Friday, November 15, 2013

Wandering HOBOs

I've said it before, and I will probably say it again: I am a fan of HOBOs. They are cheap and break-proof enough that I can use them with my Introduction to Oceanography Class, but also accurate and reliable enough that we use them routinely now in our efforts to understand the changing biological community around the mouth of the Elwha River. Most of these HOBOs have a pretty boring life - they get zip-tied to some fixed structure for days to months at a time, and sort of sit there doing their thing. In the video below, for example, you can see a few HOBOs attached to a "mooring" built and deployed by my Oceanography class in Port Angeles Harbor.

Occasionally, though, one goes rogue. And that was the case for the HOBO in the photo at top. This HOBO was found on August 7th, 2013 by Olympic Peninsula resident Vance Heydorn while beach-combing on the outside of Ediz Hook. Vance was kind enough to bring it to the Feiro Marine Life Center, which set off a round of serious head-scratching amongst a group of us that use these for research and education purposes. We all assumed that it was one of ours, lost from a mooring or mount somewhere in Port Angeles Harbor or the adjacent Strait of Juan de Fuca. We finally worked out that it definitely wasn't one of ours...which led me to contact the University of Washington's Friday Harbor Lab. It didn't take long to get word from one of their research teams that, indeed, this HOBO had been deployed in the intertidal zone at a site on the west side of San Juan Island on the 11th of July, and had gone missing at some point after that.

Temperature data recorded by the HOBO

Its sort of hard to figure out exactly when this HOBO broke free from its mount on San Juan Island, but based on the temperature record, I would guess that it was sometime between July 27 and 6 August. The 27th is when the big daily spikes in temperature, which are characteristic of the intertidal zone (which undergoes wide temperature swings in the summer as it is alternately exposed to warm air and cold water) go away...and on the other end we know it made it over here by the 7th of August. Either way you slice it, it was a fairly quick journey from the San Juan Islands (a straight line distance of about 45 km).

Map of the journey

The light intensity data recorded by the HOBO doesn't tell us a whole lot more...except that Vance stored it in a fairly dark spot before he brought it back to the Feiro Marine Life Center:

Light intensity data recorded by the HOBO

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