From lab to onsen: The effects of warming on grazers and students

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    • From lab to onsen: The effects of warming on grazers and students

      oceanblogs.org schrieb:

      This year’s participants of the GAME project in Japan are Takaaki, an undergrad student from Hokkaido University, and Franz, a master’s student from Rostock. The project’s objective is to evaluate how the feeding rates of prominent local invertebrate grazers change with temperature, how temperature increase impacts the macroalgae they graze on and, finally, whether trends, if such are observed, change with latitude (i.e. this year’s 6 GAME sites in Portugal, Wales, Israel, Indonesia, Japan and Chile).

      A bike trip with Mizuho, Franz, Heather and Takaaki (from left). Photo by H. Glon.

      After both of us have arrived at the Akkeshi Marine Station in the south-east of Hokkaido in April, we started preparing our experiment. To be able to subject our grazers simultaneously to as many different temperature regimes as possible, whilst having a sufficient number of replicates per temperature level, we needed a lot of tanks, containers, heaters, pumps and regulators. Fortunately, the marine station in Akkeshi is not a new member of the GAME network and has already participated for almost 10 times since 2006. Because of this, we could recycle tanks by building our waterbaths from them, which were used for a GAME project two years ago, and we did not had to buy new electric equipment for the heating system. Just add a couple of party cups, lunch boxes and silicon tubes and you get yourself a decent self-made flow-through-system.

      The lab building on a sunny day, the sampling site at low tide and boxes with equipment from former GAME projects.

      The marine station is located directly at the Akkeshi Bay on a nice and remote stretch of coastline just outside of the town of Akkeshi. Hence, we can collect our study organisms at spring low tides on the beach just outside the lab. Being located far in the north-east of Japan on the Pacific coast, it is the only marine station in Japan that is exclusively affected by the cold Pacific Oyashio current, which brings nutrient rich water from the Arctic Ocean and leads to high productivity off the coast. Akkeshi itself is a small but charming fishery town that is located in the wide rural areas of eastern Hokkaido. Here, hardly a day goes by where you don´t see some deer or a fox poking their heads out of the woods. The town is most famous for its oyster farming that goes on in the Akkeshi Lake (which actually is a lagoon), where the plankton rich Oyashio water from Akkeshi Bay meets the mineral-enriched freshwater that is carried there by rivers from the near mountains.

      A deer in Akkeshi.

      Most houses in Akkeshi are small family houses, while the town lacks big apartment buildings. This leads to a shortness of shared flats and it would have been difficult for us to find a place to stay in for as short as half a year. Fortunately, the marine station has us covered. Takaaki took residence in paradise – a small bungalow on top of the shore, where he lives with a fellow student mostly surrounded by forest and deer. Franz got a single room in the dorm/guesthouse next to the lab, which he shares with almost no one at times and with large crowds at other occasions. The lab is mostly inhabited by two handful of students (undergrad to PhD) doing their own research, which creates a friendly and supportive atmosphere, where we can easily find help and advice when facing issues. Moreover, there are three permanently employed scientists, an office worker and two technicians who also offer further help to us whenever needed. Beyond that, you regularly get to see new faces since there are many scientists, mostly from Japan but occasionally from other countries as well, who come to the Akkeshi Marine Station to do some research. Some come just for a couple of days, some for as long as two months. And especially in summer, when student courses are held at the station, the dorm can get crowded to the limit of its capacity for a couple of days.

      The small dorm as seen from the lab.

      After almost a month of preparing and installing, we finally started our experiment using the isopod Idotea ochotensis and the amphipod Ampithoe valida. We acclimatized them to higher temperatures by rising the temperature in our flow-through-systems by 1°C per day for a period of roughly two weeks. Afterwards, we measured the response variables that the GAME teams had agreed upon in advance: feeding-rate, faeces production, respiration, wet weight, dry weight. Unfortunately, we faced a lot of issues in our first attempt – like a power blackout overnight and food pellets that quickly disintegrate after production – and in the end, we had to repeat the experiment. The final problem was that we could not find any more Ampithoe individuals for the restart of the experiment. Although former surveys and consultation with lab members suggested that those amphipods should be abundant in Akkeshi throughout all summer, we could hardly find them at all – let alone in sufficient numbers. In the end, we settled on continuing our experiments with Gnorimosphaeroma rayi, which is another local isopod. Like Idotea this one is both: feeding on Ulva as well as very abundant. Furthermore, it seems to have no issues with surviving in our set up. The rerun is almost finished by now and looks very promising so far, since we didn´t face any obvious problems and are now looking forward to analyzing our data.

      The pictures show our flow-through-system. Each water bath resembles a different temperature and contains 30 cups (15 replicates for Idotea and 15 replicates for Gnorimosphaeroma). The lunchbox is needed to distribute the sea water from the tab to those 30 cups.

      Hokkaido is a beautiful place and we try to explore it in day- and weekend trips whenever we can. Unlike the mainland of Japan, you can hardly find old buildings here showing the traditional Japanese architecture. This is because Hokkaido’s affiliation with Japan is relatively recent and temples and shrines here are relatively scarce and much younger. But in terms of landscape Hokkaido has everything to offer. Whenever our schedule allows it, we squeeze in short trips to visit the vast Pacific coast or a volcanic lake or hike in the mountains. Additionally, at many places people celebrate small local festivals in summer, which display a great variety of food, costumes and music.

      From left-top: cherry blossom in the Nenohi Park in Akkeshi, Pacific coast just to the east from Akkeshi, parade at Summer Festival in Akkeshi (photo by H. Glon), lake in the Shiretoko National Park.

      Something that has almost become a weekly routine is our visit to an onsen, what is a hot spring. Although Akkeshi itself does not have an onsen, there are some within a 50-min car ride. We go there after work and refresh our body and mind. In other words, experiment and onsen are inseparable for us. We can say confidently that we cannot keep working without paying a visit to an onsen on a regular basis. In this area, onsens are characterized by a high content of organic matter, which colours the water almost black and makes it much more soft than usual.

      Onsen in the Teleno Kisen hotel in Shibetya-Town (© www.recruit-hokkaido-jalan.jp/ ).

      Sunset as you can see it from our lab on a sunny day

      It has already almost been 4 months since we started our work in Japan. With less than 2 months left we hope to finish our experiment successfully and maybe even find a little more time to experience Japan. Finally, we wish all GAME-teams good results.

      頑張る!

      Team Japan (Franz and Takaaki)

      Quelle: oceanblogs.org/game/2017/08/14…-on-grazers-and-students/
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