By getting started around 7:30 am I was able to beat the traffic out of Iga. I believe I followed the same route I used coming in, but now I had more time to look around and realized that all around me, on the steep slopes of the canyon, are tea plantations. They only cover a dozen acres here and one half acre there, but add the charm of a carefully tended garden in the middle of the wilderness.
By 9:30 am I was on the east side of Lake Biwa, at the just-opening gate of the Lake Biwa Museum, Aquarium, and Research Center.I spent a delightful 5 hours in the museum, which is very well done. Turns out that Lake Biwa occupies a half graben and thus has much in common with Lake Tahoe. The graben has the largest fault displacement to the west, where the majestic Hira mountain range dominates the horizon. The lake is about 100 m deep along its western portion. To the east the faults that define the graben are poorly developed, the depth of the lake is under 20 m, and the eastern horizon is dominated by low hills, small lacustrine deltas, and rice fields (which now occupy what used to be peripheral lagoons and wetlands). Portions of the graben have been occupied by lakes for the last 4 million years, but the modern Lake Biwa was only developed over the last 500,000 years (to judge from the ages of lacustrine sediments recovered in deep borings).
There has been a lot of work done on the stratigraphy of the lake sediments, and on the fossils (macro, micro, and pollen) found within them, which clearly shows four big swings in climate over the last 500,000 years. Pollen studies have allowed the museum researchers to "reconstruct" the type of forests that were present in the Jomon period, ca. 10,000 years ago, and 200,000 years ago. They have been physically reconstructed as part of the landscaping of the museum grounds, so I was honored to walk through Late Pleistocene forests! A couple of hundred thousand years ago there were giant elephants tromping through the lake mud, as well as some nasty looking crocs.
Clearly the biologists have had a field day collecting specimens of beautiful butterflies, nasty looking beetles, mollusks, birds, fishes (more about them when I tell you about the aquarium), mushrooms, bugs, and all sorts of microorganisms, and in very biologist-like fashion have shed many crocodile tears over the lost diversity as wetlands were transformed into rice paddies. In response, the rice industry has launched a big research project, through the same museum, to document the many environmental services provided by rice agriculture. The results are quite impressive (a little like what Ducks Unlimited has done for the rice growers of the Sacramento Valley).
Clearly the lake has been a unique resource for the local inhabitants, past and present, and the museum includes very interesting displays on the ethnography of the area. At some point very interesting comparisons are made with Lake Baikal (which is at least 50 times larger than Lake Biwa, and seems to be a formal "Sister Lake"), Lake Tanganyika, and Lake Malawi (but in the map on the display no mention was made of Lake Tahoe, the Great Salt Lake, or even the Great Lakes).
If I could add my two cents, I would have liked to see more about the physical limnology of the lake, like dissolved oxygen variations, temperature vs. depth distribution, or shallow and deep circulation patterns. Standing on my favorite soap box, I think that by overlooking the physical environment of the lake in favor of the biological aspects only tells half the story of this fantastic body of water.
This blog entry is getting to be too long, but I must make honorary mention of the aquarium, which is devoted to the many fishes, turtles, frogs, and other wet things that live in or around the lake. The Big Guy is a species of catfish, but there are lots of other types, which give great variety to the night life of the lake.
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