From the Field: Night Shift in the Santa Barbara Channel

’Tis the season for Frank Sinatra to start crooning about “New York, New York” on the holiday radio station, but the real city that never sleeps is actually found under the ocean’s surface.

Every night, the biggest migration in the world happens not on land, but in the ocean, as zooplankton move up from the ocean floor to the surface to feed in a process called diel vertical migration (DVM).

This booming oceanic night life is what UC Santa Barbara graduate students Nicholas Huynh and Kelsey Bisson will begin investigating on December 15th during their research cruise aboard Scripps Oceanography research vessel Sally Ride.

Huynh and Bisson designed this student-led cruise to measure the physical, biological and chemical variations in the Santa Barbara Channel that occur on diel scales, or 24-hour periods.

They will be accompanied by a team of graduate and undergraduate students, a K-12 teacher, and faculty advisors.

Together, the team hopes to study how coastal ecosystems are structured and how the ocean changes at night.

Specifically, Huynh and Bisson are interested in understanding the ways predator-prey dynamics affect the chemical processes of the channel. In short, they are looking at how organisms occupying the upper ranks of the food chain, such as zooplankton, impact lower-level organisms such as phytoplankton, and how these relationships alter general oceanic cycling.

One of the ways Huynh and Bisson will investigate the impacts that predator-prey dynamics have on microbial processes is by tracking both the biogeochemical fluctuations in the Channel and the migration patterns of plankton.

To do this, Huynh, Bisson and their team will stay in the channel for six days, sampling the water four times per day while simultaneously collecting 24-hour sampling measures.

These will be some of the first measurements of the channel done on such short-term scales. 

“The Santa Barbara Channel is studied pretty heavily on longer time scales,” said Huynh. “This means we only see monthly and seasonal changes and we don’t really understand the processes that are going on between night and day. These measurements will shed some light on the fine-scale processes occurring in the channel.”

Over the course of their six days at sea, the team will conduct about 30 CTD casts to measure the seawater’s conductivity, temperature, and pressure. This will help them track salinity and develop a better understanding of the dynamic biogeochemical makeup of the channel. Doing a CTD cast involves sending a CTD package, or a collection of sensors and collection containers, into the ocean and collecting water samples at different depth intervals as the package travels back up to the surface.

Twelve of these casts will be conducted following mixed layer-drogued drifters, surface buoys equipped with GPS sensors that float in the upper layer of the ocean. This layer is known as the mixed layer because it is continuously moved around by wave and wind activity. The mixed layer is significant to Huynh and Bisson’s research because it is where the phytoplankton live.

In short, the drifters mark the area the team is interested in studying.

Following these drifters ensures the team stays in the same water mass. This allows them to track three full diel cycles within a single water mass. By staying in a single water mass, the team can avoid the mixing effects of water masses and collect more precise data.

In addition to using mixed-layer drogued drifters, Huynh and Bisson will be using an Imaging Flow Cytobot to take microscopic images that depict how light interacts with water and the phytoplankton, zooplankton, and bacteria living in the water.

The most important tool at the team’s disposal, though, is the R/V Sally Ride, as the ship was designed to support the kind of precise measurements Huynh and Bisson plan on taking.

The ship’s dynamic positioning system (DP), for example, engages the ship’s propellors and thrusters to help the team to maintain their position relative to a specific spot on the ocean floor.

And the bottom of the R/V Sally Ride is constructed to facilitate acoustics measurements. This design will allow the team to track zooplankton migration with an echo-sounder, which captures the sounds of the ocean to track the movement of marine organisms.

Because the migration of zooplankton occurs nocturnally, the measurements Huynh and Bisson take will be crucial to help the broader scientific community develop a more comprehensive image of the nocturnal ocean.

“A lot of our understanding of the ocean in recent decades has come from satellite images,” said Bisson. “You can’t really take great images in dark, and it is not like the whole ocean goes to sleep.”

While Huynh and Bisson’s research is unique in its temporal focus, their student-led cruise is also special because it represents the first time UCSB has exercised their eligibility in the UC Ship Funds Program. This is a program designed and operated by Scripps Oceanography to give faculty and students opportunities to conduct research at sea on Scripps’ vessels.

“You really have to have the right group with the right question and energy level to prepare a proposal and then organize a research cruise,” said Professor David Valentine, UCSB’s liaison to Scripps tasked with inviting UCSB faculty and students to apply to the UC Ship Funds Program.

Though Huynh and Bisson are the first at UCSB to capitalize on this opportunity, Valentine anticipates more use of the UC Ship Funds Program by UCSB faculty and students in the future.

“There is an annual call for UC Ship Funds out now and I have already had people expressing interest far more seriously than ever before,” said Valentine.

The UC Ship Funds Program is unique in the way it allows students to design and conduct their own research projects. This rare opportunity helps students hone their research skills and grow into independent marine scientists capable of making valuable contributions to the global scientific community.

“Student-led cruises help graduate students learn what being in the field is about,” said Huynh. “This kind of learning is difficult to do staring at a computer screen.”

The UC Ship Funds Program gives students and faculty the critical opportunity to seek out answers to their research questions at sea.

“It is the biggest privilege and honor I could imagine to co-design my own research cruise,” said Bisson.

As vessel operator for the entire University of California system, Scripps plays a key role in the UC Ship Funds Program.

“The crew and the technicians that accompany our students come from Scripps,” said Valentine. “They are absolutely essential partners in making this happen, as they do the critical work to enable scientists to utilize the facility to do their research.”

While this ship time is helpful to Huynh and Bisson’s research, it is also key to the artistic successes of the illustrator, musician, and videographer on board with the scientists for the cruise.

Together, these artists plan to make a music video, a documentary, a series of illustrations, and a cruise magazine. This collaboration is part of Huynh and Bisson’s aim to communicate scientific understanding to the public in a more accessible and engaging manner through art.

“We feel like we owe it to ourselves and our community to make the most of the ship time that we have,” said Bisson.

While at sea, the team will also stay in contact with elementary and high school students from 14 sister schools around the U.S. along with a school in France in an attempt to inspire younger students to pursue science. 

“We wouldn’t be able to do this without the UC Ship Funds Program,” said Huynh.

You can follow this cruise on the team’s website and  Instagram.

— Mariah Furtek, UCLA