What’s That Sound? Ocean Noise Associated With Hearing Loss in Bobtail Squid

Boat engines, whale songs, wind turbines—the ocean is a loud place.

How does that noise pollution—both natural and human-caused—affect the animals that live there? That’s precisely the question Rosalyn Putland aimed to answer with her research on the hummingbird bobtail squid while she was a Grass Fellow at the Marine Biological Laboratory (MBL) in 2022.

Like most marine organisms, cephalopods (squid, octopus, and cuttlefish) rely on sound to communicate, find food, and avoid predators. The hummingbird bobtail squid (Euprymna berryi) has a short lifespan of about six months and grows to sexual maturity in around 90 days. These tropical squid spend much of their lives hidden under sand in shallow coastal waters and are an important part of local food webs.

Noise associated with boats causes hearing loss in these squid across different stages of their life cycle, according to a study Putland and collaborators recently published in Frontiers of Marine Science.

“If these critters live in busy waters, which [means] pretty much most of the ocean globally, they could be exposed to noise on a regular basis,” said Putland, now a senior scientist at the Centre for Environment, Fisheries, and Aquatic Science in the United Kingdom. “That could be masking important biological cues around them.”

Putland tested the hearing of juvenile, adult, and late-adult hummingbird bobtail squids and then used underwater speakers to expose them to 15-minute intervals of boat noise at frequencies between 100 – 1000 Hz. Noises in this range are common from shipping, geophysical activity like volcanoes, and construction. It also overlaps with the bobtail squid’s hearing range. Then she let the squid recover and tested their responses after two hours.

All animals tested had a decrease in hearing sensitivity after noise exposure, with the frequency affecting varying age groups. The juvenile squids experienced a significant decrease in hearing sensitivity after exposure to noise between 400 - 800 Hz. Adult sensitivity decreased after 200-500 Hz exposure and the late adults experienced decreases in sensitivity at 200 Hz and 400-600 Hz.

This is the first study to compare hearing thresholds at different ages in a cephalopod species.

This hearing loss could impact the squid’s ability to assess their environment, avoid predators, and find food. Another concern is that these animals could shift habitats in response to increased noise pollution.

“It’s just like us,” said Putland. “If we’re in a noisy construction site, we want to walk away to another side of the road. These animals might move habitats.”

Squid occupy a vital place in coastal food webs and if they leave, it could have unforeseen impacts on the tropical ecosystems they inhabit.

Putland’s work at the MBL was supported by the Kavli Foundation.

Citation: Putland R.L., Mooney T.A. and Mensinger A.F. (2023) Vessel Sound Causes Hearing Loss for Hummingbird Bobtail Squid (Euprymna berryi). Frontiers in Marine Science. DOI: 10.3389/fmars.2023.1151605

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.