2010 Midwater Ecology Expedition Logbook

Our planned dive for today, at the MRS station offshore, had to be postponed because of rough weather that arrived last night. After making the call this morning around 6:30 a.m., we decided to steam to the MidWater 1 (MW1) site, located in the middle of Monterey Bay, and hunt for animals there--particularly squid for Henk-Jan to use in his experiments.

But that meant we didn't have much to do this morning, so I spent most of it playing with the Western Flyer's scientific echosounder, an instrument near and dear to my heart. Sound travels much farther than light does in water. To see anything far away, we have to use sound--just ask the dolphins and toothed whales who use echolocation to hunt for prey. An echosounder transmits a brief pulse of sound into the water and then listens for its faint echoes bouncing off of objects in its path: animals swimming in the water column, for instance, or the bottom of the ocean. Because we know the speed of sound in water, the time it takes for an echo to return allows us to calculate the distance to the object it bounced off of. And because larger objects tend to reflect more energy, the loudness of the returning echo allows us to estimate the size of the object. A single ping lets us record the distribution of animals through the entire water column nearly instantaneously. In effect, it allows us to see the water more like a dolphin rather than an ape. My research uses DEIMOS, an echosounder that was deployed at the Monterey Accelerated Research System (MARS) until last week, when it was recovered after a year and a half on the ocean floor. During that time, it recorded changing distributions of animals every five seconds--an impressive data set. (You can read more about DEIMOS here.) The data does not tell us, however, what animals we are seeing.

One of my main goals for this cruise is to see some of these animals in their natural deep-sea habitat, up close and personal, courtesy of the high definition cameras on the ROV Doc Ricketts. So far, I have not been disappointed. Sitting in the ROV control room, it's easy to forget you're sitting in a ship on the surface. Very quickly, I start thinking of myself as sitting inside the ROV itself. In fact, the scene through the widescreen displays in the control room looks as much like outer space as anything else, with particles of marine snow flying by like stars, and translucent squid and jellies floating across like shimmery alien spacecraft. A very different, more intimate view of the bay than what you see from an echosounder, and one I wish I could see more often.