初めまして。

This is a Japanese greeting that is used when Japanese meet someone for the first time and introduce themselves.

We are team Japan from the Akkeshi Marine Station (AMS).

The Akkeshi Marine Station as seen from the sea.

Akkeshi is a small town that is located in the east part of Hokkaido. It has a port and is surrounded by a unique wetland terrain and a brackish lagoon that is connected to the inner Akkeshi Bay. It is famous for fishery and especially for oyster farming. There are about 10,000 people living in Akkeshi and many of them are fishermen. We have two oyster festivals, one in spring and one in autumn, as well as a summer festival that is celebrated to wish for the success and the safety of the fishery. However, there is not only the sea around Akkeshi, but also a lot of green land and forests. So, we frequently encounter wild animals like deer, foxes and eagles. Sometimes, we even see brown bears, but that is an encounter that the people here usually don’t want. 

The marine station is a little far from the town of Akkeshi and it is sandwiched between mountains and the sea. It is a fantastic place to research marine life, because there is a rare and important marine ecosystem close to the station: eelgrass meadows. Furthermore, it is a good place to study the effects of ALAN (Artificial Light At Night), as, due to its remote location, there is not so much light pollution around the marine station. 

The Akkeshi Marine Station at night.

The Akkeshi Marine Station was built about 90 years ago and since then it has been used by many researchers. However, not only scientists, but also students from the University of Hokkaido and other universities (inside and outside Japan) come here. Actually, hundreds of researchers and students visit the station every year, especially in summer, since it offers a wide variety of research facilities including various instruments, boats, and a big aquarium.      The latter is here because the station was used as a public sea life aquarium from 1965 to 1996. Nowadays, it is not open to the public anymore, but the professor and students sometimes inform the local community about marine ecosystems. So, it is important not only as a research facility but also as an educational institution.

As I said before, Akkeshi is located in Hokkaido, the northernmost prefecture of Japan. It is freezing cold in Hokkaido in winter, so many people, also from outside Japan, come here to enjoy winter sports. In summer, a lot of tourists visit Hokkaido to escape from the summer heat in other parts of Japan and to enjoy the pristine and spectacular nature. Hence, Hokkaido is Japan’s leading tourist spot. The east part of Hokkaido is famous for its wildlife and there are numerous national parks in this region. The Akkeshi Marine Station is located in the Akkeshi Kiritappu Konbu Forest Park – Konbu means kelp. 

Although Hokkaido is rather rural and pristine, there are some large cities that emit significant quantities of ALAN. For instance, Hakodate, which is a big port town and famous for its marine products, is very bright at night and it may affect the marine life nearby. Furthermore, in Japan fishermen often install bright LED lights on their boats to attractsquid during the nighttime. This method may also affect marine animals that live far away from the coast and which are otherwise not affected by the light that is emitted by installations on land.     

In terms of oceanography, Hokkaido exhibits a high marine biodiversity. Because of its cold climate, there are a lot of characteristic life forms in the sea that surround Hokkaido, such as cliones, i.e. small actively swimming snails, and sea otters. Furthermore, along the coastline there are various seaweed species as well as eelgrass, which form habitats that are used as a nursery by many marine animals.

To sum it up, here is the best place to do research in the framework of GAME in Japan.

The boat pier of the Akkeshi Marine Station.

The practical part of our GAME project started in the beginning of April and due to the pandemic, every team faced some problems. In Japan, many strict Corona rules were implemented during the last two years and therefore the whole organisational process was quite complicated. For instance, I (Linda) had to do a lot of bureaucratic work to get the student visa from the consulate. When I arrived in Akkeshi, my project partner Itsuki unfortunately just got Corona, but after his recovery we then finally could start with our experiment by the mid of April.

First, we went to the beach with wet suits on to look for our test organism: the blue mussel Mytilus spp.     

Our target species.

Unfortunately, we only found very few mussels, which were fixed strongly to the rocks underneath some macroalgae, and they even did not belong to the genus we were looking for, since they were horse mussels (Modiolus Modiolus). However, in Akkeshi Bay the right mussel species Mytilus spp. is cultured by farmers under natural conditions. 

A rocky shore near the Akkeshi Marine Station.
Horse mussels that live attached underneath a macroalgal canopy.

This was the perfect alternative for our experiments. The mussel Mytilus spp. can reach more than 60 mm of shell length. Then, we visited an oyster farm to obtain a diatom starting culture from them, which we needed to establish a microalgal culture to feed the mussels. We had to maintain this culture during the whole experiment.

Microalgae in small culture flasks.

My experiment was designed to find out whether stressed mussels are affected more strongly by light pollution than non-stressed mussels. For this, I exposed the mussels to the chemical cues emitted by a predator.  However, before I started with this, several pilot studies needed to be conducted and the next step for us was to build the equipment for these pilot studies. The first of them aimed at finding out whether Mytilus spp. exhibits a natural biorhythm, i.e. day-night activity pattern, while the second tested if red light affects the behavior or the performance of the mussels. Red light is absorbed quickly on its way down into the ocean and is therefore generally not relevant for marine organisms. For this reason, most marine animals are insensitive to red light. However, in our experiments the mussels would live in tanks with a volume of 3 l and the water column between the mussels and the light source was not long enough to fully absorb the red light. Furthermore, we did not know whether our test species is actually insensitive to red light. Hence, we had to test whether there is an effect of the red light on the blue mussels. If there would have been an effect, we would have had a problem with the camera recordings of the animals in the control group (i.e. the absence of ALAN) during 24 hours – for which we needed the red light. It allowed us to take pictures in an otherwise dark environment. Furthermore, we also had to find out whether the chosen predator, the sea star Asterias amurensis, exhibits a certain biorhythm.     

A lot of seastars in a storage container.

During the experiments, several difficulties and challenges occurred, but we solved them with our own ideas. First, we put up a plan for the experimental set up. For this, one needed a lot of spatial thinking to arrange 60 or more mussels within the same experiment but in different treatment levels. I, for example, had four treatments levels and one tank with the predator.      

In the first pilot study , we wanted to identify the biorhythm of the mussels. From our background knowledge, we already knew that Mytilus trossulus filters in the dark (= during the night) when their predators cannot see anything and are therefore inactive. To assess the biorhythm, we made photos of the mussels from different angles and from different distances to assess the degree of valve gaping. For the photos, we had a LED-system that we could arrange in different ways, so that the light was shed on the mussels either from the bottom or from the top and in varying intensities. We then inspected the photos on a computer and checked for each single one whether the mussel valves were open (= mussels are filtering) or were closed (= not filtering).

We quickly found out that this method does not work well with the completely black shells of the mussels and we therefore painted the edges of the valves white. With this, it was clearly recognizable on the pictures if the shells were open or closed. Also, the position of the mussels in their containers was changed multiple times to find out from where they can be observed best. Still, at this point, there was no ultimate working protocol due to the fact that the method for measuring the mussels’ filtration rates was not set. Our plans about using water clearance rates, so the loss in algal cells from the water column per unit time, to assess the mussels’ metabolic activity were nullified after finding out that the microalgae sink to the bottom of the tank very quickly. Hence, we changed our plans and started to quantify the production of faeces. For this, we took the container in which a mussel sat for 24 hours, sucked out the water and filtered it. We measured the weight of the filter before and after it was loaded with the faeces. 

The red-light regimes that was used during the camera recordings.

On top of our experiments, we also had to culture the microalga Chaetoceros gracilis with which we fed our mussels. We cultured them in several tanks with a volume of 30 l each, while a temperature of 25°C proved to be perfect for their growth. In addition to this, we found that a 18 h light : 6 h darkness ratio was an effective way to reach maximum growth. Microalgae need vitamins as well as minerals, with which we provided them every five to six days. Furthermore, it was important to shake the tanks regularly to generate a water movement. The sterility of all objects was also of great importance to avoid contaminations of the culture. 

Despite some difficulties in this first phase, we both did not give up and always kept on working. In July, we already had a concrete plan, could estimate foreseeable mistakes and already knew with what strategies we could solve them. Working in this free and self-sufficient way was a great possibility to learn how to organise yourself and your work, how to assess and overcome problems and how to transfer our theoretical considerations into practical experiments. We both learnt so much and had a lot of fun during that process. At the same time, we were able to test and further develop strategies for the future handling of similar problems.

A lot of mussels

It was interesting to observe the behavior of the mussels, since they seemingly had different characters. For example, some mussels liked to put their foot out frequently to move to other places within the aquaria, while other mussels didn’t like to move at all. We planned to measure many response variables, for example the byssus strength. For this, we made a hole into one shell of each mussel to attach a newton meter. These measurements took place only once at the end of the experimental period and the mussels were killed afterwards to assess their dry weight. During the experiment, we measured the number of byssus threads produced within 24 hours for each batch of mussels that left the experiment. 

Our laboratory set-up.

Linda: It was an adventurous journey. It was also kind of funny that Itsuki got Corona in the beginning of our project, while I got Corona directly after the experiments were finished. Therefore, we were lucky that our project was not affected by the pandemic. For me, scientific work was exciting and valuable and there were many ideas and inspirations. Despite me being deaf, I am relieved that I didn’t had problems with the communication. We often had to bite through to not give up and we needed a high frustration tolerance throughout. Through the experimental period, numerous questions arose. Some remained unsolved, while we found the answers to many of them. We worked with a lot of freedom and space for self-organisation. This also applied to all the scientific aspects of our work, what was very pleasant. The experiments also gave me the chance to learn a lot about myself and to get to know my character. In addition, it was associated with a lot of travelling, which was remarkably interesting for me. Due to the direct work with the mussels, I also got to know this species much better and feel very close now to nature and to the organisms I worked with. I hope that we will have interesting results and can provide some      answers to our study questions as soon as we have fully analysed the data.

Itsuki: As this is my first research project at university, I was so excited but also nervous before it started. Even after the March course had begun, there were so many things I was not familiar with that I had a hard time keeping up with the other participants. But when Linda came to Japan, I felt easier as I got a reliable team partner. We were going well for a while after we had started with the preparations for the experiment, but we were getting into trouble      gradually. Of course, as we have different backgrounds, our thoughts are different and we sometimes had quarrels. But I think it was good for me to have a team partner with whom I can discuss everything openly and honestly. As we discussed a lot, we came up with a lot of nice and useful ideas. There had been lots of difficulties until now, so my heart was often going to break up, but every time I got over an obstacle, I think I grew not only as a scientist but also as a person.

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