ph.D. course in 2008 at The Graduate University for Advanced Studies (SOKENDAI). She was appointed to her current position in April 2013 after working as a Researcher at the National Institute of Polar Research and later as a JSPS Research Fellow at the Graduate School of Frontier Sciences, The University of Tokyo. In January to March 2014, she was Visiting Researcher at the Centre for Northern Studies, Laval University. In 2014, she received the Young Scientists’ Prize, Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology.

She has been fascinated with the polar regions since elementary school and took time out from her studies during her fourth year at university to live in an Eskimo village in the middle of winter at the foot of the Brooks Range in Alaska. After traveling far and wide, including in Alaska and Peru, she decided to switch from a career in engineering to science. She participated as a Scientist of the 49th Japanese Antarctic Research Expedition (JARE), 2007-08; Scientist of the 51st JARE, 2009-10; and Scientist of the 53rd JARE, 2011-12. In the summers of 2010, 2013 and 2014, she carried out field surveys at the Svalbard Islands in the Arctic. In 2014-2015 she plans to take part in a joint international expedition to Antarctica.