by Tim Stephens, UC Santa Cruz
Roxanne Beltran, assistant professor of ecology and evolutionary biology at UC Santa Cruz, has been awarded a $600,000 grant to listen in on ocean sounds heard by elephant seals. The grant comes from the Arnold and Mabel Beckman Foundation through its Beckman Young Investigator Program.
The grant will fund a new project to develop and deploy a novel acoustic recorder for eavesdropping on the ocean soundscape. Beltran plans to use this new technology to monitor the acoustic environment of elephant seals, which migrate thousands of miles across the North Pacific Ocean. By using elephant seals as a mobile sensor platform to carry the acoustic recorder, Beltran will explore poorly understood areas of the open ocean, including the “twilight zone” just beyond the reach of sunlight (below about 650 feet).
“We want to figure out what the open ocean and the twilight zone sound like to an elephant seal—what sounds they are exposed to in terms of both manmade noise like shipping traffic as well as other species like whales,” she said.
For over three decades, UCSC researchers have been tagging and studying elephant seals at Año Nuevo Island Reserve, managed by the UC Natural Reserve System. Daniel Costa, distinguished professor of ecology and evolutionary biology and director of UCSC’s Institute of Marine Sciences, has been a pioneer in the development and use of electronic tags to track the movements and behavior of elephant seals and other marine mammals and to gather oceanographic data.
Beltran, a UCSC alumna (Stevenson ’13, marine biology) who joined Costa’s lab as a postdoctoral researcher before being appointed to the faculty, has a decade of experience working with elephant seals and other marine mammals. The new project will expand into the acoustic realm her lab’s ongoing efforts to study the ocean environment and ecology of migrating elephant seals.
“The importance of understanding ocean sounds has increased significantly in recent years, but our ability to monitor the soundscapes of the open ocean is logistically difficult,” Costa said. “Elephant seals have provided an excellent platform for measuring ocean temperature and salinity, and Roxanne’s study will add ocean acoustics to those crucial baseline measurements.”
Oceanographers and biologists have used various approaches to monitor sound in the ocean, but most are limited to areas near the coast. Ship-based surveys can go beyond coastal regions, but they are expensive and limited by the noise of the ship. Elephant seals migrate far offshore and move quietly and rapidly through the ocean ecosystem in search of prey.
“Using elephant seals is like having a smart sensor for biological hot spots, because they navigate straight to the regions with lots of productivity and prey. They can tell us a lot about the environment out in the middle of the open ocean,” Beltran said.
The tags will effectively eavesdrop on whales by recording their vocalizations and echolocations, and will also detect ships, sonar, and other sounds in the open ocean. Beltran said she is excited to find out what the tags will reveal about the soundscape of the North Pacific Ocean. Among other things, she hopes to learn more about the elusive beaked whales, a poorly understood family of deep-diving whales.
“We will also be able to learn if elephant seals are exposed to noises from sonar or oil exploration and how that affects them,” Beltran said. “We think acoustic cues are hugely important to elephant seals because they spend a lot of time in complete darkness, feeding at night and at depth, but we have no idea what they hear out there.”
By enabling more comprehensive monitoring of ocean noise and revealing the most prevalent and harmful sound sources, the project will provide valuable information and recommendations for marine mammal conservation.
The first stage of the project will be to develop a durable high-capacity acoustic recorder with the specifications needed for the project. Beltran will work with her colleague Holger Klinck, an acoustics expert at Cornell University, to develop the necessary hardware and software. Improvements in the acoustic tags will include longer duration recordings and a stronger housing to withstand the extreme pressure of the deep ocean.
After testing and validation of the new devices, the researchers will attach them to 24 adult female elephant seals over three years starting in February 2022. The tags are attached to the seals’ fur and are removed when the animals return to the beach and molt. The fidelity of elephant seals to their breeding grounds enables the researchers to reliably recover the tags. Beltran plans to train a team of UCSC undergraduate students to assist with the field work and undertake independent projects through the Undergraduate Work-Study Research Initiative.
“In addition to teaching us about large marine vertebrates, our fieldwork provides an ideal outdoor classroom for the next generation of biologists,” she said.
The Beckman Young Investigator Program provides research support to the most promising young faculty members in the early stages of their academic careers in the chemical and life sciences, particularly to foster the invention of methods, instruments, and materials that will open up new avenues of research in science.
“I feel lucky for the opportunity to be a part of this foundation and to contribute to the legacy of Dr. Beckman, a kind and curious innovator who is making it possible for young scientists to dream big,” Beltran said.