Comparing century-old maps of kelp beds in the Pacific Northwest to modern aerial surveys, a University of Chicago professor was able to track the long-term abundance and health of the beds, which in most cases remained remarkably constant: Journal of Ecology article. The kelp bed maps, made from surveys in 1911 and 1912, were the result of U.S. concern about the nation’s potash supply, which in the runup to World War I was largely imported from Germany. The kelp beds were, for some reason, seen as an alternative fertilizer source. That plan never came to fruition, but the maps remained, to be put to use for an entirely different purpose more than a century after they were made. [WMS]