By PIFSC EOD guest blogger Laura Lilly, guest scientist acoustician aboard SE1501, under Chief Scientist Phoebe Woodworth-Jefcoats.
As with all meticulously-arranged science plans, the original schedule for our April cruise aboard the NOAA Ship Oscar Elton Sette from Honolulu to the North Pacific subtropical frontal zone (STF) went out the window before we even set sail. After remaining in port several extra days to sort out gear issues and chase down a rat that had stowed away onboard, we finally steamed out of Pearl Harbor on the night of Friday, April 3.
The goal of our cruise is to examine and document the physical oceanography and biology of the North Pacific subtropical frontal zone, an area of high biological productivity marked by both a chlorophyll and a temperature front. The chlorophyll front is an important foraging ground and thoroughfare for sea turtles, elephant seals, tuna, swordfish, and seabirds. Additionally, there is evidence that the STF is experiencing long-term shifts in its position and intensity, with the chlorophyll front shifting farther north and decreasing in concentration. Sampling the STF during the present El Niño conditions and positive phase of the Pacific Decadal Oscillation will contribute to our understanding of these long-term variations.
Due to our pre-cruise delays, we had to remove the northbound sampling leg of our cruise, which meant that we have spent the past three days steaming straight from 22oN latitude (Oahu) to 32.5oN, just north of the frontal zone and roughly at the same latitude as Los Angeles, CA. Now that we’ve arrived at our northernmost station, we will turn around and begin seven days of southbound sampling, ending up back in Honolulu.
But in the meantime, our three-day transit has not been wasted! What does one do to pass the long, tedious hours floating through monochrome blue and grey? As it turns out, plenty! Below is a sampling of ways in which we’ve occupied ourselves while we wait for science operations to begin.
- Sea legs – The first, and arguably most important, step of any sea voyage is to re-settle one’s balance and stomach after the seasickness that comes from being on a constantly rocking platform. Thanks to plenty of sleep, Dramamine, Saltines and a calmer swell, we’ve all finally found our sea legs.
- Nighttime shifts – Our cruise involves round-the-clock science operations, so half the scientists have to change their internal clocks from a normal daytime routine to a nocturnal, middle-of-the-night “dead-watch” setting. As the days progress, more and more people are sleeping (and waking up) at odd hours. Breakfast is now nearly empty, while dinner finds many dead-watchers stumbling out for their first cup of morning coffee. Thanks to our extra transit time, everyone seems to have successfully made the transition, and is ready for nighttime collecting!
- Exercise – In the interest of keeping up (physical) appearances, some high-energy members have ventured into the ship’s small gym, rotating between the elliptical, rowing machine and free weights in attempts to keep workouts from getting too monotonous. The more intrepid and strong-legged have even attempted the treadmill, which, in choppy seas with large swells, can feel like running inconsistent rolling-hill intervals. Needless to say, we’re staying sharp on our toes!
- Bird-watching – As one of several (or perhaps the only) enthused birders on board, I have been vigilantly scanning the horizon non-stop with my binoculars, and informing everyone in sight every time I spot an albatross flying behind the ship…even if it’s the same albatross that has been following us for three days. In the absence of actual data collection during our northward transit, the frequency of birds can be a useful proxy for our impending arrival into the highly productive region of the chlorophyll front. Yesterday, a flock of red-footed boobies accompanied the ship for several hours (and left their mark on the bow, much to the Commanding Officer’s chagrin). Sadly, our troll-lines have not had corresponding luck in catching fish for dinner.
- Easter Sunday – It’s easy to forget what day it is when you’re at sea, but we had an amazing Easter dinner, thanks to our galley whizzes Clem, Lenette and Doc.
- The ship’s crew! – Over the past three days, we’ve gotten to know our wonderful, industrious, humorous and accommodating ship’s crew, who have navigated us through rough seas and squalls (aka a minor drizzle yesterday afternoon) to arrive safely at our first sampling station. Let the science begin!
Our science collection will fall into a familiar round-the-clock routine. During the day, we will conduct CTD casts and water sample collections, which give us information about the temperature, salinity, oxygen, nutrients and chlorophyll levels in the water column. At night, we will conduct trawls of the upward migration of the deep scattering layer (DSL), a huge subsurface layer of mesopelagic fishes, squids and crustaceans, part of which moves up toward the ocean surface at night to feed. Sampling this layer helps us understand the composition of species that larger predators forage on. In between CTDs and trawls, we will conduct transects focused solely on acoustic backscattering of the DSL, to give us even more information about the location and concentration of mesopelagic organisms.
We are all excited to begin sampling, and to discover the current composition of the STF and surrounding areas this spring. Stay tuned for more!
Photo caption: A partial lunar eclipse on our first night underway – a nice reward for those trying to transition over to the night watch (photo by Jessica Chen).
Photo caption: Blog post author Laura Lilly scans for birds while riding a stationary bike on deck (photo by Adrienne Copeland).