What's it like to be a scientist at sea?

Marina Klemm, Associate Curator Te Mana o Rangitāhua takes us on a voyage to Rangitāhua, to spend a day in the life of a scientist conducting research at sea. 

Day one, at sea

Today I woke up at 6AM to be on time for the amazing breakfast that awaited me. “The food on the RV Tangaroa is very good” is one of the first sentences in NIWA’s “Guidelines for New Voyage Participants on RV Tangaroa,” and I quickly understood why their manual mentions it so early on. Jo, Shane, and Keren—the steward, leading hand, and 2nd cook, respectively—provide such amazing food that everyone's clothes are feeling a bit tighter, despite of a few days of seasickness. 

Today marks the sixth day since we left Wellington, and the worst is now behind us. In the last 72 hours, RV Tangaroa has weathered a big storm, massive swells, and even had to seek shelter around Mayor Island/Tuhua. Luckily, the team is great to work with, and RV Tangaroa offers plenty of onboard entertainment during unexpected downtime, so you’re never bored.

 Breakfast buffet at RV Tangaroa

Yesterday, we saw Macauley Island, and today we finally see Rangitāhua with our own eyes! For the last eight months, I've been managing specimens collected there, attending meetings about future expeditions, and listening to everyone’s stories about the motu. Now, I finally get to see all of Rangitāhua’s majestic energy for myself.

It’s going to be a busy day. The trip is a few days delayed, so there’s no time to waste. The experiments as soon as we arrive at the northeastern part of the main island, around 6PM (or 1800 if you are into nautical lingo).

Janynie Lelievre-Rhodes photographing whale tails for their identification, as part of a larger tohorā project.

Whales stopping by to say hello throughout the voyage

After lunch, the scientific team gathers for a toolbox meeting, going over the experiments planned for each day. The team is divided into 12 hour shifts; 3AM to 3PM, and 3PM to 3AM, so this is the last time for a while that everyone is awake simultaneously. Because my main job is to assist in all data collection, I'm rostered on for the 9AM - 9PM shift alongside Jaynie, the Ngāti Kuri kaitiaki.

The first set of experiments involves deploying the CTD cast, which stands for conductivity, temperature, and depth. This is the first time I've seen it, but it's a well-established oceanography instrument. A rosette with Niskin bottles (each holding 10 litres of water) is lowered into the ocean. From a computer linked to the rosette’s sensors, you “fire” pairs of bottles at various depths, filling them with water until they’re all full. Once back on the ship, they’re processed to reveal details about salinity, chlorophyll, oxygen levels, temperature, and even the microscopic creatures at each depth. The team have planned 27 CTD casts across all transects and times of the day, so although it sounds complex now, I'll get plenty of practice and might become an expert by the end of the voyage!

As a biologist, one aspect of the CTD cast is particularly exciting: the microscopic creatures hiding in them. Filtering the contents of at least one Niskin bottle from each cast through a mesh and concentrating it by thousands (from 10 liters to 4 ml) to see these creatures under the planktoscope: a microscope for plankton. This portable device, fitted with a camera, takes 20 pictures per second as water flows through, giving you a snapshot of the microscopic biodiversity in this part of the ocean. It is really fun to see all the legs and appendices these bugs have that allows them to live underwater.

Marina Klemm preparing CTD cast with 12 Niskin bottles. Photo by Emma McGuigan.

With the CTD processed and set aside, the ship moves toward the first MOCNESS transect of the voyage. MOCNESS stands for Multiple Opening/Closing Net and Environmental Sensing System. Just by giving it a quick glance, you can see why it has such a name: the gadget is a few meters tall, and it has seven long nets that make it look like a many-headed monster. It follows a similar setup to the CTD, with its sensors opening and closing at different depths, but its mesh collects organisms instead of water.

The MOCNESS samples everything from gelatinous plankton to larger specimens at various depths. Back at Auckland Museum, I got to see the infamous cookie cutter shark that was collected at a previous voyage to Rangitāhua, and I'm hoping for to see more cool specimens again. The final product, once washed and placed into sample tubes, looks like bubble tea - if bubble tea were made of diverse groups of marine animals. Although the deployment, recovery and sorting of samples only takes a few hours per transect, hundreds of hours will be spent on the identification of each individual specimen in the upcoming months or even years. This will be part of Emma McGuigan’s PhD project at University of Auckland, under the supervision of Mary Sewell, both pictured below.

Filtering system to recover nutrients from the seawater. 

MOCNESS set up for deployment

Sample visual analysis. In pictures: Jeff Forman, Emma McGuigan, Mary Sewell and Jaynie Lelievre-Rhodes. Last picture shows a tuna (eel) larva recovered from one of the nets.

After the samples are preserved in either formalin or ethanol, their labels are added to the tubes and the samples log are filled out, it is time to go to bed. This is only the first day and a lot has been achieved already. While some of the team sleeps, the plankton team will be deploying a few more MOCNESS, and after they go to bed, the CTD team will take over and recover all the needed water samples.

The rocking of the boat helps everyone fall asleep and we dream of plankton, pancakes and Niskin bottles.


Blog by Marina Klemm, Associate Curator, Te Mana o Rangitāhua. 

Rangitāhua expedition

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