And we’re off! Yesterday started a little before 10 as we arrived on the ship to finish securing gear before the first induction of the day- CTD orientation! CTD stands for conductivity, temperature, and depth. But the name simplifies this equipment a bit- more on that a little later!
Our ship, the R/V Investigator at the wharf in Sydney Harbor
After CTD orientation was lunch- food is a major part of life at sea. And this voyage is no exception. Science happens around the clock so food is available around the clock. Many scientists work in shifts- so they need to be able to eat when they are awake, whether its during the three fixed meal times or not. These 3 main meals are served in addition to the 24-7 options and they are always delicious.
Red fish and blue fish decorate the lounge, here is blue fish.
Many of our meetings occur in a lounge near the “mess” (mess is the equivalent of a dining hall) decorated with a Dr Seuss theme. And quite convenient as full ship board inductions began once we were fed- all the important details to be a happy and safe community (population 60) for the next 3 weeks. Everything from emergency preparedness to meal times, laundry to science objectives, general policies to ship tours. A lot goes on at sea and it takes everyone on board to make sure we meet our goals scientifically while keeping everyone safe. It’s a different life style at sea- there’s people on board that have done this many of times, others have never experienced anything like it. For those working shifts, you may fall into a routine. Others are more on-demand, the CTD will be up at 5am means you’ll be up at 5am.
Most of us went to the outside observation decks following the induction to watch as the ship left port- what an operation! Manuevering a large vessel through a harbor takes a collaborative effort. We had a tug assist us away from the wharf and around the aircraft carrier docked next to us, then we had pilots (think of them as a local captain- they know the harbor inside and out, where every rock is, where the deepest passage is, and how each boat can pass safely) to escort us to the heads of Sydney harbor. In addition to the pilot on board in the bridge, a pilot vessel leads the way- keeping small craft clear. We were barely through the heads exiting Sydney harbor and spotted a humpback whale breaching off the bow.
While the pilots left, we enjoyed the views of Sydney disappearing in the distance before it was back to work! Time for our emergency ‘muster’ drill. The muster area is the designated meeting place in the case of any emergency. They sounded the general emergency alarm, we grabbed our safety gear and went to the muster area for roll call. They showed us the life rafts, explained their operations, and then the safety inductions were complete for the day. Then it was off to our first full science meeting of the cruise. We have quite the science party including CSIRO, University of Technology Sydney, University of New South Wales, and Macquarie University- you’ll meet many of the scientists as the cruise goes on. This time the meeting was mostly logistical- chain of command, goals, trainings, safety, and next 12 hours of operation. But as we continue (we’ll meet daily), the fun begins! We’ll start sharing our projects and interests and really be able to appreciate just how much information is being produced from this voyage.
Immediately following the science meeting, it was time for… more food! Dinner! (and a delicious strawberry shortcake desert option). Then most of us headed back outside for sunset before our first hands on shake-down and training CTD operation.
First night’s sunset from the ship
As I said earlier, the CTD is much more than the simple conductivity, temperature, depth name implies. The CTD itself, a cluster of instruments that produces profile measurements as it is lowered through the water column, is mounted on a larger “rosette.” This consists of the CTD and a ring of bottles to sample water at depth- all in constant communication with the ship via an electronic cable. There are 24 of these 10L bottles, called ‘niskin’ bottles, on the rosette and they are deployed ‘open.’ Essentially all this means is that water can freely flow through them as they are lowered through the water column. The bottles are held open by a pin, a scientist sitting on the ship sends an electronic trigger to ‘fire’ (close) a bottle, the pin releases and the spring loaded caps snap into place. Very important that the bottles aren’t lowered closed: the increased pressure could implode a bottle. The scientist decides where to fire the bottle based on the data being sent back from the CTD- they are looking for features such as the thermocline (relatively rapid change in temperature), chemocline (relatively rapid change in salinity), or chlorophyll maximum (i.e. the photosynthesizers!). Watching these parameters on the way down, the target depths are noted and the bottles are fired from the deepest target to the shallowest as the rosette is brought back on board. A science team and the ship’s hydrochemists process each CTD deployment for standard measurements such as oxygen and nutrients- then the rest of the water is carefully divided among projects based on a predetermined water budget (more on the projects later!)
The CTD rosette being recovered — you can tell its on the way up because the bottles are all in the closed position.
After a busy first day, it was time to call it a night to be ready for the first station in the morning!