Looking south towards the Olympics from the San Juan Channel
Last week our class had one day of time on the R/V Centennial that we have traditionally used to make a long one-day cruise to Elwha. But we decided instead to stay local, partner up with other classes at Friday Harbor, and make a trip out to the sand field in the San Juan channel. We had two over-all goals. First, many of the students had projects focused on investigating the use of this sand field by Pacific Sand Lance...and much of our time was spent pulling sand samples from the field, and sorting the PSL out of those sand grabs. Next, we wanted to sample around the sand field to get a sense for the grain sizes immediately adjacent to it. How distinct was the boundary of the field?
|The name of the game is plucking as much sand as possible off the bottom using the biggest grab available|
|Sorting through a sample of sand|
|Pacific Sand Lance, and coarse sand|
|Pacific San Lance emerging out of a sample of sand|
|2 of these shellfish came up, from 10 grabs. Juvenile Clinocardium?|
|One sample included this beautiful worm. Flatworm I think?|
|And out of 10 grabs, one amphipod.|
Our samples away from the sand field were, perhaps unsurprisingly, pretty coarse. The currents in the channel are intense, which presumably makes this area unsuitable for the deposition of most fine sediment. But it begs the question...how is the sand field itself maintained? How does it persist? These samples outside of the sand field were also notable for their relatively high invertebrate diversity.
|A characteristically coarse grab sample from the San Juan Channel, outside of the sand field|
|We pulled up a good number of these beautiful brachiopods...its been a good long while since I've seen one of these. I think maybe Hemithiris? There is a lot of interest in these, not least because they are so prevalent in the fossil record.|
|High chiton abundance, but we dredged up only tiny specimens like this one|
|A couple of these came up...juvenile Cancer oregonensis I think?|
|A great wealth of Podedesmus at these sites...shown here with a nice encrusting bryozoan|
|The only scallop we pulled up, and I'm not totally sure, but maybe a rock scallop (Hinnites) just prior to cementing itself in place (?), with maybe a boring sponge (Cliona??)|