Bladderwrack to be sent into space

Lena Kautsky at the Askö Laboratory with the type of small shoots of bladderwrack that will be sent into outer space. Photo: Nils Kautsky.

Lena Kautsky, Professor Emeritus of Marine Plant Ecology at Stockholm University, has devoted her professional life to researching the Baltic Sea, especially the ecology of the bladderwrack community. To many, she is known by the nickname "Aunt Seaweed” (Tant Tång in Swedish) and is still very active as a researcher and lecturer.

Reproduction during full moon

Bladderwrack (Fucus vesiculosus) is the most common species of seaweed in the Baltic Sea and it reproduces by releasing eggs and sperm into the water where fertilization takes place. In the mid-1990s, one of Lena Kautsky's doctoral students discovered by chance that bladderwrack reproduces during the full and new moon. But why bladderwrack follows a lunar cycle is still a mystery to the scientific community. How does bladderwrack in the Baltic Sea synchronize its reproduction? In the Atlantic Ocean, it is easy for the seaweed to keep track of the lunar cycles because they are linked to the tides. When the water is at its lowest, during low ebb, the bladderwrack is exposed to air and dehydrated. When the tide turns, the seaweed releases its eggs and sperm when it is again covered with water and the fertilized egg can easily reach the bottom and attach. In the Baltic Sea, there is no lunar tide. Here, the bladderwrack lives constantly submerged under the surface. The release of eggs and sperm is not triggered by dehydration, should it be exposed to air.

Caused by the moon's gravitational pull

One theory to explain the seaweed's reproduction in the Baltic Sea is that it might be controlled by the moonlight. But when researchers have tested the theory, it has been dismissed. Another theory is that the bladderwrack is affected by the moon's gravitational pull and this causes the macroalga to release its eggs and sperm in the Baltic Sea. One way to test this theory would be to send bladderwrack into space so it gets away from the Earth's gravitational pull and is exposed to weightlessness (or microgravity as it is called in scientific contexts).

Rocket launch from northern Sweden

This theory will now be tested. When Lena Kautsky appeared in Swedish public radio the other year, she mentioned that it would be fun to be able to test the theory and send bladderwrack into space. She was then contacted by Gunnar Florin at the Swedish Space Corporation, who told her that there is room on a sounding rocket that will be launched from the Esrange space base in Kiruna in northern Sweden.

Lena Kautsky and her research colleague Ellen Schagerström did not hesitate when the offer came.
"It felt absolutely fantastic to have the opportunity to test something that we have been thinking about since the discovery that bladderwrack reproduction seems to be affected by the moon's gravitational pull. Of course, it was a big yes!” says Lena Kautsky.

Six minutes in weightlessness

The small shoots created by the bladderwrack when its top is damaged, can in this photograph be seen just above the air bladders to the right. Photo: Lena Kautsky.

The structure of the experiment is to take bladderwrack from the Baltic Sea and place it in a small experiment module together with other experiments on a sounding rocket sent from Esrange. The flight reaches a maximum altitude of 250 kilometers and lasts about ten minutes, six minutes of which are in weightlessness. When the bladderwrack returns to Earth, it will be sent to the University of Helsinki, where a research colleague will investigate how the seaweed's genetic material (RNA) has been affected. The results are then compared with seaweed samples that have remained on Earth.

Hoping for a trip to the space station

On this first space trip, the researchers will investigate how bladderwrack is affected by the journey itself.
"We will test whether bladderwrack is a good space traveler by seeing how it copes with major changes in gravity. We also want to develop the methodology of keeping small shoots of bladderwrack in a small volume of water. The plan is to then write a research application to be able to send fertile bladderwrack to the International Space Station (ISS) and find out whether it is the moon that controls the release of eggs and sperm in the Baltic Sea's bladderwrack," says Lena Kautsky.

Bladderwrack from the Askö Laboratory

The launch from Esrange was originally supposed to take place in mid-April, but due to technical problems with the rocket it had to be postponed and will instead take place in November 2024. Ellen Schagerström and Lena Kautsky have had help in constructing a small box containing several small tubes that will be filled with brackish water and small seaweed shoots. During the summer and autumn, the researchers will collect small shoots of bladderwrack around the Askö Laboratory, south of Stockholm. The shoots are then grown under controlled light and temperature conditions inside the laboratory to be ready to be placed in the tubes, put in the box and transported to Esrange just before launch.

Ellen Schagerström

"Building a small box that will go up in a rocket has really been a group effort. We have been lucky to receive generous help from both experienced space technicians, research engineers and handy people to put together two boxes, one for the rocket and one as a control, for the experiment. We have checklists for how the samples should be handled both before and after the space flight. Now we look forward with excited anticipation to November and the launch," says Ellen Schagerström.