First week in Akkeshi, Japan

August 15th, 2012Blog0 comments

Nicole Kollars

by Nicole Kollars (ZEN graduate student fellow in Northen Japan)

I do not think my wetsuit had a chance to fully dry out this week as we were in the water at the ZEN field site everyday.  With several experimental pushes (setting up an experiment to measure predator impacts on mesograzers, maintaining the main ZEN experiment, and surveys of the ambient predator community) it was a busy week for eelgrass science in northern Japan!

ZEN field site in Akkeshi, Japan

Science by canoe
A team of four made maintaining the ZEN experimental plots a smooth and efficient process.  We used a canoe to keep bags of plaster blocks, extra cable-ties, and spare scissors easily accessible. While one person paddled around the plots and handed out supplies, the rest of us used mask and snorkel to change the old blocks out for the new.  Luckily, the tide was at a good height to make snorkeling easy but the ever-present jellies still makes working at this site quite challenging!

Close up image of the field experiment

Learning how to catch a fish
Before traveling to Japan I had never appreciated how creatively scientists can modify their use of the same or similar experimental gear to overcome obstacles posed by working under diverse field conditions. I’ve surveyed small aquatic predators before using a seine net (a large net attached to two poles dragged through the seagrass to capture fish and other predators).  But, I had never seen one used quite like they do at the ZEN site in Akkeshi.  We used a typical seine design (floats on top, weighted on the bottom), but with the addition of a tow net attached to one side of the seine.  In the water, the seine net was walked out until completely stretched in one direction. Then we walked the ends of the net toward each other to form an enclosed circle.  Moving very slowly, we gradually decreased the circle in size until all the fish were forced into the tow net.  The tow net could then be emptied into a bucket and the fish counted, measured, and released.  It was an effective design that did not require spending time picking the fish out of the netting of a traditional seine.  I think this purse seining technique is similar to techniques that shrimpers and other commercial fishermen use to capture fish in the open ocean, but it’s not something I’d ever seen before. But that’s part of why I’m in Japan – to learn new techniques and do rigorous science at the same time.

Nicole finds the seaweed Gracilaria in its native range in northern Japan

A surprise trip to a tidal flat
To my absolute delight, after finishing work at the ZEN site one morning we swung by a tidal flat where I could collect samples of the local Gracilaria seaweed for my thesis research.  While this species is introduced and invasive in the Southeastern USA, it is native to mudflats here in Akkeshi. The shallow water prevented the boat from getting too close to the shore, so we had to hike over one kilometer in shin-deep mud before we started seeing the seaweed.  This happened to be the day when the sun shone bright and my 10 mm worth of neoprene grew unbearable as I made my way through the mud.  But the end result of seeing Gracilaria in its native habitat was well worth the exertion and I was able to collect enough samples for my project and make some useful observations.

Interestingly, in the Akkeshi mudflats most of the Gracilaria is settled onto the shells of a local gastropod.  This contrasts to the Southeastern USA where the decorator polychaete Diopatra attaches fragments of Gracilaria to its tube.  In both cases, the seaweed is using an animal for substrate but through very different mechanisms.  I also found amphipods living on Gracilaria.  Similar to how the amphipods in the eelgrass beds are larger in Akkeshi than in the Carolinas, the amphipods I found on Gracilaria are gigantic compared to what I have seen in Charleston.  A huge thanks goes out to Dr. Nakaoka for facilitating the endeavor, Dr. Honda and Kyosuke-san for hiking through the mud and collecting samples with me, and ZEN for bringing me to Japan!

Wetsuits drying in Akkeshi

All in a week’s work
Now at the week’s end my wetsuit finally has a chance to dry out and I look forward to a weekend of rest, a lab dinner party (with the promise of local Hokkaido seafood and good sake), and a canoeing trip up the Bekanbeushi River.  “Work hard, play hard” definitely describes the life of a marine field ecologist here in Japan.  Otsukaresama (thank you for your hard work) ZEN team!