Yesterday we began by continuing to box core along the slope. With a thick morning fog and placid waters, this went quickly, and we were able to put down four cores before lunch. The fog came on again during the late afternoon when we deployed the submersible pumps, and in both cases of fog, the boat had to use its fog horn. The codes we used were 1 blast for moving under engine, and 3 blasts for sitting stationary. While the labs are soundproofed reasonably well, out on deck, a fog horn is something you feel all they way through yourself, especially if you aren’t used to it. We did finish the day safely, though, and the coastal fog was really a beautiful sight, especially as it burnt off with the morning sun to reveal the mainland.
The box coring along the slope allowed us to achieve a transect, with cores at a range of depths spaced 50 meters apart vertically. This has a variety of interesting effects biologically and geologically. Biologically, it allows us to observe the changing ecosystem as available oxygen diminishes, and macrofauna disappear from the environment, as the deep anoxic depths are found, along with characteristic bacterial mat material. Witnessing this transition and characterizing it may tell us a range of interesting things. Geologically, we observe a transition from the heavily bioturbated, well compacted slope sediments to the undisturbed, gelatinous deeper sediments. Characterizing this in detail can tell us a lot about rocks observed in other places, by understanding their formation in a location like this one. This has been a very productive study for producing samples.
With the continued pumping of water at two depths finished, we turn things over to the night shift. Overall, the day went extraordinarily well.