If you’re a scientist, almost all of your professional reading comes in the form of scientific papers. These days, that usually usually means between 10 and 20 pages of fairly dense information packed into a PDF. This format is great for organizability and portability, but it does lack a certain je ne sais quois. It also lacks a lot of the older papers—ones you see cited over and over again, but have never actually read, and ones you’ve never heard of that embarrass you with their relevance. Here you thought you were so clever, and all of the sudden you realize some dude was writing about your brilliant idea in the mid-fifties.
I had this experience about a year ago, when my advisor came across a citation for a dissertation written by a student named Eric Barham at Stanford’s Hopkins Marine Station in 1956. Barham’s thesis, titled “The Ecology of Sound Scattering Layers in Monterey Bay,” is in some ways almost eerily similar to mine, using active acoustics (that is, sonar) to study changes in the ecosystem through time and in relation to oceanography. The length of the study is about the same, as is the location in the Bay. Other parts are different—he got his data every week or two from a boat, I got mine continuously from an ocean observatory, he had net samples to go along with the acoustics, and only I wish I did. I have a calibrated, quantitative, digital sounder, though, where Barham had a Navy surplus machine whose output didn’t get more quantitative than varying shades of gray burned onto a moving scroll of iodized paper. Even so, I spent a few days last year rooting around in Stanford’s special collections to see if I could find those old echograms. I didn’t…but if I had, they would have made for a neat comparison.
Barham’s thesis is part of the early literature on the “deep scattering layer,” or DSL. This was a phenomenon that began receiving attention with the wide adoption of sonar during World War II. Ships with acoustic depth sounders would often see what appeared to be a second ocean bottom much shallower than the one they were expecting. Even stranger, this “false bottom” suddenly rose to the surface every night, frightening more than one captain by making him think he was running up on an uncharted shoal. It would descend again in the morning. The deep (sound) scattering layer, or layers, was present most places in the ocean, somewhere between 200 and 800 meters below the surface. After the war, some scientists began to investigate it in earnest.
One of the citations in Barham’s thesis is a paper by Gordon Tucker, from 1951. I recognized the name Tucker, because it is the name of a type of net widely used for sampling zooplankton. In fact, I spent a week my senior year of college struggling with a sticky release mechanism on one of these nets aboard the NOAA Ship McArthur II in the Gulf of the Farallones, offshore of San Francisco. On a whim last week, I decided to go up to the UW’s main library on campus to find this paper, which of course is not available electronically yet.
Back in my office with a pleasantly musty hard-bound copy of volume 10 of the Journal of Marine Research, I discovered that Tucker (1951) was the paper where he invented the Tucker net. What’s more, he did it to try to figure out what what was causing the deep scattering layer. His answer, based on cruises in the Bering Sea and near San Diego? Mostly myctophids, or lanternfish: little bioluminescent guys an inch or two long, with some krill in the upper layers as well.
In the same volume, I stumbled across, completely by chance, another paper on the composition of the deep scattering layer, this one by a Norman Marshall. Independently from Tucker, who published in the subsequent issue, he had argued for the same biological cause of the DSL—lanternfish—based on their theoretical sound-scattering properties, known widespread distribution, and daily vertical migrations. It was really cool, reading these old papers, to see the evidence for the “biological hypothesis” coming together into what would become our present-day understanding of the DSL.
But there was still more. On the back cover of each issue, the editors of the journal were listed. I did a double take. One was C-G. Rossby—yes, that Rossby. Another was Harald Sverdrup. If you haven’t heard of him, he was no big deal. Just has a unit of measurement named after him. And there was Thomas G. Thompson. He was the sort of guy who you might choose if you were trying to pick a namesake for a 274-foot research vessel, and wanted to name it after the father of American chemical oceanography. These guys were all giants, and it’s kind of funny to think of them scrounging for reviewers and hassling authors for revisions.
What was I talking about? Oh, right. PDFs. My walk up to the library to look for an old reference turned into a field trip to the Cambrian Explosion of modern oceanography. Thinking about it, this experience wasn’t totally unique—these kinds of bang-bang-bang connections often happen when I spend time flipping through hard copies of journals. I find interesting and useful things I didn’t expect to. For whatever subtle design reasons, the electronic paper-reading experience doesn’t yet do that. If you know a librarian, let them know.
Even better, if you know a California legislator, let them know. Cuts to that state’s higher education funding may force the largest oceanography library in the world to close. There’s old stuff at the Scripps Library that cannot be found anywhere else. If it’s moved to an offsite storage warehouse, it probably won’t be found anymore, period. The UW has already lost its Fisheries and Oceanography Library to cuts by a state legislature ambivalent to higher education. Don’t let it happen at Scripps.